jetting 03 KX250 to pc pipe

[tristan18au]

i have just purchased a Pro circuit platinum pipe for my 2003 KX250 which is bone stock and was wondering whether anyone can help me with jetting my bike, im running silkolene 2sx plus at 32:1 with 95ron pump gas. all jetting is stock at the moment but i just find it a difficult task for my self to jet this bike with out screwing it up. any help would be great.

 

[SpectraSVT]

Call Pro circuit. They look it up in 5 secs. Only place I could get the info for my bike.

 

[a454elk]

Usually they have you drop the main jet down a couple of spots and make the needle one notch leaner. If you can't call Pro Circuit from their, let me know and I'll call and get your specs for you. Oh, and make your air screw one and one half turns out, usually, for normal conditons.

 

[joereitman]

Been considering the pc for my 03, let us know how it works. I would like more upper mid and top.

 

[a454elk]

That's exactly what that pipe does, mid to top. Works great on mine.;)

 

[joereitman]

thanks!

 

[tristan18au]

i cant phone pc so that will be great if you can for me. mean while i have gone to 180 main jet from 162 and turn the air screw out 2 1/2 turns and left stock plito and needle and clip pos and it seems to be going strong, i did a plug chop at full and half throttle and the plug was taned brown and just slightley black.

 

[a454elk]

Air screw is right, needle clip they say needs to be one notch leaner and the main jet was supposed to go the other direction. At stock, they are usually real rich. I believe PC is closed Sunday so I'll get it on Monday for you, if that's cool. What elevation are you at?

 

[tristan18au]

180 feet (56m) above sea level and the temp is around 18-37 degrees celcius. thank you very much for doing this for me.

 

[HobRoff]

For what it's worth Tristan, I have an 02 kx250 -PC pipe and spark arrester. I run maxima 927 40:1, 100 octane aviation gasoline, 160 main jet, 52 pilot, needle one clip leaner, air screw 1 1/4 turns out. In the middle of a top end rebuild - all componets look great. The bike runs clean and strong. Eric Gorr is currently waving his magic wand over it as we speak, er, write. Good luck!

 

[a454elk]

Those setting sound right, my airscrew setting was way off, sorry (just adjusted my WR fuel screw at that setting:)). I'll call tomorrow and post it for you, they are only 5 miles from my house.;)

 

[a454elk]

OK, here's the deal from PC. They said 162 main jet, 50 pilot, 1 1/2 out on the air screw and you need to use a different needle (part #NAFG) from the dealer and set it in the #2 clip position. I asked if you could still run the stock one and they said you really need to change the needle. Hope that helps, good luck.

Elk

 

[tristan18au]

thank you

 

[HobRoff]

Tristan, do you have an owners Manual? I know they miss giving them out here in the states sometimes - it will point you in the right direction. Also a very good source of info is Eric Gorr's book which is probably available from his site with a new edition in the works. What is the bike's use going to be? i.e enduro, motocross, etc. Keep tweakin, it'll work out and thats all part of the fun to me. Cheers! Oh, another cool book that gives away my age, is "Design and Tuning for MotoCross" by Jim Gianatsis. Out of print but still available.

 

[joereitman]

This is a lot of good info. My 03 KX250 is almost 3 out on the air screw (need to go 1 leaner on pilot), needle in top clip (need to go to a bigger (Leaner) needle probably, especially next summer, and I will probably go a little leaner on the main once I get a pipe. Any thoughts on this? Thanks.

And HobRoff- be careful with that AV- used to run it in my turbo car til I learned it was formulated especially for steady rpm airplane engines, maybe not so good for car and bike engines. Though it sure is cheap, and is a good thing to mix in, in moderation.

 

[tristan18au]

i had a bike mechanic look at it today and he jetted it for me, he left stock needle and setting went to a 168 main from my previous 180 and 165(stock) and left stock pilot and turned the air screw out 1 1/2 turns, now it is very very fast this thing is and animal up mid and top. although it still is a tad rich down bottom but its going good now and i have given it one hell of a hiding in 30+ degrees C and its not batting and eyelid. (to the extent where the silencer packing caught on fire). thanks for alll your input guys.

