Discussion in 'Norton Motorcycle Rebuilds' started by Fast Eddie, Feb 11, 2019.
Very clean look.
What's the advantage or thought behind a one piece rear axle ?
My motivation was twofold. Firstly, I just prefer the notion of a solid axle, especially in a tuned bike that will spend time on the track. Secondly the stories I’ve heard of two piece axles breaking. I must say that I have never had this happen, but those two factors swung me in that direction.
That is good but how? if an offset sprocket is replaced with a flat sprocket, then one must be out of line.
While you can get to it, could you measure the distance from the inside of the gearbox sprocket to the gearbox case where the top bolt goes through on both boxes (can't get to mine without stripping it), I am wondering if the sleeve gear holds the sprocket further out on the TTI box.
I had to use a offset sprocket on the Seeley but that was to clear the 130 tire, I am now wondering if I would have had to do something with a standard box setup to clear the tire.
I can only assume that both front and rear sprockets were slimmed down the same way, ie shaved the same amount off of the same face (front face I think).
I’m not sure I’d describe the standard sprocket as offset. Technically, the centre line is, but the back face is flat, it’s slimmed down or ‘dished’ in the centre of the front face where the nut goes.
Machine the dish off of the front face and you’re basically gonna have a flat sprocket.
Machine the front face of the rear drum sprocket and bingo!
And I should quantify my ‘cock on’ claim... I mean it’s cock on according to the ‘length of string and eye’ method, no laser alignment tools involved !
Ah well, lucky it lines up anyway because offset TTI sprockets are less common than hens teeth, I am having to make a 21 and a 22 for the Seeley just now.
Side benefit of skinny tyres !
Just like Norton made the frames
I just spin the wheel and make sure the sprockets centre between the chain inner plates, if they touch one side, something is wrong.
I wouldn’t try that on any original bikes yewth...!
Neat solution to the speed sensor and some nice finished parts .
Some more progress boys n girls...
Not a massive amount of work, but a significant ‘milestone’.
Barrels are empty, only on to ensure crank case alignment.
I find it intriguing just how much pleasure I get from this part of the process... I almost feel guilty...!
Is the light flywheel a good idea in a 920 engine ? My friend is building a 750cc Triumph engine for his Triton. He has rebalanced the crank, but it won't rev above 4000 RPM, because the vibration causes the carbs to flood. Below 4000 RPM, it pulls like a train.
Dunno, I’ve never tried one.
Steve Maney clearly thinks so though.
Shoot, don't feel guilty Nigel, I'm really enjoying this thread!
No need to feel guilty Nigel. It was an honest question. My friend has a real problem with this. He has gone back to resurrecting his 650cc motor. Making a Triumph 650 become a 750cc motor is not as straightforward as we might imagine. The Commando crank is much heavier. With a light crank, throttle response might be better - but with a close ratio box, the problem of response with the heavy crank, is not a big one. Even on the slowest corner my motor is usually revving above 5000 RPM. With a wide ratio box, the heavy crank is absurd. I tried racing with the standard box and the bike was hopelessly slow. In the past, I have found that a lighter crank does not really improve performance. On an racing up-change, the crank inertia is used to provide acceleration. If you rely on the throttle to spin the motor up, the process is slower. So I never let the motor bog down.
What really surprises me is that the 850 motor is so good in near-standard form. Mine is quick enough to win races against the fast guys, and I have done almost nothing to it.
Thanks for the pics and write up; it's not that easy to drop what your doing and stage it all at the right moment, save the pics, and write it up.
It’s quite easy these days John, even for a Luddite like me. I’m an i phone and i pad guy, so long as I have the phone with me, it’s easy!
I will be interested to see how you go when you race the bike. One of the old A graders used to race an 850 Commando for S.R.Evans in Melbourne and he always did OK. I once looked at building a bike using the Commando frame, but I could not bring myself to buy it. I think is really great when guys persevere with older bikes. What amazes me, is my mate used to do pre-delivery on Commandos and Kawasaki two strokes for S.R.Evans. They used to take the bikes to the Richmond Boulevard in Melbourne to test them. There was nothing in it between an H2 Kawasaki and a Commando. I would have thought the Kawasaki would be much faster.
Al, I’m really not sure if you don’t read... or just don’t remember...
Well, I had a right carry on today. Got there in the end though...
Thought I’d cobble the timing side together, got a load of new gear so (rather naively) thought it’d be a quick ‘nail it together’ job.
Ha! No such luck, it didn’t go together nice at all, felt tight and just generally ‘not nice’.
Fortunately I’ve got the old engine still, so was able to mix n match parts until I got, what felt like, a nice feel to it on both engines.
So, on with the spindle plate and tighten it all up:
Cam followers are a lovely fit in the Maney block:
Those who have been paying attention will recall me announcing that I was done with fancy piston coatings. Well, here are my pistons... complete with fancy coatings!
In my defence however, the coating hasn’t been applied by a bunch of drunk, blind, pikey’s as it probably was in the past. This coating is a result of discussions with the piston supplier (JS) and I sent them back to him for the treatment. Fingers crossed it’s as good as it’s supposed to be:
But when I dropped the barrels and pistons on (without rings) the thing still didn’t feel nice! Since tightening it all up something had changed and felt slightly ‘nothcy’ at one point in the crank rotation. I could turn it over quickly and pretend it felt good, but when I turned it over slowly I wasn’t happy with the feel. The culprit turned out to be the new crank pinion. That’ll be going back to AN.
This time I decided to fit the Comnoz auto chain tensioner, just because I could really.
I’ve got 3 head gaskets of different thicknesses from JS so will hopefully be able to get the squish and CR where I want it without having to get too drastic:
Just waiting for the head to come back from being tumble cleaned and I can crack on...