I'm Done With It-No More T-Xp...Parts for sale

turbo800 · Feb 1, 2012

I agree with Gus, nearest I can tell from the crown pic it looks like light deto on the top. Cast pistons with only take so much rocking back and forth in the cylinder before they break the skirt. Usually you see more ring landing problems with deto, but not so much with yours. I dunno why your connecting rod snapped. Forged pistons work great if you can find the happy balance between expansion clearance and rattling in the bore when cold (1150's and 1200's were known to do this). It is possible you have been fighting a bad crank. Its also possible you have been fighting a combination of ignition timing, compression, quality of fuel to support each other...

tukernater · Feb 1, 2012

X2 on gus's respond and Turbo 800.

utah_sledder · Feb 1, 2012

Yep, I agree with above. I had MCB pistons fail after one ride with a little bit of deto last year. Stock pistons all the way for me. They can take lots of abuse.

motoxracer42 · Feb 1, 2012

man that just sucks. now im nervous lol. gonna put my kit on next week. just bad luck.

hivoltagesledhead · Feb 1, 2012

turbo800 said:
I agree with Gus, nearest I can tell from the crown pic it looks like light deto on the top. Cast pistons with only take so much rocking back and forth in the cylinder before they break the skirt. Usually you see more ring landing problems with deto, but not so much with yours. I dunno why your connecting rod snapped. Forged pistons work great if you can find the happy balance between expansion clearance and rattling in the bore when cold (1150's and 1200's were known to do this). It is possible you have been fighting a bad crank. Its also possible you have been fighting a combination of ignition timing, compression, quality of fuel to support each other...

Had the crank checked for phasing and run out before I put it back together. Bench tested it for leaks and it would hold 10psi for ever. Compression is 11.8:1 with ski-doo racing domes, 140 psi per jug. Last time I took my sled to dealer the timing curve was stock.

highmark00700 · Feb 1, 2012

hivoltagesledhead said:
Had the crank checked for phasing and run out before I put it back together. Bench tested it for leaks and it would hold 10psi for ever. Compression is 11.8:1 with ski-doo racing domes, 140 psi per jug. Last time I took my sled to dealer the timing curve was stock.

Checking phase and runout wont always catch a bad rod bearing. I think the lower rod bearing failed initially.

turbo800 · Feb 1, 2012

hivoltagesledhead said:
Had the crank checked for phasing and run out before I put it back together. Bench tested it for leaks and it would hold 10psi for ever. Compression is 11.8:1 with ski-doo racing domes, 140 psi per jug. Last time I took my sled to dealer the timing curve was stock.

Looking closer the PTO connecting rod end/bearing let loose causing the hole in your cases. Phasing and run out wont tell anything about those bearings.

What elevation is your BC riding area? What grade of fuel you running? I'm running 12.5:1 on my HO @ 5500'+ and see about 130psi on the top hat style MXZ head w/ SPI single ring pistons.

hivoltagesledhead · Feb 1, 2012

Vp112 race fuel. 100% for break in and 80/20 or 70/30 mix with 91 octane. Elevation is 2000 to 8000 ft jetted accordingly. Crank and sled only have 700 miles on it. The. Guy that checked my crank didnt split the case but said the bearings were good.

hivoltagesledhead · Feb 1, 2012

I will have a complete turbo kit for sale. Pics and price will be up in a couple of days.

BIG JOHN · Feb 2, 2012

Shawn- Sorry to see any motor fail...the one pic of top of piston is a little fuzzy...but the "ring of truth" is pretty obvious...I bet in person that top is pretty etched...classic heavy deto...not light deto...dont know exact scenario...but by the one pic the problem is not enough octane for boost,compression,timing you were running...or a combo of all 4...

as for the MCB nay sayers...knock yourselfs out...but there is 1 turbo going on 3rd season with them installed..so with correct fueling (general statement) they work just fine...

Nick...the lower comp head/good fuel in yours (if its still on there??) is a turbod 2 strokes best friend (if you dont have a custom timing curve)...you will be fine...unless you took that head off and put the high comression one back on??

DETO in a turbo motor will demolish any piston...you guys blaming MCB make me laugh...classic old wiseizco scenario..."stock piston burns...wiseco installed and burns asap....owner finds problem, fixs problem and uses stock piston and then sled runs just fine"...moral of the story, wiseco pistons suk...LOL-BJ

TT670 · Feb 2, 2012

When deto occurs you might as well yank the egts and toss em in the woods. Detonation actually lowers EGT's and typically raises coolant temperature. It can drive you nuts if youre using instrumentation and dont know deto is occuring. If you're familair with your sleds sound, you can hear detonation, just like the ear can distigush proper jetting.

TWARD700 · Feb 2, 2012

I've been running MCB pistons in my sled for two years now with no issues 7 to 12 lbs of boost on straight avgas with 36 to one pre mix 3 to 7 k . Also had the head cut to lower compression.

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nuttyn01 · Feb 2, 2012

MCB pistons

Pulled my head off and the MCB's look great!!!! No high compression head John!!! Thanks for caring though...lol

MOSKIDOO · Feb 2, 2012

H2O

Couldn't a guy run a gauge like a Koso digital for water temp for another safety factor?

hivoltagesledhead · Feb 2, 2012

I'm going to get the VP 112 fuel tested to check the octane rating. I broke this engine in on straight race fuel and had no issues at 2200 ft.. It would build boost and SOUNDED great. Would not build boost at elevation....never did. I ran 11.8:1 compression head with ski doo racing domes. My timing curve is stock. So,of all these things, only two of the variables should have caused the problem...bad gas or bad ecm or both

Either way, I am going to keep the sled and research a BB to install. Will be selling the T-kit as a whole, probably with the NPP pipe.

I never heard any pinging at any time. The only abnormal thing at the time was a really really warm charge tube.

hivoltagesledhead · Feb 2, 2012

Why would I only have deto in one cylinder? The other piston and cylinder look great.

TWARD700 · Feb 2, 2012

My guess it was bad fuel have had many friends use Vp and lose motors never know how long its been in the drum. That's why I went with avgas chances of bad fuel very low you can't have planes falling out of the air because of bad fuel.

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Bendy · Feb 2, 2012

I always buy my VP fuel in 20 litre containers, I think its safer this way! Also... what jets are you running at 2200ft. I know if I run my 800HO with anything smaller than a 400 main at that elevation she's bye-bye motor! When I ride at home I've got the 400's in. When I head out to the mountains I change to 360's. We unload at 3500ft and quickly advance to 6500 where we spend most of the ride at that elevation.

Bendy · Feb 2, 2012

That looks bad! I don't think that failure had anything to do with air/fuel mixture. Something had to have been out of balance to break that rod like that! I don't know??? If Gus had that in his hands he might be able to give you a better diagnosis.

hivoltagesledhead · Feb 2, 2012

Well boys, I dropped the deto piston with half con rod off at a local race engine builder and he is of the opinion that it hydrolocked. Again this is just an opinion. So for the sake of chits and giggles, I am going to remove the case tonite and make a little gopro vid so that the images are more clear and we can get a real good look at the damage. He showed me some deto pistons and they look nothing like mine, but that doesnt mean it didnt deto. Hydrolock would explain why there were no symptoms of deto, no codes, no knock sensor and the fact that it suddenly happened without warning. I dont know why it would hydraulic but he has seen it before on his own 04 rev turbo.
Anyway, off to make a vid. Will post shortly.

Oh yeah, wont be getting the octane checked in my drum....anyone want to guess how much that test cost.......

I'm Done With It-No More T-Xp...Parts for sale

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