Banshee street bike - first (non)start

[xander450]

I think I did a bad job of describing what it's doing. Basically, it will idle fine, but it won't rev up. If I give it throttle it'll usually go up a couple thousand RPM (maybe 3-4k). But it won't even hold that - usually it will drop back down to idle speed, or just quit running entirely. With the choke on, I am sometimes able to get it to rev up (with throttle) to higher RPMs. I realize that suggests it's lean, but I've tested all the way up to 360 on the mains without a change - not to mention that, even with smaller mains (280, for example) I wind up with soaked plugs.

 

I haven't done a leakdown test. Are my symptoms consistent with an air leak? I figured that would give me an out-of-control rev, which is not at all what's happening... quite the opposite, an almost complete inability to rev.

[n2otoofast4u]

I think I did a bad job of describing what it's doing. Basically, it will idle fine, but it won't rev up. If I give it throttle it'll usually go up a couple thousand RPM (maybe 3-4k). But it won't even hold that - usually it will drop back down to idle speed, or just quit running entirely. With the choke on, I am sometimes able to get it to rev up (with throttle) to higher RPMs. I realize that suggests it's lean, but I've tested all the way up to 360 on the mains without a change - not to mention that, even with smaller mains (280, for example) I wind up with soaked plugs.

 

I haven't done a leakdown test. Are my symptoms consistent with an air leak? I figured that would give me an out-of-control rev, which is not at all what's happening... quite the opposite, an almost complete inability to rev.

 

F that leak down bs. If you put the motor together correct I'd skip that. Sounds to me that its a low end lean issue. It doesnt matter what your Mains are, if the bike is too lean to get up in rpm and need the main then they will never play a factor. Being that it will run correct on choke tells me its lean on bottom. Where are your needles set? what happens on a dry rev if you hit the throttle while its idling?

[xander450]

Needles are on the 2nd position from the top. And the rev issue that I'm describing is dry - if I give it throttle from idle it will rev up maybe a couple thousand RPM, then drop to idle or die. Under load it dies within a second or two.

[n2otoofast4u]

IMO I would richen it up on the bottom and see what happens

[xander450]

Ha, there's really no substitute for experience. Just went to 27.5 pilots and it revs up much more gracefully. I'm not there yet, think I still need to come up in the pilots a bit, but it's starting to act more like a bike.

 

Thanks again to all of you for the excellent advice.

 

Alex

[xander450]

So I've found some more time to work on this - here's where I'm at.

 

I think I found an electrical issue that was part of the problem - corrected, and now it'll ride with chokes on. Still haven't found the right jetting. I'm currently at 27.5 on the pilots and 340 on the mains, for a trinity stage 2 ported motor with a decked head, VM32 carbs, uni pods.

 

Thoughts? Main seems pretty high as is, but it's still not making much power when it revs, and it bogs pretty hard around 5-6k.

 

Plugs wipe clean, hardly any brown at all, but they're a bit wet. Wet suggests rich to me, but clean suggests lean... wtf.