Consumer Reports, well, reported…

I guess I missed this in the LA Times when I slurped down my coffee in the morning, but thanks to the alert guys at the ChinaRiders.net site, I saw it.   It’s worth a read…

http://www.latimes.com/business/autos/la-fi-hy-consumer-reports-motorcycle-ratings-20160127-story.html

Lots of interesting findings in there, especially as they pertain to BMW.   There’s nothing that’s surprising, though.  Harley guys are convinced they love their Harleys, and BMWs are not as reliable as their public relations people think they are.  We’re too small to have been noticed yet, but folks, we’re doing okay.

Posted in CSC Motorcycles | Comments Off on Consumer Reports, well, reported…

TT250 Carburetor Maintenance

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This tutorial addresses TT250 carburetor maintenance, and specifically, carburetor removal, disassembly, cleaning, and reassembly.  If your motorcycle is running rough and the problem is related to the carburetor, or if your motorcycle has not been operated for a long time and you did not treat the fuel prior to storage, the fuel will create gums that can clog the carburetor jets and affect engine performance.  This tutorial will show you how to remove, disassemble, clean, reassemble, and reinstall your carburetor.

The TT250 uses a conventional Keima slide carburetor.   It will be much easier to gain access to the carburetor if the fuel tank is removed.  Removing the fuel tank involves removing the rear body panels and the seat, detaching the tank body panels from the frame (you do not need to remove the body panels from the tank), disconnecting the fuel line from the carburetor, removing the fuel tank, and disconnecting the fuel tank electrical connection to the fuel gage.

Loosen the Phillips head screw securing the airbox inlet to the carburetor and detach it from the carburetor.

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Unscrew the carburetor slide assembly cap and remove the carburetor slide assembly from the carburetor.

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Remove the two 10mm nuts securing the carburetor to the intake manifold.   It will be easier to access the left side carburetor mounting nut if you first detach the rear brake master cylinder.

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Pull the carburetor away from the engine and detach the vent hose such that you can move the carburetor to a clean work area.

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Remove the carburetor float bowl

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At this point, when you invert the carburetor you can see the float, the float valve, the main jet, the slow jet, and the idle jet.

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The float pivots on the float pivot shaft to operate the float valve.  The float valve is connected to the float by a wire clip.

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Gently push the float pivot shaft out of the carburetor body.

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Lift the float and the float valve from the carburetor body.  Take care not to drop the float valve; it will fall off of the float when the float is tilted.

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Remove the main, slow, and idle jets from the carburetor with a flat head screw driver.

The main jet is in a brass carrier.  It’s likely the entire carrier will unscrew when you unscrew the main jet.   You can then unscrew the main jet if you secure the main jet carrier with an 8mm wrench.

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There is a brass bushing that fits in the bottom of the carburetor body.  It interfaces with the main jet carrier.   Remove the bushing from the carburetor.  Note that this bushing has a beveled end and a square-cut end.  The beveled end will interface with the main jet carrier when these parts are reassembled.

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Remove the slow jet.

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Remove the idle jet.

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There will be a spring, a flat metal washer, and an o-ring beneath the idle jet.  Carefully remove these from the carburetor body if they do not come out with the idle jet.

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The idle jet, the slow jet, and the main jet components are shown below.   The idle jet is on the left, the slow jet is in the middle, and the main jet is on the right.

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Remove the slide adjustment screw (this is the screw used to adjust idle speed) and spring from the carburetor body.

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Clean all three jets using a suitable cleaning solvent and a jet cleaning tool to assure all passageways are open.

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Remove the o-rings from the float bowl and the carburetor body.

Clean the carburetor interior and exterior surfaces using a suitable solvent.

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Use a q-tip to clean the interior of the float valve body.

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Assembly is the reverse of disassembly.   We are including a few specific points on reassembly here in this tutorial.

When reinstalling the jets and the jet carriers, d0 not overtighten them or you may strip the aluminum carburetor body threads.

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When installing the brass bushing that faces the underside of the main jet, make sure the square end faces away from the main jet carrier and the beveled end faces the main jet carrier.  When you insert this piece in the carburetor body, it is not likely to fully seat or go in straight without assistance.  We use an Allen wrench to make sure this bushing is properly guided into its seat.

