I've seen lots of partial information on the net about getting rid of backfires by removing the white spacer (or putting in a smaller washer) on the jet needle in the diaphram assembly. I've also read some articles that suggest a full 3 turn ratio on the idle adjust screw eliminates backfires as well. Has anyone tried that in this forum? Its been suggested also that if you intend to re-jet at 155 or higher (for those at 125 & 145's) that if you removed the white spacer you actually degrade your overall performance. On the Heise forums I read that someone had changed their exhaust to a supertrap (diagonal slash pattern type), left their spacer on the jet needle, never re-jetted and had significant hp increase tested with dyno AND eliminated the backfires. I was curious if their idle adjust had been altered as well. I've been planning on putting a thinner spacer in my 02 but will probably play with the idle adjust for a couple of days first unless someone with the voice of experience will give me some suggestions?

I missed out on a bunch of posts lately because of Ivan.  Anyone interested in that can visit this page.

http://www.digimaging.net/images/267_IvanAsheville03web.jpg

As for your 157.5 main jet....Do you seem to have a "flat spot" in your throttle response when accelerating through mid-range?

Then again perhaps You shouldn't, That is what you would do on a flat slide and probably doesn't apply.

Clive W  

Gitarzan wrote on 12/31/69 at 16:00:09:


Pardon my memory, but old timers disease won't let me remember all of your bike setup.

I got the stock spacer part...What exhaust?

I'd try to eliminate the Sea Foam from "the mix" until done tinkering with jets.  After all, a "swig" of the stuff isn't a precision unit of measure  

Do you see any black smoke when you rev the engine while it's sitting still?