CRF250X Jetting - Clueless

[Pete A]

Does anyone have any experience with this?

I took out my jets as I'm trying to solve the reoccurring running issues I've been living with.

The result surprised me though.... A massive 170 main jet when the OEM jet is 130. Plus more turns on the mixture screw than I've ever seen quoted anywhere.

If anyone knows anything about where I should start then let me know.

Thanks.

Pete.

[Beerbelly]

Go back to stock and just put the needle up one notch on the clip as they run lean. If in doubt take it to Dobles they had to do mine as it was too lean from factory.

[mudeevee]

On mine (gone now) I used one of these for mixture
http://m.ebay.co.uk/itm/361008254589?nav=VI

As for main jet, I had the original 130 - crap
Then a 142 with a Leo Vince exhaust - good.
When I used a really restricted exhaust I needed to go up to 170!

Found it ran best with the 142, Leo Vince can and the air box 'opened' (see honda closed course mods).

Using the adjustable needle helped get it right.

Also worth checking the pilot, as tick over was difficult to set correctly with the stock PJ

[Pete A]

Thanks guys. I think I'll put it back to stock (but 42 slow) and see where I am.

Derek, 170 with a more restricted exhaust? I thought a restricted exhaust would richen the engine so a smaller jet is needed.

This stuffs confusing!

[Pete A]

And the verdict so far is....

Bike running better since 140/42 jets, a re-shim on the intakes and a mixture screw for easy fiddling. Plus tyres and pads and a re-bleed.

Still has a bog at quick accel for first 10 mins which I'm putting down to crud/water in the accelerator pump. I think that's more tricky to take apart though.

[mudeevee]

Have a look on the National forum...
http://www.trf.org.uk/forum/viewtopic.p ... 25#p109943
Same subject, same problem and similar solution. They mention the AP mod. I never did this one, but hear that it prevents the bog you may get....