Of the 2 or 3 options I am aware of to replace or modify the OEM Honda exhaust flange piece could anyone offer positive or negative reviews of better ways to have and maintain a good pipe seal at the cylinder end, please? Mine use the stock manifold with gobs of silicone so the o-rings sealed kits look the biz. Are they worth the $$ or just modify the stock part on the outer and inner major diameter sections to retain a few o-rings? Are Viton o-rings necessary? Cheers, fmcd
I had a manifold on one of our setups and it worked pretty well. Best thing was if you want to yank the head to check on the ring lands, etc., it was a faster process. You could just pull the pipe, and try to rock the piston back and forth through the exhaust port to see if you were getting any ring stick, without pulling the head.
I replaced the stock flange with O-ring types on both my 125s. Much much easier for anytime you need to pull the exhaust. No goop to deal with. Only two things that I need to deal with: (1) the outermost O ring gets "cooked" and needs more frequent replacing - I usually just check it when I have the exhaust off and replace if necessary. I order a bag of viton O rings from McMaster-Carr and they're quite cheap - something like 12$ for a bag of 25. (2) you need to take some extra care when installing the pipe to avoid nicking/pinching/tearing the O rings. it can also require a bit more effort to get the pipe on vs. the stock+sealant approach. using some grease on the flange and O rings helps with both of these issues.
Here's the link: https://www.mcmaster.com/#8333t14 The size seems identical to the ones that came with the flanges I have (can't remember where I got them - had to be either RScycles, TSO or Accu products). Edit: I've also used these with no issue (and they're cheaper): https://www.mcmaster.com/#1201t43
