2003 Yz 85

shane001 · May 21, 2003

If i am at idle and open the throttle all the way really fast it boggs down and sometime quits.
If i screw the pilot screw all the way in it doesnt happen it revs right up. So i went from a 45 pilot to a 48 and it doesnt help, so i went down to a 42 and tried it and still only works when pilot screw is in all the way, tried moving needle clip and all the different pilots too. If its idling a little faster and i open it really fast it revs right up.
Any one got any suggestions???????

karterron · May 21, 2003

Pilot screw? Do you mean the air screw? Turning it in means you are richening the mixture which seems to be at odds with what most of us have experienced with the YZ85. Ours was too rich from the factory. Did you buy the bike new or used? If used, tell us what the pilot, main, and needle are currently at. What fuel and premix are you using and what ratio? I'm suspecting someone may have played with the jetting since most of us have had to on ours and maybe they have it way off.

shane001 · May 22, 2003

Yes i ment airscrew.(oops)
I bought it new. The main is 138, needle clip is on second slot from top, pilot is 45.Stock like the manual says. No matter what i do it boggs unless i screw the airscrew in all the way then it revs right away and no hesitation.

shane001 · May 22, 2003

amsoil synthetic 50/1 i called amsoil cus i thought 50/1 was a little light on oil since manual recommends 30/1 but they say thats what i should mix it at because it is so consentrated, and that they supercede factory mix recomendation.

karterron · May 22, 2003

You may have an air leak somewhere also. Have you done any recent work to the motor? We run the amsoil also with high grade gas and race gas mixed. We went up one on the needle and it cured all jetting issues for us. What is your elevation, we are around 900 above sea level.

Sounds like you may have another issue.

MikeS · May 22, 2003

Look for Air leak as mentioned. Pull the carb and remove Pilot jet. Look inside for an obstruction (piece of casting etc).

I heard some KX and YZ carbs had internal cracks that made a few tuning issues.

GoodLuck

shane001 · May 22, 2003

We are at about 300ft. No work done to engine. Where would i look for airleaks?

MikeS · May 22, 2003

Reed block/ignition side crank seal. You can spray WD 40 or starting fluid in those areas and the idle may increase for a split second. That will show the leak.

Internal carb leaks are hard to find

DEANSFASTWAY · May 25, 2003

Maybe your opening it so fast that it needs an accelerator pump. Does it ride okay and make good power otherwise? You might be looking for a needle in a haystack.

2003 Yz 85

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