250-500cc Where Should I Buy Jets

In slow technical riding, l found that the transition from 1/2 to 3/4, it was getting too rich causing a plug foul or close to it, like jumping from a single trail to an open fire trail. Where the problem was, was not in the 1/2 to 3/4 or WOT range which is where the main jet starts to perform but from the pilot, needle and slide area or the 1/8 to 1/2 throttle point. JD red and blue needles helped but what l found l was a touch rich and no matter what pilot size or needle seat position there was that slight bog and it wasn't until l changed different slides that l found a near perfect setting...again this changes if l was riding more open tracks.

Good video. I think mine might be 4 stroking based on the sound in the video.

Probably testing on Thursday night. Will try air screw 3 turns out (normally at 1.5 turns out). If that produces good results I'll change the main jet to a 170 or 172 and test again.

Thanks everybody.

So I did the air screw test and it made a noticeable difference. I then went to 1-1/2 turns out and changed from 175 to 170 main. Definitely improved the top end running. However, I was only opening it up on asphalt near my house. I'll need to test it in the dirt, hopefully soon.

Thanks for your help.

nice, test well before making more changes...normally you want to make one change at a time for best results so things dont get lost in the shuffle. armed with some tuning knowledge, the butt dyno can work well!

Try this:
Leave the main at 170 for now.

Procure a Suzuki NECK and just in case a NECJ needle from Rocky Mtn ATV, leave the needles in the middle groove.

Drop the pilot to a 35 2 1/2 out on the air screw.

You may end up with the main down to a 165 but this should give you a good baseline. If you need the Suzuki part numbers pm me.

The JD needles never worked for me"

Thanks Justintendo. I plan on riding for real before changing anything else.

Rob - Are you saying to change needle and drop down from 42-35 and air screw out 2-1/2 turns because I ran better with my air screw turned out far?

I thought the optimum position is 1-1/2 turns.

Is 2-1/2 turns permanently out too much? Too lean with the 35? Or does the needle change things?

Try it one step at a time but start with changing the needle, the NECK is going to be a little richer on top, so the next step would be to get the MJ right. Chances are good you are in the ballpark with the 175. When you are happy with the needle and main and the off idle is still blubbery work on the pilot, for some reason it seems everyone runs the pilot rich. The fast guys probably don't care but if you are riding slow gnarly single track I like to have that off idle response about perfect. You'll know the pilot is right when you start seeing/ hearing changes in the idle at about 2 turns out.

Good explanation, thanks.

Let us know how it goes

Thats exactly my experience... just a waste of money!

Dunno if it was a waste of money....works for me

Like drinking brown liquor we all have our favorite..... Whatever works