high comp pistons

[grader]

it seems no one has tried this switch to high comp pistons. the 03 rings are junk and yamaha knew it and changed it for 04-05. ive got a complete bottom end to work with so the pistons can be swapped first, then the engine. the manual spec is 179-230 psi stock, so if it stays in that range then reg gas should do it.its looking like a summer project that will return some lost performance and end the oil consumption issues.

 

[nhsrx701]

crazyyamaha,

Just out of curiosity....did you by chance pull an old ring off the engine and place it down the whole and check the ring gap with a feeler gauge.....and then do the same with the new rings to check the difference......also did you find any of you ring lined up or close to lined up??? The reason I ask it because if the 03 ring tension is softer then it might be safe to say that metal make up of the old rings is softer and this causes the rings to wear faster....I'm on the fence about opening my engine up to replace the rings and just look for all the info avail...thanks and rock on!

 

[crazyyamaha]

No, I didn't check the old rings in the cylinder bore.When I did pull the pistons out none of the ring gaps were lined up. It does state in my 2003 manual that "ring material is designed to match the ceramic composite cylinder coating. I don,t know if the 05 rings are made out of a differnt material or if they are just stiffer.

 

[Ron's]

I apologize for all these posts, but I keep thinking of more things. When I rebuilt the motor it was almost a year ago. When I installed the piston rings I didn't offset them according to the manual which is about a quarter turn from each other. I did it the way I was trained I was an ASE certified mechanic for twelve years.The top ring was installed 90 deg. from piston pin .The second was installed 180 deg. from top ring. The first oil ring was installed back on the same side as the first ring but in the middle of the first ring gap and piston pin The oil expander ring is installed 90 deg. from the top oil ring on the same side as the first ring and top oil ring. The second oil ring is installed back on the same side as the second ring but 45 deg from the piston pin and top ring. Hope that makes sense. I am not saying that you have to install it this way, but this is the way that I did it and had good luck, so far.

The more posts the better, all good info thanks!