Author Topic: Does a rich mixture cause excessive wear on the cylinders? (Read 3000 times)

duane · « **on:** February 25, 2006, 02:24:13 AM »

After finding I had unusually large jets in my bike, stripes1976 wrote:

Quote

i would seriously recommend you get your compression checked after you have it running! With it running that rich there is a possibility that the bores have been worn by the excessive fuel! If the bores are worn then you wanna talk to jay (gsxr400racer) about something he has for sale!

In all of my years of motorcycling I've never heard this. I know an excessively lean mixture will run hotter causing a multitude of problems, but in the last few years I been reading lots about tuning and this is the first time I've heard this. Could some one explain why?

Red01 · « **Reply #1 on:** February 25, 2006, 10:50:18 AM »

Excessively rich mixture will wash the cylinder walls of oil. Lack of oil, as you can imagine, will not be conducive to long cylinder wall and/or piston & ring life.

Krautwagen · « **Reply #2 on:** February 25, 2006, 08:01:05 PM »

Theoretically, it could also cause lower temps, which would change the spec of component sizes at operating temp. But I highly doubt it would have any real measureable effect.

gsxr400 racer · « **Reply #3 on:** February 25, 2006, 11:42:41 PM »

Quote from: "Red01"

Excessively rich mixture will wash the cylinder walls of oil. Lack of oil, as you can imagine, will not be conducive to long cylinder wall and/or piston & ring life.

this is the correct respnse to that question .

gsxr400 racer · « **Reply #4 on:** February 25, 2006, 11:46:17 PM »

better yet buy a compression tester and find out for yourself ( peice of own mind)

banditcilik · « **Reply #5 on:** February 28, 2006, 04:16:49 AM »

I would think the lubricant film on cylinder wall that is durable enough to stand the heat and friction of piston rings will also stands from rich mixture except very rich one that is impossible to ignite.
If I would err on the fuel/air ratio then I prefer to err on the rich side than lean.

Red01 · « **Reply #6 on:** February 28, 2006, 11:16:25 AM »

Slightly rich won't wash the walls and I agree, it would be better to be slightly rich than lean.