BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: royblackburn1@btinternet. on 07 February, 2017, 11:37:24

Title: A65L engine rebuild
Post by: royblackburn1@btinternet. on 07 February, 2017, 11:37:24
Hi I am thinking of rebuilding my A65L engine with limited budget  the SRM way seems very expensive is there anything wrong with the engine as when it came out of the factory theres talk about the timing side bush being rubbish is there bikes out there with engines rebuilt with factory spec internals and running ok I would like to hear from you. Thanks Old miner
Title: Re: A65L engine rebuild
Post by: SLIPPERY SAM on 07 February, 2017, 13:21:03
Roy, I have no specific A65 bearing experience but I do know that SMR and any other reputable engine builder will give you a re-build to original or better spec bush.  You don't have to get the roller bearing conversion if you go to SRM.  My local engine builder (Rob Wardle in Gateshead) who helped me with my crank end feed (I do have the roller conversion on my A10) - said he had no problems building to original spec as long as you use the right bush (there are different versions available these days, solid, steel backed etc).
Worth a couple of phone calls - these guys will tell it like it is - it's thier business and reputation at stake.
There's been a load of discussion on the covenversion versus the bush and the way I understand it - unless you have a good reason to go roller (high or hard mileage / racing) - it is sometimes best to stick with bush - especially if you've not had any real problems with it so far.
Good news is you won't be stuck, you do have the choice - the world's your oyster.

Good luck and let us know what you go with and how it turns out.
Cheers Raymond.
Title: Re: A65L engine rebuild
Post by: bikerbob on 07 February, 2017, 13:39:47
I agree with what the previous post says you will find that it is a debateable issue bush versus roller conversion. I can only  speak from experience I restored a A10 some 20 years ago and had a new bush fitted I owned the bike for 16 years and met the new owner last year and he tells me that the engine is still running perfectly OK so that bush has well in excess of 20,000 miles on it and still running OK. I have an A65 and A7 and they have the bush fitted no problems but I do not ride my bikes hard. If you do decide to continue with the bush and are fitting a new one I reckon the solid ones are the better but the ones with the outer steel casing are perfectly OK but make sure that the inner and outer are pinned as I know from experience that the unpinned ones can if not done correctly turn and thus give rise to serious engine problems.
Title: Re: A65L engine rebuild
Post by: STAR TWIN on 07 February, 2017, 14:16:45
Not everyone has had a great experience with timing side needle roller conversions. The original plain bush gets slagged but it's not at all bad. Yes, if it wears badly it will reduce oil flow to the big ends - but by that time the big ends will be due attention anyway. The plain bush A7 and A10 in the family have been absolutely fine despite some frankly brutal treatment over countless thousands of miles over the last 40+ years. Just make sure any replacement bush is properly line reamed. Good enough for me.   
Title: Re: A65L engine rebuild
Post by: JulianS on 08 February, 2017, 10:04:42
No A65 experience with roller conversion but did have the A10 converyed back in 1985 by SRM. It has been faultless over about one hundred thousand miles including commuting.

The reason for selecting the conversion was due to bad experiences with the bush in the first 12 years of A10 ownership. Back in the 1970s it was not always easy to buy good quality spares. The timing side bushes on offer were not the original factory spec steel backed shell with a rolled insert of strip steel faced with a proper Vandervell bearing material, but were solid bushes of variable quality and sizing, and sometimes with significant variation as to position of the oil holes which in some cases did not correspond the the oil channel in the crankshaft. This caused some significant lubrication issues and several new bushes for the bike and as soon as the conversion became available I went for it.

The bushes now seem to be of much better quality than those I experienced 40 odd years ago and new oil pumps are available so would I go for the conversion again? I would consider it as a whole package including planned useage and overall cost. Whatever  bearings chosen need to be top quality, properly fitted (and shimmed for a bushed crank) and the lubrication needs to be based on a sound oil pump and pressure relief valve.
Title: Re: A65L engine rebuild
Post by: Mike Farmer on 09 February, 2017, 19:31:03
I had my A65T done many moons ago, because it was a newish thing but I never actually found or felt or in any way noticed any difference.  (Dont own it now so not up to date).
I've just had my A50 done to bog standard spec. There are many good local engineers out there trained in exactly the same way as those at SRM etc. Word of mouth is still as good as anything.
Title: Re: A65L engine rebuild
Post by: royblackburn1@btinternet. on 26 April, 2017, 11:55:04
hi all got my engine back after the rebuild the engineer said the timing side bush was fine and didn't require changing and that work had been done previous to me getting it and wasn't in a bad state how many miles will it take to run in the new pistons and rings, thanks Roy