The BSA A7-A10 Forum
Bikes, Pictures, Stories & more => Introductions, Stories, Meetings & Pictures => Topic started by: McTrucky on 21.10. 2025 07:28
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Hi,
Newbie here, just bought an A10 a few days ago. 1950 model plunger. Not yet started it, as bought at an auction with no history.
Hoping for help and encouragement in the trials and tribulations to come.
Cheers
Alan
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Don't even consider kicking over a complete unknown. A seized oil pump will be damaged, you need to proceed with care if you are new to old bikes. Search the Forum for barn and a number of previous posts come up with the pitfalls to avoid.
Welcome along, give us an intro and arrange long term finance......
This may be of interest.
https://www.a7a10.net/forum/index.php?topic=14261.msg118352#msg118352
Swarfy.
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Once sorted you'll enjoy riding a plunger, motors are sweet and normally vibe free and the guys on this wonderful forum will help.
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G'day Alan *welcome*
I still remember the day I got my A7 plunger with no prior experience 44 years ago. 1st job was a full motor rebuild as it had sat in a chook shed for 15 years.
Hopefully yours will be in better shape. By taking off the sump plate and side covers will give you an idea of it's condition.
Best of luck with it and remember there's no such thing as a stupid question.
Cheers
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Has it been in use recently or has it been stuck in a shed for 30 years? That can make a big difference in how you tackle it. A picture perhaps?
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Welcome & thanks for intro.
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Things are looking good. (Famous last words....)
All oils drained and looked almost new. Everything turns and moves as it should. Carb was a bit gunky but easily cleaned and servicable. However, the clearance for cables above the carb is so tight that the choke cable is bent and locked. Throttle works OK though so think I'll leave it as is for now.
Engine had clearly 'wet sumped' and much oil had migrated through to the primary drive. Not unexpected. I have a new sump plate with drain plug on order so I can easily drain the crankcase going forward. I also had to repair the strainer/filter that lives in the oil tank. JB Weld to the rescue.
Clutch doesn't release. I can see the plates move looking through the inspection hole, so hoping I can loosen it off by rocking the bike back and forth once I put it back together.
With luck, and a few home made gaskets later, I might get a chance to try to kick start it tomorrow. Fingers crossed.
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Early models do not have a crankshaft oil seal.... They use an Oil Slinger and a Scroll on the cush drive sleeve so migration of oil into the primary chain case is normal on long standing. Primary Chaincase Oil Level is critical, the clutch is essentially dry. Plenty on the forum about oil level on semi-unit motors. Your clutch sounds well oil soaked.
Original carb is AMAL 276 with remote float bowl. A common swap was to a monobloc, which is a tight fit and may account for the acute cable run.
Swarfy.
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welcome from Canada
enjoy your new to you BSA
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I shouldn't worry to much about the choke I took mine off altogether on mine and never missed it .
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It Lives!
It spits back through the carb and stops at lowish revs, so is not yet rideable, but with the engine spinning harder it seems quite happy. I don't think this will be hard to fix...
As suggested, I'll just leave the choke as inoperable for now. The carb is the original 276 by the way.
Very strong oil flow out of the return! - I have a Matchless G5 and an Ariel VH, and the oil return on them is just a dribble. The BSA positively squirts it out.
Clutch has still not released - I am optimistic it will loosen off without dismantling.
It has cheapo plug caps on, so will swap them for NGK caps with a new set of plugs and see if that helps low speed running. Plugs in it are NGK B6HS. I'll check on here for what is recommended and go with that. Any other thoughts on the spit back?
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It Lives!
It spits back through the carb and stops at lowish revs, so is not yet rideable, but with the engine spinning harder it seems quite happy. I don't think this will be hard to fix...
As suggested, I'll just leave the choke as inoperable for now. The carb is the original 276 by the way.
Very strong oil flow out of the return! - I have a Matchless G5 and an Ariel VH, and the oil return on them is just a dribble. The BSA positively squirts it out.
Clutch has still not released - I am optimistic it will loosen off without dismantling.
It has cheapo plug caps on, so will swap them for NGK caps with a new set of plugs and see if that helps low speed running. Plugs in it are NGK B6HS. I'll check on here for what is recommended and go with that. Any other thoughts on the spit back?
Check pilot jet is clear…. And no water in float bowl
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Hi All,
Don't use resistor plug caps *eek*
John
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Welcome to the forum. You are evidently experienced in working on motorcycles, which is more than I can say for myself when I started working on my A10 about 23 years ago. My complete restoration, after the bike sat for 23 years before that, included completely rebuilding the engine, except for one thing, the sludge trap thats lives in the crank, running through the rod journals. About 80 miles into running in, the crap in the sludge trap had let loose and blocked the hole feeding oil to one of the journals. Funny, but I can’t recall how I got home. Anyway, if you already knew about the sludge trap and have a high level of confidence that it is clean enough, or you’re willing to live with the chances, so be it. Otherwise, you may want to further search “sludge trap,” or wait for further comments from our very experienced members.
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One more thing. Don’t use detergent oil, as it will highly increase the possibility of sludge- trap crap releasing. If you’ve already filled with detergent, I recommend replacing it immediately, if, in fact, you will continue running without an engine tear down, which would have the added benefit of revealing any other hidden issues.
Richard L.
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Welcome to the forum. Early indications are good. I'm pleased for you.
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Yes, waiting for new plugs and caps to arrive, and maybe that is all it needs! Should find out in a few days.
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Meanwhile give that magneto slip ring a good clean. Carbon deposits tracking round can produce uneven running. Pick up brushes also need to be clean, free and of good quality. Some available are softer than a kid's pencil... Useless.
Weak mixture can also cause spitting back, air leak at carb joint a favourite, sticky inlet valves also worth a look but worn inlet guides and worn throttle slide also suspects. BSA Service Sheet 708 tells all.
Stuck clutch....Hooligans trick is to start as normal, then get bike moving down a handy slope and kick into second gear with the clutch lever pulled in. Then taking your life in your hands try blipping the throttle and with luck the changing loads will free the plates.
Swarfy.
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Stuck clutch....Hooligans trick is to start as normal, then get bike moving down a handy slope and kick into second gear with the clutch lever pulled in. Then taking your life in your hands try blipping the throttle and with luck the changing loads will free the plates.
For this newly acquired bike that’s getting a bunch of other work, pulling the primary cover and dealing with the clutch seems to me to be fairly simple, and precautionary on other fronts.
Swarfy, what are your thoughts for the sludge trap?
(BTW, we may be straying too far from the origional welcome theead.)
Richard L.
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(BTW, we may be straying too far from the origional welcome theead.)
Richard L.
Yes, please put further questions in their respective sections.
Cheers
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Hi all,
Just to wrap and close this thread....
Much joy! Just ran the bike up and down the farm road - and it goes pretty well. Stopping is a different story 🤣.
Clutch freed itself rocking back and forth against compression with a warmed engine.
Spitting back much improved by fiddling with the air screw - so more carb work to come.
Much oil leaking from the front sprocket output shaft (I am guessing).
But no more tech talk here, I'll open threads on brakes and so on in the appropriate places. Many thanks for your enthusiasm and input.
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*welcome*