Canadian Viper
New member
Need help, have a 2003 viper with 11,000 kms. Ran great since new. Cleaned carbs about a month ago, and put over 1000kms problem free. Rideing this morning, -15 celcius, for about an hour on twisty trail. noticed a slight power as if a plug fouled, then 10 secs later ,heat light came on and I shut it down.Checked plugs, 2 were nice sand brown, third one(mag side white!) Too late! piston melted, jug scored, middile piston pitted, first one perfect. Where do I start? and what do I look for. Sled never burnt alot of oil, as gas mileage was great. was told to adjust oil, but others said leave it as u never had any issues all its life. This all happened driving 40, 55kms an hour.Need expertise, any help would be appreciated. Thanks, TonyAttachments
mag side went down and started to take out the center? I would say bad crank seal
Canadian Viper
New member
would it be possible debris from meltodown went inside crankcase to center piston? It is only pitted
davidgboy
New member
if u had one piston perfect then this would suggest that oil delivery was adequate. mag. side on these engines are known 2 run hotter. but.... just too lean on that cylinder for whatever reason. air leak? partially clogged jet(s)?
It normally goes out the exhaust, rings and all. Unless your piston shatters.
If your crank seals are gone, your gonna have to split the cases anyways so I would not be too concerned about debris
If your crank seals are gone, your gonna have to split the cases anyways so I would not be too concerned about debris
Canadian Viper said:
no.... check if center rod bearing still good ...does look like a lean burn down ...
Canadian Viper
New member
Machine is at a friend garage, will take a pic Sun, and check that. starting to wonder if the ethanol 10% they added here took its toll. Burnt 3 tanks of premium so
far, but today burned regular. Most of last year I burnt regular as I have done all its life
.
far, but today burned regular. Most of last year I burnt regular as I have done all its life
.
not supposed to run regular in those motor ...look like u maybe found the trouble ......detonation could create the burn down ...does the air box still untouchCanadian Viper said:
Canadian Viper
New member
not sure what u mean by untouch?
Piss poor gas quality along with the mag cylinder that runs about 10-15 degrees hotter then other 2 cylinders = detonation,= burnt pistons... simple as that.
The reason the center one started it too, is also higher compression and the gas is too low of octane. The pto looks fine because its lower on compression, not making as much heat. The mid range cruising on the needle circuit is the bad spot on a viper, lots of ign timing puts extra heat in the piston, higher compression makes more heat,thats why I have been preaching to raise the needles on a bone stock sled.
You NEED to richen up the needles because the gas is very low quality these past couple years, your paying more(gas prices) for less quality......
The reason the center one started it too, is also higher compression and the gas is too low of octane. The pto looks fine because its lower on compression, not making as much heat. The mid range cruising on the needle circuit is the bad spot on a viper, lots of ign timing puts extra heat in the piston, higher compression makes more heat,thats why I have been preaching to raise the needles on a bone stock sled.
You NEED to richen up the needles because the gas is very low quality these past couple years, your paying more(gas prices) for less quality......
Canadian Viper
New member
Always valued your opion Mr VIPER700, Lesson learned, Im a bodyman, with some mechanical knowledge. Were do I start frome here? Should I do a complete gasket kit? After market weico pistons ok? If not gasket kit, should I be concerned about debris? Spent alot of time here seeing other problems here for years, but never thought I would be here posting! Never felt this bad since my hunting dog died! Lol
with the crap they sell for gas now a days premium is a must. many choose to use fuel treatment as well. most melt downs happen when crusing on the needle circuit. i would pull the carbs and check the clip positions on the needles. as this is the circuit you were on when you had the melt down. when you go to rebuild check your crank bearings thurally. make sure to put new crank seals in etc. almost any time a piston burns down on the exhaust side it was because of lean conditions. heres a few main things that can cause lean burndown 1) air leak 2) substandard fuel 3) carbs jetted to lean or partially gummed up. 4) exhaust not sealed properly by the manifold
davidgboy
New member
mrviper700 said:Piss poor gas quality along with the mag cylinder that runs about 10-15 degrees hotter then other 2 cylinders = detonation,= burnt pistons... simple as that.
The reason the center one started it too, is also higher compression and the gas is too low of octane. The pto looks fine because its lower on compression, not making as much heat. The mid range cruising on the needle circuit is the bad spot on a viper, lots of ign timing puts extra heat in the piston, higher compression makes more heat,thats why I have been preaching to raise the needles on a bone stock sled.
You NEED to richen up the needles because the gas is very low quality these past couple years, your paying more(gas prices) for less quality......
nice explanation- guess yama made a goof with the head design. that extra heat is probaly enuf to put it over the edge or certainly help. should have stuck with srx design i guess. then again gas was better back then. but that difference in temps. - ouch- yup we are getting ripped off at the pump all the way around. damn
you have a couple differnt options:
1.) replace 2 pistons(use oem yamaha only), rings, wristpin bearings,circlips and replace cylinder with used or repair. Raise needles in carb. Be back out on trail sooner like this as long as crank bearing in mag cyl is still good.
