Running Lean! Main Jet Questions

[BastinPastYou]

So I just got my Blaster yesterday (runs strong!) and I already have it all apart oiling cables, making adjustments, replacing worn out parts and cleaning the carb. Gotta get ready for the first big snowfall! It has a full FMF exhaust and bored 60 over. Thanks to the service specs sheet/thread I learned that the stock jetting was 230. When I took the carb apart I learned that it still had the stock 230 jet!! Along with the parts came a new 240 jet still sealed up. I assume that they put the exhaust on and were too lazy to rejet!? Sounds like it could have been running dangerously lean with the mods?

My question would be if its bored 60 over with full exhaust is 240 the proper main jet to put in? How about if I were to run it with airbox mods (no lid or drilled out) then what would I want to run for a main?

Thanks!
Eric

 

[hickskateboarder]

it probably was runnin lean, throw the 240 in there and do a plug chop. if you take the lid off ur probably gonna have to be like 270

 

[cirame1]

yea ide pull the lid off now and just start jetting to it instead of jetting to it now and then taking lid off and jetting again ide graba 270 and 280 main with no lid.

 

[xjma]

I've got an FMF fatty and no airbox cover and 270 works for me.

 

[gscx2.0]

You cant tell him what size jet he needs just from what he said. For all we know he could be 10000 ft above sea level and 110F.

 

[xjma]

You cant tell him what size jet he needs just from what he said. For all we know he could be 10000 ft above sea level and 110F.

I didn't tell him what was going to work for him, I told him what works for me. If he wanted a better answer, like it's going to depend on your elevation, he should have been smart enough to post his location.

 

[CC&Fabb]

I am running rull FMF with K&N filter bored .10 over and I am running a 250 main.

 

[coreyownz]

I've got an FMF fatty and no airbox cover and 270 works for me.

me too

 

[BastinPastYou]

I live in CT. Below 5K feet I think.

 

[89custom]

not sure about elevation factor, but if you have a fmf pipe and the airbox lid off and bored .060 over id say a 260. better to be richer then plug chop and have to adjust down in jetting then to burn your rings by having it running lean.