Author Topic: Time for a rebuild  (Read 3752 times)

Offline BSA500

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Time for a rebuild
« on: 03.11. 2014 16:35 »
I was thinking of taking the A7 off the road this winter for a little overhaul(big one really, shes done 15,000 miles in the last three years). She took things into her own hands and stripped the magneto gear, hopefully some pics follow showing the damage. As a background it has been using a little-lot-of oil and rattling....



When she broke down I dropped this into the plug hole duh










And there goes my hope that the bottom end didn't need to much attention

[imghttp://][/img]

Offline muskrat

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Re: Time for a rebuild
« Reply #1 on: 03.11. 2014 18:51 »
G'day BSA500.
She looks like she could do with a freshen up.
Going by the amount of blow by on the piston, I'd check the little end bush and the rods for straightness. What does the bore look like (any scuffing on the sides)?
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, .
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Muskys Plunger A7

Offline BSA500

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Re: Time for a rebuild
« Reply #2 on: 03.11. 2014 19:41 »
No real scuffing but I can feel a little rock on the small ends. This barrel was relined to standard approx 15 years ago and about 5-6 years ago re ringed as there was only 1-2 thou wear. She has done well but I suspect a rebore is on the cards. Also found the ider pinion has some movement in the bush. Of course the bottom end has to come down but there is no twist/up down movement on the big ends but I will measure up everything that can wear.

Offline BSA500

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Re: Time for a rebuild
« Reply #3 on: 05.11. 2014 10:02 »
Took another piece or two off the engine yesterday, mainly the dynamo. It had been on so long it had 'glued' itself on with a combination of rust and road grime. I had to free it off with a rubber mallet!!

Offline BSA500

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Re: Time for a rebuild
« Reply #4 on: 10.11. 2014 09:57 »
More pics of the strip down.....



Valve measuring 0.31 inch so spot on, one less thing to buy



A look inside the timing side conrod has a bit too much movement compared to the drive side :(



I think the valve springs need replacing initial measurement was 1.81 inches(outer)



Offline muskrat

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Re: Time for a rebuild
« Reply #5 on: 10.11. 2014 19:20 »
G'day BSA500.
I know where you'll be over winter. Looks like a full rebuild, but it's not that bad compared to modern stuff. We're all here to help.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, .
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Muskys Plunger A7

Offline bsa-bill

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Re: Time for a rebuild
« Reply #6 on: 10.11. 2014 19:36 »
hi BSA500
What is the mark arrowed
All the best - Bill
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Offline BSA500

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Re: Time for a rebuild
« Reply #7 on: 10.11. 2014 20:56 »
BSA bill That mark is just a lump of carbon. Muskrat-yep looks like a winter project but I have rebuilt her before kind of looking forward to it. Pity it has to cost money. More piccys as I go

Offline muskrat

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Re: Time for a rebuild
« Reply #8 on: 10.11. 2014 21:18 »
Ahh, that dreaded cost thing. I bank on a full rebuild costing about $1000AU (one weeks gross pay). If I do 5000 miles in a year that's only 20 cents a mile. Or If I do 50,000 miles between rebuilds it's only 2 cents a mile. Less painful that way.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, .
Australia
Muskys Plunger A7

Offline BSA500

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Re: Time for a rebuild
« Reply #9 on: 11.11. 2014 11:54 »
Just had a duh moment. I have said about micing the crank etc to see if it needs a regrind as I have a micrometer. It dawned on me today I have a 0-1 inch mic, not quite big enough I think :(

Offline BSA500

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Re: Time for a rebuild
« Reply #10 on: 13.11. 2014 13:17 »
As I move forward with the strip down the issue of rebore etc comes to mind. Down Sarf we lack many engineering firms. I was wondering if anyone has any recommendations for firms based in and around Kent. I have contacted Modus Langton Green and the quote for £420 for rebores, possible regrinds and possible line reaming of the timing bush made my eyes water  *eek* *eek*.
I have yet to talk to Hodson engineering at Gaza Barracks near hildenborough and I am awaiting a reply from Dartford rebores.
Thanks Andy

Online RichardL

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Re: Time for a rebuild
« Reply #11 on: 13.11. 2014 15:50 »
You're in the UK, shipping to Wales should be cheap. For the work you've described, SRM shows about £231 on their website, including a  new timing-side bush. Now, you may need other work, but this is for what you've described and you are fairly assured of the highest quality results.

Richard L.
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Offline Topdad

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Re: Time for a rebuild
« Reply #12 on: 13.11. 2014 15:55 »
Andy, I'd wait to get some companies used by other members ,could save alot of greif down the line. Also why not at least get a quote from SRM and there is also a member who has done quite alot of work for members with good feed back, can't for the life of me think who he is ( apologises if he reads this ) but sure someone else will provide it ,best of luck BobH.
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Offline Topdad

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Re: Time for a rebuild
« Reply #13 on: 13.11. 2014 15:58 »
I was typing when Richard posted this so theres one confirmation from across the pond and also I agree with what was posted ,mine was done by them 10yrs plus ago and still going well, BobH.
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Offline BSA500

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Re: Time for a rebuild
« Reply #14 on: 13.11. 2014 16:35 »
I am still in the process of strip down so it will be a little while before I am ready for the machining. I was hoping for a local firm as I also need an accurate measurement of the bores before I can order the pistons. I will get a quote from SRM but even though I am in the UK the postage costs there and back will still be steep. Them old crankshafts and barrels are bloody heavy old things :)
Things like sludge trap cleaning, small end bushes and shimming the crank are not an issue and easy to do.