Carb idle jet size issue?

[nzspokes]

Me old xr200 still wont idle properly. But getting there.

Im thinking the idle jet is to small. Idle will go up and down to stall. At idle it pops out the exhaust.

This doesnt change no matter how much I adjust the airscrew.

Ive checked for air leaks etc and all good.

Its got a 35 idle which is stock. But the motor has a Wiseco piston and has been ported. The main jet has been made bigger but not the idle.

Could I be on the right track?

[rok-the-boat]

You could be on the right track. Have you cleaned out the pilot jet? Spray some carb cleaner in there - it's amazing stuff, just don't inhale it as it smells of cancer.

[ducatilover]

Is the carb clean? (I'm assuming yes)
If so, raise the needle or change your float height.

[F5 Dave]

Me old xr200 still wont idle properly. But getting there.

Im thinking the idle jet is to small. Idle will go up and down to stall. At idle it pops out the exhaust.

This doesnt change no matter how much I adjust the airscrew.


getting there? so what made it better.

So you can adjust the idle speed up? or you do & it alters too much? Presumably not on the sidestand or anything dumb. New plug cap & plug?

If the float height is ok then may as well fire a size larger pilot jet. changing needle won't do a thing at idle of course.

Is idle jet blown out?

I'm still thinking leak if the idle changes.

[nzspokes]

getting there? so what made it better.

So you can adjust the idle speed up? or you do & it alters too much? Presumably not on the sidestand or anything dumb. New plug cap & plug?

If the float height is ok then may as well fire a size larger pilot jet. changing needle won't do a thing at idle of course.

Is idle jet blown out?

I'm still thinking leak if the idle changes.

Where im at now on this. I believe the jet is th cause. My carb according to the manual does not have an idle jet. So I believe I have a non stock carb. Later models have a 38 idle jet. mine has a 35. I tried drilling a old jet to .1mm and started it with that. Different bike. Now idles without back fire etc and has a stable idle but on part throttle its way to rich. So im going to see my guy to get a 40 idle jet as my bike has been ported and is running a lighter piston.

[nzspokes]

Is the carb clean? (I'm assuming yes)
If so, raise the needle or change your float height.

Carb fully rebuilt, needle has been tried in many heights but this doesnt effect idle.

[nzspokes]

Now finally sorted. Fitted idle jet 3 sizes up on stock and lifted the needle to the max. Bike now starts first kick and doesnt need choke. Revs fine once warm. Keep going out and starting it to see what it sounds like.

Now just need to find a way to improve the front brake.

[GrayWolf]

Now finally sorted. Fitted idle jet 3 sizes up on stock and lifted the needle to the max. Bike now starts first kick and doesnt need choke. Revs fine once warm. Keep going out and starting it to see what it sounds like.

Now just need to find a way to improve the front brake.


Then it could now be too rich!!
from memory of playing with jetting on a quite highly tuned LC 350.....idle jet to get it right, if stock size? once the motor is warmed up if putting the choke on does not 'kill the engine' but gives it a fast tickover, then the idle jet is too small. the main jet (no needle) comes in at about 2/3 throttle. Raising the slide and/or needle can mask a too small idle jet to an extent. get the idle jet correct first, then play with the main and needle sizes/settings.

[nzspokes]

Then it could now be too rich!!
from memory of playing with jetting on a quite highly tuned LC 350.....idle jet to get it right, if stock size? once the motor is warmed up if putting the choke on does not 'kill the engine' but gives it a fast tickover, then the idle jet is too small. the main jet (no needle) comes in at about 2/3 throttle. Raising the slide and/or needle can mask a too small idle jet to an extent. get the idle jet correct first, then play with the main and needle sizes/settings.

It doesnt seem to rich. Ive not tried putting the choke on when its hot. I dont have the room at home to give it some WOT but it seems to be going better than ever. Idle jet now up 4 sizes over stock. The motor has Wisco piston and is ported.

But im not bothered if its a bit rich as everything ive read on these motors say they drop valves if even a bit lean. Currently its got enough power to scare me so thats fine.

[ducatilover]

It doesnt seem to rich. Ive not tried putting the choke on when its hot. I dont have the room at home to give it some WOT but it seems to be going better than ever. Idle jet now up 4 sizes over stock. The motor has Wisco piston and is ported.

But im not bothered if its a bit rich as everything ive read on these motors say they drop valves if even a bit lean. Currently its got enough power to scare me so thats fine.
Easy way to test if it's rich,
rev it.
If it drops below normal idle before it settles again, it's too rich.