Mega cycle cam and bushing questions

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Kthomas

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I am rebuilding a 73 850 engine . It came with a megacycle 560-so camshaft. When I look it up the recommendation is to use it with modified piston and springs. Am I going to have to relieve the pistons for valve clearance? Also, what springs are best ? Ive already put my head together with new springs but they aren’t racing type which I would think would be hard on the valve train ?
Another question —- I know this has been discussed before —- I’m at odds as to whether to switch out my cam bearings. I don’t have a proper small bore gauge to measure the inside diameter. With cam installed I do feel measurable play but it seems like I’ve read just as many people saying to leave them alone as to replace. I thought about getting a .875 reamer and making a setup but ? We have a number of good machine shops around but no specific Norton enlightened ones .( I don’t think )
ANY thoughts appreciated
 
My first thought would be to ask what type of performance do want from your engine...then decide if the cam included fits your needs?
Lift and duration of the cam profile can have a huge influence on spring choice.
When high lift/high performance cams come into play there is a big domino effect of supporting components needed.

Not trying to lecture, just need more insight from you. ;)
 
This is just the cam I have. The only other cam I have is in a early 750 set of cases which I suppose I could split and use if it was a scrolled cam . I would rather use a stock cam. I didn’t think this cam s profile was all that radical but ?
 
The 560-SS is higher lift cam and is better used with a higher compression, so the normally flat 850 pistons will need cut-outs so the valves do not hit the pistons. Higher spring rate valve springs will also be needed. The early 750 cam will have the same profile as the standard 850 cam so no mods needed, but if its too early it will not have the tapered hole on the timing side of the camshaft for the points AAU or the EI rotor.
 
The 560 SS is basically the 2S Combat cam.

Its a full race cam, requires high comp, and gives great top end power at the expensive of power below around 4,500 rpm.

Its a great cam…IF thats the kinda ride you want…
 
Ok
Thanks
You’ve helped me make a decision. I’m not going to use the combat cam. I’m going to pull the other one and see what it looks like. If it isn’t good I’ll have to find another stock cam
 
I pulled the other cam. It has notches on the drive end and had a small spring as well as a piece that fits into the notches ? Can I use this and if so would I need the spring and notchy piece. It also has a largish bulbish area around the middle with holes. Sorry about the misspelling but I’m not sure how to post pictures
 
Kthomas said:
I pulled the other cam. It has notches on the drive end and had a small spring as well as a piece that fits into the notches ? Can I use this and if so would I need the spring and notchy piece. It also has a largish bulbish area around the middle with holes. Sorry about the misspelling but I’m not sure how to post pictures
Click to expand...
That is the timed breather fitted to pre 72 cases which came out on the driveside, so no need for it on 850 cases as there is no hole on the driveside as the breather is untimed and comes out on the back of the crankcase timing side. It won't do any harm so can be left as is minus the spring and the notchy piece but neither will it function as intended.

See 45 and 46

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Andover Norton Parts Drawings - Andover Norton Factory Parts - Commando Parts

Andover Norton Parts are the only Norton spare parts in the market manufactured to original drawings, within the factory-approved tolerances, from the correct materials, and with the correct finish.
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and 41 etc

andover-norton.co.uk

Andover Norton Parts Drawings - Genuine Andover Norton Factory Parts - Commando Parts

Andover Norton Parts are the only Norton spare parts in the market manufactured to original drawings, within the factory-approved tolerances, from the correct materials, and with the correct finish.
andover-norton.co.uk
 
Kthomas said:
I pulled the other cam. It has notches on the drive end and had a small spring as well as a piece that fits into the notches ? Can I use this and if so would I need the spring and notchy piece. It also has a largish bulbish area around the middle with holes. Sorry about the misspelling but I’m not sure how to post pictures
Click to expand...
Yes you can use that cam.
It's early models 750 with the timed breather on the drive side end. I use it in my 75 850 as a replacement for the soft lobe issues known about with some MK111 models.
How do the cam lobes look ? They should have no scratches or dimples or wear marks on the lobes.
Mine is scrolled to provide lubrication to/ at both camshaft bushes.
Removing and replacing these 2 bushes is a chore at best so I would not go there if they are O.K. to use .
 
Torontonian said:
Yes you can use that cam.
It's early models 750 with the timed breather on the drive side end. I use it in my 75 850 as a replacement for the soft lobe issues known about with some MK111 models.
How do the cam lobes look ? They should have no scratches or dimples or wear marks on the lobes.
Mine is scrolled to provide lubrication to/ at both camshaft bushes.
Removing and replacing these 2 bushes is a chore at best so I would not go there if they are O.K. to use .
Click to expand...
Good point on the bushes, if the camshaft has plain journals then you need the bushes with a scroll or add a scroll groove to the cam journal. Both cam and bushes can be scrolled but never fit plain cam to plain bushes.
 
It’s scrolled and the bushings are plain. I’m looking forward to getting this bike back together. I started on it 2 years ago but got sidelined waiting on exhaust port work
 
My stock cam was built up and reground to 2S profile and I still run flat top Hepilite pistons, am still running original valves and springs, my head has been shaved and ported, I have been running this set up now for 39 years, the valves haven't touched the top of the pistons, my motor is a 850 but its easy to check valve/piston clearance before final assembly.

Ashley
 
I attempted to measure crank float today. I installed a new bearing in the d4ive side. I ground down an old bearing to use in the timing side ( so I could remove easy ) .The crank in the drive side is a real tight fit. I put it all together with no shims and when I put it all together andtightened up the bolts the crank wouldn’t turn. I imagine it might not have been completely seated into drive side. Either way, how would I measure float if it won’t move side to side in the drive side bearing. I guess I should have ground both old bearings down and went from there. Aaarrrrggggghhhh.
I don’t want to knock it out.
im using new superblends.
 
A race cam will usually give you a surge of power at about 4000 RPM, regardless of the compression ratio. If you ride your bike in traffic, that might not be desirable. I have a 2S Combat cam I was going to fit into my 850 motor. But I don't like modifying pistons to get valve clearance. Once you have done it, you need to keep doing it every time you change a piston.
I like the buzz a race cam gives me when it comes on song, but even for racing, a standard cam with a bit more lift, might be better. Smooth power delivery allows you to go faster in corners. A race cam with megaphone exhausts can make a race bike difficult to ride fast.
A two into one exhaust system might make your race cam easier to live with, as long as it has minimal restriction.
 
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