Author Topic: Speaking of vibration  (Read 13760 times)

Offline Hubie

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Re: Speaking of vibration
« Reply #75 on: 02.12. 2010 05:08 »
Hi Trev,

A mate who collects RE two strokes has bought it.  I am just holding it for him until he gets back from serving in east timor.  Bill, I'm aiming for 1-1.5thou end float.

Cheers,

Dave.
1959 BSA Golden Flash
1956 Royal Enfield Super Meteor
1955 Royal Enfield 350 Bullet
2007 Harley Davidson Sportster 1200 Custom

The early bird gets the worm, but the second mouse get's the cheese!

Offline Hubie

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Re: Speaking of vibration
« Reply #76 on: 09.12. 2010 01:16 »
Well it runs.  Very rough so far though.  More compression on the left than the right so I will re check the tappet clearances and have to double check the timing as well.  The kick starter gets stuck every now and then also so a few things to sort out before it runs the way it should.  any advice would be appreciated.

Cheers,
Hubie.
1959 BSA Golden Flash
1956 Royal Enfield Super Meteor
1955 Royal Enfield 350 Bullet
2007 Harley Davidson Sportster 1200 Custom

The early bird gets the worm, but the second mouse get's the cheese!

Offline Hubie

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Re: Speaking of vibration
« Reply #77 on: 09.12. 2010 06:52 »
Have now checked compression and both are the same.  One cylinder does not seem to be firing very well.  The left side is alot hotter than the right.  Have swapped plugs and leads and also re timed the bike.  I am starting to think it is cam timing but I did line up all the timing marks when I assembled the motor.  I wonder if the new cam has anything to do with it?  Tis the same 356 cam as what was in it.

Any advice would be much appreciated.

Thanks,
Dave.
1959 BSA Golden Flash
1956 Royal Enfield Super Meteor
1955 Royal Enfield 350 Bullet
2007 Harley Davidson Sportster 1200 Custom

The early bird gets the worm, but the second mouse get's the cheese!

Online muskrat

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Re: Speaking of vibration
« Reply #78 on: 09.12. 2010 10:05 »
G'day Dave,
                   sounds like the timing is uneven. Re check the timing on both cylinders. You might find that one is firing at 5/16" and the other at 3/8". This is due to wear on the cam ring (magneto). The best way to check is with a strobe and degree wheel on the crank. If it's only a couple of degrees out split the difference. Say one side at 35 the other at 33 isn't too bad, but.
If that checks out it might be induction bias. Both plugs should be the same colour. You can get a anti-bias gasket to cant the carb towards the weak cylinder to fix that.
Don't think it would be cam timing as both cylinders would be out. But then again I had a cam reground once and the inlets were 5 degrees out and the exhaust 15 degrees out. Easy enough to check with a degree wheel on the crank that they open and close at the right times
Kickstarter sticking (they all do that sir). Wear in the bushes/shaft and or pinion.
How did you go with the end float ?
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
Muskys Plunger A7

Offline Hubie

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Re: Speaking of vibration
« Reply #79 on: 09.12. 2010 21:07 »
Hi Musky,

I've re timed the bike three times now and I am not convinced that ignition timing is the issue.  Once the bike is running, opening the throttle delivers next to no response.  It is very flat, like the valves are not opening and closing when they should.  I am certain that I lined up all the dots on the pinion and idlers but there is a new camshaft in there as well.  Going to have to pull off the inner cover and just see how things go I suppose.

Cheers,
Dave.
1959 BSA Golden Flash
1956 Royal Enfield Super Meteor
1955 Royal Enfield 350 Bullet
2007 Harley Davidson Sportster 1200 Custom

The early bird gets the worm, but the second mouse get's the cheese!

Online chaterlea25

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Re: Speaking of vibration
« Reply #80 on: 09.12. 2010 22:21 »
Hi Dave,
Just  thought or 3!!
Did you wedge the auto advance in the fully advanced position before timing the engine?
Also check that the pushrods are seated properly in the rockers, Are all the tappet adjusters at about the same adjustment, if one is way different to the others there may be a pushrod misplaced
Finally have you fresh petrol in the tank??

HTH
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline Hubie

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Re: Speaking of vibration
« Reply #81 on: 09.12. 2010 22:35 »
HI John,

Advance unit was properly set, pushrods are all seated (used a tiny mirror to check they were all in the cups  - although one was dislodged originally so I hope to christ i haven't bent a pushrod or a valve) petrol is the same as it was in the tank from two months ago.

Cheers,
Dave.
1959 BSA Golden Flash
1956 Royal Enfield Super Meteor
1955 Royal Enfield 350 Bullet
2007 Harley Davidson Sportster 1200 Custom

The early bird gets the worm, but the second mouse get's the cheese!

