Hi All,

Well, the old (2001) Rev 3 250 continues to fight me! It <nearly> ran OK at yesterday's Braintree trial. I had a slow puncture, which I can't really blame the bike for, and I boiled the back brake, which may have been my own fault when pushing on in the forest to complete my lap before my tyre went down...

However, it's still not running quite right. It will not run totally smoothly in the midrange. Bottom is fine and it revs out OK, but feels quite rich in the mid. I had been suffering with it dying off the bottom and have stripped and cleaned the carb (3 times!), and this is now OK.

If it is rich (and I could well be wrong), is this an airscrew adjustment? If it is rich, I would have thought that a blocked jet would make it leaner. Anything else I should look at?

Thanks

Graham

Graham

I take it that this is a recent thing (since the recent sub frame spruce up).

Taking into acount the overlap in carb circuits, the area i would look at is the needle and the needle-jet.

On high milage bikes like (diplomatic)ours, the needle taper can get worn especially if the needle doesnt naturally sit vertical in the slide.

Often the difference between needle choices is 1-2 thou in parts of the taper. Therefore a flat on the needle or an ovalised needle jet could easily create this effect and is almost impossible to spot without a vernier.

Is the blubbery performance accompanied by smokey running?

Happy to lend my carb body to help confirm that its carb related.

Dom

Quickest and simplest thing to try is drop the needle 1 notch ie move the clip to the next higher groove this should lean off the mid range.

Thanks Dom, GreyChapel,

Yes, I suspect wear is a culprit. I can't actually remember when this started. I've been chasing perfect running for some time, what with various little issues. I've replaced so much lately it's pretty much a new bike anyway!

I've got a puncture to fix, so it looks like another day of bike maintenance. I can think of worse ways to spend a saturday!

Graham