Ordinary day plugs showed slightly black yet mag side burned down and center got slightly scarred. Anybody else see this happen? Sled has less than 900 miles 2003 Viper Mountain. Oh, carb warmers off.
Was alot of blowing snow though
Was alot of blowing snow though
Bad gas? Carbs clean? Carbs rebuild? Leakey boots? Have you gone thru everything yet to troubleshoot?
no1chevyboy
New member
wet and black? dry and black?
Gas was good I believe. One cylinder looked like new so I doubt bad gas. Other sled had same gas no problems. All rubber parts look like new (under 900 miles on sled)
Only thing that made me say hmmmm...was that I opened the ram air next to the windshield and we did go down some long stretches of road at 60mph plus. Usually only mountain ride. Wondering if powder snow force fed into foam on top of air box might have caused this.
Odd though as it looks like far left cylinder was perfect, middle some light scarring, and left melted down.
Really need to find problem before I rebuild it so the problem does not reoccur.
Only thing that made me say hmmmm...was that I opened the ram air next to the windshield and we did go down some long stretches of road at 60mph plus. Usually only mountain ride. Wondering if powder snow force fed into foam on top of air box might have caused this.
Odd though as it looks like far left cylinder was perfect, middle some light scarring, and left melted down.
Really need to find problem before I rebuild it so the problem does not reoccur.
left cylinder lightly wet clean top small patch of black. Middle cylinder wet and black. Mag cylinder heavy piston scarring, stuck rings and cylinder scratches...very oily probably from 5 miles rode back on two cylinders.
RIVERRUNNER
Active member
Can you get us some pictures of the pistons and an Idea of what you were running for jets at what altitude? Need more info!
mod-it
Member
You opened up the ram air vents, had you ever rode it this way before? Or was this the first time you rode it after unblocking them? The colder air being let in will lean it out some, perhaps your needles were set right on the edge and it went lean just enough.
Sled was idled around for probably half hour and then throttle pinned for a mile or so when it happened. I am now leaning towards the "oil injected into fuel pump" oil delay to engine seen in arctic cat triples in the 90s.
Just spoke at length with a dealer who has extensive experience with Vipers. Seems there is a lean spot in the low speed circuit in the carbs. SOoooooooooooooo if you run slow down the trail you lean it out and it burns down. Said he had a snowmobile rental company lose 20 in a week!
Said the fix was an aftermarket head that promotes better cylinder cooling. That or don't ride slow!
Why if this is so common is it NOT listed in these threads?????
Said the fix was an aftermarket head that promotes better cylinder cooling. That or don't ride slow!
Why if this is so common is it NOT listed in these threads?????
lean spot in one certain area??, no, not really,but lean thru out the entire rpm curve... yes, on a viper the needles,slides and nozzles are all leaner on a viper.
the head is what causes most of the problems on a viper, its design creates a eddy,which is where the flow is impeded by the outlet of the head,and the mag cylinder ALWAYS runs the hottest on a viper with stock head,even bone stock sled. This coupled with higher compression then a srx with lots of ign. timing makes heat. The best thing to do is go to aftermarket cylinder head on a viper,or use srx heads and aftermarket water rail. This will even out the cooling and give much better reliability. this has been discussed here alot, youd just need to search to find it.
the head is what causes most of the problems on a viper, its design creates a eddy,which is where the flow is impeded by the outlet of the head,and the mag cylinder ALWAYS runs the hottest on a viper with stock head,even bone stock sled. This coupled with higher compression then a srx with lots of ign. timing makes heat. The best thing to do is go to aftermarket cylinder head on a viper,or use srx heads and aftermarket water rail. This will even out the cooling and give much better reliability. this has been discussed here alot, youd just need to search to find it.
no1chevyboy
New member
(oil pump,snow,lean low speed circiut) that cant be the issue or all cylinders would be bad,if only one cylinder is melted down then the problem is there, if i had two guess based on what you said happened with no pics i would say that cylinder ran lean from plugged carb or intake leak or crank seal,
chevyboy, it is a well known design flaw in the Viper, one that i did not know. Do a search for a viper cylinder or head on the net and see how many burned identical to mine.
The problem occurs if you run the sled slow, pin it all day no problems. Sad sad sad that yamaha built this mess. I have had yamahas forever because they DONT do this..............
The problem occurs if you run the sled slow, pin it all day no problems. Sad sad sad that yamaha built this mess. I have had yamahas forever because they DONT do this..............
mrviper700 said:
Not to steal the thread, but on a (2000-2002) SRX, is it the PTO or MAG that runs the hottest?
no1chevyboy
New member
sorry was just trying to help. im not a yamaha exclusive tech, but if this is a known comin problem (head temp on one head) i cannot believe that yamaha would not recall and repair! it would have been a problem since new.and putting out a flawed product and not fixing it, doesnt sound like yamaha from what ive read about there r@d
So......
just what Ive gathered from all the posts.....
Mag cylinder runs the hottest....
Extra forced air could lean the motor....
Small black spot in the center of the good piston only, slightly lean....
Vipers run lean at low speed....
Sled was rode slow for some time then WOT for 1 mile.....
sounds like your hottest cylinder was most effected by the combination of lean conditions.......
I would read up on how to richen it just a little by adjusting you carb pins and slides!!!
just my $.02!!!
just what Ive gathered from all the posts.....
Mag cylinder runs the hottest....
Extra forced air could lean the motor....
Small black spot in the center of the good piston only, slightly lean....
Vipers run lean at low speed....
Sled was rode slow for some time then WOT for 1 mile.....
sounds like your hottest cylinder was most effected by the combination of lean conditions.......
I would read up on how to richen it just a little by adjusting you carb pins and slides!!!
just my $.02!!!
Please note: ALL Vipers in stock form are vulnerable to the low speed burn down. If you have a mag side burn down with center hot and you rode it slow before it went you have had it already happen.