ring gaps for higher hp engines 485 - 535

[lt1bird]

what do most of you use for ring gaps in the higher hp engines using wiseco pistons? I filed the ring to .011-.012 per wiseco thier spec. It seems to work fine on my other engines ive built... wierd...trinity said they dont file them, they just install them! They come in at .008 seems a bit tight to me... anyone want to add thier opinion?

[Fastassbanshee96]

I have never filed mine either. Just thru them in and went but then again min e isn't really a high hp motor. IMO. If you do have to file them, at what hp do you have to start with what mods.

[mailman]

The Golden Rule of ring gap says that you should have about .004" per inch of bore. The 73 mm pistons would then need about .011" to .012". ( 2.87 inch diameter bore X .004 = .0115 ) The fact that the motor is high hp doesn't really come into play here except for exhaust port size. A high hp motor will usually have a larger exhaust port and therefore be more prone to ring damage. Ring gap is simply a function of piston size; larger piston means more gap needed. I would run at least .012" for a ring gap. If the gap is too small then the rings will expand when heated and have no place to go but into the exhaust port and most likely cause damage to the motor. You will lose very little by making the gap a little larger but will risk a lot if the gap is too small.

 

I hope this helps. By the way, do yourself a favor and don't ask Trinity for motor advise. Most the time you are just speaking to a salesperson anyway who has very limited knowledge. Putting in a ring without checking gap is just playing Russian Roulette. Simply Foolish! Check out some of the posts on here about Trinity.

 

Mailman

Edited June 14, 2010 by mailman

[RadarRacing]

Its really not a HP thing its a heat thing. I always do .012. When you have a new bore the cylinder is rough and the rings are smoothing and mating their outer edge to the cylinder. This causes a LOT of heat in the rings thus the reason we start em up and turn em off a few times to not heat the rings up too much which causes them to expand and possibly closing the gap completely if their isn't enough gap. The ring will then press very hard on the bore and potentially catch or snag in the exh port. A larger bore has a longer ring that can expand more but its not really a HP thing. .008 is much tighter when the ring gets up to 900 degs.

[Fastassbanshee96]

Nice little piece of info I did not know. Guess I will have to start checking ring gap when I do rebuilds.

[Modified RC]

I set my 485 ring gap to .012-.014, that was suggested by my porter.

[lt1bird]

exactly....trust no one and always check. The triniy kit is fine...Its not somthing you can slam in...Lots of extra work to make it all fit proper...machinig head holes etc...

 

I had called wiseco to confirm a few years ago.....they said .012" for 73mm bore so thats what I always do...I bet a lean running bike would be more prone to issues with a .008 gap.... I have not had any issues with my 535 with .012"

 

So we all agree.......