Top 10 2003 Yamaha YZ 250 Questions & Answers

Check the rubber boot that joins the carby to the engine to often have seen the hose clamps over tightened therefore creating a split in the rubber letting to much air in giving the rough idle eventually you wont be able to start it at all (have a good thorough look inside an outside of boot doesnt take much)

There is too much involved to include everything, but I can describe to you what everything does.

You have compression dampening which slows the rate at which the shock or forks can compress. Then you have rebound dampening which slows the rate at which the shock or forks can extend.

The compression adjuster on the rear shock is toward the top, sticking out sideways where the resivoir mounts to the side of the shock. The rebound adjuster can be seen below the swing arm on the side of the shock.

The compression adjusters on the front forks can be seen from the top. (its the one in the center, the other is an air bleed) The rebound adjuster is in the center of the lower fork leg, and can be seen from below the fork.



The settings are measured in the number of "clicks" from seated. More clicks from seated will be softer, and less clicks from seated will be stiffer. The best thing to do is to see where you are now and adjusting from there. I like to write them down as I go. Turn the adjuster clockwise untill it stops and take note of the number of clicks. DO NOT FORCE IT! You should also check your service manual and take note of the standard setting, and also take note of the maximum number of clicks you can go from seated. You dont want to screw the adjusters out farther than the max, shock damage can result.

You might try changing to the standard settings and try adjusting from there. If the bike doesnt ride at least moderately decent at the standard settings, your shock and/or forks may need a rebuild.


Generally speaking more compression dampening in the rear will result in less bottoming but a harsher ride. Less would result in the oppisite.

More rebound dampening in the rear will result in too slow of extension and packing up which will make the bike swap in the whoops, but it will not tend to buck you or throw you into a nose dive over a jump. Less would result in the oppisite.

In the front, more compression dampening will be about the same situation as described above with the shock.

More rebound dampening in the front forks can tend to take pressure off of the front wheel in corners causing washout, but too little can make the bike want to loop out over jumps.

hello
with the cylinder set at top dead center compression. using a feeler gauge between the tappets and the valves there should be .002-.003in clearance on the intake valves, and .006-.007in. clearance on the exhaust valves. thank you.

what an *******. If I had a manual or my library had one I wouldnt be asking the question. If I need help fixing something dont tell me to go jump in a lake just dont answer

You might find a free pdf service manual on this site, they have a ton of them.
http://www.carlsalter.com/motorcycle-manuals.asp

or try your local library. Often guys will donate manuals to the library.

Please rate this solution. Thanks wikusnagel!

ALWAYS have a fire extinguisher on hand when working on carburetors.
Remove the water trap bowl at the bottom of the petcock, (gas valve). Is there any water or trash in the bowl? Drain a cup of gas from the tank. Is there any water or trash in the cup? Dump it, clean it and re-mount it, ( not all bikes have a water trap bowl ).

Drain the carburetor. There should be a screw on the lower side of the carb float bowl. Remove the screw then replace it after the fuel drains. Turn the gas back on and wait a minute for the carb to fill with gas. Install a new stock NGK spark plug and try to start the engine. If the bike doesn't start and run properly then shut off the gas and remove the carburetor from the engine.

Remove the float bowl and clean the entire carb with a spray carb cleaner from the auto parts store. Wear protective goggles to avoid getting spray in your eyes. Spray into all the little airways and fittings in the carb. Before putting the slide back in the throat of the carb, move the clip on the jet needle one notch lower. Put the rest of the carb back together, clean the air filter and install the carb. Let the float bowl fill then start the engine. This process should get you back on the road.

Please rate this solution. Thanks!

The engine number will not give you what you need. The VIN is the key. You will find the VIN number stamped into the center steering stem that the forks attach to. Call a Yamaha dealer with the VIN and they can tell you what year and model of bike you have.

A “very helpful” rating for this answer? Thanks!

Oooh that's bad, there are a couple of options. The best case senario is that your carburator floats got stuck down allowing the fuel to fill up the cylinder and exhaust pipe. This creates too much compression for the piston to move inside the cylinder. You can check this by pulling the spark plug (MAKE SURE THE BIKE IS OFF!!!) then kick it over. If fuel sprays out of the plug hole then you're in luck. If you don't turn the bike off first, the spark plug will ignite the gas squirting out of the hole and catch on fire... I know from experience. Tip the bike over and let it drain out of the exhaust and plug hole of the cylinder. If the kick starter will not move with the plug out then it's time to remove the flywheel cover. With the flywheel cover removed and the plug out, try turning the flywheel. If it turns then the kickstarter gears are jammed or broken. If it doesn't turn, then the piston or the crank is seized. Good luck.

Check the frame tube, left hand side below engine.

Hi mate this will be the oil & water seals the leak from weep hole is basically a warning light to tell you it needs replacing asap, you need to remove impellor, carefull not to lose the spacer washer behind it...then remove the water seal clean the surface it came from and replace with new seal. Now to do this 100% I would always replace the impeller shaft as the shaft wearing is usually what caused the seal to fail and I would also replace the oil seal which is the other side of case that you just changed the water seal (oil seal sits behind the small bearing) I would also consider replacing this bearing but maybe not critical? all up the impellor shaft the 2 seals and bearing last time I bought cost about $160... no special tools required just quite a bit of time required as you should really remove the outer engine case to access the impellor to undo it and to get to the oil seal and bearing, how ever I know guys do just open the water pump cover then rattle gun off the impellor only replace the water seal then install the impellor and cover back on then ride away! this will work and will fix the leak but is definitely the incorrect way to repair this and will be temporary fix but thought you may like to know this alternative as is very handy way to do it if your on a race meeting and just need to get through the last race or two.

hope this help cheers... Moto X Parts online.com