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After the bushing is in place, install the main jet carrier and lightly tighten it.  Do not overtighten it.

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Install the main jet and lightly tighten it with a flat head screwdriver.

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Put the float valve on the float and guide it over the float valve seat.  Take care not to let the clip that connects the float valve to the float come off the float.

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Guide the float pivot shaft through the carburetor body tangs’ drilled pivot points and the float.

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Reinstall the O-rings on the float body and the carburetor body.   We apply a light coating of grease to the O-rings.

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Reinstall the carburetor slide assembly.   The carburetor slide assembly includes circlip that attaches the needle to the slide, as shown in the photo blow.  Positioning the needle higher in the slide will enrichen the air fuel mixture; positioning the needle lower in the slide will cause the engine to run leaner.

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Re-installation of the carburetor on the motorcycle is the reverse of installation.  After installing the carburetor and reassembling the motorcycle, start the engine and allow the motorcycle to come to operating temperature.  Adjust the idle speed with the carburetor slide idle speed adjustment screw to approximately 1500 rpm (the TT250 does not have a tachometer; we make the adjustment by sound).

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TT250 Battery Maintenance

This maintenance tutorial addresses TT250 battery maintenance.

There’s not a lot to maintaining your battery, folks.   The trick is to keep the terminals clean, keep the acid level within an acceptable range, and replace the battery when it won’t hold a charge.

In this tutorial, we’re showing everything with the battery removed from the motorcycle (which is the way I prefer to work on the battery), but everything you see in this tutorial can be done with the battery in the bike.

You will need to remove the left rear body panel to gain access to the battery.   We had more stuff removed on the TT250 we used for this tutorial, but you don’t have to take the seat or the tank off.   We just used a bike that already had those things off.

Remove the left rear body panel by unscrewing the body panel screw.  The body panel will pull off after the screw has been removed.

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Inspect the battery terminal area.  If oxidation is present around the terminal (it will appear as a white growth around the terminal), pour a water-and-baking-soda solution over the terminal area to eliminate the oxidation.  After doing this, flush the area with water.

Disconnect the battery.   Disconnect the negative terminal first (the one with the green insulation on the lead) and then disconnect the positive terminal.

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Unhook the battery’s rubber retention strap and remove the battery.

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Check the acid level in the battery.  The level should be between the upper and lower red lines on the front of the battery.  It’s a little difficult to see this in the first photo below, so I tilted the battery so you can see it better.

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If any of the cells are below the minimum level, remove the filler cap for each affected cell.  Add only distilled water to a cell if it is below the minimum level such that the cell level is within the acceptable range.

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At this point, a question we frequently hear is:   When should I replace my battery?  Here’s how I make that decision:

  • If the battery is more than 2 years old, I replace it.   That’s my opinion.  Opinions are like belly buttons (everyone has one), but that’s what I do.
  • If my battery won’t hold a charge, I replace the battery.
  • If I am going on a long trip and I am close to the 2-year mark, I replace the battery.   Before I do the Baja ride next month on my RX3, I’ll throw a new battery in it.

I evaluate the battery’s ability to hold a charge by leaving it on the charger long enough to fully charge, and then I’ll measure the voltage.  If it’s less than 12.8 volts, it’s time for a new battery.

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If you need a new battery, we stock all of the parts for your TT250.  Give us a call at 909 445 0900 and we’ll take care of you.

One last thing, and that’s using a trickle charger.  I recommend you keep your bike on a Battery Tender when it’s parked.  I’ve used a Battery Tender on all of my bikes and they do a great job.   We sell these (they’re $39.95).  If you want one, give us a call at 909 445 0900 and ask to speak to Ryan.

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RIP, Doug Bingham

Doug Bingham, a guy I admired enormously, passed away recently and I thought I would take a moment to tell you a little bit about him here on the CSC blog.

Taking Doug Bingham for a ride in a California Scooter!

I first met Doug Bingham at the annual So Cal sidecar gathering in Griffith Park (an event Doug started many years ago).   I wrote a story about that event for Motorcycle Classics magazine (you can read about it here), and a big part of the story was about Doug.   He was known in the motorcycle industry as “Mr. Sidecar,” and when we wanted to equip one of our Mustang replicas with a sidecar, we knew there was only one guy to see:  Doug Bingham.

