Tech Page and Maintenance

Lee Buchanan
Maintenance Tips

Maintenance, Maintenance, Maintenance !!!
They say that an ounce of prevention is worth a pound of cure. I say that frequent oil changes and keeping the air filter clean is worth the price of a new engine.
Todays modern motocross bikes hold less oil than earlier models in the gear box. Add to that, todays engines turn more rpms than ever, and what you have is added stress on engine and transmission parts. So, it is crucial to frequently change the oil. 80cc to 125cc machines should be changed every 2-3 hours of racing. 250cc machines should be changed every 4-6 hours of racing or hard riding. Open class machines & 4-strokes can go up to 10 hours without changing the oil.
Now, the "dreaded air filter". After each day of racing, the air filter should be changed or cleaned.
After a real dusty race, the air filter should be changed or cleaned prior to the next race. NEVER! NEVER!....repeat, NEVER clean the filter with gasoline!! This will disolve the glue that holds the foam together. Instead, use kerosine or a good quality filter cleaner. After that, wash in warm water and let dry. DO NOT DRY IN DRYER!! after it has dried naturally, lubricate it with a good quality filter oil, then let it set over night. It's a good idea to have an extra air filter, enclosed in a plastic baggy. When installing a clean filter, always grease the contact side closest to the carb for a better seal....and fer you married folks.....if ya want to sleep indoors, it ain't a good idea to do the air filter cleaning in yer wife's kitchen sink!.

Click here for detailed information on how a 2 stroke works

Click here for spark plug information and pictures

Click here for carburator set up and adjustments, street bike carbs as well

Click here for fork seal replacement

Click here for suspension set up including wheel alignment, forks, and adjustments

Clutch Replacement
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The Dreaded Clutch Job

By Mike Hobbs
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The dreaded clutch job...

It's not that a clutch job on a dirt bike is difficult; in fact it's kind of easy. When it comes right down to it, it's just one of those things you put off. Why? Well, there are tons of reasons for not getting around to it and these are mine:

My clutch adjustment is all the way out but the clutch is not slipping yet.
The garage is a mess and it would take too long to clean it in order to get the job done right.
If I do it now before the clutch is toast, it will have to be replaced sooner, and it has been raining for two weeks and it will be at least two weeks before it stops, so there is plenty of time to get it done. Right?
Let's look at these excuses logically. Waiting for the clutch to fry would probably cost more then the price of friction disks or clutch springs. My 16-year-son has a girlfriend and is always asking for money and with slick negotiation skills and ten bucks the 16-year old will clean the garage. It is raining and I can't ride anyway, I should just as well do it now. That about does it for the excuses so, let's get to work!

Before you tear into your bike, you have to make sure you actually need to work on the clutch. If while accelerating the clutch slips, you probably need new friction disks and/or clutch springs. On the other hand if your clutch is adjusted all the way out at both ends, it's possible your clutch cable is stretched. If you think the cable might be the culprit call your local motorcycle shop and see if they have a new cable in stock for your machine. From personal experience, while on the phone with them be sure to check that they have everything you might need to complete the job. Depending on their answers to your tough questions, you can now head over to the dealer. If they have the cable, be sure to match it up with yours to see if it is stretched or not. If the cable is fine, just get new friction disks and/or clutch springs and head back home for some clutch repair work. Be sure not to stop by the bar on the way home, this would probably give you time to come up with more excuses.


Detail of Clutch.
How to get it done...

Drain the oil from your crankcase.
Remove the bolts securing the clutch cover. It's best you use the correct size socket to do this. If you don't have the correct size socket and/or you can't find the clutch cover. Put the oil drain plug back in where you took it from and add fresh oil where you add oil to your motorcycle. This is not a complete loss on your part. At least you've changed your oil without the risk of damaging anything that might be important.

After removing the bolts, place them on the ground in the same pattern you took them out.
After removing the bolts, place them on the ground in the same pattern you took them out. That way you can be sure they go back into the same hole(s) they came out of. (Yes! I learned this trick the hard way.)
If you figured out where the clutch plates are and located the correct socket. You can consider yourself a mechanic and continue with our instructions.
On the face of your clutch plates you should see a circular pattern of bolts. These bolts need to be removed.

Remove the bolts, springs, and pressure plate.
The springs on the bolts you just removed might be worn out. Refer to your owner's manual for the "free length". Free length is the measurement from end-to-end on the spring and you should use calipers to check this. If you don't have calipers your local motorcycle shop should and would be happy to check this for you.
Remove the pressure plate.

Set them down in order with the side that was facing the engine up.
Pull the round plates and friction disks from where you removed the bolts in the circular pattern. Don't mix them up, as they need to be in a specific pattern.
Set them down in order with the side that was facing the engine up.
Remove the first disk and set it aside from the others.
Dip a new friction disk in oil and place it over the clutch boss. (This would be the same place you took the disks and plates from.) In case you are still unsure what a clutch boss and clutch housing look like, we have provided a picture.

Detail of clutch boss.
Then place a clutch plate (thin metal) on top of the friction disk that you already put over the clutch boss. Now put an oil dipped friction plate over the clutch plate. Get the idea? Oil each disk and plate before putting them in. Then install them in the following order: friction disk, clutch plate, friction disk, clutch plate repeating this until you have no extra circular items left. Setting aside the old friction disks of course.
While putting the disks and plates back in you will notice that there are groves in the clutch housing and clutch boss. Align the friction disks so they go into the groves. Be sure to check that they are all flush against the clutch housing.

Tighten pressure plate bolts with torque wrench to factory specifications.
Align the pressure plate over the clutch boss and put back the bolts and springs you took out - securing the clutch plates and friction disks. Now refer to your owners' manual for the correct torque (pounds per square inch). If you don't have an owner's manual send Super Hunky an email asking him to provide you with this information. He loves these types of questions. (This is a joke people.) If you don't have a manual and/or a torque wrench borrow or buy them! Save yourself the headache of putting everything back together, just to take it apart again because you strip the bolts out or something is not right.
If you didn't damage the gasket pulling the cover off in Step 2, put the cover back on. If you did damage the gasket, run down to your local motorcycle shop and get a new one. Trying to "rig" a broken gasket makes you a hillbilly and not a mechanic. I don't make the rules; I just try to enforce them.
Because you have the bolts already set aside in the order they were removed, putting them back in is a snap. While putting the bolts back in be sure to tighten them in a crisscross pattern.

Be sure to check your manual for any "tips". For example: on the WR 400 you need to line these goofy things up. This concludes our program on doing a clutch job on a dirt bike. Don't forget to put oil back in the bike when you're done! Jeezzz, do we need to ride the thing for you too? ;-)

Mike Hobbs