2.) tear down engine and replace crank seals, only because of mileage and age now. Replace other above mentioned parts, raise needles and ride it for at least another 11,000 kms if you want to keep the sled.
I feel bad for ya, I know how much it stinks to have failure in the riding season and be down. It is the gas quality that bit ya in the butt, the reason it ran fine on the premium earlier this year was the octane was higher, and then this tank of regular its too low, coupled or multiplied with the mid range cruise and poooofff, bye bye piston.
I cant stress enough how cheap it is to carry octane booster in the trunk and dump a half bottle in at every fill up. Its certainly not going to make 87 into 93 by any means but it will keep the slight edge off the fuel and its much cheaper then pistons. You need to keep the premium gas in a 2 stroke these days, no matter how much the premium fuel $$ adds to the ride, think about it..... its not as much as 1 piston is for sure. Everyone thinks its a big bother but I sure would prefer to add some juice then tear down an engine and replace topends, even 1 time is way more expensive then a case of booster is. Heck ,I add it to a yamaha bravo.....LOL!
I know your up North, I can help you out on price of yamaha parts, they rape you guys up north on prices. pm me if your needing new parts.
1.) replace 2 pistons(use oem yamaha only), rings, wristpin bearings,circlips and replace cylinder with used or repair. Raise needles in carb. Be back out on trail sooner like this as long as crank bearing in mag cyl is still good.
2.) tear down engine and replace crank seals, only because of mileage and age now. Replace other above mentioned parts, raise needles and ride it for at least another 11,000 kms if you want to keep the sled.
I feel bad for ya, I know how much it stinks to have failure in the riding season and be down. It is the gas quality that bit ya in the butt, the reason it ran fine on the premium earlier this year was the octane was higher, and then this tank of regular its too low, coupled or multiplied with the mid range cruise and poooofff, bye bye piston.
I cant stress enough how cheap it is to carry octane booster in the trunk and dump a half bottle in at every fill up. Its certainly not going to make 87 into 93 by any means but it will keep the slight edge off the fuel and its much cheaper then pistons. You need to keep the premium gas in a 2 stroke these days, no matter how much the premium fuel $$ adds to the ride, think about it..... its not as much as 1 piston is for sure. Everyone thinks its a big bother but I sure would prefer to add some juice then tear down an engine and replace topends, even 1 time is way more expensive then a case of booster is. Heck ,I add it to a yamaha bravo.....LOL!
I know your up North, I can help you out on price of yamaha parts, they rape you guys up north on prices. pm me if your needing new parts.
got to run premium all times. I learned my lesson a few years ago with the same results you have. Since you were running mostly regular fuel, this probably happened a little bit at a time
Canadian Viper
New member
Thanks mrviper700, will do, step 2, and will part with it! I will miss the sound of it. Never put a mark on it,burnt amsoil, and always treated me well. Will go the way of a 4 STROKE, Thanks againe everyone for the help,Great forum!!
get a fuel injected 4 stroke put carb tuning worries in the past. i know the early rx1s were carbed. save yourself the hassle if your going to up grade. just my 2 cents.
davidgboy
New member
yup definitely fuel injection. much more adaptive. dont think them 4stroke sleds are all peaches and cream though. the design(not because 4 stroke) seems to promote the buildup of ice in the tunnel. personally that would be very bothersome. yup take the good with the bad with everything.
Canadian Viper said:
hey... didnt mean to scare you into buying a new sled
, repair your machine, raise the needles and run premium and youll enjoy it for a long time. I would borrow a 4 stroke and ride it before you pay for one, see if it fits your riding style /likes first. if anything the old vipers dont bring much money, they are worth more to keep around as a back up sled if nothin else, hard to beat the reliability and performance of 97-04 2 smoker sleds 
If you do rebuild that sled....consider putting an opticool head gasket in. It helps keep that mag side cylinder cooler by slowing the coolant through that cylinder. The coolant can grab more heat on it's way through.
Opticool, premium gas, raised needles, octane booster and that thing will be very reliable.
I have just about completed my first top to bottom rebuild, due to a burndown (exhaust leak) and it's not as bad as you my envision. If nothing else you'll learn a hell of a lot. And you couldn't have any better backing then right here at TY.
Best of luck with which ever way you go.
Opticool, premium gas, raised needles, octane booster and that thing will be very reliable.
I have just about completed my first top to bottom rebuild, due to a burndown (exhaust leak) and it's not as bad as you my envision. If nothing else you'll learn a hell of a lot. And you couldn't have any better backing then right here at TY.
Best of luck with which ever way you go.