super1c
Super Moderator
Sorry guys i know this has been beat to death. I have read every post on here about it in the past and know all the fix's. BUT here is my story/problem. My 04 viper S was CPR piped when i bought it. Last year i took it back to stock for better MPG and im more into trail riding with the family and friends now. Well ever since i went back to stock i have a idle hang after long runs no matter what the speed. And not all the time. I thought i had it fixed last year with the fuel screws but would pop up every now and then. So onto this year. First ride 3 weeks ago it started once the sled got warm and i turned down the idle and it took care of it for the most part. Now just yesterday it was back. Mostly after long runs. Ive done all the tricks, fuel screws are at 2 1/4, idle down to 1200 when warm. Throttle cable fine. My next move is 47.5 pilots. And i have sprayed a ton of starting fluid at it without any idle change so no leaks. When i went to stock i bought all the parts used, can, pipe, reed cages, reeds, cluch weights ect... Could any of this effect it? Plugs look perfect, wash better then its ever been. Using just over 1qt of oil per tank of gas. Im stumped? I know this is the nature of the beast with pipped vipers but i shouldnt have so much trouble with it being stock. Just seeing if you guys had any other thoughts or ideas of somthing i missed, or should check. Should i even bother with the 47.5 pilot jets? I dont want it to run like a dog. Thanks
Bousez
New member
- Joined
- Jan 22, 2012
- Messages
- 21
- Location
- Riviere Beaudette, Quebec, Canada
- Website
- www.riviere-beaudette.com
Jetting could be the answer i think
Every scenario I have heard of with this problem was resolved with the idle hang, that's very odd it worked for you, but only temporarily.
Open the fuel screws another 1/2 turn or go up 1 size on the pilots
Agpetro
Member
Idk but this may be worth a try. Are all your exhaust joints sealed with yamabond?? It makes a big difference I have found. Mine would hang here and there with pipes at the beginning of the year, so i took all the pipes off and resealed them and it was fixed.
super1c
Super Moderator
Agpetro said:
That is a good thought but i did seal both donuts with copper silicone sealant. I know that no 2 sleds are the same, and my other 2 vipers dont have this problem. I might just have to change the jetting and see what happens. Another though i had was are the viper and mtn viper the same stock pipe? I cant remember for sure but i think my pipe and can were off a MTN viper.
Agpetro
Member
super1c said:
Could be leaking at the gasket between the exhaust and engine?? or a crack in the manifold?? I only use yamabond to seal off my exhaust. Only thing that i have found that works great. I have used exhaust sealer before thats just melted off too. Lol never use car quest hitemp sealer.
Chris,
I have mtn vipers and I believe the pipes are the same. I had an idle hang problem also with one of my vipers and like you I read and read. I was conflicted between two thoughts that I had. One was the obvious idle hang problem. The other was that the jetting chart for my viper at 6700ft to 8300ft was:
mj:143.8
pj: 52.5
jn: 2.5
ps: 2 7/8
which is exactly what I rejetted my sleds for. In my reading it said to not be more then 2 turns out on the fuel screw (if you are go up a pilot and then readjust the fuel screw below 2). I was almost 3 out. Because I was afraid vibrations would work the fuel screw out. I went the opposite of the normal cure for idle hang and closed it to 2. I was hoping that maybe I was running slightly rich in the low circuit.
After coming back to 2 on the fuel screw and dialing my idle down to around 1600rpm the idle hang ceased (no pilot change). And odd as it may seem I had tried to dial idle down prior to dialing the fuel screw down. Not sure why it worked but it did. It may be worth a shot for you.
I have mtn vipers and I believe the pipes are the same. I had an idle hang problem also with one of my vipers and like you I read and read. I was conflicted between two thoughts that I had. One was the obvious idle hang problem. The other was that the jetting chart for my viper at 6700ft to 8300ft was:
mj:143.8
pj: 52.5
jn: 2.5
ps: 2 7/8
which is exactly what I rejetted my sleds for. In my reading it said to not be more then 2 turns out on the fuel screw (if you are go up a pilot and then readjust the fuel screw below 2). I was almost 3 out. Because I was afraid vibrations would work the fuel screw out. I went the opposite of the normal cure for idle hang and closed it to 2. I was hoping that maybe I was running slightly rich in the low circuit.
