The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Duncan R on 15.12. 2010 18:06
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I decided to get my engine sorted, so yesterday dropped it up to the guy who is doing it for me and handed over the complete bottom end. First susprise was that he informed that it is actually a 650 with thick flange barrels (its registered and insured as a 500 - will have to get that changed) Got an email today to say crank and rods are US, I gave him a spare crank that I bought as an A7 crank but it turns out it is an A10 crank, so thats a result. When he dismantled the old crank he was amazed to find the rods are large journal sitting on a small journal crank with 2 sets of big-end shells to take up the slack ! and a 1/8 " of end float *eek* No wonder it was a bit vibey! I have covered nearly 2000 miles like that.
Surprisingly he has reported the rest of the engine is in good shape(cam,followers,bore is on +20 and in good condition) Looking forward to a much improved engine *smile*
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G'day Duncan,
I've seen (and done) some bodge tings in my life but that takes the cake.
An old mate once fixed a noisy big end in a tractor with a piece of leather belt. Helped the tractor but his pants kept falling down !!
Cheers
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the rods are large journal sitting on a small journal crank with 2 sets of big-end shells
*eek* + *eek*
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I was going to stick the head back on it after finding a stray nut in the combustion chamber and just run it (the original reason for the bike being off the road) Glad now that I took the decision to go for a rebuild as it sounds like a nasty mess waiting to happen.
Cheers
Duncan
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Years ago I bought a Moto Morini 3-1/2 Sport from a guy in Eastbourne, I lived in Mansfield at the time so went down on the coach and rode it the 200 miles plus back home. Engine was suposedly rebuilt but there was something not quite right so after a week or two I tore it down. Turned out that whan he re-ground the crank (Morinis are plain bearing big ends) he didnt re-fit the crank plugs so I drove it non stop all the way home with next to no oil pressure!! Amazing thing was that the crank and shells were unmarked so after fitting new plugs all was well.
I was pretty amazed when I found that out but not as amazed as a mate of mine that found a single oak piston in his Mini!!
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I was told that you could get more power by shaving your head, but all I got was cold ears!
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Cold ears ! Where you live ! Sunburnt maybe. *smile*
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On the topic of bodges, with my bitsa engine I failed to check the valve collars and collets were the same taper!
Luckily no major harm done but taking the valves out today removed 26 collets. I'm sure I only fitted 8 *eek*