Engine Modernization

Fast Eddie · May 12, 2015

grandpaul said:
Just for grins...

Art's water-cooled Triumph

Some people are SO able!

And have SO much spare time on their hands!!

I can't believe he went to all that work and kept it 4 valve! He could have gone to 8 valve, 900cc+ and used the water cooling to allow 13:1 CR. THEN the water cooling would have added some actual value...!

Fast Eddie · May 12, 2015

So, you want to: "rebuild an 850 Commando with modern bearings, valvetrain, crank, rod, and piston" do you?

That's what I thought when I bought my first Commando a little while ago. My therapist wasn't impressed. Here's the evidence he used against me:

engine-build-prep-t18461.html

Rohan · May 12, 2015

Rotaries and similar things have been around for over 100 years too.
It just took a bit longer to figure out how to successfully seal them.

Someone commented that a whole slew of patents for rotaries and swashplate engines came from somewhere near Bristol was it,
just after the turn of last century - all in the same street that Alfred Scott lived in (of Scott motorcycle fame).
He contributed some too...

72Combat said:
But pistons aren't modern, they have been around for over 100 years.
Norton did modern some time back

john robert bould · May 12, 2015

comnoz said:
chipdossjr said:

I love Nortons. I love everything about them. It has always been my dream, though to take the classic British design and breathe new life into it through use of modern technology in one of these old engines.

What I want to do is rebuild an 850 Commando with modern bearings, valvetrain, crank, rod, and piston.

The longer the skirt the larger the load area ,plus the piston tips less .as Jim states these CBR pistons run in tighter bores .they will work but for how long?

The important thing in this build for me is the pistons. I come from the Motogp/ WSB side of cycling, so I cant help but see how big and inefficient these pistons are. I've learned that a lighter piston translates directly to more power and a more dynamic engine. I feel that this would be one of the best ways to advance one of these engines. Not only will the new piston be much lighter, but has much shorter skirts and smaller rings, so even less friction is present.

What I would like to do is find a way to make a modern superbike piston fit. The CBR 1000rr pistons happen to have the same bore as the 850. Perhaps some work could be done to make this happen? I should already be tearing so deep into the motor anything extra doesn't really matter. What will I have to do?

Click to expand...

Well you better get some nikasil lined water cooled barrels first so you can get the piston to bore clearance down to the CBR's figure. While your at it you might as well cut the stroke in half too. Jim

lrutt · May 12, 2015

Even a nice running stock 850 has good power, very respectable and can easily travel at interstate speeds.

So what is to be gained but sinking thousands of dollars more into a Commando? You could drop $20k into a commando and end up with a bike that might be almost as fast as a $3500 used Ducati M900.

but....if that is your passion and hobby, by all means, have at it. Makes for interesting reading on this site. I enjoy CNW's tech posts.

and...if your pistons were that small and light, you'd have to swiss cheese the crank so much to balance out there'd be hardly anything left.

worntorn · May 12, 2015

The stock Commando is smooth, powerful, easy shifting ,and if given reasonable maintanenance, reliable. On top of that they are great looking and handle nicely. What more can you ask for from a 40-45 year old bike?
Reading thru the 961 forum and the problems there with a modernized air cooled bike, I'll take my chances with the 40 year old one. It seems maybe Norton had things worked out pretty well back then.

Not to say improvements aren't possible. The front brake wasn't great, but there are multiple easy solutions for that.
As for additional power, it's might be fun but it sure isn't needed. Open the throttle for a few seconds and modern traffic gets left far behind.
The other issue with pumping up the horsepower greatly is that the gear box is the next weak link.
The fix for that is about the same $ as most Commandos are worth.

Glen

Hobot · May 12, 2015

The factory bikes won endurance races back in their era of being the best bike of Cycle World magazine 5 yr in a row so factory parts and power are pretty good as is and main thing to do for better life would be cryogenic tempering, ceramic coatings and dry friction impregnation. Norton Service Notes state 850s good @ 5800 forever.
Scan Jim Schimdt Norton site and RGM and CNW and NYC Norton, Steve Maney, Geof Collins for expensive upgrades from valve springs to crank shaft construction. Fast Eddie is good example of going over board and loving it, me too catching up fast as I can afford.

