Jetting problems

[blaster003]

I have a 2003 yamaha blaster that I have installed an fmf powercore 2 and has a 260 main jet with a 32.5 pilot jet and the needle clip on the 3rd slot. I jetted it based on the fmf website and it bogs at half throttle but when I remove the airbox lid it runs fine I have had this problem once before with my stock exhaust but I fixed it with adjusting the float level but it is not running the best with the fmf should I keep the lid off but I ride in dusty conditions I want to keep the lid on but it just won't run right. If anyone could help me thanks.

 

[tbrooks]

Did you add just the silencer, not the fatty pipe? If so I don't think there is really reason to up the jet, but riding with the lid off would just about compensate, prob still on the rich side. You could get an outerwears for the filter, I hear K&N work better for dusty conditions. Plug chop to confirm your jetting

 

[speedyslyder]

what is the air screw set at? it should be at 1.5 turns out from fully seated.I had that problem myself but with the toomey exhaust. i also had full fmf with no trouble with the lid and snorkel on

 

[blaster003]

It has the full exhaust setup but I can't figure out why it is running this way

 

[98blaster]

Is everything else stock?

 

[blaster003]

Yes

 

[98blaster]

Did you read the note on the fmf jetting chart? If not go look at it again

 

[Larry's Shee]

what is your elevation and temps?

 

[Blaaster]

Silly question I know, but you said you run in dusty conditions.

How clean is the air filter?

Check the float level, make sure it is not flooding, and adjust the idle as per specs.

Try the old trick of pulling on the choke whilst riding, if it gets worse you are too rich, better you are too lean.

Plug chop to confirm the jetting.

 

[Wifesblaster]

Well leave the lid off! If you need to run a lid due to mud, water, ect go 2 sizes down on the main.

No two bikes are the same. Don't put to much faith in FMF's website. We run a 270 main on our bikes with full FMF and no lid at sea level. This doesn't mean you will run the same. It should be really close though.

All jetting should be done AFTER the motor has passed a leak test, filter has been cleaned, and no leaks from flange to header.

 

[blaster003]

The note on the jetting chart said removing the snorkel. I removed the snorkel and it ran fine but after riding a while it started doing it again

 

[Larry's Shee]

The note on the jetting chart said removing the snorkel. I removed the snorkel and it ran fine but after riding a while it started doing it again

Is the filter getting dirty in this period of time (how long?)
Unless mud/water is huge problem, leave the lid off, you will actually make a bit more power.
If you really need the lid, drop the main one size and plug chop/read.

 

[speedyslyder]

you can put breather plugs on top of your lid as well...there like ten bucks or so..