It seems to me that all this story is a trick to make the people buy new cars (and bikes) !!
1) Octane rate :
Unleaded gas has 95 octane rate and leaded one has 98: is this difference so important ?
2) lubricant power of lead in valve system:
how could all the LPG and CH4 conversion cars work properly without lead ?
Please, any comment is wellcome
Michele
Unleaded gas consideration
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Allan Atherton
Re: Unleaded gas consideration
I think the lead allows a higher octane rating than can be gotten without lead. The highest commonly available unleaded octane in the US is 93, and the old car and bike engines seem to run OK on it. Perhaps very high compression old engines would need 95 octane, and I have not heard of any highway-use engine that needs 98 octane.
I think the lead residues lubricated the valve guides and the lead deposits cushioned the valves' impact on the the valve seats. New engines use materials that do not depend on lead. Old engines can suffer erosion and recession of the valve seats without lead, but this is only a problem if the engine is run hard for long periods.
I am told that vintage engines may go a long time on unleaded gas if they are gently used and the valve adjustment is checked every 1000 miles.
If and when a valve job is done, parts are available of materials that are designed for lead-free gas. I used them in my R27.
I think the lead residues lubricated the valve guides and the lead deposits cushioned the valves' impact on the the valve seats. New engines use materials that do not depend on lead. Old engines can suffer erosion and recession of the valve seats without lead, but this is only a problem if the engine is run hard for long periods.
I am told that vintage engines may go a long time on unleaded gas if they are gently used and the valve adjustment is checked every 1000 miles.
If and when a valve job is done, parts are available of materials that are designed for lead-free gas. I used them in my R27.
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rolf
Re: Unleaded gas consideration
I wrote this some weeks ago as answer for "unleaded petrol for R27":
In Germany,in the 50", nearly no petrol was leaded.ARAL had only unleaded petrol until (about)62.There are so many opinions about that theme, I think it was only a kind of faith. I used,since it was available(about1980) only unleaded fuel for my R67/2sidecar+25/2.
I driving 20000km every year (to work + holidays) with them.Driving slowly (this is often said , the only reason not using special valves+seats) isn"t possible in our days, it"s more a race only to flow with the normal trafic(especially for that little12 hp cycle). I check my valveseats every year,no,really no, problems.
If you check your valveclearance every 1500 km( what you have to do ,look your manual) ),you will see early enough if the clearance(inspite of my words) disappeared and so you have time enough to spent your money for unleaded valves etc..
Rolf Gehrke Hamburg
In Germany,in the 50", nearly no petrol was leaded.ARAL had only unleaded petrol until (about)62.There are so many opinions about that theme, I think it was only a kind of faith. I used,since it was available(about1980) only unleaded fuel for my R67/2sidecar+25/2.
I driving 20000km every year (to work + holidays) with them.Driving slowly (this is often said , the only reason not using special valves+seats) isn"t possible in our days, it"s more a race only to flow with the normal trafic(especially for that little12 hp cycle). I check my valveseats every year,no,really no, problems.
If you check your valveclearance every 1500 km( what you have to do ,look your manual) ),you will see early enough if the clearance(inspite of my words) disappeared and so you have time enough to spent your money for unleaded valves etc..
Rolf Gehrke Hamburg