Doug knew exactly what to do, and the rig he put together for us was awesome.   I visited his So Cal shop as he was finalizing construction, and before I knew it, Doug pushed the California Scooter out of his shop, hopped in the sidecar, and gave the keys to me.   It was a hell of treat.   Little old me, piloting a sidecar, with none other than Doug Bingham as my passenger!

Let me tell you a bit about this man.   If you’ve ever seen a movie with a sidecar in it, Doug Bingham would have been the guy who built and piloted the rig.  Think The Great Escape, Indiana Jones and the Last Crusade, and many, many more.   With all those good things on his resume, Doug was Mr. Nice Guy.  He was not pretentious at all, he took all the time I needed to explain things to me about sidecars, and he was a real decent human being.  I enjoyed being around him immensely.

If you’ve wondered what it is like to pilot and ride in a sidecar, you can get a bit of a feel for it from this YouTube video we did featuring the rig Doug built for us…

RIP, Doug.   We’ll miss you.

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TT250 Steering Stem Bearing Adjustment

This maintenance tutorial addresses TT250 steering stem bearing adjustment.

The concept here is to adjust the steering stem adjustor nut and the steering stem bolt such that there is no free play in the steering stem bearings, but not make them too tight.

You only need to do this if there is free play in the steering stem bearings, or if the bearings are adjusted too tight.  Sometimes you can detect this by applying the front brake when coming to a stop, or by rocking the bike back and forth with the front brake applied.  If you hear or feel clicking in the front end, it is likely you need to adjust the steering stem bearings.

The best way to test for appropriate steering stem bearing adjustment is to put the bike on a lift to get the front wheel off the ground.   Once the wheel is off the ground, grab the front forks near the front axle and pull the front end back and forth.  If you feel any play and hear the steering stem bearings clicking, the steering stem bearings are too loose.   Next, turn the front wheel from left to right and from right to left.  If you feel too much resistance (it’s a subjective assessment), the steering stem bearings are too tight.

Note that in the photos below, we show the fuel tank, the seat, and the rear body panels removed.  You don’t need to remove these components for this maintenance activity.  We had a TT250 with the panels removed for the other maintenance tutorials, and we left the bike in that configuration for this tutorial.

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If your assessment indicates the steering stem bearings require adjustment, loosen the upper triple tree pinch bolts on the left and the right side of the motorcycle.  You don’t need to remove the bolts; you only need to loosen them.  The intent is to allow the upper triple tree to move with respect to the fork legs.  The upper triple tree pinch bolts take a 10mm wrench.

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Loosen the steering stem bolt. It takes a 22mm wrench.   You don’t need to remove the handlebars to do this, but it is a tight fit for the wrench if you do not.  In this tutorial, we did not remove the handlebars.

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Use a spanner to either tighten or loosen the steering stem adjustor nut.   You’ll want to tighten it if the steering stem bearings are too loose (as indicated by free play or clicking when moving the forks back and forth).  If the forks have too much resistance when turning them from left to right (and vice versa), you’ll want to loosen the steering stem adjustor nut.

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After making the adjustment, tighten the steering stem bolt.  If you are a stickler for torque values, tighten it to 50 ft-lbs.   Check the front end of the motorcycle again to make sure the adjustment provides no clicking or movement of the forks when pulling the forks back and forth, and that the steering is not restricted when turning the front end from side to side.   When you are satisfied with the adjustment, tighten the upper triple tree pinch bolts to 10 ft-lbs.

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Police Bikes!

150129_3711-650Our service department works on all kinds of bikes, and last Friday Gerry serviced a BMW boxer twin police bike from one of our local So Cal police agencies.    I couldn’t resist getting a photo of the bikes side by side.

The police Beemer was brand new (it was in for its first service), and it was an impressive bike.   So was the purchase price.  According to the motor officer who brought it in, the new Beemer goes for a cool $28,000!  Wow!   The RX3-P, on the other hand, goes for $4,295.

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TT250 Electrical System Tutorial

The TT250 electrical system is simple, easy to understand, and easy to maintain.  This maintenance tutorial explains the system’s main components, their locations, their functions, and some suggestions in the unlikely event you’ll ever need to troubleshoot the system.

