Time for some more A10 engine rebuilding including the cylinder head, oil pump and magneto.
It was time to rebuild the cylinder head. Upon inspection the valves and their seats appeared in very good condition and it was becoming obvious that this Super Rocket had had some attention to the top end more recently in its history. There was a marked difference between the top of the engine and anything that was inside the crankcase. So it was just a case of lapping the valves into their seats and, using a valve spring compressor, refitting the double valve springs, collets and caps.
That done, The head could now be offered up to the top of the cylinder block with a new head gasket and 9 new cylinder head bolts. The head tightened down beautifully using a criss-cross order for tightening the bolts to the correct torque. By the way neither the Haynes manual or the BSA service sheets tell you the correct torque setting for the head bolts. But a visit to the SRM web site lists them as 32 ft lbs.
It seems to happen over and over again, when building a classic bike, that just when you think you've made real progress something goes wrong. It happened this time, when I decided to drop the four push rods into place. The idea was to just rotate the crankshaft and feel them going up and down. The two inlet rods moved up and down beautifully, but the two inner (and longer) exhaust rods moved up and then stuck and it needed a tap with a soft faced hammer to make the cam followers drop back down onto the camshaft. There was no choice, the head and the barrel had got to come off again.
After stripping the head off and getting the cylinder block back on the bench it was revealed that the peg that fits between the two exhaust cam followers was not quite seated properly and had trapped the followers slightly twisted in their guides. I took much more care this time to ensure that the cam followers moved easily before clamping the peg in place with the small ball bearing and grub screw. Then it was out with the piston ring clamps again and rebuild the engine again. In with the push rods and this time they moved easily.
Time to set up the valve timing. This is quite easy. The cog on the crank shaft has a small dot punched on one of its teeth. The gear on the end of the camshaft has a line punched on the side of one tooth. The gear in the centre that meshes with the two has both a dot and a line punched on it. It's just a case of lining up the two dots and two lines and the valve timing is done! Easy!!
Time to look at the oil pump. It has been my intention that to make this bike look like a Rocket Gold Star, it must have both a speedo and a tachometer. Upon inspection I found that, whilst my Super Rocket had never had a tacho fitted, the casing did have the tacho drive mounting point. Lucky! Most A10 engines don't have them. The tacho drive is taken off the end of the oil pump shaft where there should be two small tongues that mate with the drive pin. My oil pump shaft had one tongue broken off. After a fair bit of searching around, I found a new oil pump shaft at SRM engineering. It fitted, but I then discovered that I should have fitted the oil pump before fitting the worm gear on the end of the crankshaft. Reluctant to disassemble the crankshaft gearing again, I decided to remove two of the oil pump fixing studs and rotate the pump up on the remaining stud until it meshed with the worm gear and then replace the studs. That worked.
According to the BSA service sheets, the magneto should be fitted next. After spending some time on the buffing wheel, the magneto cleaned up beautifully and fitted to the engine with nice new stainless steel nuts and the special long nut, that fits under it.Don't make the mistake of using an ordinary nut under the magneto. You might get it on while the bike is stripped down, but you will never get at it again once the bike is rebuilt. Magneto in place, things are really begining to look good!
I would love to read your comments on this blog. If you would like to make some please click "Subscribe to: Post Comments (Atom)" at the bottom of this page. If you would like to be automatically informed when a new episode is posted then please tick the "Join this site" box at the bottom of the page. Thanks for reading. Kevin
Copyright K. Hopcroft 19.08.12 All rights reserved
You can contact me on: hopcroftscoot@gmail.com
My Other Blogs:
1961 Ariel Arrow Super Sport Motorcycle :
http://60sclassicmotorbikes.blogspot.co.uk/2014/01/1961-aerial-golden-arrow-restoration.html
Miniature Land Rover Defender:
http://miniaturelandrover.blogspot.co.uk/2016/02/1-miniature-land-rover-defender-idea.html?view=timeslide
1971 VW Karman Ghia Convertible Car:
http://karmannghiarestoration.blogspot.co.uk/2017/03/1-karmann-ghia-retoration-project.html
Motorcycle Trailers / Caravans:
http://motorcycletrailersandcaravans.blogspot.co.uk/2018/01/1-motorcycle-trailers-problem.html
It was time to rebuild the cylinder head. Upon inspection the valves and their seats appeared in very good condition and it was becoming obvious that this Super Rocket had had some attention to the top end more recently in its history. There was a marked difference between the top of the engine and anything that was inside the crankcase. So it was just a case of lapping the valves into their seats and, using a valve spring compressor, refitting the double valve springs, collets and caps.
That done, The head could now be offered up to the top of the cylinder block with a new head gasket and 9 new cylinder head bolts. The head tightened down beautifully using a criss-cross order for tightening the bolts to the correct torque. By the way neither the Haynes manual or the BSA service sheets tell you the correct torque setting for the head bolts. But a visit to the SRM web site lists them as 32 ft lbs.
It seems to happen over and over again, when building a classic bike, that just when you think you've made real progress something goes wrong. It happened this time, when I decided to drop the four push rods into place. The idea was to just rotate the crankshaft and feel them going up and down. The two inlet rods moved up and down beautifully, but the two inner (and longer) exhaust rods moved up and then stuck and it needed a tap with a soft faced hammer to make the cam followers drop back down onto the camshaft. There was no choice, the head and the barrel had got to come off again.
After stripping the head off and getting the cylinder block back on the bench it was revealed that the peg that fits between the two exhaust cam followers was not quite seated properly and had trapped the followers slightly twisted in their guides. I took much more care this time to ensure that the cam followers moved easily before clamping the peg in place with the small ball bearing and grub screw. Then it was out with the piston ring clamps again and rebuild the engine again. In with the push rods and this time they moved easily.
Time to look at the oil pump. It has been my intention that to make this bike look like a Rocket Gold Star, it must have both a speedo and a tachometer. Upon inspection I found that, whilst my Super Rocket had never had a tacho fitted, the casing did have the tacho drive mounting point. Lucky! Most A10 engines don't have them. The tacho drive is taken off the end of the oil pump shaft where there should be two small tongues that mate with the drive pin. My oil pump shaft had one tongue broken off. After a fair bit of searching around, I found a new oil pump shaft at SRM engineering. It fitted, but I then discovered that I should have fitted the oil pump before fitting the worm gear on the end of the crankshaft. Reluctant to disassemble the crankshaft gearing again, I decided to remove two of the oil pump fixing studs and rotate the pump up on the remaining stud until it meshed with the worm gear and then replace the studs. That worked.
I would love to read your comments on this blog. If you would like to make some please click "Subscribe to: Post Comments (Atom)" at the bottom of this page. If you would like to be automatically informed when a new episode is posted then please tick the "Join this site" box at the bottom of the page. Thanks for reading. Kevin
Copyright K. Hopcroft 19.08.12 All rights reserved
You can contact me on: hopcroftscoot@gmail.com
My Other Blogs:
1961 Ariel Arrow Super Sport Motorcycle :
http://60sclassicmotorbikes.blogspot.co.uk/2014/01/1961-aerial-golden-arrow-restoration.html
Miniature Land Rover Defender:
http://miniaturelandrover.blogspot.co.uk/2016/02/1-miniature-land-rover-defender-idea.html?view=timeslide
1971 VW Karman Ghia Convertible Car:
http://karmannghiarestoration.blogspot.co.uk/2017/03/1-karmann-ghia-retoration-project.html
Motorcycle Trailers / Caravans:
http://motorcycletrailersandcaravans.blogspot.co.uk/2018/01/1-motorcycle-trailers-problem.html
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