Author Topic: non matching numbers (cases)  (Read 1127 times)

Offline flaboy

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non matching numbers (cases)
« on: 23.11. 2011 10:08 »
My 58 a10twin cases are not matched and the bike was running back in 73 is there any way to tell if it was line bored and not remarked?  also what damage would show up?  Any help on this would be greatful!  I'm so happy i found u guys  thanks Murray

Offline terryk

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Re: non matching numbers (cases)
« Reply #1 on: 23.11. 2011 13:36 »
If the bike was running ok in 1973 you should be able to use them. Just examine all the engine parts. Make sure when the cases are bolted together that the cam can turn ok. It may be a little tight because the bushes are tight but as long as it turns its ok.The next thing to do is line bore the timing main bush true to the bearing housing on the drive side. As long as the cases are level where the barrels bolt on it should be ok. I have heard of many A10/A7s the run just fine with non matched crankcases although I havent done it myself.
1950-53 A10 rigid/plungers, 1958-61 A10 super rockets, 1947-50 A7 longstrokes, 1949 Star twin,
1951-54 A7 plungers, 1940s M21, WDM20s,
1948-50s B33s rigid/plunger/swingarm, 1948-50s b31s rigid/plunger/swingarm

Offline Goldy

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Re: non matching numbers (cases)
« Reply #2 on: 23.11. 2011 18:09 »
Murrey. I had this problem and what I did was to go along to my local engineering shop and asked them to check it out. They can put the cases onto a surface table and then using a vernier height gauge they can check it out. The datum has to be the crankcase mouth, because if that is not perfectly in line the cylinder base joint will leak. Next the sump plate faces have to be correct or the sump plate will leak oil. Thirdly as you have said the bores must be in line. This type of work is quite normal for an engineering machine shop and certainly in the uk ,if you let them fit it into their schedule I am sure they will help. all the best with it Goldy
56 A10 Golden Flash - Restore, ride, relive.                                          
56 C12 BSA project ongoing

Offline flaboy

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Re: non matching numbers (cases)
« Reply #3 on: 23.11. 2011 19:42 »
Thanks, Goldy and Terryk for your advice! I would be lost with out the replies, great place!! Murray in sunny Florida

Offline chilblayth

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Re: non matching numbers (cases)
« Reply #4 on: 13.12. 2011 00:29 »
to be honest i  dont think they do well with unmatched casing halves  *conf*    the reason they were stamped was to keep the sets together after they were line bored , if it was unnecessary they would not stamp them !   i know theres no solution if thats how you bought it but i remember friends running bikes with different cases and they were never as smooth ,quiick , or oiltight as matched pairs   *smiley4*

beezermacc

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Re: non matching numbers (cases)
« Reply #5 on: 13.12. 2011 08:46 »
When building a new engine a few years ago I used non-matched halves (the customer insisted on using the 'original' cases in spite of me telling him the cases couldn't be original). I line bored the timing side bush (that takes care of the possibility of the crank running out of square, same process with the cam bushes. I had about .003" skimmed off the crankcase mouth. Job done, no probs!