Motorcycle Repair: wr 250 starting problems, two stroke engines, plug cap

Question
hi there
ive just bought a 97 wr 250 it has been standing for over a year and a half? prior to it standing the guy had the carb over hauled and the top end of the motor over hauled... when i got the bike the fuel was pretty much rotten... i have drained the fuel tank and have opened up the carb again and cleaned it all out, but i cannot get her started? ive checked the sparkplug and it is working 100%?  there is however an issue with the kick start.. it does not spring all the way back up to the top you have to pull it up every time with your foot to get it up to full compression again...??

can you give me some sort of advise on what else i could do or where i should be looking to try sort it out??

thanks a million Chris

Answer
Hi Chris,

Sounds like it needs a new kickstart spring.
Watch out it doesn't backfire with that
kick lever down or the lever can come rushing
upwards at a powerful speed. Don't ask how
I got the scar on my forearm :/ ouch!

Anyway the wr250 has to have good compression
to start (100 min to 175 psi) which it should if the rebuild went well.

Next is the fuel which means physically cleaning
the brass main and idle jets out with something
like a smooth guitar string. The jets will be plugged
unless you put something through them or replaced
them with new ones.
The carb may need soaking in some good yamaha carb cleaner.


The carb float level has to allow the float bowl
to be nearly full of fuel.

The carb and it's intake tube must not leak any
vacuum or air or the fuel will not get pulled in.

Even a drop of moisture under the main jet will
stop the fuel.

Replace the spark plug cap, they are just bad.

Use NGK spark plugs if you can get them.

If you have spark and compression you can try
spraying some carb cleaner or wd40 type
spray into the carb mouth and see if it fires
on that. If it does then you know you still have
a fuel supply problem.

Another problem that can occur on two stroke engines
is losing crankcase vacuum/pressure.

This happens when the crankshaft seals leak.
The left side crank seal leaking will suck air instead of
piston vacuum pulling the fuel into the engine.

If the right seal leaks then it sucks the transmission
oil into the engine and fouls the spark plug.
There is a way to pressure test some engines
with the right tools.

If you get it to fire on the spray it might eventually
run as the crank seals may straighten out a bit
after running. If not they would have to be replaced.

Check if the exhaust pipe is clear.

Luck!
Wayne S.

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