many charts floating around the net with varying values. This one seems to be pretty close IMO, based on what people are posting for results on the klx.

FAQ Mikuni vs keihin vs dynojet

 

Thanks guys. That's just what the doctor ordered.

 

Jetting is only hard the first time you do it. Once you've done it a time or two, it is simple. Takes me longer to get everything out of the way (since my luggage rack uses the seat bolts and has to be removed to get the side covers off) than it does to change out a jet.

And at least on mine, I had to deal with the gorilla tightened screws on the carburetor. I actually had to grind a slot in one of mine so I could use a flat head screw driver to remove it. It was ridiculously torqued down...

 

Oh, don't get me wrong - I've done a couple dozen rejets.

My KLX331 was a breeze to remove/rejet/install. I could have the entire carb in or out in 3 minutes. Evey other dirtbike I've had is the same breeze. The KLX - not so much. It's a PITA to pull that f$%^ing carb. And if you elect to just rotate the carb - yoiu risk unseating your float needle like I just did. And on reinstall, the airbox boot loves to pucker up and not seat properly.

I Put it all back together (well far enough to hook up the gas) and it's leaking like a SOB from the overflow, so obviously, my float needle came unseated again as I rotated it back into place. I tried tapping on the carb body to reseat the float needle but to no avail. So now I have to tear the mother down yet again...

That's why I was wishing I could do it from the top - not the bottom.

Sorry for the rant. Been a long morning. I'll get it.

 

if you haven't already, replace the bowl screw with sockets screws and get a ball end Allen wrench . It make life so much simpler. Also if you put little grease on the float pivot pin it won't try and fall out while your fumbling the bowl back on.

 

Thanks RB.

I replaced the stock marshmallow screws with allen head SS screws 1st time in.

I ended up totally pulling the carb this time.Turned out the little wire holder/pivot that holds the needle onto the tang was hung up at an angle on the tang which was not allowing it to float like it should. Fixed it in about 10 seconds and the reinstall went slicker than before. I was even able to find the crimp in my tank vent that was making the reserve spigot draw slowly.

Thanks for the help and sorry to all for the rant. It was a really hot day - even here in Maine.

BTW - bike runs great with the 125K main. I may play with the clip position just to see but I think I'm set for a MJ unless I go to a BBK in the future.

 

take a trip out here its like 90 where i am but i'm about ride to the river with sme friends to fish and swim i would go up in the hills but where i reall like to ride has tons of snow still

 

So I ran through my 1st tank of gas with the rejetted carb and KLX250R (same as 300R) exhaust. I expected to see a mild drop in gas mileage. Not so, had my best mileage yet at 64.xx mpg with a mix of off/on. Previous best was 63.xx with the same mix.

It started me thinking, I think I may still be running a bit lean. TNC published an excellent tutorial on jetting and some common-sense symptoms to denote which direction you need to go. It definitely still runs better in warm temps than cooler temps up on the top end. Also, mileage improved with a bump from 122K to 125K main.

I'm planning on ordereing a 128K main to check it out. It's a lot cheaper than paying for a dyno run. Just for reference this is with no snorkel, UNI, smog off, airbox plug out and a 250R exhaust.

Sounds great - at idle. For those of my generation, it sounds exactly like a Huey just popped over hill 461 in southeat asia. It's a comforting sound. A little louder than I'd prefer at higher revs but methinks it may be identical to a Q4 by sound.

I think I just underestimated how much more air it moves than stock and need a size bigger on the main. It's great low and mid.

 

I have successfully re-jetted mine by removing the throttle cables and rotating the bottom of carb to the right. Allens would make life a LOT easier... I haven't replaced mine yet.

When I re-jetted, my MPG took a total dump! I went from 70 MPG to somewhere around high 40's to 50 something MPG. OUCH! However, the thing has MAD power now!!! Like a different bike...

 

It's interesting to see all the different mileage results in many of the different setups on the forum. It's apparent that not all the bikes are set up the same nor do they all have the same components. My mainly highway mileage dropped about 3-5 mpg from early modding to my current setup, but performance suffered noticeably on hills at highway speed...and that's about 60mph for my use and gearing. You'd think because it struggled more as a 250 on highway cruising that mileage would have been bad, but it wasn't. I'll take the small hit in mileage on the highway for the noticeably improved performance for going up hills, in the wind, and the occasional passing situation. However, when going off road, the 300 setup actually increased mileage by at least 5-8 mpg. Not having to frequently wring out the motor in challenging situations obviously helped mileage. This stuff also points out how everyone isn't riding in the same conditions with the same priorities, so mileage results can be all over the board.