I am building a 650SS and want to convert it to a pressure feed rocker like the commando. Besides fitting seals, has anyone determined if the scrolled rocker shafts need to be replaced with commando type to maintain oil pressure at the crank? I plan on using a 6 start gear.
Pressure Feed Rocker Conversion 650SS
- Thread starter KHK
- Start date
I believe there are several issues to consider when installing a 6-start oil pump and pressurized rocker oil feed in earlier engines: drilled versus undrilled connecting rods and bearing inserts; scrolled versus unscrolled camshafts, bearings and rocker shafts; rocker oil-line piping dimensions and perhaps even the internal drillways in the earlier heads
Tim Kraakevik
kraakevik@voyager.net
Tim Kraakevik
kraakevik@voyager.net
When you switch an early bike with scrolled rockers and back-feed oiling to the later style pressure oiling then you definitely need to install the plain rocker spindles otherwise you will have a massive oil leak in your head.
The other thing that was done when Norton switched to the faster oil pump gears was to enlarge the oil passages in the pump, cases, oil manifold and pipes so the higher pumping volume could be utilized more efficiently.
I recently put a 650ss engine together with the faster gears and there are some photographs of the early and late pumps and the work I did on the oil passages here:
http://www.facebook.com/media/set/?set= ... 123&type=3
You can read about the modifications that Dunstall did to the oiling systems of Dominator racing bikes in the papers here:
http://www.facebook.com/media/set/?set= ... 123&type=3
Heinz Kegler, ex Norton experimental department and head technician for Berliner said that he flips the rod bearings upside down and blocks the oil squirt holes in the connecting rods. He said it was a band-aid fix that was not necessary after other things were fixed.
If you can get your hands on a late 60s Norton engine to take apart and look at you will see what parts and machining they changed on the later bikes.
I did throw a set of 6-start gears into an early Norton with no other mods before and it worked fine, but that was because the back-fed rocker oiling was kept. I am sure it had a lot more oil trying to get places especially at low rpm. I am also sure that it would have been happier yet with all the oil passages checked out and enlarged.
Good luck.
The other thing that was done when Norton switched to the faster oil pump gears was to enlarge the oil passages in the pump, cases, oil manifold and pipes so the higher pumping volume could be utilized more efficiently.
I recently put a 650ss engine together with the faster gears and there are some photographs of the early and late pumps and the work I did on the oil passages here:
http://www.facebook.com/media/set/?set= ... 123&type=3
You can read about the modifications that Dunstall did to the oiling systems of Dominator racing bikes in the papers here:
http://www.facebook.com/media/set/?set= ... 123&type=3
Heinz Kegler, ex Norton experimental department and head technician for Berliner said that he flips the rod bearings upside down and blocks the oil squirt holes in the connecting rods. He said it was a band-aid fix that was not necessary after other things were fixed.
If you can get your hands on a late 60s Norton engine to take apart and look at you will see what parts and machining they changed on the later bikes.
I did throw a set of 6-start gears into an early Norton with no other mods before and it worked fine, but that was because the back-fed rocker oiling was kept. I am sure it had a lot more oil trying to get places especially at low rpm. I am also sure that it would have been happier yet with all the oil passages checked out and enlarged.
Good luck.
beng said:
The Atlas and 650ss were almost the same bikes and for the 1966 year they fitted a double speed oil pump in the Atlas along with the mods you mention.
I upgraded my 1965 Atlas to ’66 spec which required drilling out the oil holes from oil block to pump, a larger dia oil block along with commando rocker feed.
Only downside is that the engine, which I did not use a thick treacl e oil, with all these larger holes, became more prone to wet sumping when left unused.
Re; “he flips the rod bearings upside down and blocks the oil squirt holes in the connecting rods.”
This was also done on the Commando as it was originally a Commando mod.
Great info and pics on FB, are you going to pressure feed the rockers on the latest 650 your building?
The bike I am working on is a 61 Manxman that I recieved partially restored, fresh bore, valve job, need to make inserts for the head as the barrels are decked / no spigots.
As a commando owner I have plain rocker spindles and 6 start gear parts on hand, however if the geared up pump will deliver adequete top end oiling, why bother taking a fresh rebuilt head and remove the guides to add seals? I good friend puts seals and pressure feeds triumph twins, and I just finished a 650 TR6 that we put harley seals on the guides and pressure fed the top. He says I have to do this to my 650SS, but do I?
The bike will see mostly city driving, and if I were to go on long road distance I would gear it to run lower RPM.
Thanks for the great info and feedback.
The bike I am working on is a 61 Manxman that I recieved partially restored, fresh bore, valve job, need to make inserts for the head as the barrels are decked / no spigots.
As a commando owner I have plain rocker spindles and 6 start gear parts on hand, however if the geared up pump will deliver adequete top end oiling, why bother taking a fresh rebuilt head and remove the guides to add seals? I good friend puts seals and pressure feeds triumph twins, and I just finished a 650 TR6 that we put harley seals on the guides and pressure fed the top. He says I have to do this to my 650SS, but do I?
The bike will see mostly city driving, and if I were to go on long road distance I would gear it to run lower RPM.
Thanks for the great info and feedback.
I am keeping the cylinder head oiling to the top of the 62' 650ss as it left the factory for now. I drilled some holes in the shoulders of my lifters and a hole through them near the bottom so oil can drain through onto the cam easier, I also went up a drill size on the oil drain from the intake spring area that goes down through the back of the cylinder.
I would not put any seals in the engine that were not used originally by Norton. If the valves and guides are in good shape and have the right clearances then there should not be a problem. I would rather err on the side of a little too much oil than not enough. The Manxman did not have oil seals on the stems when it was new and I do not think any Norton will miss them if the oil and breathing system is sorted out.
Since my bike is not getting any power enhancing modifications and I am not planning on beating it too hard I am not worried about having anything get out of control. I will save the later upgraded parts for something "built for speed" and high rpm. I will always try to keep the rpm below 6000. There is no reason to rev any Norton higher unless it will make you money or you have so much you don't know what to do with it.
These bikes would last a long time with a mature rider in the saddle. In the USA motorcycling was looked upon almost exclusively as sport and recreation, which means that crazed speed-fiends with ham-fists usually rode them at full throttle and at red-line, thus the truck-loads of scarred and holed crankcases laying everywhere. So I do not look at upgrading to later specifications as a must, but more of as an insurance policy, and also if the engine is completely apart and you enjoy tinkering why not do simple things that cost little or no money at all.
I would not put any seals in the engine that were not used originally by Norton. If the valves and guides are in good shape and have the right clearances then there should not be a problem. I would rather err on the side of a little too much oil than not enough. The Manxman did not have oil seals on the stems when it was new and I do not think any Norton will miss them if the oil and breathing system is sorted out.
Since my bike is not getting any power enhancing modifications and I am not planning on beating it too hard I am not worried about having anything get out of control. I will save the later upgraded parts for something "built for speed" and high rpm. I will always try to keep the rpm below 6000. There is no reason to rev any Norton higher unless it will make you money or you have so much you don't know what to do with it.
These bikes would last a long time with a mature rider in the saddle. In the USA motorcycling was looked upon almost exclusively as sport and recreation, which means that crazed speed-fiends with ham-fists usually rode them at full throttle and at red-line, thus the truck-loads of scarred and holed crankcases laying everywhere. So I do not look at upgrading to later specifications as a must, but more of as an insurance policy, and also if the engine is completely apart and you enjoy tinkering why not do simple things that cost little or no money at all.