Author Topic: Crank rotation  (Read 1603 times)

Offline Guy Wilson

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Crank rotation
« on: 21.05. 2011 11:00 »
I get the sense the entire history of my rebuild will be on this site by way of questions I'm asking.

I've just refitted the barrels onto the bottom end. The engine has not turned over for a number of years, (I don't know how many) The engine was dry stored and was cleaned out thoroughly before the barrels were refitted. I can turn the engine over fully by hand and the crank turns over freely for the most part although there are couple of tighter spots.  The primary drive is not connected, just the magneto and oil pump.
Would a couple of tighter points on be normal on the crank if the oil pump and magneto were connected or is it something I should investigate further?
Many thanks
Guy

Online bsa-bill

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Re: Crank rotation
« Reply #1 on: 21.05. 2011 12:58 »
I would think a little more definition of what you consider tight would be helpful, having said that with the head off mine spins over pretty free even with pump, magneto and clutch connected.
Magnetos do show a resistance to be turned by hand at two spots per revolution, if you could find out if your crank tight spots coincide with the respective firing points then that might point to the magneto
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 Guy Wilson

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Re: Crank rotation
« Reply #2 on: 21.05. 2011 13:01 »
my gut feeling is its over tight. I can turn it over freely with my hands from the crank.
I'll do as you say and check the firing points to see if they coincide,
thanks
Guy

Offline muskrat

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Re: Crank rotation
« Reply #3 on: 21.05. 2011 13:51 »
You might find it a little stiffer to turn at mid stroke than at top and bottom as there is more drag from the rings.
Is it the original crank/rods/rod bolts in the cases? Has been known for new nuts to foul the cases (mine did), same for 357 cams.
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Offline Guy Wilson

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Re: Crank rotation
« Reply #4 on: 21.05. 2011 14:00 »
Its all original and I had the same thoughts about the nuts holding the back of the primary case, so that was the first thing I removed before trying again. I'll check it for high and low points on the stroke. It sounds like a logical thought and worth checking.
Thanks again,
Guy

Offline Guy Wilson

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Re: Crank rotation
« Reply #5 on: 21.05. 2011 15:12 »
I've checked as Muscrat suggested and I'm reassured i think. The tight spot appears to be mid way through the stroke. The end play on the crank is with the .024 thou that's allowable. I can turn the crank the full 360 with my hands easily,
Guy

Online bsa-bill

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Re: Crank rotation
« Reply #6 on: 21.05. 2011 15:20 »
hope that's a typo Guy the end float should be 0.003 max so if you meant 0.0024 that's good
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 Guy Wilson

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Re: Crank rotation
« Reply #7 on: 21.05. 2011 16:51 »
i need to check the reading . my feeler gauges are a bit rusty....

Offline wilko

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Re: Crank rotation
« Reply #8 on: 21.05. 2011 20:21 »
Hope your oil pump isn't binding?

Offline A10Boy

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Re: Crank rotation
« Reply #9 on: 22.05. 2011 18:21 »
Quote
The engine has not turned over for a number of years, (I don't know how many) The engine was dry stored and was cleaned out thoroughly before the barrels were refitted.

Probably better to strip it down and start again to make sure everything is OK.
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Andy

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Offline cus

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Re: Crank rotation
« Reply #10 on: 22.05. 2011 22:47 »
Just another quick check, have you got the primary inner case on,
if the 3 larger diam. bolts that go tru into the c/case are too long,
they might hit the crank. Just a thought,

Cus
56 G/Flash project

Offline Guy Wilson

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Crank rotation
« Reply #11 on: 23.05. 2011 06:25 »
Thanks Cus,
I had the same thought. Its not that. I think the resistance is normal from what everyone has said so far. Its more that I had nothing to reference against.

I'm enjoying the forum. Its keeping my accountability going and reminding me that I shouldn't forget the bike in the garage,
All the best
Guy

Online bsa-bill

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Re: Crank rotation
« Reply #12 on: 23.05. 2011 10:01 »
Just had a little light come on in my noggin Guy
If it's around mid stroke and the engine had been dry stored it could be a bit of resistance as the cams come around and lift the followers, suggest you pour a bit of oil down the pushrod tunnel and turn the crank over a few times , see if it get easier.
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 Guy Wilson

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Re: Crank rotation
« Reply #13 on: 23.05. 2011 11:43 »
The resistance was extreme on the cam followers and were seized when I found the barrels.
The history of the bike is its ex an South African Police bike, either Lesutu or Swaziland and it came to Kenya dismantled and in boxes. Part were separated and some were stolen. Most of the larger chunks were together and dry stored. Some of the smaller, frustrating less common parts, went to various locations around Kenya. It took almost 2 years to trace were all the parts went and to find what was remaining. The barrels were caked in cow shit which in a strange way, once it was dry seems to have protected more than it damaged. The cam followers were solid and were removed, cleaned before refitting and I know they are moving freely now.
I'm going to fill the bottom end up with oil and let it soak for a few days as a precaution. As I said, I don't have anything to reference the resistance against and it could be fine and normal and I'm imagining its tight when its not.
Its all a learning curve at the moment!
Guy