Idle hangs sometimes but not always at wot....

hereismylife

hereismylife

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holds 4000 for about 20-30 sec then comes down if you just watch it.

If you hit the blip the choke once it will come down to 3500 then go back up to 4000.

If you blip the choke 2 or 3 times to get it to come down to 2500 it will come down and almost stall.

I had no problems last yr at all....

I am at 2 turn on screw now. turned the idle down to 1400 -1500

Trying to figure this out.....

Thought it was only at wot lean or pipes getting hot....

When I am doing some jumps just tops out at 40 with some play around group it will do it.

You can just be cruising and come to a road to cross and stop it will do it...

I have no codes and runs great....

top speed is 95-100 and seems less hp from last yr.

last year speeds were 105 to 109 just hard to get to 100 this year...


Well I had a couple of long hard pulls....it does not always do it....

I could be putting around and it will hang...

I thought maybe a fuel pump,electronics,clutching,compression

Cant see how clutching would affect it since it is at idle.

This got me pretty confused.....
 
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Manifild

I've had this problem on two vipers lately. It was a cracked manifold in both cases. One was creacked on the top and bottom and the other was only cracked on the bottom so was very hard to spot. Let the sled idle and put your hand under and over the "Y" pipe where they all come together. You'll feel the exhaust pulses if it's cracked bad enough.

Madmatt
 
modsrx said:
turn the pilot screw another 1/4 turn should work
Click to expand...

The thing with this screw is it should do this always at wot or it should have a pattern....

I was at 1 7/8 then now 2 turns.... It did not change anything...

When you turn this each time should you see some kind of change?
 
Madmatt said:
I've had this problem on two vipers lately. It was a cracked manifold in both cases. One was creacked on the top and bottom and the other was only cracked on the bottom so was very hard to spot. Let the sled idle and put your hand under and over the "Y" pipe where they all come together. You'll feel the exhaust pulses if it's cracked bad enough.

Madmatt
Click to expand...

Why would it only do this sometimes though? Not a pattern?

What did you do to fix this?
 
daman said:
1-are carbs clean? you sure?
2-any air leaks suspected?
Click to expand...

Carbs were cleaned 3 times. Pilots were clean and you can see through them.

I checked the boots but like I said before this does not have a pattern to it so the air leak should have some kind of pattern..

Maybe I am just missing something
 
j_k_auto said:
Carbs were cleaned 3 times. Pilots were clean and you can see through them.

I checked the boots but like I said before this does not have a pattern to it so the air leak should have some kind of pattern..

Maybe I am just missing something
Click to expand...
Try another 1/4 out with the pilots but thats getting out there,is this a stock sled?
 
Do you take the shelf off air box to make sure carb boots are sealed good?....... Check reeds also.......
 
Stock exhaust?

Above you said "pipes"....are you still running the stock exhaust or did you put pipes on it. The fact that it doesn't always do it and does it "putting around" and/or at WOT doesn't necessarily mean anything. If you havn't changed anything there is no reason your fuel screws should need to be out further than they were last year. Did you check the manifold yet? When I first heard about it I thought it was rediculous but when I found two cracked manifolds and BOTH sleds had hanging idle issues I started taking it pretty seriously.

Madmatt
 
I checked the manifold with a light and mirror...all looks good.

Looked for about 15 min looking it over again.

The sled is all stock.

I always check the reeds when I pull the carbs. I make sure there is no gap with all of them. I dont pull them I just look very good at them.

With the airbox I always take the carb side off not at the box. I did check all the boots from the box to the engine. no cracks all tight...

I was hoping to find something.....
 
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You should just do a search, this has been discussed at length.

you need to run your idle lower than stock by a few hundred rpms and It wil get rid of most of it. It will then only do it after long wot runs and quick shut downs.
 
BETHEVIPER said:
You should just do a search, this has been discussed at length.

you need to run your idle lower than stock by a few hundred rpms and It wil get rid of most of it. It will then only do it after long wot runs and quick shut downs.
Click to expand...

I did search this for a week now.....

I read about the exhaust heat....leaning....adjusting the idle...turning the fuel screw....

It does this just putting around the yard.. just playing some....sometimes at wot but not always...

Maybe 1 out of 3 wot runs........

I tried for the last week to figure this out and find out how to repeat the problem....

Idle hangs when it wants......
 
You have an air leak,,,,,,,, take shelf off air box and wrap that seal around the carb inlet...........
 
update.....

took carbs apart again... I took the floats out and the main seat. The middle carb had alittle dirt in the screen.

I checked everything again and cleaned the pilots for the 4 time.

I looked at the boots at the box

everything looks great....

4 of us looked everything over...

pilots at 2 turns

Time to test run and report back....... ;)!

THANKS GUYS FOR ALL THE HELP...

During the ride I am going to adjust the idle to 1200-1400

bypass the tors

maybe get a vid if it acts up.....
 
update....

Well I ran alittle last night. Had to cut the trip short.....

It seems like it only does this once it warms up. also I did not get a chance to test anything...

Anyhow atleast I know the carbs are now very clean......

I was hoping this was going to be solved.... :o|
 
In regards to a possible air leak, have you tried spraying carb cleaner around the boots ,carbs, crankseals and gaskets while the sled is running. If there is a variance in the idle when you spray the cleaner, you have an air leak. Good luck
 
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