Supermini Compression and Maintenance.

[justalonewolf007]

Alrighty. Here is the thread where I hopefully dig into some wiser, more mechanically inclined minds than my own.

I have a 2005 Honda CR85 Expert, converted to a 105 Supermini by a company called PR2 (PR squared). It is set up to run 110 octane fuel. Having had it for almost a year, it's time for maintenance (doing my best for preventative) and preparing for that ever impending grinding noise of doom.

I consulted my manual, feeling really quite young and bullet proof and bold, only to realise that the specifications for most anything engine might not be accurate anymore. What to do!?! :whoa:

Question #1

- What compression should this thing be at? Today's testing had it at 150 psi. I am thinking that it is due for rings and/or probably an entire top end.

#2

- What is the ring gap limit supposed to be? I'm assuming that it is different with each piston size.

#3

- When it comes time to order a replacement piston/rings, which size do I order? Wiseco's site only had a 101cc displacement listed for my bike, and this was at a 52mm bore (here's hoping I remember the termages and units correctly). This is the same deal for a lot of the other online ordering places I've tried. They list bore sizes, but not displacement.

Is it a matter of busting out the ruler and tearing off the head to measure things up?

#4

I forget this one now that I've been typing other stuff. :whoa: Give it a sec, it'll come back to me in a bit!

Yep, it did. I plan on calling or emailing PR2 during work hours (once I get the chance later on this week) using the information I found online about them. Have I got things covered? If I missed something, what other questions should I ask (stuff not found in the manual) to make sure I've got the right information to keep this awesome little bike running sharp and ridiculously fast?

 

[_JOE_]

Compression will depend on how they set up the motor. When it's back together and broken in take a preliminary reading. Use this as your starting point.

Ring gap should be like .004-.006" PER INCH OF BORE SIZE. It will tell you on the instruction sheet with the piston kit.

Yes, the best thing to do is to disassemble and inspect/measure everything so you only have to make 1 parts order. Be aware the lower end will require more frequent maintenance with the modified engine.




Good luck with the project! I would still call up PR2 and ask if they have any precautions or suggestions of things to look for. They should be able to provide you with a piston kit or at least a part number.