2002 Kawasaki KX 250 jetting w/pipe..?

I know there's a ton of info out there and I've been doing lots of research. I just need figure out why it's cutting out right in the last rpm's of the powerband right before I shift up. I'm just an average rider that likes trails and wide open areas.

 

I bought this used 2002 Kawasaki KX 250 with a Pro Circuit Platinum chamber and had the stock silencer installed. I just took the silencer off and the tube inside the silencer was broke off with burnt up packing. I have a new Pro Circuit 304 Factory silencer on the way..

 

The carb is cleaned and has stock jetting  #165 and a #55 pilot and stock needle at in #2 position from top. The air/mix screw is opened at 2 turns. The bike is very responsive and doesn't backfire. The only problem is right before I change gears it sounds like its not getting enough fuel or spark to pull thru. My spark plug color is good with a nice golden tan look to it. I'm using a NGK Iridium BR8IEX. I drained old gas and put fresh 40:1 Amsoil Dominator / 93% octane gas mix.. Its an injector oil that is formulated to mix 50:1 to any spec. I just like the added oil for lube. I use this mix in all my 2 stroke for years without any issues. 

 

I cleaned all grounds to bare metal with dremel and used electrical grease on all connection including plugs. 

 

Here's where I'm puzzled.. I did a compression text and factory is 171 lbs. I use a Motion Pro compression gauge. With a cold engine and the throttle wide open I'm getting 215 lbs of compression. I can only assume there been some kind of boring or head work. 

 

Here's what I'm thinking: When the new silencer comes, I'll install it and test it out. If that doesn't work I'll go up to the next jet #168. Does anyone think I should try racing fuel..? What would you do if you had this problem..? THX..

 

 

 

 

Stock reeds? After market like dual stage and  carbon fiber will run richer...

PC says to run a 160 main and Air screw at 1-1/2.

 

http://www.procircuit.com/jettingspecs3.htm

 

Yes, I forgot to mention that I've checked that site out a few days ago.. So the PC jetting website is showing my model and what it is with stock settings and the Pro Circuit under the model # is the info I need to switch too right..? Thank you for clearing that up..!! 

 

Can anybody tell me if the set of 5 main jet kit on eBay $23.90 shipped are junk or ok to use..? Is a jet a jet or are there good quality ones vs junk..? Any links would be awesome.. I was checking out these and there $82.95 shipped for the set. If there worth it I don't mind spending the money but if the eBay jets work then I'll get them.. http://www.jdjetting.com/xcart/product.php?productid=22&cat=1&page=1 Thx again 

I'm assuming that in Indiana elevation is not an issue.

 

I have not heard of anybody with an '02 going bigger on the jetting. I am at 5,000' elevation so my needs are very different from yours but I run 155/52 jets in mine and the air screw adjustment tells me I could go smaller on the pilot even. The plug is a perfect chocolate brown after a "main jet" run or long moto. I have the FMF Fatty/Shorty combo and have not run a PC pipe/silencer on this so I don't know if they would react in a similar way or not. I also went to a two-stage reed which improved throttle response but I did not have to change the jetting at all.

 

FWIW.

I'm assuming that in Indiana elevation is not an issue.

I have not heard of anybody with an '02 going bigger on the jetting. I am at 5,000' elevation so my needs are very different from yours but I run 155/52 jets in mine and the air screw adjustment tells me I could go smaller on the pilot even. The plug is a perfect chocolate brown after a "main jet" run or long moto. I have the FMF Fatty/Shorty combo and have not run a PC pipe/silencer on this so I don't know if they would react in a similar way or not. I also went to a two-stage reed which improved throttle response but I did not have to change the jetting at all.

FWIW.

I'm around 760' above sea level.. I also forgot to mention I have the v-force reeds installed too. There in perfect shape with no chips or daylight. Could this affect jetting too..?

I have the #160 jet on the way along with the silencer. Once installed I'll report back. Thx

Update:

 

Great news..!!! I fixed my issue with it cutting out at wot.. It was all a jetting issue and maybe partially a silencer issue.. I installed a 160 main jet from the stock 165 and kept the rest of the settings stock according to PC specs. I also installed the new PC 304 Factory silencer and man let me tell you.. I can't believe the difference in power from start to wot and no more bog/cutting out through the powerband. I installed a new plug and rode it wot a few times then cut the engine off from wot and the plug color was like a chocolate brown color. Thx for all the replies..

Glad you got it figured out. A crisp and clean running 2t is a thing of beauty!

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