Jetting Starting Point

[turnchaser]

1987 TRX250R. Stock carb. I just bought it and it is way rich. I want to redo the carb completley. FMF full exhaust and a boysen rad valve, otherwise it is stock(Thats what I was told). Freshly rebuilt with stock size cylinder.

Mixture ratio and fuel: 32:1 93 pump fuel and amsoil dominator oil.

Keihlin Carb PJ standard bore

Main Jet size: Have not been inside yet.

Slow (pilot) Jet size:Have not been inside yet.

AirScrew (number of turns out):Have not been inside yet.

Needle (what groove is the clip in, Brand, etc):Have not been inside yet.

Reed brand and type:Boysen Rad valve

Airbox: no lid on airbox

Pipe: fmf full system

Engine Displacement: standard 250cc

Compression ratio: stock

Porting type:stock

Altitude: where you normally ride 500-1500feet.

I just want to know what to order for now. I read that OEM jets are best, better build quality. Is this accurate?


Does the rad valve affect jetting?? I cannot find an answer to this!

[08 BANSHEE]

32:1 with amsoil.. i think you cn run like 40:1?

[Les]

I am still learning to jet my 250r as well but I think a good starting point for you might be 158 on the main possibly 160. You are getting more air in with the box open and the reed cage, the pipe in my opinion isnt doing much for you though, prolly chocking it on the exhaust since I think the fmf is kind of a stock clone. For you pilot follow these instructions. http://www.duncanracing.com/techfaq/...-jetting.phtml

[catch me if u can]

i run amsoil and i mix 44 to 1

[turnchaser]

Ok It looks like I will be running 927 oil next(hearing too many good things about it). Is the only jet I have to change the main and the other I'll move the clip and keep the needle? What if I switched to my LRD exhaust(team B) It is full of carbon and I don't know if I should try cleaning it?

[chavo80]

yup,
44:1 maxima with 93 is what i run.
stock jet for your 87 is: 152 main/48 slow.