I am trying to help a friend get his Banshee going and I need a little help. This Banshee used to be ran at the dragstrip before he purchased it and had K&N filters with outerwears on the carbs(no air box). After he purchased it he realized that this setup would not work for him here around our wet area so he has purchased a factory airbox and installed it. Since he has had trouble with it running. I told him it needed to be rejetted so I said I would help.

When he brought it to me it would not run. I took out his plugs and replaced them with new ones. It has good blue spark. I removed the carbs and cleaned them. The main jets were 280. I replaced them with 270, which should make up for the airbox being reinstalled. The problem now is the same as he had before, will not take the gas and is backfiring through the right side muffler. I reset all the air screws to the same settings as they were, which doesn't mean they are correct. I drained all of his fuel, because he said he was running 24:1 Bel Ray. I replaced it with my 32:1 Klotz. He is running 93 octane pump gas. It cranked, but remained the same.

Here is what he has had done to it: ported and polished,0.030 over Weisco pistons, Toomey pipes.He said it had alcohol reeds also.

Here are my questions
1)How do you adjust the carb Idle with those things on top? Can you take them off? What exactly do they do?
2)What is the gap between the flywheel and the armature(pickup)
3)Are the alcohol reeds compatible with gasoline?
4)Any other suggestions?
5)Just for curiosity, what are stock main jets in a banshee? What do you run in your modded Banshee?

Thanks for all your help.

 

Stock size for a banshee is 200 main jet with the needle in the middle position and the air screws 2 turns.Looking at what you described i would say that your needles are set wrong.I would start with a 300 main 30 pilot and 2 1/2 turns on the air screw with needle in the middle slot.You didnt say what kind of pipes you had on there so thats a guess.

 

The backfire sounds lean. Check for clogged carb passages and airleaks at the carb boots. I agree with 300 mains if the airbox lid is off. With lid on 270 sounds good.

 

Take the right side carb off and unscrew the pilot jets. There are two of them actually. One just behind the main jet and one on the front of the opening of the intake passage way. This is the cause of your back firing. Make sure you put a fuel filter on the gas line so it will not clog up with junk in the tank. You might also want to clean the air filter more often.

 

Since the main jet is mostly for higher throttle ranges...I would start with your pilot jet and needle position....You should be able to get it started...even with a larger main jet.
Have you checked compression? Are the carbs in sync with each other? Is the tube connected between the carbs.
I would change the reeds too if they were intended to be used with alcohol..though I'm no expert in that area.

I think that your main jets seem to be pretty close at 270 -280. Needle clip in the stock position or one notch up. Depending on your pipes (which you did not mention)

Good luck.

 

Ya check the tube that connects the 2 carbs that is what it sounds like to me and get rid of those reeds.

 

Yes, that is exactly what it was. After I reassembled the carbs I forgot to connect the tube. Actually I didn't even realize it was there until I purchased a manual.