I Have a 03 Viper that the center rod stuck on the crank and then took
out the bottom of the case. I have read many post's on here and took some
of you guy's advice to others with like problems. I bought a new case, crank,
piston kit, gasket set ect. The question is how do I keep it from happening
again ? I understand it was suffering from detonation from the hammered top
of the piston and extremely hot from the discoloration of the rod and crank.
But I don't understand exactly how the oiling system works, I thought I read
on here it goes through the fuel pump as well as being injected into the case,
is that true ? Thanks in advance Steve
out the bottom of the case. I have read many post's on here and took some
of you guy's advice to others with like problems. I bought a new case, crank,
piston kit, gasket set ect. The question is how do I keep it from happening
again ? I understand it was suffering from detonation from the hammered top
of the piston and extremely hot from the discoloration of the rod and crank.
But I don't understand exactly how the oiling system works, I thought I read
on here it goes through the fuel pump as well as being injected into the case,
is that true ? Thanks in advance Steve
Any number of things could have caused your burn down. You could have had an intake leak on either end of the carb boot, you could have had an exhaust manifold leak. I think the more common ways of having a burn-down include:
bad gas
jetting incorrect or too close to right on (no wiggle room for a temp drop)
plugged / clogged jets (especially the pilot jets which effect your mid-range)
As for the oil pump. I would guess it wasn't your problem. First, I seldom read about failed oil pumps on this site causing a burn-down, second you probably would have lost your other pistons and rods as well.
The oil pump receives oil from the oil tank. Oil is pumped to your bearings and to the fuel pump from the oil pump. The fuel pump is where that oil is mixed with the fuel which of course goes to the carbs. The rate at which the oil is delivered is pre-determined by a cam in the oil pump. However, you do have control of how much oil is being delivered by setting where on that cam you are starting from. You're actually setting a gap on the oil cable (which is connected to your throttle cable) and this gap determines when you hit max oil on the oil pump cam (it actually hits it earlier but for simplicity think of it this way). This being said it also determines where the beginning of that oil pump cam comes in, or starts while you're adding throttle. So the more gap you put in your cable equates to the cam coming in later which means less oil delivered. Less gap means the cam will come in earlier meaning more oil delivered.
What this all boils down to is that you need to use the book specs for setting up the oil cable gap and you'll be fine. It's a range and as long as you're within that range you should be ok. Some people play around with it a little (like me) but for the most part if you shoot for the middle of the range you won't have to worry.
There's no easy way to know what caused your burn down but you can lessen the chance of it happening again if you use good fuel (highest octane available), jet it with some slop for a temp drop, and you should perform a preseason carb cleaning. Other then the above make sure your carb boots are seated and clamped well. Also you don't want to have any gap between your exhaust port and your exhaust manifold.
Hope this helps
bad gas
jetting incorrect or too close to right on (no wiggle room for a temp drop)
plugged / clogged jets (especially the pilot jets which effect your mid-range)
As for the oil pump. I would guess it wasn't your problem. First, I seldom read about failed oil pumps on this site causing a burn-down, second you probably would have lost your other pistons and rods as well.
The oil pump receives oil from the oil tank. Oil is pumped to your bearings and to the fuel pump from the oil pump. The fuel pump is where that oil is mixed with the fuel which of course goes to the carbs. The rate at which the oil is delivered is pre-determined by a cam in the oil pump. However, you do have control of how much oil is being delivered by setting where on that cam you are starting from. You're actually setting a gap on the oil cable (which is connected to your throttle cable) and this gap determines when you hit max oil on the oil pump cam (it actually hits it earlier but for simplicity think of it this way). This being said it also determines where the beginning of that oil pump cam comes in, or starts while you're adding throttle. So the more gap you put in your cable equates to the cam coming in later which means less oil delivered. Less gap means the cam will come in earlier meaning more oil delivered.
What this all boils down to is that you need to use the book specs for setting up the oil cable gap and you'll be fine. It's a range and as long as you're within that range you should be ok. Some people play around with it a little (like me) but for the most part if you shoot for the middle of the range you won't have to worry.
