Author Topic: Engine strip  (Read 1676 times)

Offline A10Boy

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Engine strip
« on: 18.06. 2009 21:12 »
Because of the end float on the crank and some "up and down" on the timing side bush, I bit the bullet and stripped the engine today - before any damage occurred.

Its mostly good, the top end has obviously been rebuilt by the previous owner, the bores are on +020, the  pistons and rings are good, although I will fit new rings at the rebuild, he's even had the barrels and head powder coated.

The cause of the end float was that there were only two very thin shims fitted and they were worn and blue but there were no fragments of any other shims in the sump. I expected to see a lipped roller bearing on the drive side but found a standard ball bearing effort which can't be right on 62 engine. There is slight evidence of the inner race having been turning on the crank, but its not really loose so a bit of locktite should sort that. The splines are quite worn so I will get T&L to repair them when they do the timing side bush.

Questions, my pistons are solid skirted, not split skirted are they right for the year? Am I right in thinking it should have a Lipped roller bearing, does anyone know where I can get a set of +020 rings? also, what is the maximum gap between the pistons and bore before slap occurs?

Cheers
Regards

Andy

1958 Super Rocket
Plus
1974 Kawasaki Z1a
Yam XJR 1300

Online trevinoz

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Re: Engine strip
« Reply #1 on: 18.06. 2009 23:54 »
Andy,
            I would change the main bearing to the correct lipped roller NF206.
The ball bearing will not be up to the job long term. It should not have had any end float with a ball bearing fitted unless something is loose.
The rings should not be a problem, try C&D or one of many others. You can even use Triumph unit 500 +.060 if you like.
I don' know at what clearance slap occurs but I am sure someone will hazard an informed guess.
Trev.

Offline MikeN

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Re: Engine strip
« Reply #2 on: 19.06. 2009 12:00 »
A crankshaft will have endfloat even if fitted with a ball bearing .I assume you discovered it after removing the shock absorber assembly.
 The shock absorber, when fitted will pull it all over hard to the drive side,which takes up the endfloat.
Mike

Offline A10Boy

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Re: Engine strip
« Reply #3 on: 19.06. 2009 12:33 »
No, it had float even with the shock absorber fitted, the nut was was tight too. I am assuming that the whole bearing was moving in the drive side case, which it wouldn't do if it was shimmed correctly ???

I think I will do a trial reassembly [without the case] to make sure its all locking up correctly. My understanding is that the shocker nut tightens on the sleeve - distance piece - bearing - shims - crank web, so in theory the shims are held tight and cant spin and over heat, although I've read here before of that.

It has got some wear on the splines which T&L cant repair so it will have to go to SRM for that as they seem to be the only people who can repair them ? They might as well do the bush and set the float too while they are at it.
Regards

Andy

1958 Super Rocket
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1974 Kawasaki Z1a
Yam XJR 1300

Offline beezalex

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Re: Engine strip
« Reply #4 on: 19.06. 2009 21:05 »
You're absolutely right in that the only way you can have more than .001" of endplay with a ball bearing in there is if a) the bearing itself is knackered or b) the outer race is loose in the case.  A decent ball bearing shouldn't be a problem on a cooking A10.  Early A65's used them and I've only ever heard of problems with the high-twitch models.  I ran a Thunderbolt with a DS ball bearing for a long time with no issues.

Shouldn't be too hard to tell if the bearing is loose in the case.  Did it drop out?  Or is it still in there?  You should not be able to remove it without heat.

Now...are you SURE that the crankshaft nut was absolutely tight?  The shims being blued indicate that it was loose at one time.
Alex

Too many BSA's


Offline A10Boy

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Re: Engine strip
« Reply #5 on: 19.06. 2009 22:08 »
Yep it was very tight but it could have come loose at some point as there are marks inside the primary cover.

I dry assembled it without the cases and the SRM nut which I fitted locked it all up just fine. However the splines are worn badly on the crank and the cush sleeve is new so it probably had a lot of lash in the splines, maybe this caused movement and wear on the shims which then let it move around.

It is possible to push the bearing in and out by hand so a bit of locktight will hold it ok when the splines have been repaired and its set up with the right end float.
Regards

Andy

1958 Super Rocket
Plus
1974 Kawasaki Z1a
Yam XJR 1300

Offline MikeN

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Re: Engine strip
« Reply #6 on: 19.06. 2009 22:49 »
Andy,
 Im sure you know this but.If your main bearing is loose in the crankcase, you can have the case bored oversize and a liner fitted and then bored to bring it back to specification.
Mike

Online bsa-bill

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Re: Engine strip
« Reply #7 on: 19.06. 2009 22:57 »
BTW how does the SRM cush nut get locked up, I've got mine to torque up and wondered how you lock it - is there room to get a split pin in or is it a job for locktite

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline A10Boy

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Re: Engine strip
« Reply #8 on: 19.06. 2009 23:20 »
No it covers the pin hole. its just the "tightness" which keeps it tight. 65 Ft/LBS is fairly tight.
Regards

Andy

1958 Super Rocket
Plus
1974 Kawasaki Z1a
Yam XJR 1300