Another pwk cr125 jetting thread...

Well my 03 cr125 with an 01 kx250 pwk is having a strange bog on the bottom end but its very odd.  If I start off in first and the rpms are low and I go wot is will bog and almost die and sometimes sputter.  Mid to top it runs excellent once  the rpms are up.  Now I know this sounds like a lean condition but Im gearing down to a 12/52 and heres my specs:

175 Main

45 Pilot

NC3G #5

#8 slide

AS 1 turn out

I have the 05 airboot with six holes drilled in airbox, stock exhaust and motor.

Is the 5.5 slide that important? Theyre around $50 and Im thinking of ordering one. 

Btw I just put a new cylinder, head and piston/rings in and compression is at 135lbs. I really like the bike but im puzzled at the moment because this bog is so severe yet sometimes it doesn't happen.

All 2 strokes will bog down when underneath the power band. If your riding slow and not in the high RPM's and you crack the throttle wide open it will bog right out. What kind of riding do you do? Cuz there are things that I no that you can do to help fix the problem.

Slide #8 will not work fpr a 125 .... Get a #6 or a #5.5 instead

You can compensate for that #8 slide by putting a 48 or 50 pilot in there.  Your pilot is too lean that is why it bogs when you mash the gas. 

All 2 strokes will bog down when underneath the power band. If your riding slow and not in the high RPM's and you crack the throttle wide open it will bog right out. What kind of riding do you do? Cuz there are things that I no that you can do to help fix the problem.

 

Really?  I have 2 of them and neither do that.  In fact my 250 in 1st gear will throw you off the bike if you mash the gas right off idle.  the OP's pilot is too lean and that is why it bogs.

Really? I have 2 of them and neither do that. In fact my 250 in 1st gear will throw you off the bike if you mash the gas right off idle. the OP's pilot is too lean and that is why it bogs.

well then maybe I have a problem with mine as well but I'm also riding a 125. Not a 250.

well then maybe I have a problem with mine as well but I'm also riding a 125. Not a 250.

 

My 125 (with an eric gorr 144cc big bore kit), is the same way.  I can be just about at idle and crack the throttle and there is no bog.  It pulls hard and will lift the front wheel while accelerating, shift into second and it lifts the wheel then too, shift into third, same thing.  No off idle bogs.  If you have an off idle bog it is because the pilot circuit is too lean, or you need to richen your needle circuit or both. 

Ok sounds good, I was actually going to richen up the pilot, when I do I will report back.  Should I really consider the 5.5 slide out of the earlier cr250 carbs? I do have a number 7 slide on my cr250 that I can swap.

Ok sounds good, I was actually going to richen up the pilot, when I do I will report back.  Should I really consider the 5.5 slide out of the earlier cr250 carbs? I do have a number 7 slide on my cr250 that I can swap.

 

The 5.5 is better for a 125.  I am running a #7 on my 144 big bored 125 and I like it better than the 5.5.  If you have a #7 that you aren't using, it will help because it is richer than the #8 you have. 

A  CCK or a DDK  needle, The CCK has a harder hit, with 50 pilot and a 182/185 main seems to work similar to N3xx Yamaha/KTM needles and is a little richer, which will get rid of the off idle bog. 

Edited by rtv

CCK or DDK huh?  Well I just threw in a 50p and 180m and the #7 slide and it still does the same thing, I even swapped the pwk on my cr250 just to be sure and no bueno.  Its very strange because it only happens with the rpms are real low and I go wot instantly, if I go half throttle or so it is ok.  The mid and top pull great, front wheel comes off the ground.  I really don't think its a lean issue, gotta be something else at this point.  Thinking of buying a phathead for a little boost in compression...

As you describe it me too i would say it is lean. Usually you should be able to get rid of such  bog by going 1 step richer on the needle position. Thus if you are now in 3rd groove from top try the 4th. If that still doesn't help try even 5th.

CCK or DDK huh?  Well I just threw in a 50p and 180m and the #7 slide and it still does the same thing, I even swapped the pwk on my cr250 just to be sure and no bueno.  Its very strange because it only happens with the rpms are real low and I go wot instantly, if I go half throttle or so it is ok.  The mid and top pull great, front wheel comes off the ground.  I really don't think its a lean issue, gotta be something else at this point.  Thinking of buying a phathead for a little boost in compression...

 

What you are describing is the needle jet being too lean. I've run into this dozens of times while experimenting with different  needle jets. For $10 it's worth a shot, and I'm pretty sure it will solve your problem.

Im in the 5th slot already on the needle (n3cg). I will give those two needles a try. I do have the ne1i needle that nino runs, should i try it first?

Im in the 5th slot already on the needle (n3cg). I will give those two needles a try. I do have the ne1i needle that nino runs, should i try it first?

 

 

Sure,  give it a try, You're not going to hurt anything, but I think it will be to lean for you.  

If you are already in 5th why not just go up one size on the slow jet ??

A 8 slide seems also a bit off. Never heard of someone using that size.

Edited by nino

Ok I ordered both the CCK and DDK needles.  I will report back after I try both.  I also have a NAFF out of the KX carb and Im going to try it again to see how it does.  Those 250's are sooo much easier to get dialed.

Where are you guys ordering these needles from , my local parts guys basically throw a box of jets on the counter an say here ya go

Thanks a ton ill hop on tonight any thoughts for a bone stock 05 Cr125 michigan- sea level, 70F degrees ill buy a few but a good idea where to start?

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