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Banshee street bike - first (non)start


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Ya dude that's pretty sweet. There's a dude down the street from me that has an RD he wants to sell at a decent price. I'd b all over it but am trying to buy a house so the wife shut me down. I'd be interested in pics and info on yours. See how and what you built it out of. That be cool. Maybe start another thread with a ton of pics in the images section or something then throw a link in this one. I'd bet a bunch of us would be interested in seeing that.

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Sure, I'll get to that at some point... kind of focused on tuning at the moment, but I'll get to it here in a few days. Btw, it's a shame about the RD... that was the bike the got me to give up 4 strokes, and which eventually set me on a path to building this crazy thing.

 

Meanwhile, here's a bit more info: frame is RD400. Motor is a Trinity stage 2 ported stock bore/stroke banshee. A lot of welding had to be done to make that happen, with special attention to chain line and exhaust routing. Swingarm is CalFab. Exhaust is WickedATV. Tank and seat are fiberglass pieces from Airtech. Ignition is Dyna FS. Wheels are 2.15" and 2.5" Excel aluminum rims from Buchanans. Front brake system is Brembo 32/34 (stock for a Ducati Sport Classic). Front forks are RD350 up top with XS500 lowers, resprung and revalved. Front hub is XS500 (for dual discs). Clip-ons are Woodcraft. Master cyls are Brembo gold 16mm (brake) and 12mm (clutch). Clutch cyl is Streamline.

 

That's the bulk of it. I'll post more info when I'm done tuning.

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Ok, I swear I'll get some pics up soon. Hard to get the camera out when I'm too busy cursing the day I ever decided this was a good idea, haha.

 

Meanwhile, I am stumped on jetting. I've jetted my share of four strokes, but somehow this one is just doing me in.

 

I think I've already posted the specs, but here's a bit more detail:

- stock stroke/bore, stage II ported by Trinity, with shaved head

- 32mm VM carbs (had 34s on it but they were problematic for other reasons)

- Dyna FS ignition

- Boyesen 2-stage reeds

- WickedATV pipes, which have very large diameter bellies

- Uni foam filters

 

Currently I'm on 25 pilots, and it starts and idles well. Here's the confounding part: I've tested mains from 210 to 360, and goddamned if it doesn't do exactly the same thing on every set of mains: it idles perfectly, but when I get on the throttle it revs to 4k or so and then falls off entirely, usually stalling out. I'd say it was rich, but how could it possibly want less than 210?? On the other hand - to make me even more confused - it seems to run better on choke, and will even rev all the way up (some of the time) on choke - but if it were lean, unless it was extremely lean, I'd think it would rev up great but heat up quickly. And again, could it really want more than 360?

 

Any ideas?? Carbs are visually synced.... not sure where else to go here.

Edited by xander450
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None of that makes much sense. It doesn't seem possible for it to run the same on 210 mains as it does with 360 mains. Are you running a Banshee stator and a Banshee CDI? The RZ 350 electronics are different than Banshee. Any chance something is wired wrong? Check the pickup coil gap. Check to see if the flywheel key is sheared and the flywheel is turned slightly so that the timing is late. Check to see if the petcock is plugged up. Check that the gas tank vent is venting. Any chance that the filters are overoiled? Any chance there's a broken reed? Spark plugs fouled? That's about all that I can think of. Your compression is kinda low and your Boysen reeds are crap, but it still should run halfway decent.

Edited by Starwriter
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None of that makes much sense. It doesn't seem possible for it to run the same on 210 mains as it does with 360 mains. Are you running a Banshee stator and a Banshee CDI? The RZ 350 electronics are different than Banshee. Any chance something is wired wrong? Check the pickup coil gap. Check to see if the flywheel key is sheared and the flywheel is turned slightly so that the timing is late. Check to see if the petcock is plugged up. Check that the gas tank vent is venting. Any chance that the filters are overoiled? Any chance there's a broken reed? Spark plugs fouled? That's about all that I can think of. Your compression is kinda low and your Boysen reeds are crap, but it still should run halfway decent.

 

I know it shouldn't run the same on 210s and 360s - hence the confusion. Yes, Banshee CDI and stator - CDI is Dyna FS, stator is Ricky (I know they're crap, but unless its crapulence could cause this particular problem, let's just skip that bit). Wiring: sure, but what could be wired wrong that would cause it to rev up to 4k and then tank, but sometimes rev all the way up with the choke engaged??? Petcock's fine and flowing, tank vent is venting, filters are not overoiled, reeds are intact. Plugs foul frequently during the tuning process and I replace them.

 

That leaves: pickup coil gap and sheared flywheel key. Either of those sound like they would produce this particular set of symptoms?

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Ok, checked flywheeel alignment and pickup gap. Flywheel was fine. Pickup gap seemed slightly wide so I set the gap closer. No change in running.

 

Tested the coil - 61k ohms between secondary windings, .7 ohms between primaries. That seems to be out of spec (spec is .28-.38), but I've read a bunch of threads here on coil testing and that seems to be in the range of typical and functional. Spark looks good.

 

Also rechecked float heights - both spot on.

 

Other ideas? I feel like it has to be in the carbs since it will sometimes rev out with the choke on. Maybe my pilots are too small so it's idling fine but won't make a graceful transition to the mains?

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What are the chances the carve are worn out and sucking air past the slides? Or just have a leak somewhere in them? Had a machine do that once. While riding you could control it with the clutch but in neutral it would just rev. Only way to kill it sometimes was to block off air to the carb.

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61K ohms is WAY high for the secondary. Measuring plug wire to plug wire you should have 5K for the coil and 5K for each plug cap, if you are running resistor caps, for a total of 15K. If you pull your caps off and your coil measures 5K, your caps are shot. Run either resistor caps and non resistor plugs or non resistor caps and resistor plugs. Don't run resistor caps and resistor plugs. It's also possible for a coil to arc internally under load but test OK with an ohm meter. Most bike shops have a coil tester.

 

Ricky Stators have been known to cause all kinds of strange problems, even if they test OK. If you exhaust all other possibilities, see if you can borrow a stock stator and CDI from somebody for a test.

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