Combat cam in an 850 ?
- Thread starter Rohan
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TC used to tell me that 850's responded well to the Combat cam--you'd absolutely need valve cutouts in the pistons--a shaved head, no base gasket--and perhaps shortened pushrods and more room in the cam tunnel to accommodate the higher-lift lobes. The inherent torque advantage of the bigger engine apparently offsets the slight loss of torque that the 750 Combat engine experiences at lower revs
Tim Kraakevik
kraakevik@voyager.net
'72 Combat, '74 RH10 850
Tim Kraakevik
kraakevik@voyager.net
'72 Combat, '74 RH10 850
ashman
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Hi Rohan
I got my srtandard 850 cam build up to SS Cam specs (Combat) and have been running it in my 850 for over 30 years now, I am still running flat top pistons (40thu over), still have my orginal valves but have had a bit of port and head work done, still running orginal pushrods and lifters and balanced crank as the motor is in a Wideline Featherbed frame, there was enough room in the cam tunnels with out grinding them out, the motor revs very freely and the cam kicks in just over 4,500 RPMs, this cam has made such a big improvement in over all power and is also very good down low revs for running around town, but get it out on the open road and hang on, give it a hand full from the lights I find it's very hard keeping the front wheel on the ground :twisted:
I would never go back to a standard cam in my 850 as the SS cam has been the best improvement I have ever done to my motor and its so reliable as well.
Ashley
I got my srtandard 850 cam build up to SS Cam specs (Combat) and have been running it in my 850 for over 30 years now, I am still running flat top pistons (40thu over), still have my orginal valves but have had a bit of port and head work done, still running orginal pushrods and lifters and balanced crank as the motor is in a Wideline Featherbed frame, there was enough room in the cam tunnels with out grinding them out, the motor revs very freely and the cam kicks in just over 4,500 RPMs, this cam has made such a big improvement in over all power and is also very good down low revs for running around town, but get it out on the open road and hang on, give it a hand full from the lights I find it's very hard keeping the front wheel on the ground :twisted:
I would never go back to a standard cam in my 850 as the SS cam has been the best improvement I have ever done to my motor and its so reliable as well.
Ashley
The ss cam is still considered a street cam. Most guys just shave the head to go with it. Norton's original mod from the 750 9:1 motor to the combat was shave .040" off the head, 32mm intake ports from the 30mm + bigger carb, shorten push rods (however there have been many unshortened pushrods reported in combat engines) and larger valves. Pistons are the same for both engines.
Depending on your valves (how many grinds and how deep in the seats, brand) you may not need to shorten the push rods but I think the manual calls for .020" taken off. It would be a good idea to ensure you have .050" valve to piston clearance too.
Depending on your valves (how many grinds and how deep in the seats, brand) you may not need to shorten the push rods but I think the manual calls for .020" taken off. It would be a good idea to ensure you have .050" valve to piston clearance too.
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