Stepped key for cam timing

It is difficult to get more torque by adjusting cam timing to suit the exhaust system. If you get a gain it is probably good luck. Everything acts with everything else. My cam is almost standard and my exhaust is 2 into 1 with a large diameter tail pipe. I advanced the cam 12 degrees, and the ignition advance 4 degrees. Then tuned the motor to suit it using methanol fuel. With methanol fuel, the heat build-up is less. However the paint on my exhaust system is burned-off for a very long way, and the bike is too loud. The bike is fast enough to be competitive against some very fast bikes. But that is because I can get on the gas much earlier in corners. When you come out of corners faster, you are faster for most of the next straight. I have not raced recently, because I have one fear in road racing - that is the likelihood of hitting other bikes, as I reach the end of a corner. When my bike reaches that point, the speed differential is too big. It accelerates hard from the beginning of corners. I did not know my bike could do that until I tried it. It is not something I would normally do.
All that silly stuff about trail and transition point is relevant - it gives a significant advantage. It cannot be done with a peaky motor, and more lean.
 
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marshg246 said:
IMHO:

The simple fact that a Triumph camshaft is much shorter is a plus and the fact that each is only stressed half as much and the bushings are stressed half as much is an advantage over Norton. In fact, everything in the timing chest of a Triumph makes more sense to me than a Norton, especially the oil pump and timing gears. It would have been nice if Triumph had built the pushrod tunnels into the cylinders, but that's the only valve train fault I find with them.

The side benefits are the individual intake/exhaust valve timing.
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Casting in pushrod tunnels into the cylinders (like Norton and BSA did) would have been a GIANT improvement for their motor. Very few people can correctly install the head so the pushrod tubes don't leak AND the head doesn't bend over the pushrod tubes.
And imagine the savings in production time at the factory.
 
The separate inlet and exhaust cams in Triumphs are good for tuning. However the non-splayed cylinder head of Nortons, and the shape of the combustion chamber give a much better performance result. A Norton cylinder head cannot be fitted onto a Triumph motor. And a Weslake cylinder head does lot do much for a Triumph motor - the Norton cylinder head is the best. One of my friends has the most developed Triton in Period 3 historic races and has been class champion several times. He said he cannot beat the Nortons.
When I was a kid, a mate had a twin carb Manxman. I wish I had been smart enough to buy one.
 
acotrel said:
The separate inlet and exhaust cams in Triumphs are good for tuning. However the non-splayed cylinder head of Nortons, and the shape of the combustion chamber give a much better performance result. A Norton cylinder head cannot be fitted onto a Triumph motor. And a Weslake cylinder head does lot do much for a Triumph motor - the Norton cylinder head is the best. One of my friends has the most developed Triton in Period 3 historic races and has been class champion several times. He said he cannot beat the Nortons.
When I was a kid, a mate had a twin carb Manxman. I wish I had been smart enough to buy one.
Click to expand...
Norton heads are good, very good considering when they were designed.

Weslake heads are better.

I have finally got my 1007 Norton engine producing the same rwhp as my old 900cc Triumph based Nourish (the bike in my avatar).
 
Setting the pushrod tube crush height isn't rocket science, IMO, I think most guys do the measuring part wrong. I do think the valve angle in the triumph head is the biggest bottleneck
 
If you're curious (and please don't put this in the Triumph section) , I had shims made....020...008...005 that fit around the lifter block and inside the wedding band. Then I removed .060 from the lifter block, top of the flange. Surface both head and cylinder.
With the lifter blocks reinstalled, put in (probably) the thinnest square o-ring and the round o-ring in the head and then the pushrod tube sans pushrods. This can be done on the table, off the bike. Assemble the pieces including the head gasket and put in the 5 (or 6) center head bolts. Use the for outside head bolts for this. torque the head. Now you can figure how many shims you need to achieve .035 squeeze. Or close to it. If anybody would like the shims...I can also cut down the lifter blocks by .060.....I can have another batch made. I get 60 shims made of stainless stock and laser cut for the outrageous price of $200...no joke. This is the only way I've found success installing
triumph heads where they do not leak and do not bend over the pushrod tubes. Anything else is guess work.
If I get a few people interested I will order another batch of shims. It comes to roughly $3.50 per shim.
 
Fast Eddie said:
Norton heads are good, very good considering when they were designed.

Weslake heads are better.

I have finally got my 1007 Norton engine producing the same rwhp as my old 900cc Triumph based Nourish (the bike in my avatar).
Click to expand...
I am an idiot - my comment about the Weslake head was based on Rod Tingate's experience - it was a Rickman 4 valve head. In Australia, a bike with a Triumph motor with a Weslake or Rickman 4-valve head would probably not be eligible to race against pre-1973 machines. My 850 motor is of 1973 - so probably is really only eligible to race against post 1972 machines. It does not really matter. If I ever race again, I will simply log-book my bike post 1972 and race against the Kawasaki Z900s. If Peter Williams can win a race on a power circuit against Yamaha TZ750s - Nortons must be fast enough when they get going. Would you like to race a Norton 850 against a Z900 in a 3 kilometre circuit which has 12 corners ?
 
