jetting my 87

[Banshee_370]

So I just picked up an 87. It has a fresh stock cylinder, rebuilt crank, fmf gold pipe and silencer, foam filter with no lid, new stock reedcage.

I decided to pull the carb, which I think is a stock pj.

It has a 45 pilot and a 148 main. It runs good in the mid but it feels like its lacking power up top.

Any ideas?

[1promodfan]

Originally posted by Banshee_370
So I just picked up an 87. It has a fresh stock cylinder, rebuilt crank, fmf gold pipe and silencer, foam filter with no lid, new stock reedcage.

I decided to pull the carb, which I think is a stock pj.

It has a 45 pilot and a 148 main. It runs good in the mid but it feels like its lacking power up top.

Any ideas?

It could be how your bike is set up. That FMF pipe, PJ carb, and stock reeds probably is only going to pull good through the mid-range. I'm not going to say that jetting doesn't help it run better, I don't believe its going to give it more top-end. Saying that, your main does control the from 3/4 to full throttle. Hope this helps you out a little.

[Honda 250r 001]

maybe try one richer on the main, 148 seems small to me, heck stock is a 150.

[86 Quad R]

have you performed a plug chop at WOT to see what color the plug is? if not, i'd suggest that and then rejet accordingly. if lean then i'd bump up one size at a time.

[Saul76]

Some jetting tips and reading .... might help you determine where you need to be and how to get there.

http://www.airfoolers.com/performance/jetting.html

Let me know if it helps at all. :)

[Banshee_370]

fmf says i should try a 158-160 main....any thought on this?

also, anyone use pro x jets from rocky mountain?

[zedicus00]

from experience i run keihin jets. im not necessarily saying they are the only good jets. more so that you should pick one brand of jets and only use them.

as for jetting i would say plug chop at WOT, but really i would almost stick the 160 in it before i did anything. i try to start rich and 150 sounds lean. (just a guess, theres too many variables to say what jets to use for sure.)

[Banshee_370]

yea i thought it was a little lean also...i am at sea level if that helps, sometimes go up to 1000 but thats rare.

[RyanWsly]

FMF settings were close for me when I had one with their system, if it doesn't run decent there, checking plug and air screw, electrical components could be getting weak, ran into that on one of mine, had to run everything lean and and it lacked power, couldn't figure out why for a while. I pretty much had good wiring and that was about it, every part I changed made it better but didn't fix the problem. CDI box helped top end out, went up like 10 jet sizes on the main, you should be around a 160 can't remember on the pilot but it's on their web site somewhere, Everything tested ok, just had to start throwing parts at it, just something to keep in mind, good luck.