2002 Kawasaki KX 250 jetting w/pipe..?

[xdriver72]

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..

 

 

 

 

[Blackwoodz]

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

[xdriver72]

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 

[firehunter]

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.

[xdriver72]

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

[xdriver72]

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..

[firehunter]

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