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Brooking 850 said:
I have been using a stepped key in my race bike since day one of the build.JS2 cam
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Which way did you go and how many degrees with the cam timing?
acotrel said:
If I ever race again, I will simply log-book my bike post 1972 and race against the Kawasaki Z900s. If Peter Williams can win a race on a power circuit against Yamaha TZ750s - Nortons must be fast enough when they get going. Would you like to race a Norton 850 against a Z900 in a 3 kilometre circuit which has 12 corners ?
Click to expand...

Roberts probably would have given Williams a hard time on a TZ750. The Norton was probably a heck of a lot easier to control than a TZ750.

The stock Z900 was not what I would call a road racing bike. It had a tendency to stand up braking hard entering corners. Probably partly responsible for the popular push down on the bars saying one used to hear in the 1980's.
 
Schwany said:
Which way did you go and how many degrees with the cam timing?


Roberts probably would have given Williams a hard time on a TZ750. The Norton was probably a heck of a lot easier to control than a TZ750.

The stock Z900 was not what I would call a road racing bike. It had a tendency to stand up braking hard entering corners. Probably partly responsible for the popular push down on the bars saying one used to hear in the 1980's.
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My friend has Suzuki Bandit which stands-up as he brakes. It is a symptom of understeer caused by less trail. If you could simply flick a Z900 into a corner then immediately accelerate hard all the way through it, it would be extremely dangerous. With a Commando based bike, you are much less likely to be grabbed by the throat. Down the straights a Z900 really gets mobile. They can demoralise anyone who is a bit defeatist. My problem has often been in coming into corners too fast behind those sorts of bikes. I have actually ridden a Z900 - to me they feel like a British 350. I was a bit surprised. When you are accustomed to riding a Triton, a Jap bike is a breeze. Tritons usually feel really big and awkward, and take more effort. My Seeley feels small and nimble. The one two-stroke I built was too easy to ride fast, so I sold it. It was much quicker than my Seeley, but not what I wanted to race. The kid who bought it won 28 races and 4 championships with it. It turned up again in about 2023 - I out-rode it with the Seeley. T250 Suzuki on methanol is not all bad. I did not know about the pilot jets in VM Mikunis, so I locked it up at high speed. I don't like that.
 
I think a lot of guys worry too much about getting beaten, it is probably an ego thing and presumption. It can be surprising what can be fast enough to be competitive. The rider adapts to the bike. I have always ridden old garbage - I would never race a modern bike. - I only ever raced to have fun, and develop the bike. My working life was similar. There was one job I had, for which I would pay to do again.
 
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Fast Eddie said:
Norton heads are good, very good considering when they were designed.

Weslake heads are better.

I have finally got my 1007 Norton engine producing the same rwhp as my old 900cc Triumph based Nourish (the bike in my avatar).
Click to expand...
In the meantime, someone, has gotten a bunch more rwhp out of a 900 Nourish! :rolleyes:
 
robs ss said:
Although more agricultural in many other senses the ES2/Model 50 is far more advanced than the twins in having separate inlet and exhaust cams.
I had 2 extra keyways machined in the cam gears (at 120 degrees) giving the ability to separately vary the timing of the inlet and exhaust valve action, something that is impossible with a commando without a new cam (or cams)
I recall the gears had 40 teeth meaning 9 degrees per tooth - 120 gave you a 1/3 tooth variation (3 degrees)
You could do similar with the pinion (20 teeth) which would give 6 degrees movement for both inlet and exhaust.
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Good to know. I will start a 47/48 es2 restore after my current projects are done.
 
Brooking 850 said:
I have been using a stepped key in my race bike since day one of the build.JS2 cam
Click to expand...
Similar, I made my own the day I installed the JS2.....before that I hadn't needed (used?) a stepped key to get the required timing with various cams (or, I hadn't been as fussy for that last degree!)
 
ilikevelos said:
Later the Z1 was marketed as DOHC and a big improvement over the SOHC Honda.
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I once got silly and lowered the gearing on my 500cc Triton. I led a race full of Z900 and H2 Kawasakis for almost a complete lap, but they blitzed me down a straight. I came into the corner at the end of the straight much faster than them. There was nowhere to go, so I speared-off to miss them. A Z900 or H2 is at a disadvantage in corners. If I race, I always take note of what the other guys are riding. It helps to know where they will be when push comes to shove. Under pressure, they sometimes run wide, where it can help. A good two-stroke is more difficult to beat.
 
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When you race a Commando-based bike - the real competitors are bevel Ducatis and the Laverda 750. Z900 and H2 Kawasakis and CB750 Hondas do not mean much. The others actually handle. There was a Laverda 750 which was over-bored to 900cc - it was unbeatable. It came from New South Wales, and a mining engineer owned it.
 


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