Tappet clerances on twins

Information relating to the Matchless G11 or AJS Model 30 600cc twin
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Tappet clerances on twins

Postby silverspur » Mon May 08, 2017 6:02 pm

I've just been reading a 1957 book "Motorcycle Maintenance and Repair" by F W Neill who is billed as the Service Manager of Associated Motor Cycles Ltd.

After going through the adjustment procedure for tappets and the usual .006"/.008 recommendations, he then says, and "I quote:"If speeds over 85 mph are not desired, rocker clearance can be reduced to nil for inlet and .002" for exhaust, with a cold engine."

Really? Any comments from people who know much more than I about these engines.

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Re: Tappet clerances on twins

Postby ajscomboman » Mon May 08, 2017 6:06 pm

Post 60 twins .006 inlet and .008 exhaust for pre 60 models it's .006 for both inlet and exhaust. As for closing the gap down, not something I've ever tried or would recommend, ever.

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Re: Tappet clerances on twins

Postby Groily » Tue May 09, 2017 5:48 am

My copy of Neill makes the same point somewhere. (As if an old 500 would even do 85 easily or at all!) But I have always gone with 6 and 8 (even on earlier engines) as it seems wise. They're not the quietest motors, and I suppose that's why the idea might appeal to some, but I wouldn't.

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