so is it recommended to move all needles from the stock middle setting (3) down to the 4th setting to richen things up and help prevent the notorious low rpm meltdown? This would be for a stock viper and midwest riding conditions. would this be too rich during low to mid throttle?
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journeyman
Active member
How long have you owned this sled and how many miles have you yourself put on it? I noticed you said it came with the boost bottle which seems curious. I am wondering if someone has been into this thing beyond what you know about it. Like having pipes on it in the past and then throwing back on the stock stuff but not putting everything back to where it was like your jetting etc. Also like the one fella mentioned about a twisted crank.....things that would occur in a much more modded state.
just wondering.........
just wondering.........
srxman06
New member
I have put about 300 miles on it since i bought it.If the crank was twisted,wouldn't it show signs of problems right away? The guy i bought it from said he transfered the boost bootle and vforce reeds from his srx after he crashed it.
journeyman
Active member
Does the boost bottle require different jetting? My assumption is the two wouldn't help a stock Viper much without triple pipes. Also are the cylinders stock or are they ported. If someone ported them I could see a ring hanging up on a port.
ottawaair said:
not arguing,but thats not possible to do on a engine that fires every 120 degrees, they dont all line up. you could check 2 but not 3 rods.
how many miles are on this sled? what may be breaking the rings are the stops worn in the cylinders, this lets the powervalve go too far forward and contact the rings,then piston,the cylinders would need welded and machined to repair or trade them in on replated good shape ones.
srxman06
New member
Sled has 5800 miles on it. All looks stock to me.I'm going to replace the cylinder and piston. take off the boost bottle and put stock reeds back in it>anyone know what the stock jets are suppose to be in it in case they changed them when they put the bootle on it? Love the sled but i'm gun shy of this thing now. might have to sell it and try something else
srxman06
New member
srxman06 yours had alot more detonation than mine. Mine was jetted rich so it was just heat that did mine in. Not heat like see it on the warning panel but localized heat from a poor head design. Yours shows detonation in the way the top of the piston was blasted off. I have a collection of auto pistons that look just like that from my stock car racing days. Same issue with heads caused both failures though.
2003 Viper Mountain came with 156.3 main jets if that helps you any.
2003 Viper Mountain came with 156.3 main jets if that helps you any.
srxman06
New member
do think the power valve hitting the piston would have caused this damage? I rode it another 5 miles after the cylinder went down
I say you have the jetting way too lean as your exhaust side melted. This is obviously the hottest side and hardest to cool. The ring just caught once the piston was gone. Make sure no intake leaks. Clean your carbs. Make sure everything is stock with jetting. pilots, needles and mains. Guys may recommend richer jetting, take that advice.
Mostly, when it is back together don't just assume it is good. Keep checking plugs. Lean how to read jetting wash on the pistons.
Make sure you have NOOOOO exhaust leaks. That is such an overlooked factor in burndowns. Of exhaust leak than it will cause a lean condition.
Lastley, this is not your problem but I'm guessing the viper has a thermostat(srx's do). I have seen them stuck wide open on srx's. A guy replaced cyliner and piston twice! Twice!.....the intake side was scored from running too cold. It was a 30 or 40 dollar problem and he learned the third time. OUCH.
Mostly, when it is back together don't just assume it is good. Keep checking plugs. Lean how to read jetting wash on the pistons.
Make sure you have NOOOOO exhaust leaks. That is such an overlooked factor in burndowns. Of exhaust leak than it will cause a lean condition.
Lastley, this is not your problem but I'm guessing the viper has a thermostat(srx's do). I have seen them stuck wide open on srx's. A guy replaced cyliner and piston twice! Twice!.....the intake side was scored from running too cold. It was a 30 or 40 dollar problem and he learned the third time. OUCH.
chris189 said:
How do you test for a functional thermostat without taking it apart?
chris189, that was good generic info but wrong in this case. The Viper has a head problem that causes localised hot spots in the cylinder. And of course since the most heat is built up on the exhaust side that is where the probelms occur.
His Viper once the hot spot occured caused detonation that blasted off the top of the piston which then let pieces of piston catch on the power valve.
Mine was jetted rich so it didnt detonate but it did melt down.
Some recommend changing the needles. While this may help it still does not address the real problem and that is the head. I am going to try the Bender Opticool gasket which alters water flow and check it every couple miles for a day to see if that is a real solution.
His Viper once the hot spot occured caused detonation that blasted off the top of the piston which then let pieces of piston catch on the power valve.
Mine was jetted rich so it didnt detonate but it did melt down.
Some recommend changing the needles. While this may help it still does not address the real problem and that is the head. I am going to try the Bender Opticool gasket which alters water flow and check it every couple miles for a day to see if that is a real solution.
srx700, the bad thermostat I saw was stuck wide open.
stingray719, I did say this was not his problem however when spending this much time and money on and engine the thermostat is something I would atleast do a visual on. yes it burnt on the exhaust, it was too hot.
stingray719, I did say this was not his problem however when spending this much time and money on and engine the thermostat is something I would atleast do a visual on. yes it burnt on the exhaust, it was too hot.
srxman06
New member
I am going to use the bender head gasket this time around. Do you think the exhaust valve will be ok to re-use? Carbs are clean but i do not know how they are set>i would be interested in someone firmiliar with these yamahas set them for me