Here's the scoop. I bought a new 2001 Banshee and installed the Motion Pro twist throttle kit. I then noticed that the throttle seemed to stick a little and that during wide open runs in the dunes it would lean out a little(just on top end). This bothered me so I tried the next logical solution. I pulled my needles up a 1/2 notch. It only caused my quad to load up at mid throttle. This was very disconcerning. I tried cleaning the carbs, changing jets and needles, honing the slides and jet ways, etc.. Nothing worked. So my friend (Banshee owner) and I looked into this and this is what we found. On a stock Banshee with stock carbs and caps, you will notice in the windows on the sides of the carbs, that when you hold the throttle wide open, the white dots on the slides center themselves in the windows. This is a good thing. Now look at the dots on the modified carbs at full throttle. They should enter the windows at the same time but you'll notice that the slides overextend. See the aftermarket caps allow the slides to pass maximum throttle. This is the problem. See after a certain point on your throttle no more fuel is being introduced but more air is, thus causing the lean condition at top end. See once the needle passes the top of the jet no more fuel will be introduced, but with the aftermarket caps it still allows your slide to open farther, thus allowing more air. Also we found that when the slides came up to a certain point that the air and fuel pressure would be great enough to hold the slides open. So this is how we fixed this issue. My friend took some measurements and came up with a spacer that installs in the aftermarket caps. He allowed about .002 over overextension but not enough too lean the mixture out. Not only did this fix the lean condition but it also fixed the sticky throttle condition. If anybody is interested we have the dimensions or program to run these on a CNC machine. We have also contacted Motion Pro and other manufacturers about this issue. Hopefully this helps. [img]i/expressions/face-icon-small-happy.gif[/img]

 

I love you!
Sinc I put my Motion Pro twist, my throttle is sticking...it's been since november (with a break from january to march because of snow)...and the throttle still sticks...but my problem is also when I open it a little...Should I put harder springs?

 

If it sticks at any position, I would look at a couple of items. Number 1 would be the twist throttle itself. Here's what I would do take your air filter off and look into the carbs(engine off of course). While looking at the slides give it full throttle a couple of times and let off quickly. If you notice one slide sticking or hesitating I would look at that particular carb and slide. But if you notice both carbs sticking or hesitating then look to see if the throttle is catching on the handle bar itself IE: When you installed the twist kit, you probably made sure that it slid all the way onto the handle bar and that it was snug(I did this one myself the first time). This will cause the throttle to stick, see the throttle is tapered at the end and will catch on the handle bar (poor engineering). Another thing is to make sure that you clean and lube the cables( take the caps off the carbs for this, it will deposit grit into your slides if you don't). Also make sure you clean your carbs well with a good cleaner(I use brake cleaner, seems to work the best). And last but not least make sure that you back your carb caps out 1/2 turn from snug so they won't compress the housing that the slides are in. After you have put the spacers in the caps and checked all this you should'nt have anymore troubles. [img]i/expressions/face-icon-small-wink.gif[/img]

 

This is what I like to see. Owners that are really into their bikes and willing to share it with everyone else to help them make their ride that much better. Good work!!! [img]i/expressions/face-icon-small-cool.gif[/img]

 

Great information. I don't have a Motion Pro twist, but I think it is great that you took the time to figure it out, and let fellow riders know what your results were. It is people like you that make these forums enjoyable. Keep up the good work.

 

I always put a dab of grease or graphite powder on the inside of the throttle tube before installation, helps prevent sticking on the bar.

Make sure that the end of the grip isn't hitting the very end of the handlebars causing drag/sticking.

 

So what kind of feed back have you gotten from Motion-Pro? I havn't had a problem with my throttle sticking, but I will check to see how far the slides do move.

Since you created a "spacer" to fit inside the cap to prevent the slides from traveling as far, what did you use for another seal?

One thing that also does happen with the Motion-Pro cables (and maybe other brands), is that when you are at the dunes or dusty situation, you will actually suck sand or dirt thru the rubber boot that is on top of the cap because it is not truly sealed tight, I found this out at the dunes. So for a quick fix after I pulled the carbs and cleaned them and the caps, I wrapped the boot ends with electrical tape to seal it up.
Also when Motion-Pro puts the seals inside the caps, they use a contact cement to hold them in, I found that gas will make the contact cement soft, then pieces of it fall down inside and around your slides. So pull the rubber seals out and clean out all the contact cement and lay the rubber seals back in.

 

Your needle jet does not supply fuel at full throttle. Your main jet does. If you are truly supplying more air, and running lean at WOT, then you need to go richer on your main jet until the condition is cured. The needle jet supplies fuel from one quarter to about three quarters throttle opening. From there on up, you are correct, the needle will not supply any more fuel. When you raised the needle, you only richened up the 1/4 to 3/4 circuit. That is why it loaded up on you. It sounds like you only need one or two steps richer on the main and you will be good to go. You should richen up the mains when you go duning anyhow as you are doing a LOT more WOT riding.
Good luck.

 

1- Motion Pro was very interested and they took the information we supplied and are going to look into it. In fact I got a call Friday about the dimensions of the spacers. So it looks like they're on the ball.

2- As how the spacers fit, they sit in the recessed part of the carb caps. We found that it works best if you clean your caps(of course) and apply a little dab of Locktite 77 (red), on the top of the spacers and then tap them into place. They'll never come out again. As for the sealing of the spacers, we used the rubber gasket supplied. Since the spacers fit in the recess and fit exactly in the center of the rubber gasket we did'nt have to make another seal.

3- Last but not least. I did jet up. I now run 310's on clip position 3-1/2. It seems to run better at top end now. I also installed Pro Design's adjustable timing plate. This was an awesome difference. I advanced it 2 degrees. It pulls alot harder and faster than it ever has. I would say this has got to be one of the cheapest and most noticable mods I have done. If anybody knows what the optimal timing is It would be appreciated.

 

Now from what I hear from a couple different engine builders is that anymore than about 6 degrees you're not making any more power, but creating more heat in the motor.

I have a modified stock timing plate (savings of $90 fro Pro-Design)) on mine and I pull about 4 degrees. When we modified the timing plate and put it back together, you could feel a big difference. The stock timing actually retards on the upper end of the RPM range of a banshee, so advancing your timing lets it rev quicker on the lower end, plus is corrects it for on your upper end.

I also had my flywheel lightened and that also helped out alot.