Jump to content
Sign in to follow this  

Need help with JD Jetting... Cold Temps.

Recommended Posts

I installed the JD jetting today and I'm having some trouble. The bike runs terrible, I need some help.

2006 YZ250F

Conditions:

4500 Ft.

30-40 Degrees

Dry (Nevada)

Setup #1:

45 pilot

JD Blue Needle #4 clip (middle)

175 Main

This setup runs very poor, unridable on a track. Very low RPM and 1/8 throttle is OK. Anything above that the bike pops and is raspy and has no power at all. No top end power at all. Dangerously slow.

Setup #2:

45 pilot

JD Blue #4

180 Main

This setup runs better, but still not very good. As before, the first 1/8 throttle is OK. The midrange is OK, still not very good but a little better, unpredictable. WOT the bike falls short and it feels like I'm dragging an anchor. Midrange is boggy, but has better power than before. Bike bogs if whacked WOT at any RPM while riding.

I'm tempted to go back to stock on this, It ran better on the stock jetting for sure. I'm running a 45 pilot because it was giving me alot of popping and was hard to start hot without the choke. 45 pilot seems to have helped that.

What should my next step be? Should I try the RED needle. Or go up on the main again or maybe just adjust the clip?

JD or Burned, what can you suggest?

This JD jetting hasn't quite worked out like I expected.

Share this post


Link to post
Share on other sites

no... nothing else changed. Didn't remove the slide or the carb from the bike. I was suprised how poor it ran. Im guessing that it still lean on top, can that be?

The JD needles seem to be larger diameter than stock. Is that right? Do all JD kits use the same needles? Is it possible I have the wrong needles in my kit? I verified that I have the JDY003 kit.

Share this post


Link to post
Share on other sites

stock:

42 Pilot

178S Main

OBEL-Q Needle on #3 clip

Share this post


Link to post
Share on other sites

JD Jetting Says to Use White needle for cold Temps and use 170 Main to start withand 3rd clip and follow you manual on turns out of air jet screw, but that could be way diffrent when you use the JD Kit However i dont know what your bike is stock.

My Cr125 Is 172 main 50 pilot and 3rd on clip Stock from Factory But now im using white needle now i tried red and blue no good. im using 170 main but might go down to 165 main or up the clip one notch. Cuz White needle is rich for Cold temps. let me know if you tried white needle ok peace out good luck Jetting can be very touchy as we all know :applause:

Share this post


Link to post
Share on other sites
no... nothing else changed. Didn't remove the slide or the carb from the bike. I was suprised how poor it ran. Im guessing that it still lean on top, can that be?

The JD needles seem to be larger diameter than stock. Is that right? Do all JD kits use the same needles? Is it possible I have the wrong needles in my kit? I verified that I have the JDY003 kit.

The blue marked needle is much leaner than your stock needle at full throttle in this kit. Yes, go to the #185 MJ from the kit (per the instructions at sea level to 4000ft).

Thanks,

James

Share this post


Link to post
Share on other sites

Upon further investigation I was incorrect in my first posting. I started with the 180 Main and went to a 185. Still lean on a 185 at WOT? I find that hard to believe. Perhaps JD jetting runs a little leaner on the main anyway? The only real contributing factor I can think of is that the air is really really dry, (nevada high desert) and really cold. It was probably 30 degrees that day. Would I be better going up on the main again? or down a few on the needle. If I go down on the needle, that wont effect WOT correct, so better to go up on the main again? ... also up on the main might make the mid range too rich? ..Im lost again.

Share this post


Link to post
Share on other sites

Are you running pump fuel or a race fuel?

The next suggestion I would make is to run a clip position richer, at #5 from top. This would be a rare case with pump fuel and the red needle at #5 might be a better choice to richen the upper range and not lower.

Not sure... try Red #5 with #185 main

James

Share this post


Link to post
Share on other sites

Just a general question ....

Does the needle still come into play at WOT? I was under the impression that at WOT the needle was completely out of the jet and fuel is being pulled directly off of the main? .. ...Im not sure, just generalizing.

PS... pump fuel 91

Share this post


Link to post
Share on other sites

Have you tried covering one of the radiators while testing?

(close it off by putting tape on one of the plastic radiator protectors)

Maybe it runs to cold...

just an idea...

/Jerry - 2005 yz250f

Share this post


Link to post
Share on other sites

Do you think thats its possible to damage the motor running it as leans as mentioned in the first post? on a 180 and 185 main?

Share this post


Link to post
Share on other sites

I have had the same problem. I made many free mods to my 06 wr250f and ws going to put in the JD kit. After getting some great information from Mr J.D. I started the tuning process. I am at 4000' SLC,UT area and am dealing with cold temps too. I ended up with a 175 main, red needle on the 3rd clip down and the fuel screw out about 1 1/2 turns. Plugged my leak jet with a small bearing, plugged the ACV and removed the AIS system on the wr. Now the bike will freely lift the front wheel in 3rd.

I will do more tuning and adjusting as he bike breaks in and the temps change.

Jeff

Share this post


Link to post
Share on other sites

Yak,

The needle still affects the air/fuel mixture at full throttle. Using a smaller main jet would not have caused any damage. There is a wide range of tolerance with the main jet on 4-strokes where the motor will simply use less fuel and make less power.

James

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×