Need repair advice! (1991 YAMAHA WR250Z)

[BIGTACO]

Ok so I am new to dirtbikes and just recieved a 1991 Yamaha WR250Z from a buddy. Bike runs well, barring a few small issues. I plan on using this bike for a while until I can afford a newer 4 stroke of my choice. Until then, this is my ride. That being said, I need help...

The issues:

1) Engine runs great! But, when I let off the gas totally to bring the engine to an idle it dies. Could this mean a re-adjustment on the throttle linkage is needed or possibly clean the carb?

2) Rear shock is totally gone. Basically no dampening at all. Its just a spring at this point. Whats needed to fix? Can I do the work myself?

3) Front shock is leaking.

I ordered the repair manual for this bike today but I just wanted to get a head start and possibly go ahead and order the needed parts now...

Any help greatly appreciated :)

 

[Matt90GT]

1. Your pilot jet is plugged up. Remove the carb, clean all the jets out, blow out all the passages in the carb including the air screw and reassemble/reinstall. Then set the idle screw and air screw per the manual.

2&3) you need a few special tools. If you never have done suspension, best bet is to take it off the bike and to a local shop or suspension company. Most of the suspension companies charge under $100 for new seals and fluids.

FYI you have FORKS in front and a shock in the rear.

 

[BIGTACO]

Great! Thanks for the advice!

 

[DougTx]

If it won't idle but it runs well then I would imagine that the pilot jet is clogged up. It may be something else but I would start with the simple things.

Pull the carb, pull the jets (might as well pull both if it is open) and soak them in carb cleaner for a while (like over night is good and what I did). Rinse them with water and then blow them out real well with compressed air and then put it back togeather.

You could also clean out the bowl and change the fuel if it is old. While you are at it throw a fresh plug in there for good measure.

Simple things but I would say that would answer the question. If you can pull the entire carb and clean it taht is obviously better and good preventative maint. but to get it running, that is what I did and resolved my idle problem.

Good luck... I know nothing about the shocks except to have someone re-do it. There are guides out there and kits to rebild them with the parts. I hear it is not to tough but have not tried myself. Free bike is a good thing, most of the time :ride:


Good luck...

 

[rmc_olderthandirt]

Like others have said the idle jet could be clogged, but it could also be the idle adjustment is just way off. There are two adjustments, the idle speed and idle mixture.

I believe that on your bike they are both on the left hand side of the carburetor. The idle speed is above, has a lock nut on it. The idle mixture is below, should have a spring under the screw.

Start by setting the idle mixture to 1-1/2 turns out and the idle speed to the slowest speed that it will actually idle at. Adjust the idle mixture for best idle. If it won't improve regardless of the mixture adjustment then the jet is probably clogged. Adjust the mixture for best idle, then lower the idle speed and re-adjust the mixture. Repeat until you have it idling well at a reasonable idle speed or until you get it as best that you can.

If the best idle is achieved with the idle mixture screw more than 2 turns out then it indicates that the pilot jet is too small. If the mixture screw is less than one turn out then it indicates that the pilot jet is too large.

Rod

 

[helio lucas]

maybe it´s better at this time to do a compression test... if you have leaky rings will be very hard for the engine to idle as it should...

i will advise you to buy a book "mx and off road performance handbook" from eric gorr... along with the service manual you will know everything you need fom the maintenace of your bike...

good luck with the bike...