Author Topic: 1952 A7 valve gear  (Read 1256 times)

Offline anjimehra

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1952 A7 valve gear
« on: 09.06. 2018 06:12 »
Hi guys
Back to bother you again.
Valve gear on Both my A10 & A7 plunger is noisy. New valves, guides, seats. Tappets at .010 . Old pump. Noise persists even if I block the return pipe hole in oil tank Any suggestions. Otherwise running fine. Taken the A10 on a 1500 km ride to Goa recently
Ride safe
Anji

Offline anjimehra

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Re: 1952 A7 valve gear
« Reply #1 on: 09.06. 2018 06:33 »
Hi guys
Back to bother you again.
Valve gear on Both my A10 & A7 plunger is noisy. New valves, guides, seats. Tappets at .010 . Old pump. Noise persists even if I block the return pipe hole in oil tank Any suggestions. Otherwise running fine. Taken the A10 on a 1500 km ride to Goa recently
Ride safe
Anji
Just opened the rocker covers to find rocker box dry. oil coming up to the rocker feeds from return pipe . Have also cleared oil galleries in rocker shafts. Could it be an oil pump issue.

Offline muskrat

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Re: 1952 A7 valve gear
« Reply #2 on: 09.06. 2018 08:49 »
G'day Anji.
Have you checked the banjo bolts are clear?
Do you have a solid feed pipe from the return to tank junction all the way to the banjos? I have a rubber hose section in mine so I can disconnect it (block off the tank side) and use an oil can to squirt oil up there. If you could do this to make sure there's no blockage. The banjos only have a small hole and there's not much pressure coming up to them so the rockerbox isn't flooded in oil, just enough to keep things wet.
I remember a while back you were having concerns with the pump. Did you do anything with that?
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online Klaus

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Re: 1952 A7 valve gear
« Reply #3 on: 09.06. 2018 09:25 »
There are two kind of banjoblots with small hole and big hole. Check if the holes are blocked.
A good oilflow had to be with bolts loose.


If you think, everything is under control, you are not fast enought.

Offline muskrat

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Re: 1952 A7 valve gear
« Reply #4 on: 09.06. 2018 10:49 »
Both the banjos have 3/64" holes.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online berger

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Re: 1952 A7 valve gear
« Reply #5 on: 09.06. 2018 11:01 »
hi musky I think he means rocker box oil bolts which I have seen two different sized holes in some ive got knocking around somewhere

Offline muskrat

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Re: 1952 A7 valve gear
« Reply #6 on: 09.06. 2018 11:24 »
Which are called banjo bolts https://tinyurl.com/y7brkqwo
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline anjimehra

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Re: 1952 A7 valve gear
« Reply #7 on: 09.06. 2018 11:38 »
G'day Anji.
Have you checked the banjo bolts are clear?
Do you have a solid feed pipe from the return to tank junction all the way to the banjos? I have a rubber hose section in mine so I can disconnect it (block off the tank side) and use an oil can to squirt oil up there. If you could do this to make sure there's no blockage. The banjos only have a small hole and there's not much pressure coming up to them so the rockerbox isn't flooded in oil, just enough to keep things wet.
I remember a while back you were having concerns with the pump. Did you do anything with that?
Cheers

Hi Muskie
I have removed the cu rocker feed pipe & blown it clear.Have also slightly enlarged the oil holes in the banjo bolts. Can only think of 2 other reasons 1) rockers are worn & or b) gears on the return side of pump worn out. I did solve the delivery pressure problem by finding & fitting new gears on the feed side. Fast idle pressure went up to 45 psi from 0 initially. Couldn't find the return side gears though. Still looking
Did you sort out your pressure problem Muskie
Thanks & cheers

Offline anjimehra

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Re: 1952 A7 valve gear
« Reply #8 on: 09.06. 2018 11:40 »
There are two kind of banjoblots with small hole and big hole. Check if the holes are blocked.
A good oilflow had to be with bolts loose.
Hi Klaus
See my reply to Muskie. I have enlarged the bolt holes slightly but no luck
Thanks

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Re: 1952 A7 valve gear
« Reply #9 on: 09.06. 2018 11:47 »
o yes cheers musky I often wondered why the small holes were slightly different, different part numbers, another confused. com sorted cheers

