5500 miles, virgin motor.

I have a lean condition on my center cylinder and antifreeze ingestion in the engine, here is what happened.

I was trying out my new BM pipes and after about 10 miles I blew a belt at around 100 mph. I have never blown a belt on this sled. I only had around 500 miles on the belt. It exploded completely and stopped the engine dead. The only thing left was a thin top portion of the belt. I limped home around 4 miles with my spare as there was belt residue everywhere. Went around 40-60 mph, all lake. It was around -7C out.

When I got home I noticed my antifreeze was very low and put some in to fill the bottle. I started the sled and whoosh, away went the antifreeze. I turned the sled off. I thought the worst (balance shaft/water pump seals, previous experience here http://www.hardcoresledder.com/forums/inde...c=62304&hl= ) but had noticed no antifreeze dripping from the weep hole.

I got the sled home from the cottage and took off the water pump, lots of oil/gunk in the antifreeze. The water pump seals were perfect, not only that there was no wobble on the impeller and the impeller washer looked like new, no wear of rubber and the small oring was great. No grease found on the outer balance shaft bearing, appeared to be washed clean. All 3 orings on the water pump assembly appear to be fine. I happened to check the pistons through the exhaust ports and wow, a slight lean burn down on the center cylinder. Off comes the cylinder and sure enough, it was lean. The base gasket appeared fine. I removed the other cylinders and they were fine, the PTO seemed a little richer then the MAG side. In the bottom of the case there was apparently oil/gas/antifreeze in all three. I checked the head orings and although stretched after taking them out, they seemed OK. At this point I had my ex-Catmaster buddy over and he had no answers.

I later split the crank and all bearings appeared to have been somewhat washed of oil. The balance shaft bearings were also washed of grease. I installed a grease nipple on this motor when it was brand new and have greased it plenty. On the upside, the BS bearings are in extremely good shape as is the water pump shaft so I believe my grease nipple was working great.

I cannot figure this one out. I didn’t check the fuel in the float bowl but I am religious with ISO and good premium fuel. Not one hiccup in 5500 miles. I store the sled in an air-conditioned garage and maintain it 110%. The sled has 12,000 miles on it and looks like new. I later installed the BM pipes on my similarly set up 02 T-Cat and it ran great (even rich) for 400 miles. My settings on the 01 are as follows when it went down.

Vforce3 reeds (day1, 0 miles)
2.5 degree key (day1, 0 miles)
BM clutching (day1, 0 miles)
Reed spacers (day1, 0 miles)
Stock jetting/airbox 320’s mostly lake riding at -10 to -20C, 1000’ (day1, 0 miles) 120 on GPS, long lake runs at WOT
BM pipes
330 mains and 1 clip raised needle for the BM pipes, works great on the 02


I have included pics of the pistons on exhaust, intake and top sides. For the first time ever on a lean condition I did not seize the rings in the piston, they are free. Whenever I used to check the piston wash it always looked like the mag piston in the pictures, appeared very happy. If anybody has ideas it would sure be appreciated

Well I do not know what happened. But I do know some thing is a little strange with your jetting.
I have a few T cats and have ran CPR pipes on them. Some one has said they are close to the Black Magic pipe.
I have had to run 410 jet to keep my motor alive
I live in Ontario so I do not thing elevation is playing a big part here.
But two of your pistons wash looks good
Seems like strange stuff, small jets and that much wash.

The middle pistons looks like it had antifreeze ingestion. Look at that cylinder very closely for anything out of the ordinary. Any cracks in the grroves where the o-rings seat? I think the blown belt is just a coincidence? Something messed with the ports by looking at your piston. Are they grooved or just discolored? Check the crankcase where that cylinder is as well, make sure it did not crack due to the belt explosion.

BM recommends 2 sizes up from stock and 1 needle clip position and that is with a 3.5 degree key.
I have run reliably with 320's at -25C, it was -7 that day so I only upped it by one to 330's. I did 400 miles the next 2 day's with my 02 T-Cat with the same 330 jets and 1 clip richer with no problems.




I agree, it has antifreeze ingestion. The compression oring seems slightly cracked but does not look serious enough to cause this, all the rings look the same. The head, on the center cylinder only, has a shiny thumb removable black slime unlike the other 2 heads.
Can the antifreeze ingestion cause the lean condition? I cannot see anything wrong with the scuffed cylinder or case. Piston is slightly gouged/grooved but mostly smooth where seizure is.

What does the underside of the case look like? The gummy black stuff would be antifreeze residue. The antifreeze is coming from somewhere. Are you sure the base gasket is good? All the bolts were torqued to the proper amount. My guess is the antifrezze is coming from below the piston, that is why the port marks are so clean. You would think if the o-ring was bad it would have smoked and ran like shit Check that crank case very carefully, both halfs. It should be fairly obvious. Has it been using antifreeze for a while or all of a sudden?

The base gasket is in one piece and appears to be fine. What would it look like if it was bad. I have never seen a bad Cat base gasket in 20 years. I always observe the overflow bottle and I am sure I would have noticed it when installing the pipes 15 miles ago. This engine has never used coolant since I installed it new 5500 miles ago. The engine is virgin so torque specs ??? I cheked both halves but will clean 100% and do so again. I have not noticed anything fairly obvious but I will compare it with a good one I have. The bottom of the cylinder also looks fine. I still have to remove reeds but intake rubber looks fine.

Would the antifreeze cause the lean condition with the seizure and hole in the top of the piston?

I agree with rcat7. Man that just don't sound right to me. 320's with BM pipes on an 01 with a key. Are you sure BM didn't miss understand you somehow? When I purchased my 2000 t-cat that was the set up in mine except for the 01 ignition and key and I popped it when it was around 12 degrees out. I was running 320 in it when it happened. I now have 420 straight across. I got mine so hot it cracked the cylinder head and burned up the pistons. Had to buy a used head. Back then, D & D told me I was way to lean on the mains. The gentleman I bought it from said the dealership had set everything up and it was ok. Guess he was wrong! Back then this was all new to me.

I have read that after a few miles the coolant hose will rub through down by the recoil somewhere due to sharp casting burrs. I'd check this out. Maybe your dealing with acouple different problems at the same time. Low on coolant and running lean nailed your pistons. Just my .02c.

I'd have to say putting the pipes on had something to do with it. Over the years I have learned that when ever you put on pipes and/or mod. the air box you get a midrange hot spot. (usually around 7000 rpm's) My guess would be it was getting hot at mid range and caused the o-ring to leak. If you can see anything wrong as you stated you did, with the o-rings they are junk. Heck I used them over when they looked good but where old and had them leak on a stock motor.

The antifreeze should cause it to run like shit, but not lean since it will not burn??? You are lean with pipes as well. I do no know about flatslides, but I always go up a few sizes with pipes

you will need way more jet .... youll need 400-420...whenever i see a hole on top of piston, i think water in gas or bad gas{ pre-detonation}.although your was looks good on your pto piston, i would go alittle more for the long pulling we do around here on our trails and lakes.
also when jetting these make sure you g o 1 size bigger in the middle, these tripples need it.

Yikes, that is way too lean... I am running 400's with a tempa flow using d&d trail pipes and that is dancing on the hairy edge.