Offline Hubie

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Re: Speaking of vibration
« Reply #82 on: 09.12. 2010 22:52 »
I should add compression is even on both sides, one in firing well the other not so.  Have swapped plugs and leads and that is not the issue either.  I'll get there eventually!
1959 BSA Golden Flash
1956 Royal Enfield Super Meteor
1955 Royal Enfield 350 Bullet
2007 Harley Davidson Sportster 1200 Custom

The early bird gets the worm, but the second mouse get's the cheese!

Offline Hubie

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Re: Speaking of vibration
« Reply #83 on: 10.12. 2010 05:18 »
Very good mate who just closed up shop after over 40 years popped over today, answer is a bent valve.  I don't have the tools to remove so he's taken the bike away for me and will sort it out and fine tune everything.  Shouldn't be too long.

Cheers
Hubie
1959 BSA Golden Flash
1956 Royal Enfield Super Meteor
1955 Royal Enfield 350 Bullet
2007 Harley Davidson Sportster 1200 Custom

The early bird gets the worm, but the second mouse get's the cheese!

Offline Hubie

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Re: Speaking of vibration
« Reply #84 on: 15.12. 2010 04:08 »
Well lads,

The valves are fine but after checking, my pistons sit about 1/4 below the lip of the barrels at TDC.  This should not be the case as it's only giving 90-95 PSI per cylinder.  Looks like I have to find a new pair of pistons and rings.  They are oversize at 71.5mm anyone who knows a good place to get them would be much appreciated.  Also, the height of the piston from the top of the piston to the gudgeon pin if anyone has one lying around would be great.

Cheers,

Dave.
1959 BSA Golden Flash
1956 Royal Enfield Super Meteor
1955 Royal Enfield 350 Bullet
2007 Harley Davidson Sportster 1200 Custom

The early bird gets the worm, but the second mouse get's the cheese!

Offline Hubie

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Re: Speaking of vibration
« Reply #85 on: 15.12. 2010 05:43 »
Just got back from having a look at it,

pistons sit down about 11mm too low in the bore.  Has be wondering if they might be A65 pistons instead of A10 ones.  They are GPM and are 71.5mm.  No wonder the bike had no go heading above 50mph.  The top of the piston to the top of the gudgeon pin is 30mm and I need 11mm more than that.

Cheers,
Dave.
1959 BSA Golden Flash
1956 Royal Enfield Super Meteor
1955 Royal Enfield 350 Bullet
2007 Harley Davidson Sportster 1200 Custom

The early bird gets the worm, but the second mouse get's the cheese!

Offline A10Boy

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Re: Speaking of vibration
« Reply #86 on: 15.12. 2010 09:06 »
I have to confess to being a little baffled by all this. I would have thought you would have noticed this when you stripped and rebuilt the engine? Didn't you turn it over after fitting the barrels and before fitting the head? It's a natural thing to do to check that it all turns and has not bound up. How did you time the ignition, how did you find TDC?
I would make sure you have the right crank and con rods before you go any further.  *conf*
Regards

Andy

1960 A10 - Black Golden Flash
Plus
1974 Kawasaki Z1a
Yam XJR 1300

Offline Hubie

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Re: Speaking of vibration
« Reply #87 on: 15.12. 2010 09:24 »
Thanks Andy,

I've gone as far as I can as I had the whole thing up and running.  I should have checked it before I put the head on but as the machine was running before I had the crank rebuilt and I timed it before then anyway and the timing tool I marked up was lining up exactly the same as before so assumption has made an ass out of me.  The conrod numbers are G7270R3R2R which I don't recognise so maybe someone could help me if they recognise this number and also to tell me the stock conrod length for a small journal crank?

Cheers,
Dave
1959 BSA Golden Flash
1956 Royal Enfield Super Meteor
1955 Royal Enfield 350 Bullet
2007 Harley Davidson Sportster 1200 Custom

The early bird gets the worm, but the second mouse get's the cheese!

Online muskrat

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Re: Speaking of vibration
« Reply #88 on: 15.12. 2010 18:33 »
G'day Dave,
                    the plot thickens ! Is your crank a large or small journal ? You might have 6" A50/65 rods in there instead of 6 1/2" A10 rods if it's a LJ. Or A7 rods if it's a SJ.
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
Muskys Plunger A7

Offline Hubie

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Re: Speaking of vibration
« Reply #89 on: 15.12. 2010 20:15 »
Hi Musky,

It's a small journal crank.  The bike is coming back home tomorrow so I will get a better chance to check the numbers and measure the rods.  I think I am now on the lookout for some small journal rods.  If anyone here is able to help with that, I would be over the moon!

Cheers,
Dave.
1959 BSA Golden Flash
1956 Royal Enfield Super Meteor
1955 Royal Enfield 350 Bullet
2007 Harley Davidson Sportster 1200 Custom

The early bird gets the worm, but the second mouse get's the cheese!