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Thoughts needed 2007 crf 150r jd kit just installed

Posted: Tue Sep 14, 2010 7:06 pm
by sak384
Here are the specs:
Location: Orlando, Florida
Temps: 90 plus
Elevation: sea level to 200'
main jet: 145 per JD crf's only
pilot jet : 42 per JD crf's only
jet needle: red needle 5th positon from top per JDcrf's only
fuel screw: 2 turns out flex fuel screw crf's only
Leak jet: 45
Ap cover; boyesen QS2
Ap mod: yes thick o ring
TPS: set @700 ohms black to yellow.
Airfilter: twin air
Backfire screen: stock
Exhaust: FMF power core 4 slip on
Pipe; stock
works connection: tach/hr meter

Went for a test ride short. Don't want to stir the neighbors have to wait til Saturday for full test at the trails. First initial thought about JD kit was okay solved small bog off idle. Might be a combination of the larger main jet and the jet needle diameter. Already had the QS2 and ap mod so that did not change. Did change the leak jet to 45 to increase the squirt. My only beef left is the idle and low end response. After 1/4 throttle it rips. I have used in the past 40, 45,48,50,52 pilots and they made the idle smooth but had a little bog. Too small and you get a hanging idle because the slide cutaway influences the transition. Too big a pilot and the slide is too closed and you get a slow response
when cracking throttle open from full closed.
Now my problem is no bog but hanging idle. I can increase the pilot but in doing so the idle is perfect but the circuit is rich and hot starts become an issue after the engine is hot. You have to hold the hot start and give 3 kicks and it fires up.Because of the richness of the start circuit. I am tempted to go down one size on the pilot air jet on the intake side. Factory service manual says idle rpm 2100 + or - 100 rpms. When i attempt this using the works conection tach, things get interesting. I know a bunch of folks set their idle to what sounds best but it would be nice to know that you are in idle speed rpm and have everything working.

~ need some help

Posted: Thu Sep 16, 2010 8:28 am
by sak384
Made these changes.......
pilot jet:48
main jet:140
pilot fuel screw:2.25
Ap mod:thick o-ring removed
Ap linkage screw: adjusted to full open
leak jet: 60 stock
AP cover:QS2

Bike ran great.No bog anywhere in the throttle range.
Idle's well no hanging idle at all. Works connection tach fluctuates between 1950 and 2250. Throttle crisp and really powerful.
Here's the question. Is it possible that the ap squirt is too rich causing the plug to get saturated with fuel and the plug misfires for an instant during hard acceleration or cracking the throttle open from idle?
I am having issues making the distinction between "bog" lean and "bog" rich. How can you tell?

The increased pilot size allows the bike to idle without so much help from the idle mixture screw and valve slide. When i cracked the throttle using a smaller pilot the ap squirt was putting too much fuel in and the bike would hang high until this extra fuel was spent. Thus causing the "rich bog" plug wet.
Does the 2007 model 150 r really need the AP mod?
If not can i go back to the factory set gap on the linkage and try a larger leak jet to slow the delivery of the ap squirt. What size would you recommend?

Posted: Thu Sep 16, 2010 7:34 pm
by sak384
Spoke with JD from Jd jetting this a.m. He is a very smart dude. He joked that I am a perfectionist. I took up most of his morning with questions and he was cool about it.
He was thorough and i was surprised at his level of testing. No 2 bikes will be the exactly the same.
1) The bike should idle and at the proper rpm.No hanging idle.
2) Eliminate the bog. If you are riding this bike and you are over it"s designed weight you could be the "bog".
3) learn the difference between a lean surge and a rich bog.
4) Save yourself time and money and buy the kit first. You may find that these aftermarket this and that is not helping anything. After you buy it you have the right to call him as many times as it takes. I love that last one.....
5) go through the bike and eliminate clogged jets, etc ,etc.