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CR125 jetting problem...Experts Please Reed!!!

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Posted by: Durt Cycler---------------------

My Cr runs absolutly perfect and my throttle response seems great but from idle it seems u have to crank the throttle from idle postion to wide open 2-3 times to have it rev real high cause it don't on the first twist. I pulled the plug today (RN2C Champion = NGK BR9ES) and it seems the bike was running rich. I also had some a wet mist of spooge on the real fender. I am running VP C-12 with Motul 800 @ 32:1. The spooge started when I first started riding it today at low speeds untill I got my crap together and took my bike for some wide open running (holy crap it's fast! ) and also kept the RPMs up when I wasn't wide open riding. Here are the jetting specs also.

Stock Jetting
-172 Main Jet
-58 Pilot Jet
-R1469N Needle
-3rd Clip Position
-Air Screw 2 Turns Out
-NGK BR9EG plug - Champion QN84

Current Jetting
-165 Main Jet
-55 Pilot Jet
-R1468N needle
-3rd clip postion
-Air Screw 2 Turns Out
-NGK ????? - Champion RN2C

I have a FMF Fatty pipe, Boyesen Pro Series (CF) reeds, Pro Design Cool Head, and running VP C-12 fuel. I was thinking maybe I should turn my air screw 1/2 turn out and going 1 size lower on the pilot jet (52). Also running a NGK "8" heat range plug. I noticed the different plug codes from my manuals Champion plug code and the plug the lady at the hardware store gave me from a cross reference to a NGK BR9ES (hopefully she didn't give me the wrong plug ). Also could this be from a over oiled filter causing it to run rich? I don't think I over oiled the filter but that is a posibilty. Sorry for the loooong question but someone please help me! :whiner:


Posted by: Jaybird---------------------

Durt,
Look in the lowest part of your airbox. If there is a puddle of oil, then yes you have over oiled it, and yes it can cause spooge.
My personal thought is that many folks have jetting woes that can be traced to an overly oiled filter.


Posted by: Durt Cycler---------------------

Ok Jaybird I just took my seat off and looked into my airbox and found no puddle of air filter oil in there. There was tiny thing of dirt/mud in there and on the filter but nothing got through the filter (airboot was clean as can be). I am in the process of cleaning the filter and I will re-oil but this time I will give it a light coat so you don't see any blobs of air filter oil on it (good thing about Twin-Air filters if you can see how much you put on the filter).
I'm still leaning towards a 8 heat range plug and MAYBE i should go leaner on the clip position (1 slot up). Turn my air screw 1/4 turn out not a full 1/2 turn and see about a 52 (?). :think


Posted by: soquel---------------------

It sounds like your pilot jet is too lean and your main is too rich, but I'm no expert, eric gorr's website has a great jetting guide.


Posted by: whyz---------------------

I'm no expert but when i wick my throttle from idle it responds right there braaaaapppp!!!.which on my bike i had to turn the AS in. I started from only 3/4's of a turn out first and checked response from idle then kept turning out until it bogged then turned it back in to find the best response off idle.now its at 1 turn out . Have you tried it at only 1 turn out and see how it responds?
With my bike i found that i went richer on the PJ, 2nd notch on the clip,and leaned the MJ one. I know these are 2 different bikes but i think the variables are still the same. :think
See Ya.
Take it Easy.


Posted by: Durt Cycler---------------------

Hey whyz, from the help of nikki I started to mess with the air screw. It was set at 2 turns out *factory setting* and I had the bike idle very low on it's own. I then started to turn the air screw in and when I had it all the way in the bike died. I then started it with it all the way in and it didn't like idle or 1/8 throttle . I then set it back to 2 turns out and had it idle on it's own. I started to turn the air screw out and didn't noticed a peak in the idle's RPM untill I got it almost out at like 5-7 turns out I lost count LOL, then you could hear alittle difference in rpms. I beleive this means I should go leaner on the pilot (52), raise the clip to the 2nd position and run a NGK 8 heat range plug. I also found something else out. I made another thread about it in this forum it's under "Stuck powervavle causing jetting problems?". Check it out. Thanks DC


Posted by: IBWFO---------------------

go to 40:1 and get a new piston or at the very least get a new ring.
V-Force reeds will give you better low-end response and Boyesen will do better on top.
Is your plug a nice light gray or is it black?

D


Posted by: Durt Cycler---------------------

I'd like to stick with 32:1 because 40:1 will just cause richer condition over 32:1. The bike has gone through a major rebuild since December when I fell racing on a banshee so I put Race Tech 5.4 kg/mm (Thanks so much Jeffro ), recharged it to 175psi, all new brake fluid (Bel-Ray DOT4), '95 cylinder with Pro Circuit porting, Vertex Race piston, Pro Design Cool Head, gaskets, seals, o-ring gaskets, silencer packing, etc. The Boyesen Pro Series (CF) reeds gave a much throttle response coming from the fiber glass Power Reeds. I'm happy with the way it runs and how the power delivery is I just want to get the last peice of the puzzle fixed (jetting). Like I said in the first post my plug came out black, but not real oily and it sitll gave out great spark. I don't think Motul 800 oil likes low RPM riding so I'm gonna try Maxima Super-M which has a low flash point. Also don't think I will run the gallon of Klotz BeNOL I bought after I heard it clogged up everything fi you don't keep the bike pinned..:whiner:


Posted by: IBWFO---------------------

I just told you what we (my son) has been running for the last year on his CR.
What you described would lead me to re-ring or both piston and ring.
We run Motul 800 mixed 60:1 with MR2 and we run a Factory Honda ignition we got from the Plano Honda team. The bike eats plugs now but man does it run!

D


Posted by: Durt Cycler---------------------

Yea I used to run Motul 800 50:1 when I first got my bike cause I thought "hey this oil is really thick and expensive, why can't I just mixed it alittle less over others oils?" The bike ran great untill it would foul a plug after a few hours of riding but it ran like a champ for those few hours! I just had enough Motul premix to mix up with 4 gallons of VP C-12 @ 32:1 so I did.


Posted by: whyz---------------------

Thanks for the info bout the powervalves..
Yeah,, nikki has helped me also,,she's >>>

Do you know if the idle screw has anything to do with the As?
:think Just asking.
Thanks.


Posted by: nikki---------------------

Quote:
Originally posted by whyz

Yeah,, nikki has helped me also,,she's >>>


Awww... thanks guys! <blush>



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