800 Cylinder Problems

JakeR · Dec 15, 2009

Ok guys maybe you can help me out on this.. Last year I traded a bike for an 03 800 rmk vert edge. When I traded I knew that the Pto side cylinder was bad.. So I tore it down sent the cylinder to have it replated.. The other cylinder looks like it was just done and has a Wiseco piston.. So while I was in there I put a big bearing kit in it bored the cases and put new seals in the bottom end.. I put a wiseco piston in the burnt down side to match the other and new rings in both.. I cleaned the carbs and put it all back together and it ran great.. I heat cycled the motor and ran oil in the gas. I rode it 3 rides last year. So I get it out this year and we head up the trail and half way to the top it loses the pto side cylinder again....... It was jetted the same as last year for the same location and the same temp and it was running great then, I was going to go to the top and check the plugs but I didn't make it that far and the other cylinder when I pulled the plugs it was chocolate brown.. The intake side of the piston is really bad.. The pin bearing also does not look to be in good shape..

Am I missing something here guys??? A friend thinks it is the wiseco pistons... But the other side looks brand new..

Mods
Slp twins
v-force 3 reeds
de comp holes plugged
wiseco pistons
big bearing kit

Any help would be great!!

HankScorpio · Dec 15, 2009

The first thing I can think of is you did not warm up the sled enough before riding and it cold seized. Wiseco piston are forged not cast forged pistons take a lot longer to come up to temperature. I am no engine whizz but I am sure some other guys in here will have some feedback.

BB454 · Dec 15, 2009

Cylinder

Cold sieze is on the intake side like yours. Snow being sucked into the carbs can also cause what you are seeing. Overheating is usually on the exhaust side. Do you happen to know what the plater made the clearance at on that cylinder? They usually like you to send the new piston along so they can do it right.

Is the bottom end of that cylinder got a good oil film on everything? Check oil line to the carb too.

JakeR · Dec 15, 2009

It was warmed up good. It had sat there a ran for 20-30 min before i got on it. I am thinking It is snow I have talked to a guy here that has had the same problem and then went to a stock piston and it does a lot better with getting snow in them... It also has the slp air horn kit and the speedo vent..

johnsodo · Dec 15, 2009

carb boot ? bad carb? what is the jeting btw

kylesrt · Dec 15, 2009

Its probably the pistons wiseco pistons do not work well in these sleds. Spi pistons or O.e.m work the best

JakeR · Dec 15, 2009

Im really thinking that I will go back with oem pistons. How could the carb be bad? what should I look for in the carb it was cleaned last year before i fired it up ...

freak58trio · Dec 15, 2009

If the carb boot was cracked or not sealing good to case and carb it could possibly suck air and lean that cylinder out causing it to seize.

sled_guy · Dec 15, 2009

What does the piston look like exactly? Post a picture.

sled_guy

JakeR · Dec 15, 2009

I will post a pic tomorrow... The intake side of the piston the skirt is about an 1/8" thinner then it was before..

skibreeze · Dec 15, 2009

johnsodo said:
carb boot ? bad carb? what is the jeting btw

freak58trio said:
If the carb boot was cracked or not sealing good to case and carb it could possibly suck air and lean that cylinder out causing it to seize.

X2
I'd seriously consider something that is restricting the fuel or an air leak. Look to make sure the carbs are clean, and the boots are not ripped.

Think about this, it seized that side before. If you don't find the cause, you can't fix the problem. The seized piston is just the result, not the cause.

JakeR · Dec 15, 2009

skibreeze said:
X2
I'd seriously consider something that is restricting the fuel or an air leak. Look to make sure the carbs are clean, and the boots are not ripped.

Think about this, it seized that side before. If you don't find the cause, you can't fix the problem. The seized piston is just the result, not the cause.

I agree I just can't find the problem... Im thinking snow but don'twant to just stop there...

skibreeze · Dec 15, 2009

JakeR said:
I agree I just can't find the problem... Im thinking snow but don'twant to just stop there...

I feel your pain, my 800 is down and god only knows when Poo will get their crap straight and get parts to the dealer.

JakeR · Dec 16, 2009

OK another ? SPI pistons or OEM Pistons. There is a price difference.... But the dealer has it all in stock and I can have it today...

JakeR · Dec 16, 2009

Intake side

JakeR · Dec 16, 2009

Exhaust side

snowmobiler · Dec 16, 2009

looks like mine when the oil injection failed.

Grey44 · Dec 16, 2009

my piston looked identical to that and am also trying to figure out what caused it. i did notice just before the sled went down(pto side) on one cylinder that the oil injection lines did not line up. i adjusted it to spec on trail went probabaly 3 km farther and that is when the sled went down on one cylinder and i stop and investgated and had no compression in pto side.
so im suck on two therorys
oil injection-lack of oil
jetting- a little lean

or could it be a combination of both.

RYDPWDR · Dec 16, 2009

snowmobiler said:
looks like mine when the oil injection failed.

What I was thinking too, we lost one last year when the little oil valve check fitting was plugged/bad, make sure you test them pressure wise.

JakeR · Dec 16, 2009

So what do you guys think about just mixing the oil in it and taking the oil injection off?? Will the bearings get enough oil?

800 Cylinder Problems

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