 

[HobRoff]

Joe & all, Phoned Mr. Gorr to check up on the cylinder status - should have it back in 10 days or so, no hurry - no riding around here for at least another month unless I hit one of the indoors, and the bike is spread all over the shop anyhow. He said that everything indicated the bike is still running a bit rich, which is good cuz I was wondering if I was on the lean side of things. I was curious about the Av gas and asked him about it and he said there wasn't anything wrong with using it, it is what they normally run in Europe and it is better than premium pump gas. I know it isn't as good as the VP or ELF racing fuel but it is all I can afford as a dirt junkie, and all I gotta do is just run up to the airstrip and fill up my jug. As far as jetting goes a leaner needle will probably be my only change. Cheers!!

 

[joereitman]

Glad you asked him about the AV- the car turbo guru's all are scared of the stuff and made decent arguments against. But Gorr is the man in the 2 stroke world so I'll trust him. I can get it cheap, and used to mix it in the turbo car. Just got tired of the exhaust smell. No cat, side pipe, bad smell. Maybe I'll mix it 50-50 to be extra safe. I would like the 100 octane and the anti detonation benefits of lead. Then I could jet leaner and stil be safe...

 

[HobRoff]

Well, what I can tell you for sure is my bike runs pretty poorly on premium pump gas and the AV makes it very happy. When I pulled the cylinder the piston looked like I could run it for another season so I pretty much have it dialed in, and I love the way it smells with the castor in the morning -- reminds me of victory!!! (Robert Duvall- Apocolypse Now)

 

[bigred455]

Originally posted by HobRoff
Joe & all, Phoned Mr. Gorr to check up on the cylinder status - should have it back in 10 days or so, no hurry - no riding around here for at least another month unless I hit one of the indoors, and the bike is spread all over the shop anyhow. He said that everything indicated the bike is still running a bit rich, which is good cuz I was wondering if I was on the lean side of things. I was curious about the Av gas and asked him about it and he said there wasn't anything wrong with using it, it is what they normally run in Europe and it is better than premium pump gas. I know it isn't as good as the VP or ELF racing fuel but it is all I can afford as a dirt junkie, and all I gotta do is just run up to the airstrip and fill up my jug. As far as jetting goes a leaner needle will probably be my only change. Cheers!!

..........


Expect the AVGAS 100LL to run rich on the main,but don't count out the needle and pilot. I live in jersey, summer months had to drop 3 on the main from stock when switching from pump to AV GAS, 1 on the pilot. The needle and clip were fine . Temperature dropped to 55 degrees My needle was lean had to move from 2nd stock to 3rd clip ,the main was still on and so was the pilot. Do not jet by me,see for yourself please,but if you are jetted pretty close on pump, expect to motor to run a little rich when changing over to avgas. Also the weather may be cooler from when you last rode so the switch over to av gas might not need a change.

 

[HobRoff]

Thanx for the feedback, been runnin Av 100LL for quite awhile now, read back about 10 posts. Sounds like we're jetted just about identically, I am still a bit rich. Having my cylinder bored out to the 265 and ported so I will leave things where they are, need to be richer for the break in anyway

 

[bigred455]

Originally posted by HobRoff
Thanx for the feedback, been runnin Av 100LL for quite awhile now, read back about 10 posts. Sounds like we're jetted just about identically, I am still a bit rich. Having my cylinder bored out to the 265 and ported so I will leave things where they are, need to be richer for the break in anyway

..............
Gotcha on the running the avgas for a while, I rushed through the post's . I gaurantee we are not even close on the main,I would scare you if I told you what main I am running,but I have a totally different set up. I did though STOCK MOTOR have to move 3 down on the main switching over to AV.