Offline muskrat

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Re: 1952 A7 valve gear
« Reply #10 on: 09.06. 2018 12:50 »
Anji, not a good idea to enlarge those holes. Their part of a metering system. If too big more oil will go up there instead of the oil tank and could overwhelm the scavenge side of the pump.
These are not actual figures but just an example. Imagine there's 100 ml/minute of oil going in the feed side and the scavenge side can pump 120ml/minute at the same revs (that's why there's bubbles in the return to tank oil). Now say the scavenge pumps 90 to the tank and 10 to the rockers so in reality there's 110ml going in but that's OK as the scavenge can do 120ml. With larger holes say 70 to the tank and 30 to the rockers means there's 130 going in which is 10 more than the pump can handle. In theory the sump will slowly fill and the tank empty. As I said this is just theory but could happen. By increasing the hole from 3/64 to 1/16 will increase the area of the hole by 77% which is a sh!t load.
If the oil line is clear the banjos are clear and the shafts are clear there will be oil up there. With the motor running loosen one of the banjo bolts, oil should emerge. Tighten that one and loosen the other, more oil emerges. Tighten both. Remove tappet covers, start motor, finger over return pipe in tank, should be able to see oil dribbling out the rockers. If not the pump can't give enough pressure to get through the bolt holes. Time to look at the pump. Lap the end plate on a piece of glass with wet & dry (400 grit) till the gear wear marks are gone.
Well that just about wore the print off my one typing finger!
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline RogerSB

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Re: 1952 A7 valve gear
« Reply #11 on: 09.06. 2018 16:18 »
If oil is going up the pipe check that washers are not covering and blocking the holes.
(edit) Added a picture to make it clear.

1960 Golden Flash

Offline anjimehra

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Re: 1952 A7 valve gear
« Reply #12 on: 10.06. 2018 08:19 »
Anji, not a good idea to enlarge those holes. Their part of a metering system. If too big more oil will go up there instead of the oil tank and could overwhelm the scavenge side of the pump.
These are not actual figures but just an example. Imagine there's 100 ml/minute of oil going in the feed side and the scavenge side can pump 120ml/minute at the same revs (that's why there's bubbles in the return to tank oil). Now say the scavenge pumps 90 to the tank and 10 to the rockers so in reality there's 110ml going in but that's OK as the scavenge can do 120ml. With larger holes say 70 to the tank and 30 to the rockers means there's 130 going in which is 10 more than the pump can handle. In theory the sump will slowly fill and the tank empty. As I said this is just theory but could happen. By increasing the hole from 3/64 to 1/16 will increase the area of the hole by 77% which is a sh!t load.
If the oil line is clear the banjos are clear and the shafts are clear there will be oil up there. With the motor running loosen one of the banjo bolts, oil should emerge. Tighten that one and loosen the other, more oil emerges. Tighten both. Remove tappet covers, start motor, finger over return pipe in tank, should be able to see oil dribbling out the rockers. If not the pump can't give enough pressure to get through the bolt holes. Time to look at the pump. Lap the end plate on a piece of glass with wet & dry (400 grit) till the gear wear marks are gone.
Well that just about wore the print off my one typing finger!
Cheers
Thanks Muskie. Agree with your logic. Beginning to think that it's the scavenge gears in the pump. Found some on eBay but part nos don't match my catalogue numbers. Need your advice on whether the one on eBay will do
Catalogue numbers scavenge 67-1386, 67-1385
eBay nos 67-1405, 67-1406, 67-1403, 67-1404
Thanks & cheers

Offline muskrat

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Re: 1952 A7 valve gear
« Reply #13 on: 10.06. 2018 09:36 »
G'day Anji.
'47-'55 Scavenge gears 67-1385 & 67-1386, Feed gears 67-1383 & 67-1384 are correct for your pump. In '55 these were superseded with Scavenge gears 67-1405 & 67-1406, Feed gears 67-1403 & 67-1404. So yes the 1405 & 1406 will fit but MUST be a pair (not one early & one late). These gears went right through into the A50 & A65 models. Back in the day BSA would only supply the gears in a set of 4, scavenge and feed.
Cheers

PS: re your ? about my oil pressure problem. No, she's still going, no horrible noises. In fact the whole motor is quiet with 40/70 oil in there *sick*
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline anjimehra

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Re: 1952 A7 valve gear
« Reply #14 on: 18.06. 2018 11:14 »
If oil is going up the pipe check that washers are not covering and blocking the holes.
(edit) Added a picture to make it clear.

Not covering the holes Roger. Thanks