The TT250 has an 18-pole, 300-watt stator that puts out plenty of power.  Many riders like to run accessories (heated vests, spotlights, heated grips, etc.), and on bikes with smaller electrical outputs, you can run the battery down while riding with all the accessories powered up.   The TT250 won’t have this problem.   It’s got the juice you need.

A cool feature on the TT250 is the built-in accessory outlets already wired into the main harness, and the accessories switch located on the right handlebar.   On the non-US bikes, that switch was used for the headlights and parking lights.   In the US, the headlights have to be on all the time, so the switch isn’t necessary.   We didn’t want to give up the switch, though, so we’re using it to control the underseat accessories outlets.

Let’s get on to the main attraction, and that’s the CSC TT250 electrical system and its components.  Most of the electrical and electronic components on this bike are located under the seat and tank, and behind the headlight.

You can decide best which components you’ll need to remove based on which components you want to access.   In this tutorial, we’ve removed the seat, the fuel tank, and the headlight so you can see everything. The first part of our tutorial below focuses on removing these items; the second part identifies various electronic component locations.

Body Panel, Seat, Fuel Tank, and Headlight Removal

Remove the rear body panels on the left and right side of the motorcycle.  There’s a single bolt in each one.  They pop off after you have removed the bolt.

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Next, remove the seat.  There’s a 10mm bolt on either side.  Remove these bolts and pull the seat to the rear to remove it.

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Removing the tank involves:

  • Closing the fuel petcock.
  • Disconnecting the fuel line from the fuel petcock to the carburetor.
  • Removing the 10mm bolt at the rear of the tank and the two Phillips head screws under the forward body panels (one on each side of the tank).
  • Disconnecting the fuel sending unit connector plug.
  • Disconnecting the tank vent line from the carbon canister.

These actions are shown in the photos below.

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The headlight is removed by unscrewing two Phillips head screws on either side.

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Electrical/Electronic Componentry

The first component is the ignition switch, located on top of the forks.

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The headlight nacelle includes the harness running into the headlight bulb.   In this photo, you can also see the wiring for the parking light (not separately operable on the North American bikes).

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The horn is located on the right side of the frame near the front of the motorcycle.   It is accessible without removing the fuel tank.

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The connector from the fuel tank’s fuel gage sending unit to the fuel gage is underneath the tank.  This is the half of the connector that stays with the motorcycle when the fuel tank is removed.

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The battery is located on the left side of the motorcycle.  It is accessible by removing the left rear body panel and the seat.  It is secured by a rubber strap.

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As you can see from the photo above, red is positive, and green is ground.   Throughout the motorcycle, wires with green insulation are ground wires.

The regulator/rectifier is on the left side of the motorcycle near the front of the bike.  It mounts to the frame beneath the fuel tank.  If this component is not working, the battery will not charge properly or it may overcharge and boil over.  The red and green wires go to the battery to charge it.   The yellow wires come from the motorcycle’s stator.

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The ignition coil is located underneath the fuel tank on the right frame.

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The starter relay is located on the left side of the motorcycle just to the rear of the battery.  It closes when commanded to do so to send power to the starter motor.

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As you can see in the above photo, the starter relay is attached to the frame with a rubber carrier that fits over tabs protruding from the frame.  I removed it from the frame so you can see the wiring that sends a signal from the starter button to the relay.

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The motorcycle’s only electrical fuse is located in a carrier behind the battery.   This pops open to provide access to the fuse.

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If the motorcycle loses all electrical power, there are several potential causes, but the most likely are that this fuse has opened, or the engine kill switch is in the off position.   Don’t laugh about that last one.  We regularly get calls in which the caller tells us the bike has lost all electrical power.   In those cases, it’s almost always because the owner inadvertently has the kill switch in the off position.  I’ve done it, too.   I’m just mentioning it here because it’s the first thing I would check having answered a few of those calls, and because I’ve made that mistake myself (i.e., leaving the kill switch in the off position).

Several of the connectors and harnesses in the battery area (on the left side of the motorcycle) are identified below.

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The two 12V underseat accessory outlet connectors are also on the left side of the motorcycle.  These are controlled by the handlebar-mounted switch and they are provided as a convenient point for connecting accessories, heated vests, etc.   When the ignition is off, power is cut to these connectors.

