Series "A" drive side ball bearing and engine build.

greg brillus

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Does anyone have any info about the need, or not for a copper head gasket. This one looks like it might need one, if so are any available. If not I might have to get some made, thickness.........1 mm........? Any help, many thanks...............
 

Simon Dinsdale

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It appears some bikes had copper gaskets and some not. All depends upon the barrel & head been used. I have heard the barrel spigot was changed during production but what was changed exactly I don't know. When my dad & I rebuilt my bike a copper head gasket was bought from Conways, but upon assembly I measured the compression ration and with the gasket it was too low. Without it was spot on so I just ground the head to barrel joint in a similar fashion to post war and went without a gasket and its never been a problem. Sorry I cannot find the gasket to measure the thickness. I think it went in with a load of A parts to my brother.
Simon
 

davidd

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I sold my A twin to Scott Dell. When he rebuilt it a few years ago for the current owner he had to make some new gaskets because the person that restored the bike did away with them. He made them from some copper sheet. I believe that he had some fitting problems with the push rods and rocker positions that necessitated the gasket. You may need a dry build, as Simon did, to determine how things fit.

David
 

Dinny

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I have the new gasket that Simons talking about and I dont know if I need it yet. I can take some measurements off it for you and I will try and figure out if I need it. If not i can send it over to you, just give me a few days.
Mark
 

greg brillus

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Thanks for the replies, I will check the liner to head spigot depth to see what I can get away with. Ok my next one is probably a difficult one.........I have fully rebuilt/restored the Miller Dyno mag but the only part I am missing is the small duplex chain that drives the dynamo. Does anyone know of any available or what can be done to solve this issue. Cheers.............Greg.
 

timetraveller

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I'm not familiar with these bits but if all else fails then two new aluminium toothed wheels and a toothed belt might do the job. The wheels are available in a wide range of sizes, widths etc. so it should be possible to replicate and gear ratio required. These are also very cheap items these days.
 

Dinny

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I've checked the two copper head gaskets I have here, the old one is 12 thou thick and the new is 26 thou.

Looking at my head/barrel I do need a head gasket but have not had a chance to work anything out as my backs killing me!

Mark
 

greg brillus

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What are the general thoughts about a cylinder base gasket. Is it just a thin paper one or something else. Cheers..................Greg.
 

Don Morris

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From some years ago my thinking on the large spring washers was that when you tighten up the sprocket nut , and the bearing housing, the inside of the inner bearing is pushed against the flywheel. This relieves any axial thrust on the balls in the ball race.

I found that trial assembly with the drive side bearing housing fitted to the flywheel assembly (not in the c/cases) made things easier to understand and with sprocket nut tight the bearing housing spun easily on the main shaft. I must give credit to Bob Stafford here as I do not pretend to be an expert on 'A' twins but found building mine up was an "interesting" exercise especially compared to doing the same with a 'C' twin.
 

A_HRD

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Welcome to the forum Don. I, for one, look forward to your Series A words of wisdom on other aspects of building and fettling your immaculate machine.

Peter B
 
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