What's goin on guys ? Im in need of some help yet again with my blaster. I got her runnin pretty damn good for the most part, descent response from the throttle, no more sputtering or bogging in any gear or at any rpm at wide open throttle, ( slight sputter/ping when cruising at low speeds at 1/4 - 1/2 throttle openings ) but my main concern is the lack of acceleration when the powerband kicks in. The initial acceleration is pretty good but there's a flat spot when the power should kick in and it doesn't have the noticable pull like it use to. My front end use to lift when I would shift all the way through 3rd and 4th when I would get on it/floor it. This might sound weird but I was running a 260 main jet and when I plug chopped I felt like it might have been slightly lean so I bumped it up to a 270 and now I feel like there's even less power/pull then there was with the 260. I know the more nfo you guys know the better and easier it will be to try and pinpoint the problem so here it goes ... Fresh bore and hone to .020 over and new wiseco prolite piston ( .020 ) in March, Fmf Gold Series fatty pipe, powercore 2, vf3's, DIY +4 timing advance, no toil air filter, Uni air box vents, snorkel removed, stock mikuni carb, stock 32.5 pilot, 270 main, needle clip in the middle. I recently checked and there's no air leaks either. Any help or suggestions would be very very much appreciated, PLEASE help me get my baby back to pullin like she should. Thanks everyone !
flat spot when accelerating/No powerband ?
- Thread starter JBRoc01blaster
- Start date
bump that main up one more size and see if it gets better or worse, if better.. go up another size or 2, till you fell it bogging, then back down till it feels right
if worse.. return to the 260 and plug chop to confirm
i do see you're only at 550' above sea level, so richer jetting is required than those of us at higher elevations
my buddy is running a 300 main with an FMF pipe here at 1800-2400' ASL ???
and it rips
that advanced timing is gonna leave some top end on the table, in favor of more bottom end
if worse.. return to the 260 and plug chop to confirm
i do see you're only at 550' above sea level, so richer jetting is required than those of us at higher elevations
my buddy is running a 300 main with an FMF pipe here at 1800-2400' ASL ???
and it rips
that advanced timing is gonna leave some top end on the table, in favor of more bottom end
Aright my brother will do, thanks for the advice. I only have 230-280 main jets at the moment but I can get them for $3 at my local parts shop so that wont be a problem if I need to go bigger. I'm not sure if or how long they're open on Sundays but reguardless ill post my results tomorrow after I throw that 280 in there and take her for a spin !
Honestly I don't even know, I have messed with it before cause it use to idle high after it got hot so I lowered the idle some to compensate for it ( I found the air leak and fixed it ) and now I don't know where the idle should be. I dont have a portable tachometer and I don't know how to tune it properly ( besides the way in the manual which requires a portable tach ) anyone know where the idle screw should be at as far as the number of turns in or out ?
Justin warm up your bike, set your air mixture screw to one and a half turns out. Adjust the air screw out till the revs no longer hang, then set your idle to whatever keeps it running. Remeber to keep blipping the throttle while making small adjustments. The last time we rode your Blaster seemed to be running really well, what has changed. Have you checked your compression lately. I have a tester if you need one.
Idle adjusting.
Start with air screw 1.5 turns out.
Set idle screw so that it has some sort of idle.
Warm up motor and then set idle screw for a fast idle.
Adjust air screw either way to get the fastest idle.
Adjust air screw a little at a time leaving 10 secs to allow the motor to respond.
Re adjust idle screw for desired idle .
Start with air screw 1.5 turns out.
Set idle screw so that it has some sort of idle.
Warm up motor and then set idle screw for a fast idle.
Adjust air screw either way to get the fastest idle.
Adjust air screw a little at a time leaving 10 secs to allow the motor to respond.
Re adjust idle screw for desired idle .
Thanks Mike, maybe you could bring your compression tester next time we ride, I have been wanting to check where my psi is at just so I know ( especially cause I've never checked my compression : 0 ). It runs pretty good it just doesn't have the pull it use to, at wot my front end use to lift when I would shift right through 3rd and 4th gear. After thinkin about it that may have somethin to do with my clutch plates or my clutch adjustment. And I just don't feel the powerband kick in anymore, I hear it but the pull just isn't there for some reason ? I appreciate the help from both of you guys, maybe I'm just bein a little too fussy with the slight sputter/ping at the smaller throttle openings but I'm gonna go out and mess with the air mix and idle screws and see if I can get her runnin a little better. I'll post back my results later, and by the way your angry bumble bee came together very nicely bro ! Congrats on the successful build !
You have good reason to worry about a spit and a sputter, because it is a sign that something may be wrong.
I have replaced many a top end brought to me, with the owner stating that it was not pulling, and was spitting and sputtering a little.
I would not ride again until a compression and leak down test was done.
Play it safe, may save you a pocket full of cash.
I have replaced many a top end brought to me, with the owner stating that it was not pulling, and was spitting and sputtering a little.
I would not ride again until a compression and leak down test was done.
Play it safe, may save you a pocket full of cash.
I have the same problem there is a flat spot in the powerband! Did you ever figure out what the problem? Leak and compression test are good. I played around with the carb and still can't get it to pop like it use too. It's getting frustrating at this point. Can anyone help here or have any suggestions ?
