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Discussion Starter #1
Just got done rebuilding my 97 indy storm 800 (first rebuild of any kind)... partial bottom end, full top end w/ center cylinder replaced cylinder. All stock bores and sizes etc. After 150 miles of driving the sled is tuned and running near perfect. I checked the compression today and got 125 mag, 121 center, 127 pto. The sled was well warmed up (drove it to the shop) and then had cooled for about 6 - 7 min before the test was done. The had been worked on by the previous owner and the head gaskets were single layer metal gaskets. The Wiseco replacement gaskets were double layer metal. The service manual called for .8mm thich head gaskets but the wiseco gaskets were probably twice that thick. For break in I ran over several days with slowly increasing ammounts of throttle and periods of acceleration and non-brake decelleration and constantly varrying RPM. After about 80 miles of riding I made some runs up at 3/4 throttle and I'm still not running it very hard at 150 miles (I dont ride that hard anyway since the thing is almost uncontrollable at full throttle). With all that in mind, are the compression numbers ok for this sled? If they are low, should I go back to single layer head gaskets and how much change would that make in compression? Also, I read that it takes longer to break in a new engines with nikasil bores... are the rings even fully seated yet after 150 miles of trail riding/breaking in?

Thanks

mmSeven
 

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That is a good number for compression. You want them to be within 10% of each other. If you were to put the thinner gasket in, you might get another 5 pounds, but thats just a guess. The nicasil cylinders do take a lot longer to break in. More time if you use synthetic oil. After a few tanks of gas you should be good to go to let er rip! -Polaris Doc
 

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Update: Today I ran another test on the sled when it was cold, (had been sitting for 24 hours) and got 133 in all cylinders. In the other test, the sled had been warmed up then allowed to cool for about 6-7 minuites before testing.
Thanks for weighing in Polaris Doc!
 
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