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Hey everyone. Anyone w a 97 formula sl fan cool that has a problom melting down? Got one for the girlfriend last year figuring a fan cooled sled should be bulletproof and as of this sunday i am now faced w changing a piston for the 3rd time. The first time it was a crank seal so i can understand that but about a month ago when it popped the other side i was unable to find any reason except for a little bit of old gas stain on the float bowl. Figured that that had to be the culprit so changed the piston. Please note that a leak down was done the second time and no problem there. Also,carbs were checked and jets are factory,oil setting ok etc. Anyways,changed the piston and last sunday it popped the piston on the other side[the piston that was done last year].
Note that temps were anywhere from warm to cold. I have checked plugs repeatedly and it always seemed to run a little rich if anything.
One thing that may be of help is that this thing was never an easy starter,abou 5-10 pulls when cold and would sometimes have to hold throttle wide open when warm for it to start.
What the #### am i missing? I am at the point where i may just put a new piston in and dump it but i have been on the wrong end of those deals before and would hate to give this problem to someone else.
If there are any hints please send them as i am willing to check all of them
Thanks
Sid
 

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maybe you have a bad seal somewhere...ever do a compression check after the rebuilds?
Are you breaking in the engine properly?
Maybe there is something wrong with the crank?
Are you doing the work yourself? Using the correct torque specs? Ring gaps etc?

Sounds like there is something fundamental that is wrong if it keeps blowing. I would tear it all down and inspect
everything
Just a few ideas....
 

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Is the sled oil injection.  If it is did you check to see if the oil pump is working correctly.  It may be failed or may have a air pocket in it preventing oil from getting to the engine.  

Also how is the jetting.  Richen it up and go on the safer side. (plugs are cheep engines arent.)

Also use super gas or 91 for the first few times.  if not everytime.  

And go to a colder plug.  

Also make sure the pistons you are putting in are the right ones.  

Other then that i dont know whats happening to you.  

This whole thing is probably getting expencive so i suggest that if it doesnt work next time to take it into a dealer and have them work on it.  

Good luck.
 

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Sounds to me like you have an air leak somewhere , check the carb boots to the air box & to the motor , I would take a look at your fuel and oil lines to look for leaks . Also after a rebuild after your first tank you should retork your heads ... you'll be surprized . Well good luck
 

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Sid have you checked the ignition timing? maybe a cdi box advaning the timing to much.
Have you check the fuel filters? You may have a small filter in the fuel inlet on the carb's.
At what r.p.m is this happing at.
 

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HEY SID. I HAVE A 377 SERIES MOTOR THAT RUNS GOOD. I'LL SELL it for $ 75. I LIVE IN CENTRAL WI. I'LL EVEN DELIVER IT IF YOUR NOT TOO FAR AWAY. I COULD USE A ROAD TRIP.
 

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Hey sid, I have a 96 Formula S and I blew the right sided piston about 3 weeks ago now.  
So I had to get the pot bored out 10/1000 of an inch and got a new piston because it blew a hole with a diameter right through the piston and there was peices of aluminum stuck on the pot. So now one is bored larger than the other, I am still scared to drive fast because I don't want to blow any of the pistons, lol, I know I can drive fast but I am just scared to. I am hoping left piston doesn't blow now because of the ride side being bigger. Was yours bored out? Did you buy it used and do you know if it had blown a piston previously? But with my oil injection I put a touch of oil into the gas take just to be careful.

Josh
 
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