300ex help...

[drifterx]

Well, i took my airbox lid off on my 300 last night. I have an HMF s/o too) I had in a 118 MJ like Dynojet said for an aftermarket exhaust, airbox lid on, and under 3000 ft. I went up to a 128, for the same conditions, but airbox lid off (this was the stage 2 from what they said) I started it up, and gave it some gas, and it idled well after it ran awhile, but it would sputter if i punched it, and i even saw a bit of flame coming from my pipe, as it started to backfire a bit. I could rev it up all the way if i rolled the throttle on. This can't be normal, right? It wasn't warmed up completely, maybe it'd be different after a while, but i don't want to ride it, since i'm leaving for LS in 2 days, and i got my bike all shined up, plus it snowed here. I checked my plug after my stage 1 rejet, and it was good and tan, so their info was spot on, so i figured it would be with the stage 2. Any suggestions?

[TarheelRedRider]

Sounds like you need to faten it up. Its running lean.

[drifterx]

Well, I just broke down and took it for a wet sloppy ride. Once it warmed up, it pulled hard through every gear, and didn't backfire or sputter at all, so i think it might be ok. It had a lot more kick, and accelerated faster, plus i could wheelie in 3rd gear, which i couldn't do before without yanking the handlebars up. I had it going about 3/4 throttle in 3rd, and i shut it off, and coasted into my garage. I'm letting it cool down now, i'll pull the plug and see what it looks like.

[drifterx]

Pulled the plug, and its a very light tan color. Its not white, so i'm good i guess. Probably just wasn't warmed up good enough, i only had it running for about 45 seconds the first time. Thanks for your help TarheelRedRider, i appreciate it. :cool:

[quadfamily]

Sounds like it could still be lean. I changed just the head pipe on my 300, warmed it up, and the head pipe started to glow orange in my shed. I didn't even ride it. The plus was almost white! I ended going up one size in pilot jet and I forget how many sizes in the main jet but I'm thinking it was 2 or three sizes(and that was just the head pipe with stock silencer!). My plug is always like a light chocolatey brown now, not black at all and definately not white. Start with a new plug when you're doing plug readings for jetting and only look at the porcelain to take your readings.

[drifterx]

I just took it off again to double check, and the porcelain was light tan too, like a light khaki color. It could be just a smidge lean, but it's the biggest jet i got with my Dynojet kit, and it isn't white at all. Maybe i'll pick up some jets from my dealer sometime after my trip to LS and do some more testing. What would a 128 MJ Dynojet be compaired to a normal jet? Anyone know?

[bwamos]

Did you adjust your needle? You need to move the needle clip down one spot to slot 4 (raising the needle one position). Sounds like your mid throttle is too lean.

[drifterx]

Originally posted by bwamos
Did you adjust your needle? You need to move the needle clip down one spot to slot 4 (raising the needle one position). Sounds like your mid throttle is too lean.

Yes, did that earlier, and it said use the 4th on stage II also. It ran great when i had it out yesterday, after i got it warmed up, so i'm not too worried.