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Amazing low-mid, nothing up top...


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I didn't wanna start another goofy "my banshee isn't running right" thread but I'm gonna have to do something here. I've got a good idea of what's going on but I wanna make sure as much as I can before I tear into it. I'd like to have it broken in and ride it this coming weekend and don't wanna be down any longer than I have to be. So, on to the dealio...

 

All I have aftermarket is a set of T5s, K&N-style filter with adapter, Boyesen dual-stage reed petals, stock port, +4 timing, 20cc domes, 280 mains and 25 pilots, airbox with lid and snorkel, nothing else that would affect fueling I don't think.

 

Here's what I've gathered so far... When ripping around in first or second gear it is amazing just slinging dirt and what not. The power comes on really nice like it should so I think the needle is in the right spot. Take it out on the road and try to run it through the gears and anything past about 1/3 throttle is junk. This is where I think it's transitioning from the pilot to the main and it's so rich that there isn't sufficient spark to burn the fuel. The reason for running the lid and snorkel is because I despise that WAAAAAAAAHHHHH sound from the open airbox. It's got plenty of power for me and sounds unbelievable without the annoying airbox noise so I'm not too interested in leaving it off even though I'll have tons more power without it. Plus I'll be riding in and around water so I don't wanna take the chance of having the whole "water in the carbs" issue. So what I'm gonna do tomorrow is take the lid off and run it to see if I'm headed in the right direction and/or if there are any improvements. I'm also gonna look at adjusting the air gap on the pick-up as that could give these symptoms too I'm thinking. The Yamaha manual and Clymer both say .017" but the paper I got with the Chariot plate says to put a piece of spark plug box in between the pick-up and flywheel and tighten from there. This is equivalent to about .020". That extra .003" could have significant effects on mid-high RPM spark IMO. So in short, it runs amazing from idle up to about 1/3 throttle. After that it stops pulling.

 

I know 280s are excessive for having the lid and snorkel but I really didn't think it would be enough to cause it to not even be able to run through the gears. I know this is a lot to read but am I headed in the right direction?

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I would go with the more precise setting for pick up and make sure lugs on flywheel are clean. You could try no lid, if it gets better your rich , or tey pulling choke half way with lid and if better = lean. If neither it's possibly elec , plugs, caps, coil , grounds.Any possibility of being more descriptive as to what it's doing< Flat or burbeling?

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could be rich with that set up especially running airbox lid,what does your plugs look like?whats your needle clip position?You need to eliminate one thing at a time.

 

I totally agree but I guess I'm going the long way around towards getting a good baseline lol. The needle clip is in the 4th position, I think. I documented all of the details when I built it but I'll be darned if I can find the papers I wrote... The plugs are weird, they look like you took a brand new plug and dipped it into some fuel/oil and pulled it back out. I've never seen something that runs as clean and crisp but yet doesn't even discolor the porcelain. For all intensive purposes I could spray them with some carb cleaner to clean off the oily film and it would be good as new. This tells me it's an ignition problem so I look more towards the air gap of the pick-up coil.

 

I would go with the more precise setting for pick up and make sure lugs on flywheel are clean. You could try no lid, if it gets better your rich , or tey pulling choke half way with lid and if better = lean. If neither it's possibly elec , plugs, caps, coil , grounds.Any possibility of being more descriptive as to what it's doing< Flat or burbeling?

 

So you're suggesting .017" for the air gap if I'm reading that correctly? I'm about to take the lid off and try it here in about an hour or so, I'll try the choke thing too. I'll run over the electrical too while I'm at it. I read in one of the searches about a parking brake rev limiter or something? I've got an aftermarket clutch perch so all of the parking brake mess is long gone. And on the descriptive part, the best way I could compare it is when I had my old Big Shot kit on my car and would bring the RPM up to purge the stagnant fuel out of the lines it would stumble badly. You're feeding so much extra fuel into it that it can't possibly burn it all and essentially falls flat on it's face. I'm not sure how to describe the sound but just imagine it's like the rev limiter engaging when it transitions from the pilots to the mains. I hope I got that right, that's how I understood it anyway.

Edited by bigblockbanshee
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yeah, id start 230-240 w lid n snorkel on...

 

Thanks, I'm gonna try to make it work as-is so I can get everything broken in to where I'm comfortable with it then I'll start tinkering again. I just really despise that hollow airbox sound but hey that's just me, others may like it. It's just not my taste personally.

 

ditch the snorkel AT LEAST! i f you dont like the buhhh noise thats the noise of air getting into the bike!!

 

just drop mains till it runs. 250's is about where i bet you end up at.

 

Good deal, I'll try taking the snorkel off and get a plug reading from there. It reminds me of an old Quadrajet hitting the secondaries lol, just a lot deeper pitch. Glad we're all relatively in the same ballpark on jet size. I think I'm gonna give it a go here in a week or two.

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Just wanted to update my thread in case anyone else was interested in running a similar setup. Like I said before the hollow airbox sound just wasn't my taste and now it's nice and quite except for the sweet sound of those T5s. I tried the 240s with snorkel on and it performed similar to how it did before with the 280s. I pulled the snorkel and tried it again. This time the jetting was dead on. I decided to try the 230s with the snorkel and again it's dead on. I think I'm gonna leave it this way for a few rides as there are some pretty decent creek crossings where we're going in a few days and I need that extra protection from the water. I've got a good baseline now on open airbox, with lid, and lid with snorkel so thanks for the help everyone. I think I'm finally ready to dive out into the wilderness and see what this thing will do.

Edited by bigblockbanshee
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