XR 600 jetting issue

I have a 1994 XR600 with:

Staintune exhaust (standard headers),

Hot Cam

Twin air filter

Sea level

The carby has recently been cleaned.

The original problem was that bike tended to "splutter" if kept at a certain low throttle point (about 1/8 - 1/4th) and also when WOT. This was with original 62/152 jetting, 2.5 turns and 3rd clip. During acceleration it was fine as were starting and idling.

I have recently tried 68/160 to solve the issues and the WOT problem is gone but the low throttle 'stumble' continues. I've tried changing the fuel screw but the problem remains.

Any advice would be appreciated:thumbsup:

steady throttle or while opening the throttle quickly?

Hi Eddie

It only happens with steady throttle. If you gently accelerate it will tend to clear and not appear at the higher throttle setting. No real difference hot or cold.


better or worse when hot?

It's present at both but probably a little worse when hot

replace the needle jet (not needle).

replace the needle jet (not needle).

What do you mean by needle jet? doesnt the needle seat in the main jet?

Ok thanks Eddie I'll track a needle jet down and give it a try.

ps I did notice today also a slight intermitent hesitation when riding with WOT at high revs(slowly rolled on not snapped open).

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