The BSA A7-A10 Forum

Technical (topic titles must be descriptive) => A7 & A10 Engine => Topic started by: cus on 04.08. 2009 09:53

Title: Weird Noise
Post by: cus on 04.08. 2009 09:53
G'day All,
This is going to sound like a paranoid observation, but I'm getting the feeling something isn't
right in the top end of my S/r. Has new valves, seats, springs, pretty much new everything
except cam, which was re-ground. Top end was pretty noisy, with tappet noise, mechanic
said he did the clearances but must have forgotten because I could have limbo'd thru the gap,
so got that soughted & top end is heaps quiter, but when I stand behind the bike while
it idles, I can hear a tap/small knock that echoes down the pipes, fairly faint but wondering
what that would be....sounds a bit hollow like lifters maybe! no noise like this on my Bonnie,
so a little concerned,

regards, Cus
Title: Re: Weird Noise
Post by: BSA_54A10 on 04.08. 2009 09:59
Exhaust valve slamming shut.
You need louder mufflers.
Title: Re: Weird Noise
Post by: muskrat on 04.08. 2009 10:25
G'day Cus,
              is it coming from both pipes or one ? Can you hear it with a few revs or under load. Trevor may be right if the cam has been ground with steeper ramps or the valves are sticking a little. Get your hands on a stethoscope and try to track it down. Be warned though, there will be lots of weird noises from all over the motor.
         Cheers
Title: Re: Weird Noise
Post by: cus on 04.08. 2009 10:32
Thanks Trevor,
was hoping it might be something like that, I'm always a bit twitchy on odd noises on a re-build!

Cus
Title: Re: Weird Noise
Post by: cus on 04.08. 2009 22:38
G'day Muskrat,
Noise is from both pipes & is only heard at idle,

regards, Cus
Title: Re: Weird Noise
Post by: A10Boy on 04.08. 2009 23:10
To search out a noise like that, there is an old trick thats useful. If you take a good solid piece of wood, like a hammer shaft, and put one end on the back of your ear and then place the other end in various places on the engine, you can hear whats going on in the engine. If you've never done this you will be amazed how well it works.

BTW, did they re-harden your camshaft ?
Title: Re: Weird Noise
Post by: BSA_54A10 on 08.08. 2009 15:10
That sounds very much like valves hanging a little and not keeping up with the cam. Usually happens when a "hotter" cam is fitted that dose not have the closing ramps.
If you have a friend with an A 65 have a good listen to his top end as they do not have quietening ramps which is one reason why they sound a lot more rattley than A 10's.