Was running 150 main and now????

[Giz400ex]

I was running a 150 main with the needle to the 5th position and recently did some motor work and am in the process of getting it jetted properly. Questions I have is what to do now???? From a 150 to 165 main jet its still running too lean. After I got the motor work done I ask a couple of builders of what I should re-jet to and the only one that responded was LRD and told me to go up 1 main jet!! Well, I've gone up several and going by the plug its still running lean. Should I drop the needle a couple of positions???? or is there something I'm doing wrong here?????? Just to let you know that I have a LRD full exhaust w/an k&n filter with the lid off. Everyone's help is appreciated!!!! Thanks

[Wheelie]

Set the needle to one notch below stock, and step up to a #40 pilot jet. A 155 or 158 main jet should do the trick, unless you are over 2500ft. If thats the case, step down one to two sizes depending on elevation.

IMO, for jetting, go with seat of the pants feel. With all the additives in the fuel today, a spark plug reading can lead to inaccurate jetting.

Hope this helps, good luck!

[VegasEx'r]

Remember too that if it bogs at WOT, you are probably rich, and if it backfires when you let off the throttle real fast, you are probably lean (or have an exhaust leak). I still like to check my plug, but like giz said, seat of the pants testing is best.

[Giz400ex]

I am running VP fuel!! I believe its like 100 octane??

[VegasEx'r]

Race fuel will make the plug look lean. Listen for the "lean pop" or check to see if the motor bogs at WOT. Don't use a spark plug reading to determine if you are rich or lean.

[beerock]

WRONG!!!!!

race gas richens the bike up because of the higher octane....
race gas also gives a TRUE spark plug reading because there are no aditives in the gas to give improper plug readings
SPark plug reading are what all the pros jet there bikes according to :huh

[VegasEx'r]

Originally posted by beerock
WRONG!!!!!

race gas richens the bike up because of the higher octane....
race gas also gives a TRUE spark plug reading because there are no aditives in the gas to give improper plug readings
SPark plug reading are what all the pros jet there bikes according to :huh

I didn't say it makes your engine run lean, I said it makes the plug LOOK like it's lean (when it's not). I am just repeating what I read in VP's catalog under the FAQ. If VP doesn't know race fuel, who does? :confused:

[Giz400ex]

Ok!!!!!! Well, I'll see what I come up with and I would like to thank everyone for there input. Oh yeah, Vegas!!! Does VP have a catalog online or do you have there book????? I would like to read that!!

[VegasEx'r]

They do have a catalog online. It is at www.vpracingfuels.com (http://www.vpracingfuels.com/main.html) . There is also a printed catalog that I got from my distributor (more like a brocure), it had the FAQ section in it (I couldn't find it online), & I found that helpful, too.

[Giz400ex]

Also, between the 150-165 main jets it seems to run the same??? Its doesn't feel like any difference???? I've put a 152,155, couldn't do the 158 because there wasn't one, 160, 165 and you could put either one of these in and the 165 will run the same as a 155!! Does that make sense ????

[ride300exred]

Yes it makes sense main jets are only for 3/4 to full throttle.