The BSA A7-A10 Forum

Technical (topic titles must be descriptive) => A7 & A10 Engine => Topic started by: edboy on 04.06. 2021 23:10

Title: a10 barrel dilema
Post by: edboy on 04.06. 2021 23:10
another engine rebuild but no more treasure items  now, for good parts i am scrapping the barrel .
2 sets of barrels left one needs new liners but one set has little bore wear at +30 . however one of the bores has about 4 deep scores which i presume originate from piston rings. all seem below the top ring section in the bore . i am tempted to try it at +30 with new pistons and rings.
anyone here been here before me  -  and tell me their experience? too smokey?
Title: Re: a10 barrel dilema
Post by: RDfella on 05.06. 2021 10:27
If the scores are too deep to hone out then probably not a good idea. One could try used pistons to see how it goes, but I definitely wouldn't buy new ones in the hope it'd be OK. If buying new, get + .040" (or .060) and rebore.

edit - bore size ammended.
Title: Re: a10 barrel dilema
Post by: Swarfcut on 05.06. 2021 22:57
 Ever the cheapskate, a set of used plus 40's are worth a go in the damaged block bored to suit. Even cheaper, a set of used plus 30's.

 All depends on how bad the damage is and how fastidious you are. The major castings are the parts they don't make in any  economic volume and we should preserve them if we can. A set of used plus 30's in the existing bores give a cheap runner, which although  possibly a little smoker gets a bike back into use. If it smokes, you know the reason why and don't have to worry..   When it smokes for no good reason, then you get the sleepless nights!

 The alternative is a relatively big investment at current price levels for quality pistons and rings which may never be fully enjoyed depending on current use.