wr426f hanging idle and hard to start when cold.

My 426 is now hard to start when cold, if I put the choke on and kick it forever it will not start, then the 1st kick with the choke off it will run for a second, after doing this 5 times it will run (choke on 5 kicks, then turning it off and it will run for a sec. After a bit it will fire up on the choke when the engine is a little warm. It also has a hanging high idle when hot and i can kinda get rid of it by turning the fuel screw in to 1/2 a turn. The bike is stock aside from a fmf pipe and the carb is super clean. I have changed the throttle body o-ring as it was rough. The jetting is stock and pilot is a #42, and it has a gytr fuel screw in it. Any suggestions????


Edited by Markamainia
missing a few words

What was the change/what occured to precipate this?

The carb was taken off to change the intake boot which had a crack but didn't leak, new one installed., GYTR fuel screw was installed, and the FMF pipe was re-packed.

Edited by Markamainia
added more points

would this be a rich or lean problem? my manual says rich unless i have an air leak.

Hanging idle is often a combo of a too lean a fuel screw setting and too high an idle. Take a look at the stocky at the top of the forum for details.

I read up on that and the bike races faster the more i turn up the fuel screw to 3 turns and won't idle down, but it will if i turn it down to 1/4-1/2. wouldn't it bog out the richer i turn out the screw?

thanks for tips

would a bad fuel screw o-ring cause that?

would a bad fuel screw o-ring cause that?

Could be partly at fault, yes.

Fuel screw is for idle. It has nothing to do with any bog unless your jetting its terribly messed up and you depend on the pilot jet to compensate for the AP.

Sure, a bad oring on the fuel screw an cause problems, so can anything that is worn out or in bad shape. Everything must be in good condition if you expect it to run right.

If the compression also seems low when cold, check the valve clearance. Tight intake valves can cause this problem.

Sorry. I was referring to the Hanging idle issue.

So was I. If the intakes get too tight, they cause a dilution of the intake signal and artificially create a lean condition that results in a hanging idle. It also makes the bike harder to start cold.

compression is high when cold, valves are perfect and in the mid-high rpms are perfect as well, it pulls hard but down low I can't control the hanging idle with the fuel screw and also by turning down the idle screw

OK, has the bike been sitting idle for any length of time? It sometimes takes a surprisingly short amount of time for a film of varnish to form on the pilot jet. The orifice in the jet is so small that a thin film coating can cut the effective jet size in half.

This can happen whether the carb has gas in it or not.

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