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I found this info on a Big Bore web site from Dootalker, LDR. Edited it a bit and reads good to me. When it's time for new rings this will be handy, especially the part about using STP lube. See what you think.

DT

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1. Assembly Before assembling the rings on to the piston, it is important that you check piston ring end gap. Proper ring end gap on [800cc SkiDoo engines] should be at .016. Ring end gap is accomplished by installing the ring into the cylinder and then turning the piston upside down and squaring the ring in the bore of the cylinder. Then take a feeler gauge and measure the distance between the ring ends. If the measurement is less than .016 you will need to file the ring. Be careful not to over file the end gap as this will reduce performance and hurt the compression! The best way of doing this is to clamp a file into a vice and take the ring in your hand and wiggle or stroke it back and forth while applying pressure to the rings on each side with the file sandwiched between. Running the engine on too tight of ring end gap will cause engine failure and will damage the nikasil coating on the cylinder.
Before assembling the engine, wash both cylinders with hot soapy water, then blow dry them with compressed air.

The following instructions are prepared to avoid streaking and scuffing of nikasil plated cylinders. After installing new pistons onto the connecting rod and before sliding the piston into the cylinder we mandatorily recommend using STP Brand Oil Treatment to lubricate the piston as an assembly lube to the piston, rings and cylinder. It is important that the STP be applied in the piston ring land. STP is very sticky and will not run off like 2-Stroke oil. Also you must pour approximately 2 ounces of 2- cycle oil into each crankcase cavity. (Underneath the piston, before installing cylinder.) The oil in the crankcase cavity will allow additional oiling during the first few minutes of startup which is the most critical time of break-in. It is very important to use a thin film of [loctite 518] on the both sides of the base gasket. Only a small film (about .010 to .015 thick) of sealant is needed on the base gasket. Coating the base gasket will prevent antifreeze from entering the crankcase due to metal expansion caused by extremely cold and hot engine cycles.
2. Break-In How you break-in your [new pistons and rings] will determine if your engine will be fast or slow. Proper break-in procedure also requires 30 minutes of break-in time at an idle. Do not rev the engine over 2000 RPM's during the first 30 minutes of idle time. In order to avoid overheating of the engine, you should run the engine three to five minutes at a time and then allow a ten minute cool down time.

Make sure that oil injection lines are purged of any air bubbles before start-up . Also the use of high quality synthetic oils greatly increase the success of a proper break-in . After the 30 minutes of idle break-in time we suggest that you vary the running RPM's . Do not hold the throttle at a steady position for more than 15 seconds at a time. Revving the engine up and down with short bursts of full throttle acceleration will improve break-in. If these instructions are not adhered to strictly, streaking and scuffing will appear immediately, causing poor performance and ruining the nikasil in the cylinder. Do not make any hard pulls up steep mountain or Dyno pulls at Wide Open Throttle (WOT) for more than 3 to 5 seconds for the 1st tank of fuel. Do not run WOT for more than 6 to 10 seconds the 2nd tank of fuel and 12 to 15 seconds WOT for third tank of fuel. Do not make any hard pulls over 30 seconds long until after 4 full tanks of fuel.
 

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Don't agree with using stp but if it's working for him that's what matters?

Looks like a cut and paste from cuttler's site?
 

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I have been told by lots of people to never let your sled idle when putting new rings in. They say always vary your speed to reduce wear in that same spot. I have never heard about 30 min of break in idle.
 

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Don't think the whole thing is about the rings. It comes from CPC's site and is probably meant for those who have some of the big bores they build, probaly using forged pistons. The routine is probably a way to get the new big engine off to a good start and prevent early seizure and scuffing, allowing some time for the pistons to find home and shrink a little. The rings will break in later when some hard pulls are made. Not debateing the whole break in procedure, just trying to find some reason in Dales methods. Of course he could build them with huge clearances like skidoo, and tell everyone to just go out and pin it?
 
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