The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Goldy on 12.01. 2012 19:12

Title: De coke
Post by: Goldy on 12.01. 2012 19:12

I have taken the head off the A10 to do some jobs over the winter. I am amazed at the amount of carbon on the piston tops and in the combustion chamber, it,s only 1500 miles since I put it all back together. I have been using valvemaster in the petrol, could this be the cause. Any thoughts.

Title: Re: De coke
Post by: bikerbob on 13.01. 2012 16:38

Hi there
I have been using Castrol Valvemaster since it first came on the market a good few years ago and I had the head off my A10 Gold Flash last year and the amount of carbon on the head and pistons was what I expected for the mileage done  nothing out of the ordinary. If you have excessive carbon build up I would be looking elsewhere for the cause maybe you are running to rich.

Title: Re: De coke
Post by: BSA_54A10 on 14.01. 2012 15:33

Have a good look at the inlet valve stem.
If there is a heavish deposit on the stem they you have excessive clearence.
Other then that then you are looking at poorly seated rings

Title: Re: De coke
Post by: Goldy on 15.01. 2012 13:44

i think the mixture might be slightly rich but not far out the valve guides were replaced but not looked at the piston rings, thanks Goldy