A Banshee With An Attitude!

[decon]

OKAY, my buddies banshee has been giving him hell for the past year or so. He's tried everything, has been to more than one mechanic, and has spent plenty of unnecessary money to get this thing running right.

 

Breakdown:

The bike kicks over and idle's perfect, has absolutely no powerband when it gets going. You can pin the throttle and I will pick up speed VERY slowly, but once it's in the upper rpm's ( whenever it decides to get there) it pulls hard. Sometimes it doesn't even want to hit the upper rpm's. It's like a banshee with a governer on it.

 

Mods:

Dave Moore play port

T5's

30mm pwk clone's

Vf3's

Milled head

Lightened flywheel

 

Current jetting:

152 main

52 pilot

Needle middle clip

 

He has ran through all of the wiring, tested all electrical components, checked every ground wire, swapped cdi's, swapped carbs, sync'd carbs, gapped spark plugs, gapped the pickup coil, new reeds, new air filters, swapped coil packs, anything you can think of. He says his mechanic's have tried every jetting combination possible but it doesn't get rid of that horrible bog, hesitation, whatever you want to call it. It's like the bike has no power at all!

 

Any suggestions or thoughts?

Edited August 9, 2011 by dEcon

[bigblockbanshee]

Timing? Didn't see anything about that in there lol. What cc?

[decon]

Timing? Didn't see anything about that in there lol. What cc?

 

Yah tried to advance and retard the timing. It's a stock stroke 350.

[Larry's Shee]

Only thing I see that wasn't swapped is the stator and flywheel. By chance are either RS ? Swapped cdi stock? Stock coils? Check/ohm ALL wires and switches, plug caps? Does it have tors or parking brake limiter? Magnets in flywheel loose or weak? Poles on stator rust free? Timing lugs clean?

 

Has it ever run right? What does compression test say? What is the squish? What plugs being used?

[camatv]

crank drag. brake drag. maybe out of phase..

[LS3 Machine]

Im no expert by any means, but it seems like a jetting issue. Maybe the main and pilot are big?

[decon]

Only thing I see that wasn't swapped is the stator and flywheel. By chance are either RS ? Swapped cdi stock? Stock coils? Check/ohm ALL wires and switches, plug caps? Does it have tors or parking brake limiter? Magnets in flywheel loose or weak? Poles on stator rust free? Timing lugs clean?

 

Has it ever run right? What does compression test say? What is the squish? What plugs being used?

 

I have an extra stock stator we're going to try. He swapped flywheels, swapped stock cdi's, swapped stock coils, checked the ohm on all electric components. Bike has no tors or parking brake, plug caps are fine. The stock flywheels he tried were good, and I don't think their is any rust on the stator.

 

It ran bad ever since it was rebuilt, it would barely run or even kick over with stock carbs. Last time I checked the compression and squish were fine but I will double check and ask him.

 

crank drag. brake drag. maybe out of phase..

 

Not sure if he checked the crank, but It kicks over fine and idles great. Dave moore said the crank shouldnt be an issue Also, I don't think the brakes have anything to do with the problem.

 

Im no expert by any means, but it seems like a jetting issue. Maybe the main and pilot are big?

 

I said it was the jetting as well, but he claim's the mechanic he took it to has tried every different combination possible. He says it ran the best with this current jetting. The pilot does seem a bit too fat, I was thinking a 45-48 pilot and maybe a different needle? Maybe a CEL.

Edited August 9, 2011 by dEcon

[Larry's Shee]

quote: I said it was the jetting as well, but he claim's the mechanic he took it to has tried every different combination possible.

 

No way in hell he tried EVERY combo. You have air screw, pilot jet, needle, main jet emulsion tube, slide cutaway, and main jet. You figure all possible combinations and I bet it would be a huge amount. Best to change only one thing at a time, but if you do try more than one, write your previous settings down so if you go back you'll get it exact. Be sure floats are same and carbs are synced.

What plugs you using? Gap? Have you checked fuel petcock and tank vent? Are grounds clean and tite?

Edited August 11, 2011 by Larry's Shee

[rdshee]

what kind of pistons? i used vito's power pistons and i had more of a bottom end bog than with wiseco.

[camatv]

you need a new "mechanic"

[decon]

quote: I said it was the jetting as well, but he claim's the mechanic he took it to has tried every different combination possible.

 

No way in hell he tried EVERY combo. You have air screw, pilot jet, needle, main jet emulsion tube, slide cutaway, and main jet. You figure all possible combinations and I bet it would be a huge amount. Best to change only one thing at a time, but if you do try more than one, write your previous settings down so if you go back you'll get it exact. Be sure floats are same and carbs are synced.

What plugs you using? Gap? Have you checked fuel petcock and tank vent? Are grounds clean and tite?

 

We just ran through the jetting today, still runs like shit. We even swapped the carbs off of a running bike.

 

Floats are even, carbs are synced. Using br8es plugs w/ .22 gap. All grounds are sanded down, very clean. Fuel petcock is flowing good.

