crf250 jetting help

Background info is the bike is mostly stock except for a twin air filter, zip ty fuel screw and JD jetting kit. (red needle 4th clip, #172 Main, ~2 1/4 fuel screw on stock pilot) I'm in Wi and it's about 50 degrees right now. I've always had issues with an off idle bog and a hanging idle. It's irratic at times too. I've started with the FS at about 1 and turn it out at 1/4 incriments. 2.25 seems the best but it'll still fall on it's face sometimes. (same day, same conditions) :think:

With plug checking on a thumper is it like a 2 stroke? The first pic is of my crf plug after a 4th gear run. Second one is of my old cr. The crf is more of that yellow color like the cr with ~2mm black ring. I'd really rather not hack these plugs much since they're kinda expensive. Oh and I'm using power110 race fuel right now. Thats why the plugs are more yellow...could this cause my jetting complaints too?

A while back I emailed JD and this is what he said.

There are a few things that make bogging worse, like removing the screen, too rich idle or needle, too lean idle. It looks like you've found more than a few settings that aren't working.

My suggestion is to stay close to the standard setting and evaluate- (disregard the cold options)
#40 pilot jet
2 1/3 turns (a little more than the instructions)
Red needle #4 position
#172 main with backfire screen.
Stock air filter

I'm not getting any bogging with this setting in my CRF250R. Make sure the air filter is clean and try the stock filter.

Let me know how it works and, if good, make only 1 change at a time from there.

Thanks,
James

Click to expand...

At first I removed the backfire screen, put in the twin air and installed the kit all at once...dumb me. Screens back in now. I started with the blue needle but the power was way to flat for me. Red gave me the hit but still has that stupid bog...sometimes. It's just the strangest thing. I had it where it'd actually start easy hot or cold and barely had a bog. This afternoon I was out and it was running really good. I didn't get it to bog and was really happy. Took a food break and went back an hour later and it was bogging. I dunno. I'm checking the valves tomorrow...dumping the gas and getting fresh (pump or that race fuel, undecided as of yet) and see what happens. I suppose I could go back to stock just to see what it's like?!?!