There's no easy way to know what caused your burn down but you can lessen the chance of it happening again if you use good fuel (highest octane available), jet it with some slop for a temp drop, and you should perform a preseason carb cleaning. Other then the above make sure your carb boots are seated and clamped well. Also you don't want to have any gap between your exhaust port and your exhaust manifold.
Hope this helps
Last edited:
FJViper
New member
Plenty of reading on this site. Anything you have a question on, ask away. There are guys on here that know these machines inside and out. If you want to read up on anything, do a search. Here is a link to get you started. Really good "need to know" info on the Viper. Oh yeah, welcome to the site.
http://www.totallyamaha.net/forums/search.php?searchid=1331562
http://www.totallyamaha.net/forums/search.php?searchid=1331562
Thanks for the oil lesson Iron and thanks FJViper I will check it out.
Steve
Steve
look up the post on viper needles, youll need to address this or be in the same boat again, with either the mag or center cylinder.
rx1jim
New member
The explanation on the the oil circuit was partially correct but not exact. The oil pump does have two output lines. One line goes directly to the fule pump and the second line goes to a port on the bottom of the crankcase. This port feeds a gear "house" oil. The oil then flows out of a second port from the gear "house" on the bottom of the crankcase and is connected by a small plastic hose to a third port on the bottom of the crankacse. This third port is directly below the connecting rod on the cylinder on the PTO side. The oil is not fed directly to any of the crankshaft bearings. The gear "house" or compartment is between the center cylinder and the magneto side cylinder. This compartment has the crankshaft oil pump drive gear and the water pump/oil pump drive shaft. There is an oil seal and small ball bearing on each end of the oil pump/water pump drive shaft. This compartment is sealed so the drive gears, bearings and seals in this compartment rely completely on the oil fed directly from the pump for their lubrication since they are not in the gas/oil mixture stream. The oil is then fed to the PTO cylinder crankcase where it gets mixed with the incoming fuel. This is why is is a BAD idea to try to run these engines on premix only. The water pump/oil pump bearings, seals and drive gears will run dry and be destroyed. The oil lines have a coil spring cover. This spring is there to prevent the lines from getting pinched and cutting off the oil flow. When rebuilding the engine, always check the condition of these oil hoses, they will get hard and brittle over time. Cheal insurance to replace them with new OEM parts ($1.85 part) when rebuilding an engine.
Jim
Jim
Thanks Mr Viper I will look into it.
Thanks rx1jim for the info. Do you think it could be pluged center carb made it go lean
And melt down?
Thanks again Steve
Thanks rx1jim for the info. Do you think it could be pluged center carb made it go lean
And melt down?
Thanks again Steve
Mr Viper you are my hero.
I just read all your info in the viper needle posts and it makes so
Much sense and set my mind at ease. This sled only has 3600 miles
On it and I was hoping to get more than that out of this rebuild.
Thanks
Steve
I just read all your info in the viper needle posts and it makes so
Much sense and set my mind at ease. This sled only has 3600 miles
On it and I was hoping to get more than that out of this rebuild.
Thanks
Steve
rx1jim
New member
With today's gas (ever increasing amount of ethanol) the fuel mixture "window" is getting narrower and narrower. The center cylinder on my 2000 SRX was destroyed to either a very lean fuel mixture or due to detonation due to a tank of bad (low octane gas). The carbs were spotless, they had just been cleaned 500 miles ( 3 weeks time) prior to the destruction. Clean carbs are an absolute must today but the right octane gas is just as important Don't assume the engine damage was caused by dirty carbs. Mr Viper and Mopar1rules have a lot of insight in this area. I changed the jetting to the 2001 SRX spec, richer jets. I would rather be running on the rich side than on the lean (deadly) side. Some nenbers on thi site have been running some octane booster as insurance. When you get the engine back together and start riding the sled, you need to check you fuel mixture through the entire operating range by monitoring the piston wash. There is lots of info on ths site.
Jim
Jim