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The engine ECU and turn signal controller are located beneath the seat.

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When the headlight has been removed, several connectors and harnesses are visible from the front of the motorcycle.   These are identified in the photos below.

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The neutral light diode controls when the neutral light is on.   If it is shorted, it will allow the neutral light to come on whenever the clutch lever is pulled in.

Access to the indicator lights and wiring is provided when the headlight nacelle is removed.   The photo below shows the underside of the dash cluster.

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The TT250 Service manual provides a wiring diagram, which can be used in conjunction with the above photos when troubleshooting any electrical problems.

Posted in Best Of, CSC Motorcycles | Comments Off on TT250 Electrical System Tutorial

Yay!

I finished the first draft of Moto Colombia today!    From here, it’s another week or two of polishing and proofing, photo selection and editing, and then Moto Colombia is going to be available to you!   I’ll tell you…I’m wearing out my laptop’s keyboard!    We’ve published a half-dozen TT250 maintenance tutorials in the last few days, we have several more maintenance tutorials in work, I have the TT250 shop manual in work, and of course, I’ve been working on the story of the greatest adventure ride of my life:  Moto Colombia!

I’m taking a break from the book and jumping on the TT250 electrical system maintenance tutorial next.   The TT250 carb maintenance tutorial will follow right after that.   Then it’s back on the Moto Colombia book for a bit.   Wowee!  We’ll keep you posted, folks!

Cover-Prel

Oh, and one more thing: Don’t think for a minute I’ve forgotten about Baja. That trip is a go! I’ll have more details here on the blog real soon.

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TT250 Valve Adjustment

This maintenance tutorial addresses TT250 valve adjustment.

You’ll need the following tools for this operation:

  • A pair of pliers
  • 14mm socket with ratchet and extension
  • Spark plug wrench
  • 10mm wrench
  • Long handled Phillips head screwdriver
  • Large bladed flat head screwdriver
  • 6mm Allen wrench

The TT250 has a two-valve engine.  The intake valve opens to admit the fuel/air mixture, and the exhaust valve opens to expel the exhaust.   When the engine is at the top of its compression stroke, we want both valves closed.   That’s because we want to compress the fuel air mixture, ignite it, and then allow the resulting high combustion pressures to drive the piston down.   If any leakage occurs around any of the valves while this is occurring, the engine will lose power and it could “burn” a valve if the combusting fuel/air mix escapes around the valve while it is still burning.

When engineers design an engine, they want it to do the above, but they have to account for the thermal expansion that occurs as engine temperature increases during normal operation.  In order to compensate for this thermal expansion, the engineers design in a gap in the rocker arm/valve train.   As the engine warms, this gap approaches zero, and everything works the way it is supposed to.

On the TT250, the valve train looks like you see in the photo below (this photo shows the exhaust valve, but both the intake and the exhaust valve have similar valve trains).   The valve gap (also referred to as the valve clearance) is what the lower red arrow points to in the photo below.

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As the wear described above increases, it has the effect of reducing the valve gap (i.e., the clearance built into the valve train to account for the thermal expansion as the engine warms up).   What happens is that as this wear occurs, the valve actually moves higher into the cylinder head and the valve gap decreases.   If this wear goes beyond acceptable limits without adjusting the valves, the valve gap grows smaller and smaller.  Ultimately, this wear will result in the valve being held off the seat when combustion occurs.   This is bad, because when this condition exists, hot burning gases escape around the valve sealing area.  Ultimately, these burning gases will destroy the valve and the seat.   That’s what happens when we “burn a valve.”   It’s also bad because the valve needs to cool, and it is cooled primarily when it is closed against the valve seat.   That allows heat to escape from the valve and flow into the cylinder head.  If the valve never fully closes, the valve will continue to heat, and the valve stem will expand diametrically so much that it seizes in the valve guide.   That’s really bad, too, because when that happens, the valve will stick, the piston will hit it, and you’ve just bought yourself a new engine (or you’ll have to pay for expensive repairs on the current engine).

If the above sounds really bad, relax.  We avoid it by adjusting the valves.  All we are really doing is keeping the gap in the valve train within an acceptable range over the life of an engine.  As the valve and the valve seat wear, we keep everything adjusted so that when the engine is at operating temperature we still form a good seal around the valve seat.   That’s the whole idea behind this valve adjustment business.

