The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Greybeard on 09.06. 2018 12:35

Title: Timing side bush?
Post by: Greybeard on 09.06. 2018 12:35

I've got my engine together again with your help but I'm wondering if I should have got a new timing side main bearing bush put in while I had it in bits. As I've found a local place that could do the work it seems more feasible. My measurements, (using internal callipers and a micrometer) show a difference of about 2 thou between bush and shaft. Is that acceptable? I found no ovality on the shaft.

Title: Re: Timing side bush?
Post by: muskrat on 09.06. 2018 13:08

You lucky bugga, I dream of two thou. My A7 plunger has about 8 thou and still going (for how long is debatable) but I use 40/70 oil and don't go over 60mph  *bash*. She''l be right mate.
Or do you need more practice, I think you like it. *smile*
Cheers

Title: Re: Timing side bush?
Post by: Colsbeeza on 09.06. 2018 13:24

Hi GB,
I have been reading your rebuild with great interest. I have attached a graph which is interesting. Wish I could find the source. Seems 0.002" should last you quite a while. I certainly would not pull it down again. Nice to have Muskrats perspective. He has a way of keeping your feet firmly on the ground. *roll*
Colin

Title: Re: Timing side bush?
Post by: Greybeard on 09.06. 2018 13:31

Quote from: Colsbeeza on 09.06. 2018 13:24

I have been reading your rebuild with great interest. I have attached a graph which is interesting.

Wow, my head!

Quote

Seems 0.002" should last you quite a while. I certainly would not pull it down again.

*wink2*

Title: Re: Timing side bush?
Post by: Greybeard on 09.06. 2018 13:39

Quote from: muskrat on 09.06. 2018 13:08

You lucky bugga, I dream of two thou. My A7 plunger has about 8 thou and still going (for how long is debatable) but I use 40/70 oil and don't go over 60mph  *bash*. She''l be right mate.
Or do you need more practice, I think you like it. *smile*
Cheers

I don't really mind the work, especially when it's going well, (I've got rocker box fitting down to a fine art) and as I still have not put the ancillaries back on the bike, if you'd said, "Yes, you need to do this", I would have. See, you have that much influence!  *smile*

Title: Re: Timing side bush?
Post by: Greybeard on 09.06. 2018 13:40

How does one know when that bush is knackered? Is there a bottom end rumble?

Title: Re: Timing side bush?
Post by: muskrat on 09.06. 2018 14:30

Usually a rod says hello  *pull hair out*.
Oil pressure drop. Without a gauge that's hard. Big end knock just before ^^^.
Any time I have the timing cover off I use a screwdriver between the pump and end nut to feel for movement.
Cheers

Title: Re: Timing side bush?
Post by: Greybeard on 09.06. 2018 17:15

Quote from: muskrat on 09.06. 2018 14:30

Any time I have the timing cover off I use a screwdriver between the pump and end nut to feel for movement.

Me too.

Title: Re: Timing side bush?
Post by: Colsbeeza on 09.06. 2018 22:07

I see the graph has been downloaded 17 times. Thought I'd better locate the source. Attached.
Colin