The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: Drew Back on 28.07. 2014 13:44
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Im finally to the point of turning my motor over,I got the primary chain on(what a pain)but I dont have the entire clutch can I just make a locking plate to kick it over? I cant turn it by cush drive spring just slips does it matter if tranny is in gear??I dont have rear chain on I also dont have the wedge bolt to lock the kick arm on I have to find one..
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Hi Drew
The cush drive cams should ride up each other but not past each other so it should be possible to turn the engine over with plugs removed.
I'm assuming you don't want to start it just turn it
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The motor is very tight and I dont have the proper spanner for the cush drive I do want to start it just turn it over to make sure push rods are right and pistons move properly since everything is new..
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G'day Drew.
Yes a locking plate (a friction and steel plate riveted together) will work. Gearbox can be in gear (with no rear chain). A normal bolt can sub for the cotter pin, just for winding it over, not for starting.
Cheers
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Actually a locking plate is a good thing to have regardless, if you can manage it two of each type of plate makes a much stronger article
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I know this might be a dumb question when you tighten the cush drive do you have the points of the cam lobes meeting each other or is it tightened with the lobes meshed together?? any one have a good pic?
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Meshed in..if you play with it without the spring, you'll see how it works.
It's there to absorb any sudden torque action from the crank under load, and to a lesser degree from the wheel under deceleration.
Other bikes have it in different places, rubbers in the back wheel, or the clutch, and Moto Gutzzi have a surprisingly similar setup on the input shaft in the gearbox.
I was wondering why the primary chain was such a hassle, unless it's a endless one, whereby you need to fit it to the engine sprocket and chainwheel and add them on the shaft simultaneously.
At risk of stating the obvious and to save time....:...-
If it's a split chain with a conn-link, totally back off the adjuster so the bottom roller run is a straight line across the tangents of the sprockets, and have the join at the top above the adjuster plate.
There's a bit of a recess in the casting, and if you hold your tongue right, get one pin of the conn-link in halfway and then slip the other end on.
Then add the intermediate (thicker) plate, and then slide on the outer roller runs.
And don't forget the outer plate is thinner, and make sure the open end of the connlink circlip is facing AGAINST the direction of travel
.....too easy......?
*beer* *beer*
Nb It also helps to jam the chainwheel so the weight of the chain don't work agaist your efforts....more *beer*
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Got it turning over but it is really hard should the primary chain be tight to make a diference it goes so far then stops you can mess with the clutch hub(turn it back and forth) and then it will spin again??
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I had this on my last project
The two causes I found (no doubt many more)
First the line reaming of the timing side bush was not correct, engine would spin fine until the crankcase bolts were tightened the final turn - then it nipped up at a certain point,
Took it back to the shop (with another crank bush) they did it again and it was fine, eliminate this by slackening the crankcase bolts/studs one turn and try to turn the engine.
Second problem I had was a slight tight spot, turned out one of the front (long) primary case bolts was rubbing on the crank web, but don't think you have them in ?
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G'day Drew.
To me it sounds like the problem is in the gearbox, not the motor. Remove primary chain. You need to beg, borrow, buy, steal or make a C spanner to fit the cush nut to turn it over. Failing that drop the timing cover off and turn over with that side crank nut or the dynamo drive sprocket (large one) nut. With the plugs out it should turn smoothly with only a bit of drag from the rings (easier at TDC and BDC) and valve spring pressure.
Then you can try the gearbox, turning it via the clutch rather than the kicker. Run it up and down the gears.
That should tell you which area needs attention.
Cheers
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Drew, I'm not sure which part of your wording is the question.
As Bill suggested-
turned out one of the front (long) primary case bolts was rubbing on the crank web, but don't think you have them in ?
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He is not doubt referring to S/A models, but if you have the incorrect Primary-chain tensioner retaining studs in, it can do the same thing.
Did you rebuild the engine? If so did everything spin ok at various stages? Sometimes if the big-ends bolts have been replaced they can be a bit long and crash into the inside of the case at a certain point, there's not much room in there for error.
Can you pinpoint where in the revolution it catches relative to TDC, and is it same in reverse revolution too...?
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Dove into it again tonight took primary chain off clutch basket spins nice and free removed cush drive and just used the nut and a pipe wrench and it spins like a champ..Put the cush drive sleeve on and the nut and it wont budge the sleeve seems to be binding against the bearing..I will have to dig around to see if I can find another sleeve I have one for the single chain setup and it spins good to??
Gotta love these old machines.
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There's a couple of different sleeve bushes. Does your case have a seal in it?
The early ones don't have a seal, and the inner sleeve 'seal-flange' is a bit bigger diameter, (and maybe a flies dick wider ?), than the post ~'53 plunger jobbies, so possible it's had a mod. done.
You'll find that the single roller sleeves are different outer splines, but if it has a seal fitted, may fit for forensic purpose, but be fairly much totally useless without a lot of messin' 'round- I suggest don't seriously go there...
If you have a spare G'box sprocket, it should fit the cush inner sleeve, and you can maybe improvise something to use that to spin the crank.
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He is not doubt referring to S/A models,
Spot on Dutch, yes forgot what we were on about. happens quite frequently *conf*
You've got to it now though Drew - well done (despite our bum steers)
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This clutch was removed from an A7 long stroke motor and im putting on a 1956 A10 here are some pics of what I have looks like the oil seal is in I recieved these cases as a complete bottom end everything looked good so I saw no need to split them.
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Kind've hard to tell, but it looks like there's a mark around the seal like a deformation where the sleeve bush could be interferring--, ie; not going inside the seal.
if you have all the right bits (bits that will ultimately work right whatever their origin *conf*), you should be able to just put the bush on and screw the nut on/off until it binds or not.
The fact you are using a bush from the early model is exactly what I suggested earlier.....it's too big *????*
This clutch was removed from an A7 long stroke motor
I'll assume you might've meant to write 'bush' instead of 'clutch'.
you could find a proper one, or have that ground down to suit (dunno if the longstroke crew would give their eye teeth for one ?)
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It looks like the sprocket is binding on the crankcase.
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The proper bush that I would need is 67-2071 if my books are right that would be for the later plunger motors..When I got the bottom end it was fitted with a single sprocket sleeve so I assumed thats the way it went together boy am I learning the diferences now trial and error is the way you learn..Thank you all so much for your help and vast knowledge..
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Thank you all so much for your help and vast knowledge..
In my case this has only come about through the same misadventurous track you're on.... *smile*
And if you do as I suggested, then try one step at a time and see if as Trev says, "It looks like the sprocket is binding on the crankcase.
You can do it all without the spring, if you use the dangle/angle of the cushlobes- if yea know what I mean...... *beer*
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Hi All,
Does the plunger engine have a spacer sleeve between the engine bearing and the cush sleeve like the swing arm setup?
On the swing arm engine the seal runs on the spacer
(it looks as though you need one ???)
John
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Negative on that John- kind of...well not the same anyways....
Dunno 'bout long strokes, but info I have is '49-'53 have a 'bearing shim' (posing as an 'oil slinger' in lieu of a seal ? ) and a 'distance piece' outboard of the bearing, and post '53 which runs a seal, lists just a 'sprocket alignment shim'....