So too bad this died... i was hoping this thread would shed some light on my current project. my klx has been a BB 351 for 80 miles. from night one, the erratic idling began. bike runs damn near perfect under load. i have noticed some clutch slippage, but unlike Laurie i am going to attribute that to all of my clutch up second gear wheelies while it was stock. im sitting at about 6k miles, and i feel confident i have near destroyed my ceramic/kevlar discs mainly because it only slips trying to clutch it up. I will however tackle this issue. in the next few days. I have to. big supermoto ride in Austin and i refuse to be "that gay" trailing behind because he couldnt get his tard ready in time.

My buddy at Texas Track Bikes did the entire install, and i watched him and hung out the entire time. i watched him tq everything properly, lube evrything properly, the whole nine yards. Kid knows what hes doing. And im not too terribly dumb, most of the time. I work on Porsche's for a living so i refuse to be outsmarted by this bike!

I think the issue is with the carb. i mean, MAYBE an issue with the coil but i dont think it is likely because it doesnt miss, like i bad coil does. it idles fine, bogs and shuts off. and it was running way to lean to foul a plug this quickly. its only at idle, and always after it gets warmed all the way up.

I have double checked all the vent lines, all are free and un kinked. As for jetting i want to say im using the 132 or 35, i already have forgotten. pilot is now a 40. BUT IT IS NOT A GENUINE KEIHIN PART. there is no set rule for jet sizing, as dumb as it is. right now my 40 is an off brand keihin style. the oem jet will be here in the next day or two. i will have anywhere from a 38 to a 45 to play with, and a dyno at my disposal once its ready.

I have a borascope i will use tomorrow to check for irregular cylinder wall scoring, but im really not to worried. im a firm believer in black magic break ins, everyone has their own way. i personaly did a few heat cycles without riding it, then rode it a little slower then normal, then normal. all stop and go. ill change my oil at 100 miles and go back to synthetic and call it a day.

I know the valves are in spec, we just shimmed them. well, the intake ones. the ex valves were damn near perfect. my old cylinder wall looked fantastic, i almost didnt want to send it back and just make a beer holder out of it. piston and rings looked good too!

i did NOT break in the original head. changed the oil 100, 250, 500 and then every 1000 after. kind of hard to take it easy on a 250 in houston traffic. but it ran perfect.

the only thing that has virtually changed is the displacement, which means must have more air and fuel. air is free, i am running a uni filter and no lid. my bike liked it even as a 250 with full exhaust and jets. some people say its no good, in my case i didnt really notice a difference either way. just got louder. leading me to think its a carb/fuel issue. its fine under load, when its just dumping in fuel. but when it has to "calculate" it trips up and stalls. once again, making me think the pilot jet is off. because it controls the amount of fuel being flowed on decel, when it cuts out.

I will clean my fuel filter tomorrow, and if jets come in i will play with those as well. as for hard starting, i will leave it with the fact it has more compression now and not overthink it. quite a bit more than what the little battery and starter were used to. but it always does start back up. always. putting a new battery in it tomorrow as well, since mine is the oem one from 09.

As for grounding the voltage regulator, i did. surge is gone. non existent, ever.

Sorry i just basically recapped all that was said, in the last 11 pages that i spent way too long reading. Helped myself brainstorm/problem solve though. Far too many of you lucky bastards are enjoying your kit for me not to. im sure it is something within reach and it will be found. maybe i can sleep again knowing i might save this thread and another poor soul the troubles!

laurie, good luck with you KK kit. hopefully you have better luck this go around! always get a kick out of your videos. but, i will enjoy my extra 20cc

And now of course, for the pics...

 

For the best response out of that 351, maybe consider a TM36. The TM36 is easier to work on and tune than our old CV carb. Off idle response is worlds better and even top end is stronger.

 

If I could just go through and find all the posts where TNC raved about the stock CV carb!

 

lauriejennifer -
do you have an update for us? inquiring minds want to know.

 

You are correct!...LOL! I just found it hard to believe that it would really offer that much benefit. Riding with another rider who had a pumper carb on the Colorado trip revealed an increase in response that I couldn't deny. I was also concerned about fuel mileage. On the one day that we kept track of mileage with the same mileage for the ride, he beat me my .3 of a gallon. Not bad for a carb that yields more overall power and a lot more throttle response.

Scott, remember the discussion about my larger tire and gearing issue? Frankly I think I could go back to the 14T countershaft sprocket now with this carb. It makes that much difference. I just wish now that I had bitten the bullet 3 years ago. It may not be like having a supercharged KLX, but it's extremely improved.

 

Honestly, i dont have the budget for a 400 dollar carb, especially when the stock one is capable of feeding this engine. Sure it has better throttle response, but even when laurie went to the mikuni it had issues. I will not do the same! I rather put that 400 towards suspension at this point. One step at a time with this build, and right now that step is solve this idling mystery

 

Well, a TM36 pumper carb wouldn't be an issue, because some diligent forum members who came before have already plowed the ground on jetting and fitment questions pretty darned well. On the $400 suspension deal, if you had an "S" model and actually rode some fairly serious off road, I'd agree on the recommendation of the suspension upgrade. On an SF, I'd rather have better/more power for pavement use. On laurie's setup, didn't she go with the Bill Blue TM33/34 carb? If you read Mustang's posts on his experience with the TM34 vs. the TM36, it has some excellent insights on the ease of use and operation of the 36 over his previous TM34. Seems like the TM34 works darned well, but oddly the TM36 might be an even easier and more powerful option.

 

pushingluck,

I went with the #38 Keihin pilot per Bill Blue's suggestion on the 351 kit. It was too large and the bike wouldn't hold a steady idle, even with the kouba fuel:air screw turned out only 1 turn. Put the stock #35 back in and it works much better at just a little less than 2 turns out on the fuel screw.

Hit some high country (9 to 10K ft elevation) over labor day and the bike would stall out when letting off the throttle and coming to a stop. I just turned the idle up for this to get through that leg of the trip. Later the next day, I pulled the airbox lid off (had the KDX snorkel in) and made runs up a long, inclining stretch of road and was able to pull a few more mph max speed than with lid on/KDX snorkel. Running #35 pilot, #124 DJ main, needle clipped 3rd down, piped, lid off the airbox. Low end response better with lid off. Internet diagnoses are worth what you pay for them, but I suspect you may be rich in the idle circuit. Your stock piston looks pretty black and carboned possibly indicating rich conditions before your 351 kit.

 

Ahhh shiite, now I need to spend some more money.

 

Scott...don't make the same mistake I did. Just get it done and have more time enjoying your KLX with a better carb. I know you're a gearhead. You won't have any trouble installing the carb and getting it going. Mustang and some of the other guys like Mooredan did the hard work here. You'll have to do some serious grinding on the throttle cable wheel because we run the Acerbis tank, but that's an easy step.