Honda ATV Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
76 Posts
Discussion Starter #1
The compression in my '91 is a little low and it seems to be lacking power. I was thinking about taking it apart this winter and putting in a piston kit. Would I be better off having the cylinder bored over and buying an oversized piston and rings from Honda or going with a higher compression piston? I see that Wiseco offers a piston that increases the compression from the stock 9:1 to 10.25:1. Would I see a performance boost by making this change? Would the higher compression ratio cause extra wear on other parts?
 

·
Premium Member
Joined
·
23,581 Posts
Being that it's a '91 model, I would go 0.025 over on the cylinder, piston, and rings, because it probably has a lot of wear in the cylinder. Boring a cylinder isn't really going to give you any noticeable power increase. That just cleans up any scratches or wear in the cylinder walls.

Personally, I would stay away from any high compression pistons for the utility ATVs, because the closer to stock that you keep them, the more dependable they are. If you're not worried about dependability and are after more performance, then you might consider it. But without other mods, I don't know if it would give you much more in performance or not.

I believe the low compression ratio is what causes those engines to last so long.
 

·
Registered
Joined
·
2,735 Posts
The higher compression with 93 octane fuel will give you a better throttle response but nothing else.
 

·
Registered
Joined
·
76 Posts
Discussion Starter #4
Should I just buy the parts directly from Honda or from an aftermarket supplier. If not Honda, which company should I buy from?
 

·
Registered
Joined
·
25 Posts
I would recommend a Wiseco piston kit. Everyone I know speaks highly of them. I would imagine that buying direct from the make of the four wheeler is probably going to be greatly over priced.
 

·
Registered
Joined
·
2,735 Posts
Agree^^^^^!!!!!
 

·
Premium Member
Joined
·
23,581 Posts
I agree, also.
 

·
Registered
Joined
·
76 Posts
Discussion Starter #8
I checked the Wiseco website. All of the pistons they offer have a compression ratio of 10.25:1, compared to the stock 9:1 ratio. Per my previous post, could a higher compression ratio damage other engine components or reduce the longevity of the engine?
 

·
Registered
Joined
·
76 Posts
Discussion Starter #9
I found at shop called G & H Discount ATV Supply (out of TN) on ebay that will clean, bead blast, bore and hone my cylinder and send it back with an oversized piston, ring kit, piston pin, circlips, and top end gasket kit for around $200 with shipping. I contacted them and they stated the new piston will retain stock compression (9:1). Sounds like a good deal, anyone every hear of GH or order from them?
 
1 - 9 of 9 Posts
Top