Well guys I have an 05 Viper Mtn. completely stock. Was ridin the other day and it lost a cylinder...Cleaned the carbs and it idles fine and runs fine all the way through about 6000 rpms...when you get to 7000 or more its like it is a power loss and the snap just isnt there. Got any ideas what it could be. Compression is fine too. Cleaning the power valves now. Has approx 1600-1700 miles on it.
daman
New member
are you sure the carbs are clean? how's jetting,clutching where you want it?
did it just start to do this???? yes clean AND adjust P/V's..
did it just start to do this???? yes clean AND adjust P/V's..
jetting and clutching are fine...ive ran 550 miles with it the way it is this year
did u check power valve motor to make sure it work at high rpm ??
power valve motor was checked on startup and it is working...not sure about the high rpm...you can pin the throttle and get 8400rpm and nothing more...before you could rev over 9000 easily due to the clutching and gearing being for the mountains and not flatland/ 2000 ft...power valves were cleaned but not adjusted
make sure they are adjusted ...try to rave the engine on a stand and see if the power valve motor work
maybe a fire problem if u loss a cylinder
got spark on it...the plug isnt changing to brown like it should like it isnt getting fuel to burn...took carbs off again
cleaned the mag side...which is the one that the plug wasnt gettin dirty on...lack of fuel maybe?...reassembled and will try it in the morning with fresh gas...please post any suggestions as we are running out of things to try
Replace them all, you'll see a great improvement...put blue loc-tite on the screws when re-installing pedals & make sure the pedal block is seal well against the cylinders...cheersSXlover said:
only replaced the one...and right now the sled goes to 8400-8500 and then when you go to give it more throttle cuz it should climb over that like it used to due to the clutching we have it just bogs out...but it may do to the powdery snow we have gettin on the air filter and blocking enough airflow that it cant suck anymore air after that
mod-it
Member
When you cleaned the PV's, did you take them clear off the cables? I'm wondering if you have one that the cable has pulled through on. Definitely adjust them. There has to be some kind of problem for it to lose that much rpm...which brings up my next question...
Why would you clutch a stock viper to overturn the rpm's for Mnt. riding? Higher rpm does NOT equal better performance in the powder, you are way past your peak hp and losing performance. Not trying to be rude in any way, just trying to help you out. You want it clutched to hold right at 8500, I guarantee you'll see/feel a nice gain if you get the clutching to hold 8500. I'm wondering if it overturned rpm's the way it was set-up from the factory and you thought they did it on purpose because it is a mnt. sled? It was very common for them to overturn with stock set-up, needs to be adjusted.
You also brought up the powder bog, said you saw snow on the airbox. Could this be all that is bringing down the rpm's? That's how mine used to react to the powder bog, it would act doggy and not pull much more than about 6500-7500 rpm. Do you have somewhere to ride it out of the powder to test what rpm's it will pull? Try running it down a packed/groomed trail and report back.
Why would you clutch a stock viper to overturn the rpm's for Mnt. riding? Higher rpm does NOT equal better performance in the powder, you are way past your peak hp and losing performance. Not trying to be rude in any way, just trying to help you out. You want it clutched to hold right at 8500, I guarantee you'll see/feel a nice gain if you get the clutching to hold 8500. I'm wondering if it overturned rpm's the way it was set-up from the factory and you thought they did it on purpose because it is a mnt. sled? It was very common for them to overturn with stock set-up, needs to be adjusted.
You also brought up the powder bog, said you saw snow on the airbox. Could this be all that is bringing down the rpm's? That's how mine used to react to the powder bog, it would act doggy and not pull much more than about 6500-7500 rpm. Do you have somewhere to ride it out of the powder to test what rpm's it will pull? Try running it down a packed/groomed trail and report back.
No did not take the PV's off the cables but they aren't pulled through.
It's factory clutched for 10000 ft or whatever and we are at 2000 and have yet to change it. We've done one already. I know why it's clutched the way it is.
Yea I think it is the airbox problem. We dried the filter out last night and I'm gonna try it today. I get 8500 out of it at a certain throttle point, not sure where and then after I give it more it bogs out, and it shouldn't. If it's not powder we may go through and check the other reeds out.
It's factory clutched for 10000 ft or whatever and we are at 2000 and have yet to change it. We've done one already. I know why it's clutched the way it is.
Yea I think it is the airbox problem. We dried the filter out last night and I'm gonna try it today. I get 8500 out of it at a certain throttle point, not sure where and then after I give it more it bogs out, and it shouldn't. If it's not powder we may go through and check the other reeds out.
Well seems its still there but around 8000...you can pin it and it goes there and revs fine then blah...guess I'll probably take all the reeds out and go through and look at all the powervalves and adjust them
Yamahammer485
Member
SXlover said:
Check all of them. These reeds are notorious for doing this....
just did...the pto was chipped away enough we replaced it with one a guy had...gonna order 3 new ones for the top sides...the ones we have in there should at least work...gonna try it later on today
Replace them all...its all about having the same flex return (lack of a better)...when you reinstall them, hold them up to the light & confirm a good seal on the cage...also if you changed your skid & track length, your gonna have to change your gearing to match...make sure all your exhaust joints are sealed up as well...play with your clutch LAST!SXlover said:
the clutching needed to be changed for the altitude we are running...its a stock 05 mtn viper which is clutch for 8-10k i believe and we are at 2k
Powder Trax
New member
Clutching
Definately throw more weight into the primary to bring your RPMs down to be in your powerband, and maybe change out the primary spring to a lower engagement, maybe change spring tension in your secondary and/or go with a different helix.
I do now a majority of my riding @ home between 1800-2200 feet. My 2004 MNT Viper is modded up but its dialed in to pull 9100-9200 PRM for my powerband. I bought this sled in Sept. 2007, and it was already set up for around home and I know what I need to do when I make trips to the mountains.
SXlover said:
Definately throw more weight into the primary to bring your RPMs down to be in your powerband, and maybe change out the primary spring to a lower engagement, maybe change spring tension in your secondary and/or go with a different helix.
I do now a majority of my riding @ home between 1800-2200 feet. My 2004 MNT Viper is modded up but its dialed in to pull 9100-9200 PRM for my powerband. I bought this sled in Sept. 2007, and it was already set up for around home and I know what I need to do when I make trips to the mountains.