valve lifter wear

Here you can talk about all kind of TECH for the B50 B44 B25 And Other BSA unit Singles

Moderator: minetymenace

Post Reply
User avatar
FGF
>80
>80
Posts: 96
Joined: Sat May 11, 2019 3:14 pm
Location: Orleans
Has thanked: 24 times
Been thanked: 1 time
Flag: France

valve lifter wear

Post by FGF » Thu Jun 04, 2020 11:08 am

Hello ,

when you find an exhaust rocker scratched by the valve lifter like this :
decomp_us.jpg
what is the better way ?

forget it and run like this or weld it and grind it with what kind of welding ?

Thanks
Francois

User avatar
minetymenace
Gerry1
Gerry1
Posts: 7717
Joined: Wed May 26, 2004 1:00 am
Location: On the edge of Salisbury Plain, England
Has thanked: 33 times
Been thanked: 97 times
Flag: England
Contact:

Re: valve lifter wear

Post by minetymenace » Thu Jun 04, 2020 11:47 am

FGF, this is a "bump" for a question you asked in your Project Bikes topic, but without your own solution!

As you say, RR suggests welding it up, and if you have the means it would be quite easy to do if you can be arsed. Remove the ball on the end of the rocker (it is a push fit and can be drifted out) and fill the hole with weld (don't ask me how, to me welding is a black art practised by simians in the frozen north), then dress it back flat with a file. Re-insert the ball end making sure the cross drilling lines up with the oil way in the arm itself.

The indent is unlikely to be normal wear as the decompressor is only used to position the engine when starting, I guess the ding has been hammered in when the lever was pulled while the engine was running.
These users thanked the author minetymenace for the post:
FGF (Fri Jun 05, 2020 8:14 am)
Rating: 25%
There is no evidence to support the notion that life is serious.
Abyssinian Wire-Haired Tripehounds Gnash.

Jeff K
>1300
>1300
Posts: 1354
Joined: Sun Jul 13, 2014 12:30 pm
Location: Bay City, Michigan USA
Has thanked: 55 times
Been thanked: 25 times
Flag: United States of America

Re: valve lifter wear

Post by Jeff K » Thu Jun 04, 2020 2:35 pm

I am not sure if the area or the entire arm is heat treated or not. But, be aware that welding on it will change all of that. Best to find out before taking it to a welder.
Jeff
These users thanked the author Jeff K for the post:
FGF (Fri Jun 05, 2020 8:15 am)
Rating: 25%

Momus
>160
>160
Posts: 162
Joined: Thu Jul 20, 2017 6:44 pm
Location: Melbourne
Has thanked: 1 time
Been thanked: 10 times
Flag: Australia

Re: valve lifter wear

Post by Momus » Thu Jun 04, 2020 6:49 pm

:?: Just run it.

That mark will be totally inconsequential.
These users thanked the author Momus for the post:
FGF (Fri Jun 05, 2020 8:15 am)
Rating: 25%
If you love it, lube it.

beat
>1400
>1400
Posts: 5736
Joined: Sun Jun 04, 2006 5:33 pm
Location: Switzerland
Has thanked: 0
Been thanked: 49 times
Flag: Switzerland

Re: valve lifter wear

Post by beat » Thu Jun 04, 2020 8:58 pm

FGF wrote:
Thu Jun 04, 2020 11:08 am
with what kind of welding ?
if welding, use TIG for this small point.
These users thanked the author beat for the post:
FGF (Fri Jun 05, 2020 8:15 am)
Rating: 25%

User avatar
koncretekid
>900
>900
Posts: 934
Joined: Sun Nov 20, 2005 1:22 am
Location: Yarmouth, Nova Scotia
Has thanked: 6 times
Been thanked: 26 times
Flag: Canada

Re: valve lifter wear

Post by koncretekid » Fri Jun 05, 2020 1:14 am

The indent on the exhaust rocker is quite common, as there is no return spring on the decompressor lever. If you look at the motor when it's running, you can see the lever bouncing back and forth because the cable doesn't retract fully on some and even leaving excess slack won't solve the problem. And there can be consequences as the indent gets larger, the decompression lever has to rotate further and can cam over if worn badly. I just replaced one on the B44 parts bike because of this, but I haven't tried welding one up. I am considering putting a return spring on mine.

Tom
These users thanked the author koncretekid for the post:
FGF (Fri Jun 05, 2020 8:15 am)
Rating: 25%
life's uncertain - go fast now

Canberra
>1200
>1200
Posts: 1294
Joined: Fri Sep 03, 2004 11:45 am
Location: Canberra, Australia
Has thanked: 0
Been thanked: 14 times
Flag: Australia
Contact:

Re: valve lifter wear

Post by Canberra » Fri Jun 05, 2020 1:39 am

On the B50 there are two designs for the valve mechanism. The later is spring loaded to release the valve lifter. I changed mine many years ago so am unsure of the parts involved.
I agree with Momus. Welding may bring up more issues with heat treatment than you're trying to cure. I believe Stan did weld up rockers on one of his specials but he knows what he is doing.

John
These users thanked the author Canberra for the post:
FGF (Fri Jun 05, 2020 8:15 am)
Rating: 25%

Post Reply