Boxerworks.com

Was wondering if any of you that haven't converted your valve guides to the unleaded ones are using any form of lead sub in the gas? I read on another site that some use some Marvel Mystery oil in the gas. No clue on the ratio to use. Any thoughts here?

Why would someone use a lead substitute if the heads are set up for unleaded?

Kurt in S.A.

I still have the original 79 seats, have never used lead substitute and yet have seen no measurable valve recession.

You are more likely to need a lead substitute if you ride hard with sustained high revs otherwise just carefully monitor valve clearances.

The Pulse Air Injection System if you have it won't help because it makes the engine run hotter so if you do have it then remove it and plug the ports.

Anecdotal evidence alert: I use a bit of MMO in my fuel. I don't know that it does anything useful. My '84 R100RT made it to 60K miles before it needed its recession-prone OE exhaust seats and valves replaced, and that may be a bit longer than that vintage would generally go--or not. If that was good mileage out of a set of '84 OE heads, I'm not sure whether that had anything to do with the MMO, or my relatively sedate riding habits. But the MMO didn't seem to cause harm, either---no inordinate carbon build-up, or other bad stuff. And it's pretty cheap as vehicular placebos go.

Just a note...the '81-84 heads were prone to valve face plastic deformation...the valve seats didn't recede but rather they didn't conduct heat to the heads which meant the valves retained more heat and thus tuliped. The pre '81 heads did have recession of the valve seat, where bits were taken off and transferred to the valves over time.

The net result was the same...loss of valve clearance. But the action was different. Oak talked about this in an Airmail discussion many years ago.

Kurt in S.A.

Kurt,
No disrespect intended but the question was about the folks like me who HAVEN'T set up their heads for unleaded. Of course you wouldn't use the sub if the heads had already been converted. as for your last comment, and again no disrespect intended but that went way over my head, no clue as to what you meant.

Kelly

Sorry, Kelly...I must have misread your original post. Thought you were wondering about lead substitute for people who had already changed. Don't know why I didn't see it correctly. Mea culpa...

Kurt in S.A.

Not a problem Kurt, Glad to see your still in SA. BTW, I am headed to ride tail of the dragon next week, want to come along??? We should get together for a ride sometime, I have lost your # when the computer I had it on crashed. PM me so we can exchange info again.

Kelly in SA