Re: compression 96 GTX
OEM pistons in Rotax motors of that vintage use an L top ring that better uses compression to force the ring tight to the clyinder wall. If a Rotax motor with oem rings is blowing 5 lbs lower than it should, there will be damage, however mild, but still damage, or the machinist should be selling used cars for a living.
If you use aftermarket pistons and rings, the gap widens between acceptable and not acceptable standards.
I consider 5 lbs lower the maximum amount of difference that is acceptable in an oem Rotax application.
Your opinion may vary.
A machine shop or jetski/motorcycle shop that bores clyinders can vary drastically from one shop to another in the precision and tolerances of the work or their equiptment. This can drastically effect the lifespan of an engine's ability to seal the rings in the clyinders due to the quality of a boring and honing operation.
I only use the best machinist and he owns the best equiptment, a German made boring bar and a Sunnen precision honing machine, both refitted with tooling and honing stones and oil on a regular basis, for all of my in-house rebuilds. I usually do not see 2 lbs difference between clyinders on engines that we rebuild the clyinder for using oem Rotax pistons and rings.
I do not consider a racing engine any more important that the average customers engine when it comes to precision machine work on the clyinders.
OEM pistons in Rotax motors of that vintage use an L top ring that better uses compression to force the ring tight to the clyinder wall. If a Rotax motor with oem rings is blowing 5 lbs lower than it should, there will be damage, however mild, but still damage, or the machinist should be selling used cars for a living.
If you use aftermarket pistons and rings, the gap widens between acceptable and not acceptable standards.
I consider 5 lbs lower the maximum amount of difference that is acceptable in an oem Rotax application.
Your opinion may vary.
A machine shop or jetski/motorcycle shop that bores clyinders can vary drastically from one shop to another in the precision and tolerances of the work or their equiptment. This can drastically effect the lifespan of an engine's ability to seal the rings in the clyinders due to the quality of a boring and honing operation.
I only use the best machinist and he owns the best equiptment, a German made boring bar and a Sunnen precision honing machine, both refitted with tooling and honing stones and oil on a regular basis, for all of my in-house rebuilds. I usually do not see 2 lbs difference between clyinders on engines that we rebuild the clyinder for using oem Rotax pistons and rings.
I do not consider a racing engine any more important that the average customers engine when it comes to precision machine work on the clyinders.
Comment