Lean? Air leak? Wtf!?

[xander450]

Got a trail ported motor with a decked head, Wicked pipes, boyesen reeds, VM 32 carbs, and uni pods at 500ft. It's jetted right now at 27.5/340. Idles great, but hardly makes any power at throttle, and doesn't smoke nearly as much as I think it ought to. In the revs it makes good power with the choke on, but not without. Plugs are just confusing - usually a bit wet, but ring and base cone is white.

 

Here's where I'm losing the plot: 340 seems huge as it is for the light mods this bike has. But it's not doing the things I associate with an air leak either - idle's stable, revs aren't running away, etc.

 

What am I missing?

[bluebanshee98]

Got a trail ported motor with a decked head, Wicked pipes, boyesen reeds, VM 32 carbs, and uni pods at 500ft. It's jetted right now at 27.5/340. Idles great, but hardly makes any power at throttle, and doesn't smoke nearly as much as I think it ought to. In the revs it makes good power with the choke on, but not without. Plugs are just confusing - usually a bit wet, but ring and base cone is white.

 

Here's where I'm losing the plot: 340 seems huge as it is for the light mods this bike has. But it's not doing the things I associate with an air leak either - idle's stable, revs aren't running away, etc.

 

What am I missing?

have you checked your flywheel/stator pickup gap? gap it at .018. if it runs good with the choke on you prob have a air leak. you can buy a leakdown tester here

http://bansheehq.com/forums/index.php?showtopic=154986

 

if you can jet up and down with no change and have no air leaks then its electrical. have you done a plug chop? do that first, saw away the threads on the plugs and see what it reads. post pics of the plugs here

[xander450]

Pickup gap is set. Done a plug chop (though I hope you're kidding about the threads...), it certainly looks lean, no carbon deposits of any sort, plug looks a bit wet but wipes completely clean.

 

More to the point, is it possible to have an air leak that doesn't affect idle but causes the bike to require a massive main jet?

[bluebanshee98]

Pickup gap is set. Done a plug chop (though I hope you're kidding about the threads...), it certainly looks lean, no carbon deposits of any sort, plug looks a bit wet but wipes completely clean.

 

More to the point, is it possible to have an air leak that doesn't affect idle but causes the bike to require a massive main jet?

no i am serious. you have to take the plugs out. put it in a vice and saw the threads off so you can see the whole thing. i use a dremel tool ( alot easier then a hack saw) are you sure you did the plug chop correctly? not to bash you or anything but if u didnt know to saw the threads away to get a good reading and see whats really going on in there you might not be doing the chop correctly either. YES ITS VERY POSSIBLE. my bike had a air leak and i was running huge jets to compensate. it would idle fine start fine and even run fine up untill redline. i had a leak and i needed new spark plug caps. i was getting a rev limiter type of effect at redline. get a leakdown tester bro. you def need it

[Poolman]

Got a trail ported motor with a decked head, Wicked pipes, boyesen reeds, VM 32 carbs, and uni pods at 500ft. It's jetted right now at 27.5/340. Idles great, but hardly makes any power at throttle, and doesn't smoke nearly as much as I think it ought to. In the revs it makes good power with the choke on, but not without. Plugs are just confusing - usually a bit wet, but ring and base cone is white.

 

Here's where I'm losing the plot: 340 seems huge as it is for the light mods this bike has. But it's not doing the things I associate with an air leak either - idle's stable, revs aren't running away, etc.

 

What am I missing?

 

 

You are running way big on your mains. Such over compensation on the mains is making the bike run like it should at least at idle and some throttle. Your so big on the mains though that the bike cannot eat the kind of fuel your feeding it full on.

 

Honestly, Have you done a leak down test on your bike ?

 

At your elevation with pipes, pods, even +4 timing, your mains should be between 260 - 280.

 

The leak will continue to grow and if you don't keep upping the jet's it will end up lean and then you will pay a huge price for not finding your leak or leaks.

 

Ask around if you think I'm stroking you.

 

http://bansheehq.com/forums/index.php?showtopic=154986

 

Take Care !

[xander450]

Cool, thanks to you both. I'm quite certain I'm not leaking from the carb side, and it's time for a rebuild anyway - I figure this is the final bit of inspiration I need to rebuild with the serval kit I've had sitting around a few months.

[Poolman]

Cool, thanks to you both. I'm quite certain I'm not leaking from the carb side, and it's time for a rebuild anyway - I figure this is the final bit of inspiration I need to rebuild with the serval kit I've had sitting around a few months.

 

Good deal and the first thing your going to do after the rebuild and before your first start is a

 

Leak Down Test - It must be done