Fresh rebuild jetting question

[biggercb]

I finally got the jug back on my stepsons Blaster. I pulled the carb bowl last night to get an idea of where the jetting was at.....running a 360 main.

Bike is stock except for being bored one size over and running an FMF fatty with an FMF Q silencer. No air box lid...foam filter

After reading around, it looks like this may be fairly rich...maybe the previous owner had an air leak he was trying to cover up? Or does someone else have experience with this fat of jetting?

Oh, the plug I pulled out of the toasted top end had a good looking mocha color to it.......

Let me know what you think...fire it up and break it in with the 360, then plug chop and check the jetting...or swap to smaller jet from the get go...

 

[Blaaster]

First thing you do is a leak down test. A #270 - #280 main should do the job.

Running a #360 seems to say there was an airleak problem especially if the top end was toasted.

 

[sicivicdude]

First thing you do is a leak down test. A #270 - #280 main should do the job.

Running a #360 seems to say there was an airleak problem especially if the top end was toasted.

That air down your way must be thinner than up here

An FMF with no airbox lid around my way needs about a 300 main jet in the stock carburetor to be happy.

I do agree that a mocha colored spark plug with a 360 main jet is NOT right.

 

[biggercb]

I performed a leak down test late last night...have a leak around the reed cage gasket, I'll pull it back apart tonight and add a little silicone to seal it up. Dunno if that is what caused a meltdown or not, I installed all new gaskets...

Thats what I was thinking, maybe drop it down to a #280 and see how she runs...

 

[Blaaster]

#280 - #300 as ^^^^^ said depending on your location and elevation.

The air is better here in Aussie Sic.

 

[biggercb]

Arkansas City Kansas, elevation appox. 1080 ft above sea level