new topend won't idle

[banshee4life]

My banshee has just been rebuilt and I am seeking help about the rebuild job. Pre rebuild job bike would idle just fine on regular gas with 32:1 ratio. Here is what was done. Cyclinders were bored and refitted with wisceo .30 pistons, coolheads with 20cc domes, new reeds, bottom end was flushed, crank was trued and welded.

 

I just got my bike back from the mechanic and it won't idle. I have only taken the bike out twice. When I got the back back the mechanic had put 40:1 mixture of gas in it. He told me to ride that gas out of it then put 32:1 back in it. Either way it still would not idle the first time out. It was still rideable you could just tell it was bogging down at different rpm's. The second time i took it out was just yesterday. I fired it up and it idle extremely high as it did the first time out. I let it warm up for a minute then I took off. I made it about 20 yards and it started popping and sounding like it wanted to die.

 

What mixture of gas an oil should i use with the coolheads and bore?

Should I run a different type of sparkplugs(br8es ngkr)?

 

Please help?

[Tim573]

I have the same problem. I have ported cylinders factory head t-5s aftermarket carbs, what mixture should i run. I am currently running 24:1

[DRI4life]

i belive optimum ratio is 32:1 for a stock bike or modded..... not idleing and popping are two different problems. with that much work just done it could be anything and possibly a ruined motor if it wasnt broke in properly.. 40:1 on a break in is pretty lean imo...

 

take it back to the builder you have issues.. and br8es is fine

[J-Madd]

Oil mixture shouldn't cause those symptoms.

Here's a list of things to check or do:

 

- un plug the TORS

- see if the choke tube is in place (everybody's forgot that at 1 time or another..even mechanics don't put them back on sometimes)

 

- Make sure both carb tops are screwed down good. If one is loose, it'll lean out and rev up.

 

- Make sure both carbs are getting fuel and see if the pilots might be clogged.

 

 

 

Your jetting shouldn't be the issue if it ran fine before the rebuild, and you didn't get new pipes or filter. If you were stock before, and added those, then you would obviously require jetting changes. Boreing it and adding the head wouldn't affect jetting.

[watkins]

Well.. one thing I noticed that really wouldnt effect idle, but would save your top end is the increased compression & using regular pump gas. What elevation are you at? You might need to be running 50/50 race gas & pumpgas.

 

I have the same problem. I have ported cylinders factory head t-5s aftermarket carbs, what mixture should i run. I am currently running 24:1

 

32:1 should be fine. Everybody has their preference, but the majority on here mix at 32:1

[J-Madd]

Well.. one thing I noticed that really wouldnt effect idle, but would save your top end is the increased compression & using regular pump gas. What elevation are you at? You might need to be running 50/50 race gas & pumpgas.

32:1 should be fine. Everybody has their preference, but the majority on here mix at 32:1

 

 

 

I thought about that too, but with 20cc domes.............................. :shoothead: wait a minute you're right. I was thinking the 20 cc was around 150 psi, but that's the 21 cc. Even with stock timing you're probably gonna need to up the octane a little. Mine stock jugs with 20 cc domes had damn near 180 psi at 300 ft elevation. Good call.

[banshee4life]

Oil mixture shouldn't cause those symptoms.

Here's a list of things to check or do:

 

- un plug the TORS

- see if the choke tube is in place (everybody's forgot that at 1 time or another..even mechanics don't put them back on sometimes)

 

- Make sure both carb tops are screwed down good. If one is loose, it'll lean out and rev up.

 

- Make sure both carbs are getting fuel and see if the pilots might be clogged.

Your jetting shouldn't be the issue if it ran fine before the rebuild, and you didn't get new pipes or filter. If you were stock before, and added those, then you would obviously require jetting changes. Boreing it and adding the head wouldn't affect jetting.

 

Thanks man. I rode it again today and it was like night and day. Before I read your email I took it out for about 2 hours. It was running like a rapped ape but still would not idle. I paid a little more attention to the exhaust this time and both sides were smoking the same. So I beleive it's not the cyclinder job. The only other issue besides the idle problem is before I took off I changed out the plugs because they were fouled.

 

I just went out and did what you told me to and found that on the right carb the boot on top of the carb screw was not pulled down. You could of course pull the needle wire up and down. I didn't get a chance to fire it up yet because of the time but I will try first thing in the morning. Everything else checked out but what is a "tors"? I am guessing it is the spark box????

[J-Madd]

Thanks man. I rode it again today and it was like night and day. Before I read your email I took it out for about 2 hours. It was running like a rapped ape but still would not idle. I paid a little more attention to the exhaust this time and both sides were smoking the same. So I beleive it's not the cyclinder job. The only other issue besides the idle problem is before I took off I changed out the plugs because they were fouled.

 

I just went out and did what you told me to and found that on the right carb the boot on top of the carb screw was not pulled down. You could of course pull the needle wire up and down. I didn't get a chance to fire it up yet because of the time but I will try first thing in the morning. Everything else checked out but what is a "tors"? I am guessing it is the spark box????

 

 

So the plugs were just fouled then. I didn't mention to change plugs, I figured fresh ones would be installed with the rebuild. As far as idleing, that's easy. You can loosen the screw that holds the cable to the thumb throttle assembly to tighten it (the cable), and increase the idle. The TORS is probably OK if it runs good. I'd unplug it anyway. Its the little black box mounted to the frame under the left side of the gas tank. Just unplug the wires.

 

 

You can also idle it at the carbs. If they're stock, there is a big knob on top of each carb by the cable. You have to turn both of them the same amount of turns and keep your carbs in sync.