Jetting Mystery

[300excrazy98]

My R is a night mare. It runs some days, others it doesnt. After rebuilding my rear end, and getting the frame welded up, the quad has been disassembled for about a month now, and yesterday, i finally have all the kinks worked out, have it ready to start up, and it was a cold day, so i sprayed a little bit of ether in the spark plug hole and through the plug in (BR9EG) and gave it a kick, started up and was reving VERY HIGH. so i tryed adjusting the idle, and nothing, then i went for the air mixture screw and adjusted that, and the idle came down, but still pretty high. I pulled the plug and it was black as night, im running reg. pump fuel 32:1 with amsoil Dominator oil.

Main Jet- 185
Pilot 48??
A/F screw 1 turn out
needle middle clip

The carb is a 38mm Pj Keihin

Mods on the bike are-

Duncan Port and Polish
Bills header with lrd silencer
Boyosen Rad Valve
Carbon fiber reeds
38mm PJ keihin
K&N Filter
machined head
cases machined out for 340
cylinder is only bored 0.030 over

Thanks

Also it seems to run better with the choke out

[deathman53]

is this regular 87 octane or 93/94 octane?? A low quality fuel may contribute to the factor. I would check for airleaks, 185 is very rich. Based on your mods, I would say you need to use race gas, anything above 190 psi requires race gas(108+ octane)

[TheFontMaster]

I would start by taking the carb apart to clean it. It has been sitting for a while and could have gotten some crap in it. After that try switching to 93/94 octane gas, and run the amsoil pre-mix at 40:1 instead of 32:1. It won't hurt anything. The next step would be to lean out your jetting. I would go down to around a 45 for the pilot jet, and a 170-175 for the main. Do a plug chop after that and see what you have. You want a nice rich tan/light brown color on the plug. See if you need to go higher, or lower on the jets. You also might want to move the needle clip up one position.

[GPracer2500]

Sounds like an air leak.

[canada250r]

I'm sorry for this question, but what does "plug chop" mean

[300excrazy98]

well i think the boot on my Rad valve doesnt go all the way into the carb, causing a leak. I am going to have to check that out tomorrow... Also it what does it mean when it runs beter with the choke on ?

[methyman]

It means the motor is running lean with the choke on and it idles ok. Your adding more fuel to it to make it run better. Sucking air from some place!

[300excrazy98]

ok so i need to figure this leak out... also what should my jetting be? around... thanks

[canada250r]

just regarding this air leak. where would one look for it. Is it not true that an air leak before the intake will or should not effect the motor, but after the intake IE the base gasket will effect motor performance.???? Is there any truth to this. And if not how do you find the air leak????

[300excrazy98]

The right way to find an air leak in the engine would be to do a leak down test. However I think that my leak is where the carb goes to the rad valve. My boot is a little short so i think that could be the problem in my case. I haven't been able to check it out yet, but tomorrow i will definately look into it.