Pilot tuning

Fark · Apr 8, 2003

I've gone one down on my pilot and constantly fiddle with the airscrew, pay attention to the smoke, listen for the indicators (booowaaaahh and cracking).  I haven't got them down yet and I'm not sure if I can hear the bike ping when I'm riding in sand or mud and crack the throttle.

I've got the rest of the circuits close but the gas supply keeps me guessing.  I get no spooge at idle and the rpms kind of hang for a few seconds if I crack the throttle  (an indication of being lean correct?).

Looking for more indicators.  I've gotten faster and closer jetting so I'm not sure which or if both is keeping me from fouling plugs (doesn't happen often now).

PLUS I'd like to know when you should change the pilot size, what is the useable adjustment of the air screw?  1.5-3 turns I assume?  The carb is a Keihin with NO electronics on a 97 RM125.

Fark · Apr 8, 2003

One more question. Do all the circuits work together at WOT or does each shut off after they overlap for a time through the throttle operation?

Thanks and I hope this helps posters and readers to come. :aj:

David Trustrum · Apr 10, 2003

For the airflow of the WFO throttle the pilot makes negligible difference. The slide is out of the way & the needle is pulled out of the way so only the mainjet below it is the restriction

-unless a way off needle is still blocking the passage upstream & you can drop the main out to see if this is happening but for the purposes of the discussion I’d only bother checking this when doing a carb swap from a totally different engine.

Remember jetting is throttle position sensitive not rev related (much).

oh yeah clean that airfilter & throw in a new plug so your test set up is not skewed by another component.

We are talking for a 2 stroke so when you crack the throttle from closed it should blip nicely. Go leaner until it hesitates then wind the airscrew in until it doesn’t. When under load (riding it) it will need to be a bit richer than this.

Pilot tuning

Fark

Fark

David Trustrum

Similar Topics

Privacy & Transparency

Privacy & Transparency