Different engines use different approaches for adjusting the valves.   Your TT250 engine uses the best approach for easy maintenance and high performance:  It uses a threaded adjustor shaft with a lock nut to set and lock the valve gap.   In the photo above, that’s what the upper two arrows point to.  These adjustors are located in the ends of the rocker arms that interface directly with the valve stem.

So, with all that theory behind us, let’s consider what we’re going to do here:

  1. We want to gain access to the valve rocker arms and their adjustment screws.
  2. We want the engine to be at a point in its rotation such that the rocker arm is on the cam’s base circle.  This means the cam is not actuating the rocker arm.   We want the engine to have the piston at (or very near) top dead center, which means the valves should be closed (which is another way of saying the rocker arm is on the cam’s base circle).
  3. With the engine in this position, we want to loosen the threaded adjustor lock nuts, we want to set the valve gaps to the specified gap of 0.04mm to 0.07mm, and we want to tighten the lock nuts to lock the threaded adjustors at this gap.  We always make the adjustment to the 0.07mm setting.  As the valve and the cylinder head wear, the gap will grow smaller.   Setting it to the 0.07mm setting allows us to keep the valve adjustment interval (the number of miles you can ride between valve adjustments) at a reasonably high number.   Initially, we’re establishing this interval to be 500 miles for the first adjustment, and every 2500 miles thereafter.
  4. When we’ve completed the above, we want to put everything back together.

Got that?   Okay, here we go….

Most of the work in adjusting the valves is associated with just getting access to the adjustors.   The adjustment operation (once we have access) takes only a few minutes.

When you adjust the valves, you have to start with a cold engine.  Dead cold.   Let your TT250 cool down completely.    Don’t cheat on this part.   I always let the bike set, without starting the engine, for a day.   If it’s even a bit warm from running, your adjustment will be wrong, and all of your work will be for nothing.  Let your TT250 cool down completely.

Remove the rear body panels on the left and right side of the motorcycle.

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Remove the seat.  It’s secured by 10mm bolts on either side.  Once the bolts have been removed, the seat slides to the rear.

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Close the fuel petcock and remove the fuel hose from it.

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Remove the hose from the right upper hose boss on the carbon canister.   The other end of this hose remains attached to the fuel tank.

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Remove the 10mm bolt at the base of the fuel tank.  You’ll see it after you have removed the seat.

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Remove the two screws that secure the left and right fuel tank body panels to the frame.   You do not need to remove the body panels from the fuel tank.

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Slide the fuel tank to the rear.  After you have lifted it partially off the motorcycle, disconnect the electrical connector that runs from the fuel tank sending unit to the fuel gage.

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When you remove the fuel tank from the motorcycle, two hoses will hang down.  The longer one is the fuel tank overflow line.  It simply hangs down from the fuel tank; the other end is not attached to anything (it vents to atmosphere).   The shorter hose is the one that attaches to the carbon canister.  You’ll have to reinstall the end of it on the carbon canister boss when you reinstall the fuel tank after adjusting the valves.

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At this point, we have what we want, and that’s access to the valve cover.

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The valve cover is attached to the cylinder head by three 10mm bolts.  Note that there is a fourth 10mm bolt on top of the valve cover (it’s the one in the photo below just beneath and partially behind the hose).   Leave that bolt alone (do not remove it from the valve cover).   Do remove the three bolts that attach the valve cover to the cylinder head.

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Detach the large diameter hose from the exhaust gas recirculation valve shown below.

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Tap the valve cover gently to break the seal between it and the cylinder head.

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Remove the valve cover.   It will remove to the right side of the motorcycle.

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The valve cover seals to the cylinder head with an o-ring type seal.   Place the valve cover where this seal will not be contaminated by dirt or debris.  Prior to reinstalling the valve cover (after you have adjusted the valves), apply a light coat of motor oil to the rubber seal.

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Remove the spark plug.

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Remove the left crankcase engine cover.  It is secured with three Phillips head screws.

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After you have removed the cover, you will see a 14mm bolt head.  By placing a socket wrench on this bolt head, you will be able to rotate the engine (it’s why we removed the spark plug).   If you have the bike in the vertical position (straight up and down), only a tiny amount of oil will escape.   If the bike is on the sidestand, more oil will escape.

