Will these be better
Posted April 09, 2002 - 05:29 PM
Yours sincearly Pete..
Posted April 09, 2002 - 06:21 PM
The one with the screwdriver head and the emulsifier tube on the business end marked 38 is the pilot jet. The two shorter 6mm hex jets are main jets.
I believe the stock pilot jet on your bike was a 42. You are running 2 1/2 turns out on the pilot fuel screw which is on the far end but not too far. If that seems right just leave it. If you needed to go further out, you would replace the pilot with a bigger one and turn the fuel screw back in.
The two main jets are bigger (richer) and smaller (leaner) than the stock. If you don't have a rich/lean problem at wide open throttle, stay where you are.
Posted April 09, 2002 - 06:36 PM
And before you ask its not the rev limeter
Yours sincearly Pete
Posted April 10, 2002 - 07:18 PM
I think I now know what a lean bike feels like. My mid throttle would miss, pop and backfire and feel like the chain was skipping. When I would go up into the mountains that sensation would almost stop. So I figure my bike was actually too lean. I have since richened the bike and it runs pretty good right now.
I would try going to a richer Main Jet. Is this correct? Taffy, Anyone? Cause if I am wrong than I am giving up this whole jetting mess.
Posted April 10, 2002 - 08:19 PM
Pete, I can't explain why it would only happen in fifth gear. When a plug is lightly fouled, it will often run fine up to a certain throttle position or RPM (varies with level of fouling) and then act very lean (pop, backfire, and stop running for up to a second at a time) and then run fine when at low RPMs. Plug is a good guess and cheap and easy to try.
Dan, you're spot on. I assume you richened up the pilot and/or the needle. Do both. Yes, it probably needs a larger main also. JD has a jetting spreadsheet that easily lets you visualize jetting changes if you're willing to spend $20. If not try the plug test or just try the next larger size. The post in the 250F forum may help but its pretty basic. For more advanced jetting, the Jetting Q's on this forum is amazing but confusing.
Whoops, just re-read your post. If it only had popping symptoms at mid-throttle, enrichening with the needle clip (lowering clip which raises needle) is probably all that's needed for basic jetting.