R100 RS (1982) unleaded fuel mods

**John Roberts** · #1 18 Mar 2004

What modifications do I need to carry out to allow the use of unleaded in my 1982 R100RS, please. As it is, it pinks when I use unleaded (pre-ignition)-is it simply a matter of retiming-if so, can someone tell me the new setting? I'm told that the valve seats should be perfectly OK as the Germans and most of Europe had gone over to unleaded well before the UK did. Following the demise of four-star I've been using LRP and, more recently, an additive, Redex Lead Replacement, but the valve clearances have stayed OK, and neither does it pink.

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Johnefyn

**Grant Johnson** · #2 18 Mar 2004

Unleaded Premium SHOULD be fine, but if it's not, either your heads are coked up thereby raising the compression and the need for higher octane fuel, or you'll just have to retard the timing slightly until it stops pinking. No specific setting, just less advance as needed.

If you do a valve job, you may find that a good cleaning of the combustion chamber solves the problem.

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Grant Johnson

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