Topic: power loss

[nic_hayes]

hey guys, i'm running a 15hp briggs ohv single. just built it four or five races ago, it is stock except for don balanced the crank and redid the head with all his stuff. over the last few races it has slowly been getting slower, i checked the valves and there ok, the only thing i can think of is i started running 108 racing fuel about three races ago, is this bad for these small engines, thanks

[George Herrin]

You do not have enough compression for the 108 to help you at all. Its definately hurting you more than its helping. Check your timing key could be partially sheared.

[greenmachine]

Absolutly agree with George on the fuel.

High octane fuel burns slower to prevent preignition in high compression engines, the higher the octane rating, the slower the burn. Unless you are running about 11 to 1 compression ratio or better you are litterally getting less "BANG" out of the fuel.

I'd run the lowest octane I could that doesn't cause spark knock at operating temperature and and run on (dieseling) when you shut it off. I think you'll find some of your power that you lost.

[nic_hayes]

thats kinda what we were thinking but we wernt sure, just go back with 87 or 91, thanks a lot