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I have been trying to get this bike to run smooth for two days now. Brand new bike 13.5:1 piston, ap pump wired. Originally had 45 pilot and 138 main clip in 3rd position air screw 3 out. Ran ok but started to deteriorate and low end was gurgling and not smooth. leaned out screw no help. Replaced pilot with 48 and ran better with screw a t 2 out. Tryed 2nd position on clip and 4th. Bike runs good everywhere but just off idle it gurtgles like crazy and really effects how you can corner the bike. Current settings are 138 main, 48 pilot 2 turns out and 4th positon on clip. I need help to get this thing to transition smoothly fromn idle to midrange. just off idle to 1/4 throttle is absolute garbage. Tempted to just go back to our kaw superminis. Anyone want to buy a 150 with 2 rides on it? Might be mor satisfying to take a sledge hammer to the thing. By the way it runs like a raped ape up top just cant get the off idle to 1/4 throttle thing right. Makes corners a b_tch

Here are the current settings

Year: 2009
Elevation: 800 (Illinois
Temperature Range: 50 -60 degrees
Backfire Screen: yes
Air Filter: stock
Pilot Jet: 48
Main Jet: 138
Needle: stock
Needle Clip Position: 4th
Fuel Screw Type: stock (pain in the arse)
Fuel Screw Setting: 2 out
AP Modified:wired
Leak Jet: stock
AP Cover: stock
Exhaust Type: stock
Exhaust Modified: stock

welcome to the site. i have a 150r and was never able to get the jetting dialed in with the stock needle. i was however able to get it dialed in with the jd jetting kit. here's a link:

http://www.crfsonly.com/catalog/product ... ts_id/2253

ken

so you think the needle is the problem

i tried to get my jetting spot on with the stock needle and i was never able to get it correct from top to bottom. the JD kit comes with custom tapered needles designed specifically for the CRF150R and is developed from actual dyno and field testing. with this kit i was able to get it jetted correctly.

having said that, if it's off idle that is the problem then you need to look at the pilot circuit and the accelerator pump. make sure the pump is working correctly. the diaphragms are known to deteriorate over time. check yours. also, if you were into the carb and removed the slide check and make sure it's on in the correct orientation. also make sure the floating valve seal is good. if you've used carb cleaner this will break down the seal and affect off idle performance.

ken

ken

These 150's seem to need the idle set on the high side, around 2000 to 2100 rpm's works good on mine. Gets it out of that low rpm bog area.

The bike is BRAND NEW. Nothing is deteriorated. The dealer has an in house performance guywho a couple of local racers recommended. I wanted to pick this bike up done and ready to roll as I didnt have the time. He wired the ap pump and adjusted duration ect. I trusted the guy because he answered my questions before I asked them so I know he knows what he is talking about. I knew what I wanted and when I asked what he would do to the bike it was like he could read the list I had in my head. From the compression ratio to brand of piston, jetting recommendations ect. I dont have a bog, its not lean it runs great up top, it idles with no hang, starts fine but in my opinion the transition from idle to mid should and has to be seemless. At this point I would be embarrassed to let my kid ride it through the pits and to the line. I realize the problem has to be in the idle curcuit either screw or pilot jet and perhaps the taper of the needle when that needle starts to lift. Is there anyway it can be compensated for with other adjustments? Maybe it does come down to the JD needle but sorry crf only, no offense but you sound like an advertisement for them and your reply is the same I have read on other posts verbatim. We are in the middle of a loretta run and plan on top five and hopefully winning. You wouldnt be confident enough to trade one for some Prominently displayed advertising at the big dance come august would you? At this point I think It may have been a bad decision to switch brands midstream but I figured we are almost done with area qualifiers and we could concentrate all our efforts on her getting fast on the crf until regionals or worst case make the full switch between regionals and the nationals but at this point her confidence as well as mine in the bike are going south real quick. (not to mention a well planned race budget). Thanks for all your advise Her lap times are a bit faster on the honda but if I can figure this issue out they will be amazing.

sounds like you have a good handle on how the carb works and want to work with the stock needle. all you can do is test different jet and needle clip combinations looking for improvements. check out the jetting database in our 150r forum for what others are using.

