Have an '09 KLX with stock exhaust and air filter.
Installed hi-flow snorkel and Dynojet kit with the following settings:

fuel screw 2.75 turns out
needle clip on middle groove (3rd from top)
#124 main jet

In short, I'm extremely pleased with how this has transformed the bike. However, the bike stumbles a bit at high end, so I'm pretty sure the main jet is the only thing needs changing. Everything is perfect until you get above 65-70 mph. In fact, was able to hit 90 (indicated), so I know the main jet must be pretty close as it is.

My question is...I don't know whether to go up or down: bigger main jet or smaller?

I'd like to avoid removing the carburetor six times. Got better things to do with the weekend.

(or, maybe somebody can tell me how to change main jet with carb still on the bike??)

 

What's your altitude? Usual riding temps?

I'm running no snorkel, aftermarket filter, and stock exhaust, and I'm using a 128 main, and I like it. But I'm at no higher than 200 feet ASL

 

Mid TN, about 650 feet, unusually cool today (70's) but mostly 90's the rest of the summer. Been leaning toward the 128, sounds like you've got a pretty similar setup, maybe it'll work for me too. Probably install it in the morning unless I turn up some info to indicate otherwise.

 

I seriously doubt your running too large...you can go bigger, but if you want to get through the weekend, as you said your really close so you'll most liley be fine. Try a 128

 

Installed the 128 and it seems to be the ticket. Only the slightest (imaginary?) stumbling when maintaining cruise, although I'm not sure this isn't characteristic of all thumpers. You never notice unless you're paying attention...and sometimes not even then. Certainly more pronounced on my KLR, so methinks all is well in KLX Carburetorville.

 

I wouldnt think you;d be imagining it. Bump it up again. Go 132. I'm rolling with a 137.5

 

OH, wait. I just remembered, dynojet goes by different numbers....no matter, just go up one more size from where you are now. This bike likes its gas.

 

What would be the symptoms if the 132 makes it overly rich? (this is DJ's next step up from the 128)

Will occasionally have the bike in east TN mountains, over 5000 feet but not too often. I do hope to trailer it to NM next month and do some extended riding over 6000 ft. Would removing the airbox cover be an adequate mixture adjustment in those situations?

 

The bike will bog instead of cut out. It will run slightly cooler with the extra fuel though as well.

Removing the air box like might help depending on the density...however going from a snorkel (even if it is high flow) to no lid at all is a HUGE difference. SO,.. you might end up going the other way. But maybe if your up high like that in the mountains it might help.

this is all pure speculation. Just trying to jog your thought process on how all this stuff works. Your doing well, keep your chin up.

Oh, another though, I remember a long time ago (in the 90's..haha) I was reading dirtrider or something and there was a guy on an XR in there that said he raided his old lady's pantyhose drawer and stole her nylons and tights and stuff and used them to stetch over the airbox lid. I think this is a good idea. I was going to do something like this. Maybe double a thin pair up or something and then take the original airbox lid bolts and use some huge washers to help tighten down when stretched over. This will allow more airflow,but keep the junk out. And if you wanted to do a little in between thing maybe you could get like a thick pair so that the air doesn't just pour in raw. Know what I mean? Its like removing the backfire screen, yeah, it has holes in it so the air flows, but it creates drag and does block air. This is a quick, cheap method to K&N filter skins...and like those you could also give'm a quick spray down with air filter oil to help trap dust.

Just ideas.

 

A good replacement for the filter skins are hairnets. The white ones you see ladies wearing in the food industry. Oil them up, and they catch almost everything. I ride a really dusty track sometimes.
They work like magic, and they cost pennies.