The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Hubie on 01.09. 2010 23:58
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G'day all,
It's been a while but I have begun stripping down my A10 to have the crank balanced, give it a once over and a new set of seals all round. After two hours, I have the dynamo out, primary off (except for the clutch centre which is a female dog! - will need a good puller and some heat), head off and most of the timing side.
I don't forsee too many problems pulling the rest of it down but I do need to know if the cam sprocket is a left or right hand thread, and also the best way to assist the crank in parting ways with the cases. Any advice offered would be very much appreciated. I am also considering enlarging the breather and perhaps adding an additional one to the timing chest. Any thoughts?
Cheers,
Dave.
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G'day Dave.
Good luck with the rebuild. There have been some good reports on the forum for the Bunn breather kit - perhaps their website may be worth a look.
Jim
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Cam pinion nut is right hand Dave - I should know, been there too many times of late
Crank pinion nut and worm drive - left
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G'day again all,
Have stripped the motor right down now, was surprised how easy it was! Perhaps it's because I'm used to doing enfields! Just need to have the crank balanced, order a belt drive dynamo kite, full gasket set and gearbox sprocket. Does anyone know the head torque settings off the top of their heads (A10 GF) ?
I am also going to have the cam timing checked to make sure it's right. I've never done this before so I am getting a mate who is an expert to do it and teach me at the same time. Five heliciols (all on the rocker box) need to be done also but that is no big deal.
Cheers,
Dave
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Hello Chums,
I have finally got the list of all that I need to get this motor rebuilt. Dyson Motorcycle engineering is assembling my crank and making a custom size timing side bush to suit the crank pin. What I need is as follows;
Drive side main bearing (NF206)
4 conrod nuts (67-1034)
4 Conrod bolts (67-1033)
4 Conrod washers (67-297)
4 Big end shells (small journal crank) at -.030
3 new studs for the oil pump
1 new camshaft (spitfire grind)
She should go well!
I am also curious about the breather on the bike as there is a modified one fitted to the left crank case below the cam tunnel and there is a screw in the inner timing cover where the original breather is. Can anyone tell me what the original breather setup is?
Also I was going to order all this stuff from SRM unless anyone knows a better place to get them from. And lastly, It appears as my bike is not 1955 as it was sold to me, the crank case number of DA10 6480 puts it at 1959 but I am unsure of the frame which is CA72373. Any help would be grand.
Cheers,
Dave.
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G'day Dave,
The hole in the LH crank case is where the breathing exits. The screw in the timing cover is to block off the drilling. So all is normal.
I use a Bunn breather. It breaths in through the rocker box cover and out the LH crank case hole. But I modified the timed breather to be open all the time.
http://www.a7a10.net/forum/index.php/topic,2563.msg16893.html#msg16893 is how I did it.
Cheers
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Hubie,
BJ's Bikes and Bits in Brisbane (ph (07) 33917322) have most of what you want.
They specialise in triumphs but have a bit of BSA stuff.
I've seen a box full of 357 cams and they have conrod bolts and nuts and probably bigend shells.
A month ago they were rebuilding a star twin engine for someone in Toowoomba - maybe it belongs to Tod who posted here a while back?
cheers
ps: if its expensive, tell them what you can get it for over seas. They seem keen for business.
also I've no connection with them.
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Hubie,
Make sure the big end bolts are the proper items
They should be forged with rolled threads
BEWARE OF TURNED AND CUT THREADS *eek* *eek* *eek*
HTH
John O R
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Thanks John,
I shall ask when I order them as I do not know the difference. I did ring BJ's Bikes and bits, but they don't have any of what I need except the shells and they are cheaper here in Melbourne. All I need for now is the shells, nuts, bolts and washers so that the crank can be rebuilt, I can at least then get the cases together!
Cheers,
Dave.
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BEWARE OF TURNED AND CUT THREADS
Absolutely crucial. Do not use turned and cut threads under any circumstances.
John
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Have ordered the big end shells, bolts, nuts and washers as well as new studs for the oil pump. All I need now is a main bearing (drive side) and a new camshaft. I can get the bearing here in Melbourne but after discussion with the engineer, I am staying with the standard cam as the top end is not being modified at all.
Cheers,
Dave.
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Dave,
Which cam do you have?
Trev.
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Hi Trev,
I have a 356 cam with worn lobes. Am trying to work out if it is cheaper to buy a new one or have the original built back up and ground to standard.
Cheers,
Dave
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I have a manual for the bike now which is handy. Am reading the section referring to cam timing and it seems to me that all I am required to do is to align each of the gears/idlers with the corresponding dots on them and it is done. Am I right or is there some other mystic procedure to undertake?
Cheers
Dave.
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G'day Hubie,
If I tell you I will have to kill you !!
Nah, it's that simple. If the top end is off no worries. If it's on be careful as at TDC both valves on 1 side are open. Put the crank at bottom of stroke, then rotate cam so line is towards center of idler, then rotate crank to TDC and line it all up.
Cheers