The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: joecr on 18.03. 2008 15:02

Title: Compression test on a A10
Post by: joecr on 18.03. 2008 15:02
I'm about to do a compression test on my A10 plunger, can anyone give me  a round about figure for what the reading should be on a healthy engine? I've only had the bike a short time and the last owner put new pistons and rings in and it hasn't been run in yet. I would like to check periodicly to see how the rings are bedding in.
Thanks, Joe.
Title: Re: Compression test on a A10
Post by: RichardL on 18.03. 2008 15:34
Joe,

Go to  topic "Measuring Compression" (pg. 4 under "Tech Topics") and you will get a whole lot of discussion on the topic.

Richard
Title: Re: Compression test on a A10
Post by: joecr on 18.03. 2008 16:57
Oops, should have looked before I leaped, everything is there that I wanted to know.
Thanks, Joe.
Title: Re: Compression test on a A10
Post by: Big Nick on 18.07. 2013 16:51
after checking mine , its been standing for some time compression down to 80 or so to it's head a barrel off tomorrow and have a look
Title: Re: Compression test on a A10
Post by: Big Nick on 19.07. 2013 12:40
ring gap on compression ring 25
Title: Re: Compression test on a A10
Post by: muskrat on 19.07. 2013 14:55
That's not too bad Nick. I've seen them running well with gaps bigger than that. Were you holding the throttle wide open when kicking over and at least 6 kicks?
My low comp '51 A7 shows 130 Lb sq in, the high comp A10 shows 175.
Cheers
Title: Re: Compression test on a A10
Post by: Big Nick on 19.07. 2013 18:43
thanks , i also check it out with my friend gary at srm but when i pour petrol down the exhaust port it is seaping past  so grid the valves in again the next stop. the only fun i had was getting the 2 bolts out at the front holding the head down . i did not replace them last time and the head are getting a bit round and all that heat a bit firmly fixed in place but with a bit of penetrating oil they came out