 

what kind of pistons? i used vito's power pistons and i had more of a bottom end bog than with wiseco.

 

He's using wiseco pistons.

 

you need a new "mechanic"

 

Yah I definitely agree. I personally don't know the mechanic who worked on the bike, I'm going off of the information that my friend is telling me, but like I said it's definitely not a jetting issue. When you hold the throttle open it has 0 power. The only thing he said he didn't swap is the stator and the flywheel, we will be trying that next. He's running a lightened flywheel we're going to try a stock one.

[Larry's Shee]

Check your reeds, check that boots aren't leaking.

[locogato11283]

That jetting is way off. I don't give a shit what his mechanic said. It's flat out not right.

[decon]

Check your reeds, check that boots aren't leaking.

 

Reeds are fine, he has went through two different sets of vf3's just to be sure. We also did a leakdown test, no air leaks.

 

did you try sawping flywheels?

 

Mine had a miss fire that was only occuring over 1/4 throttle... and struggled to hit the power band but once it did it hauled like everything was fine... only until I held my throttle over 1/4 throttle a friend told me it seemed to be smoking more out of 1 pipe when it was under load... took flywheel off and it has a rattle..

 

Yah were going to swap out his lightened flywheel for a stock one after we swap the stator.

 

That jetting is way off. I don't give a shit what his mechanic said. It's flat out not right.

 

Yah they said with that jetting it ran the best, I really don't see how. Yesterday we switched to 28mm pwk carbs, dropped the pilot down to 48 and it still ran bad. Played with the main a little but it still does the same thing, that's why I'm convinced it's not the jetting.

Edited August 22, 2011 by dEcon

[LS3 Machine]

 

 

 

Yah they said with that jetting it ran the best, I really don't see how. Yesterday we switched to 28mm pwk carbs, dropped the pilot down to 48 and it still ran bad. Played with the main a little but it still does the same thing, that's why I'm convinced it's not the jetting.

 

 

You can not "play with the main a little" and eliminate jetting issues. If you really want to get this bike running properly I reccomend that you:

 

A. Learn how to properly adjust carb and jetting; or:

 

B. Get someone who knows WTF they are doing to do it for you.

 

Basically there are 7 different adjustments on a carb, and if one or more are off, the bike will not run right. These pointers assume the carbs and jets are clean and in good working order, and you are using fresh, properly gapped spark plugs, and fresh premium gas, mixed at 32:1 to 40:1.

 

1. Floats. The floats must be set at the correct height.

 

2. Aircrrew. Turn all the way in, then back out 1.5 turns on both carbs.

 

3. Sync. The carbs must be properly synced. Basically both slides have to pull up at exactly the same time when the throttle is moved. Then use the Idle screws to set vaccum equal on both carbs.

 

4. Carb Tuning (Jets and Needles). Set needle clip to mid position before starting. There are 3 ranges of throttle/RPM that need to be tuned. If the bike starts and idles OK, I reccomend starting with high RPM/Full throttle.

 

4a. High RPM (Main Jet) Start with a main jet size that someone else with a similar setup to yours. Check the jetting forum for this. They should have similar pipes/porting/intake/altitude to yours. Don't think its going to work perfect just because his bike has the same setup and even altitude as yours. Some people don't have their bikes perfectly tuned, and every bike may be a little different (I reccomend buying main and pilot jets 3 sizes bigger and smaller than this size). Adjust the main Jets up in size or down in size one at a time until the engine pulls smoothly from the high RPM to redline.

 

4b. Mid Range (needle position) You can only really test this range in 4th or 5th gear. Go from low RPM to full throttle, if there is a midrange stumble at all, you will need to move your needle clip up or down. Pick a direction, and move it one clip at a time. If it gets worse, your moving in the wrong direction, and vise versa. With mine, it didn't make a big change until I moved the needle 2 clips. If you have good reason to believe the stumble is a rich stumble (mine was) move the needle down (by moving the clips up). If you run out of clips, and it still has a stumble in the midrange (and your sure you went in the right direction), you may need a different size needle (not very likely).

 

4c. Idle to 1/4 throttle. (Pilot Jet) If your bike starts and idles good, you are close to where you need to be. Check the pilot jet by just taking off in first gear from idle, low speed take off. The first 1/4 throttle is the Pilot Jet. It should pull away clean with no stumble. If it stumbles, go down one size at a time until the stumble is gone. If it just gets worse, go up in size.

 

Air screw. If you are maxed out on your needle in one direction or another (Leaned all the way out equals top clip, rich all the way equals bottom clip), and you still need to lean or richen a bit, you can adjust the air screw a bit, 1/4 to 1/2 turn at a time. In makes it more rich, out leans it out. My technique is to not tune with the air screw at all, just turn it all the way in, then back out 1.5 turns, and leave it there through all my carb tuning.

 

This is not rocket science, it is actually easy and gives you a feeling of pride once you've learned it and done it yourself. It is amazing how much better your bike will run when tuned properly.

 

Good Luck and keep us posted.