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Remove the timing port cover on the left side of the engine with a large blade screwdriver or a coin.

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When you remove the timing port cover, take care not to lose the o-ring that seals it.  Place the o-ring in an area where it will not become contaminated with dirt or debris.

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Rotate the engine by hand by attaching a 14mm drive to the crank bolt.

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There are three timing marks on the crank shaft indicator wheel.  One is a double scribe line that shows when the ignition is fully advanced.  We’re not interested in that one for the valve adjustment operation; this information is included here for reference only.

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The next mark is a scribe line with an F.  This shows when the spark plug fires.   We’re not interested in that mark, either, for the valve adjustment operation.  It’s mentioned here for reference only.

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Here’s the mark we’re interested in.  It’s a scribe line with a T.   That shows when the piston is at top dead center, which is where we want it to be for the valve adjustment operation.

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This business of aligning the T mark and its scribe with the slot in the threaded area is a little tricky.   You should manually rotate the engine so that this T mark and the scribe line are aligned with the slot and both valves are fully closed.    Rotate the engine’s crankshaft through the full 360 degrees at least twice to understand what it going on here.   On one rotation, you may see that one of the valves is not fully closed.   If that’s the case, DO NOT adjust the valves with the engine crankshaft in this position.  Rotate the engine another 360 degrees to bring the T mark and scribe line into alignment with the slot in the threaded area.   Both valves should be fully closed, which is to say that the rockers should be in the full up position and the valve gap is fully open for the both valves.

Once the engine is at top dead center as described above, we’re ready to make the adjustment.  We’ll do so by loosening the 10mm nut (shown by the middle arrow in the photo below) enough to allow us to rotate the threaded adjustor (shown by the upper arrow in the photo below).   By doing this, we are changing the valve gap (shown by the lower arrow in the photo below).

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Loosen the threaded adjustor enough to allow insertion of a 0.07mm feeler gage into the valve gap, as shown below.

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Hand tighten the adjustor so that it is snug against the feeler.  You don’t want to overtighten the adjustor or you will start to open the valve and your adjustment will be incorrect.   Just make it snug so that if you try to pull the feeler out, you feel slight resistance.   Tighten the 10mm adjustor lock nut.

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Repeat the above process for the other valve.

After I’ve done this, I manually rotate the engine two complete revolutions, align the T mark and the scribe line again, and check the clearance just to make sure I did it correctly.

Assembly is the reverse of disassembly.

Once you’ve reassembled the motorcycle, go out and put some miles on it!

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TT250 Front Wheel Removal and Installation

The maintenance tutorial addresses TT250 front wheel removal and installation.

You will need 15mm, 17mm, and 10mm wrenches for this operation.

Start by securing the motorcycle on a lift such that the front wheel is off the ground.

Unbolt the front brake caliper by removing the two 10mm bolts that secure it to the front fork.  Allow the caliper to hang by the hydraulic brake line.  Do not loosen or remove the hydraulic brake line.

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Loosen the front axle by using a 17mm wrench on the axle nut and a 15mm wrench on the axle’s bolt head.

This is the right side of the motorcycle showing the 17mm axle nut.

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This is the left side of the motorcycle showing the 15mm axle bolt head.

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Remove the axle nut.

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Pull the axle out of the forks.

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There is a bushing between the left side of the front hub and the left fork.  There is no bushing on the right side of the motorcycle.  The speedometer drive mechanism is on the right side of the motorcycle.  It is located between the right fork and the right side of the hub.

Front wheel installation is the reverse of front wheel removal.

Prior to installing the speedometer drive mechanism, it is best to disconnect the speedometer cable.   You should apply grease to the inside of the speedometer drive mechanism and the right side of the wheel hub.   Note that the speedometer drive mechanism has two tabs.   Take care to align these with the front hub slots when installing the front wheel.

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Reinstall the front axle, the front axle nut, the front brake caliper, and the speedometer drive cable.   The front axle should be torqued to 35 ft-lbs.  The caliper bolts should be torqued to 22 ft-lbs.

Check the front brake prior to riding to assure proper operation, and you are ready to ride.

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