Sick of messing with jetting, I decided to check valve clearance since the bike is new with just a vew hours on it i was curious if it was still within specs which it was. It was what I found during disassembly that raised an eyebrow. The sparkplug gap was waaaaay small. So small that it looked like perhaps this ""awesome performance mechanic" that put in the hc piston and did the carb work had perhaps dropped it and smashed the electrodes or something. I even wondered if the piston had hit it but I really doubt that. I opened the gap back up to spec and made a couple more jetting changes. Hopefully I have it now. Seems smoother on the stand but I can only tell when being ridden if the breaking up is gone. Let you know tomorrow! Here is where I'm at now:

Year: 2009
Elevation: 800 illinois
Temperature Range: 50 -60 currently
Backfire Screen: yes
Air Filter: stk
Pilot Jet: 38
Main Jet: 140
Needle: stk
Needle Clip Position: 5
Fuel Screw Type: stk
Fuel Screw Setting: 2.5
AP Modified: wired
Leak Jet: stk
AP Cover: stk
Exhaust Type: stk
Exhaust Modified:stk

MOJO RACING wrote:Sick of messing with jetting, I decided to check valve clearance since the bike is new with just a vew hours on it i was curious if it was still within specs which it was. It was what I found during disassembly that raised an eyebrow. The sparkplug gap was waaaaay small. So small that it looked like perhaps this ""awesome performance mechanic" that put in the hc piston and did the carb work had perhaps dropped it and smashed the electrodes or something. I even wondered if the piston had hit it but I really doubt that. I opened the gap back up to spec and made a couple more jetting changes. Hopefully I have it now. Seems smoother on the stand but I can only tell when being ridden if the breaking up is gone. Let you know tomorrow! Here is where I'm at now:

Year: 2009
Elevation: 800 illinois
Temperature Range: 50 -60 currently
Backfire Screen: yes
Air Filter: stk
Pilot Jet: 38
Main Jet: 140
Needle: stk
Needle Clip Position: 5
Fuel Screw Type: stk
Fuel Screw Setting: 2.5
AP Modified: wired
Leak Jet: stk
AP Cover: stk
Exhaust Type: stk
Exhaust Modified:stk

Is the pilot 38 0r 48? You claimed 48 in 1st post and I thought that might even be a bit lean at 800' elev. I am using a 48 at Denver's 5280' elev. with good results. It might be a good test to try a 50 if the spark plug gap didn't fix it. The 50 would allow you to get the fuel screw at 2 turns out, there is a fine balance between the fuel screw and idle adjustment that is very touchy to get slide in the correct position to be optimal. And, replace that hard to reach fuel screw with a R&D Flex Screw.

MY BAD. SHOULD HAVE READ 48. rODE IT BRIEFLY AND SEEMS 100 % BETTER. HIGH IDLE THOUGH SO WHEN i BROUGHT IT DOWN IT WANTED TO DIE SO I THINK JUST A LITTLE TWEAKING ON THE AIRSCREW AND IM THERE. iT DOES SEEM A LITTLE FAT NOW. i THINK i WAS COMPENSATING FOR THE PLUG BY GOING FATTER SO NOW i WILL BRING IT BACK DOWN AS IT STARTS GREAT WHEN COLD WITHOUT THE CHOKE MUST BE RICH. Think I'll go back to 45 pilot 3 or 4 on clip and leave the 140 main. I bet it will be fine. Last time I let someone else touch my bike. He put the piston in, how did he not notice the plug smashed like that? Hours of screwing around for nothing. Had No one looked at the bike it would have been one thing I checked but with a supposed competent guy who would have figured. All for a sparkplug gap.

yeah...wouldn't have thought to have you check the spark plug gap! good news is you found it and are headed in the right direction now. good find!

ken