After coming back to 2 on the fuel screw and dialing my idle down to around 1600rpm the idle hang ceased (no pilot change). And odd as it may seem I had tried to dial idle down prior to dialing the fuel screw down. Not sure why it worked but it did. It may be worth a shot for you.
After a long run won't the pipe have a lot of heat? This could cause the pipe to be highly efficient. I think anyway. I would up the pilot.
Mine are doing the same thing Chris. I'm in the same boat as you. I'm trying everything I can. Read all of it. Beats the hell outta me...
super1c
Super Moderator
SXRider7Hundo said:
Yea im at a loss with ya! Im thinking the pipe theory capnviper mentioned is most likely the cause. I found a good post by BTV that said this exact same thing. Just weird it is after the change to stock that i have it now and neither of my other vipers do it. The pipe on my viper is a new take off. So by that logic the pipe is new and not all carboned up like my other 2 vipers and runs more efficient and hangs up at the sweet spot. Im going to try to back the screws back to 2 and drop the idle like newbee said and see what i get before i change jets. I dont think this is a lean hang, i think its related to the pipe. And maybe the gas, i run premium gas but who knows how good it really is. Maybe we can get a solution to this common problem. Seems to be happening a lot now.
I may be wrong about this but for the low speed circuit I think you're adjusting the fuel screw and pilots. And in adjusting them you're really looking for throttle response more so then guarding against lean burn-down. If you wanted to come down below 2, I think you could do it safely. I would just make sure it idles well and you have good throttle response.
When I brought my 2 7/8 down two 2 I noticed a slightly better response to throttle, but the idle was just about the same which was pretty good to start with.
When I brought my 2 7/8 down two 2 I noticed a slightly better response to throttle, but the idle was just about the same which was pretty good to start with.
mod-it
Member
My Mnt Viper has SLP pipes and flo-rites. Jetting for the altitude I ride at (3000-7000 feet) calls for stock size pilots, 45's. I'm running my idle at 1800 rpm and have my fuel screws clear out to 3-1/8 turns. Always use high-heat silicon on the pipes anytime I take them off and then re-install. I also always run premium, SLP prefers 91 octane or better, but like you said who knows what we are really getting. I haven't ever had an idle hang issue.
When I bought it new I had the dealer put the pipes on it and set up the jetting. He had the idle and fuel screws set where they are now. It did have a bit of a burble on the bottom end like it was too rich, until I put the flo-rites in. The extra/cold air took that away, but I still haven't had any idle hang issues. I would assume the dealer turned the fuel screws clear out that far to get rid of an idle hang issue??? It runs great where they're at, so I haven't ever changed them. I clean the carbs every year anyway, so I've always just checked them to see if they are working their way out because of being out so far. I haven't had trouble with them moving yet...
Don't know if this helps, but wanted to share the info with you. I wouldn't be worried to try the fuel screws out at a ridiculous setting like mine are at just to see if it fixes it or not. You could then go up a size and turn the screws back in if it made you more comfortable.
When I bought it new I had the dealer put the pipes on it and set up the jetting. He had the idle and fuel screws set where they are now. It did have a bit of a burble on the bottom end like it was too rich, until I put the flo-rites in. The extra/cold air took that away, but I still haven't had any idle hang issues. I would assume the dealer turned the fuel screws clear out that far to get rid of an idle hang issue??? It runs great where they're at, so I haven't ever changed them. I clean the carbs every year anyway, so I've always just checked them to see if they are working their way out because of being out so far. I haven't had trouble with them moving yet...
Don't know if this helps, but wanted to share the info with you. I wouldn't be worried to try the fuel screws out at a ridiculous setting like mine are at just to see if it fixes it or not. You could then go up a size and turn the screws back in if it made you more comfortable.
Millinocket Rocket
New member
I just took my SLP'S and SRX heads off and went back to stock too. I have jetting at: 45 pilots, 155 mains, 2.5 needles, and 1-7/8 fuel screws with no idle hang. I did have the idle hang before I put pipes on but turning down the idle fixed it. Pipe efficiency as Betheviper explains.