1up3down · May 12, 2015

The factory bikes won endurance races back in their era of being the best bike of Cycle World magazine 5 yr in a row

no, Cycle World was/is an American motorcycle magazine and it did not name the Commando best bike

you have that honor confused with Motor Cycle magazine which is an English publication and very supportive and biased of English bikes

Yes, the Commando did have a good record in endurance racing, winning the Thruxton 500 a couple of times, in England of course

L.A.B. · May 12, 2015

1up3down said:
The factory bikes won endurance races back in their era of being the best bike of Cycle World magazine 5 yr in a row

Click to expand...

no, Cycle World was/is an American motorcycle magazine and it did not name the Commando best bike

you have that honor confused with Motor Cycle magazine which is an English publication and very supportive and biased of English bikes

It was 'Motor Cycle News' (MCN), a weekly motorcycling newspaper: http://www.motorcyclenews.com/ not (The) Motor Cycle: http://en.wikipedia.org/wiki/The_Motor_ ... agazine%29

http://en.wikipedia.org/wiki/Motor_Cycle_News

MCN have been presenting an annual awards ceremony almost since they were founded in 1955. These included the popularity poll 'Man of the Year' and the overall 'MCN Machine of the Year' award:
Year Country Bike
1968 UK Norton Commando
1969 UK Norton Commando
1970 UK Norton Commando
1971 UK Norton Commando
1972 UK Norton Commando

chipdossjr · May 12, 2015

Woah, you guys. I don't think most of you are really understanding what I'm going for here. I don't want a new bike. I love the Norton. I love engines which are brought out to the fullest of their potential. I'm leaving the chassis, brakes, everything else that isn't the engine untouched. I want to live as if I were hot-rodding back in 1975.

I don't need to be told that I'm blaspheming the machine or that my efforts are hopeless. I'm here to learn. Tell me what I would have to do to make it work, not that it shouldn't.

What I'm asking is what sort of problems I could face by attempting to put a modern piston in this bike. From what I've read so far, things I will need to take into consideration aside from obvious piston dimensions: skirt length, if the crank can handle it (I figured a new one might have to be made), cylinder axis, rod length, cooling. What else am I missing?

Mark · May 12, 2015

chip:
there is a lot of norton knowledge and experience here on this forum.
If comnoz says it isn't worth the effort, I strongly suggest that you heed his advice.

Modifying an engine to work with a certain piston sure seems like a lot of work.

why do you want to do this anyway? do you already have a set of cbr pistons that you want to use?
what is your motoGP/WSB experience? racer? mechanic? fan?

There are guys here that make lightweight pistons, rods, etc.. already designed for your engine.
If I just had to spend money on my bike, that's definitely the route I would take.

OH....... welcome to the forum.

john robert bould · May 12, 2015

Hi
You might find a lot of piston slap.due to the air cooled clearance and the short skirt. longer skirts and greater area reduces this.? [less piston rock} Just my guess.

Fast Eddie · May 12, 2015

hobot said:
The factory bikes won endurance races back in their era of being the best bike of Cycle World magazine 5 yr in a row so factory parts and power are pretty good as is and main thing to do for better life would be cryogenic tempering, ceramic coatings and dry friction impregnation. Norton Service Notes state 850s good @ 5800 forever.
Scan Jim Schimdt Norton site and RGM and CNW and NYC Norton, Steve Maney, Geof Collins for expensive upgrades from valve springs to crank shaft construction. Fast Eddie is good example of going over board and loving it, me too catching up fast as I can afford.

Steve,
"Overboard"!? How dare you sir?
Define "over" ... !

worntorn · May 12, 2015

chipdossjr said:
Woah, you guys. I don't think most of you are really understanding what I'm going for here. I don't want a new bike. I love the Norton. I love engines which are brought out to the fullest of their potential. I'm leaving the chassis, brakes, everything else that isn't the engine untouched. I want to live as if I were hot-rodding back in 1975.

I don't need to be told that I'm blaspheming the machine or that my efforts are hopeless. I'm here to learn. Tell me what I would have to do to make it work, not that it shouldn't.

What I'm asking is what sort of problems I could face by attempting to put a modern piston in this bike. From what I've read so far, things I will need to take into consideration aside from obvious piston dimensions: skirt length, if the crank can handle it (I figured a new one might have to be made), cylinder axis, rod length, cooling. What else am I missing?

Not hopeless but perhaps heading in the wrong direction. We could all cheerfully agree with your plan and send you off into the land of misfortune, but that wouldn't really be fair would it? It might make you happy right now and not so happy in the future.
Kenny Dreer had the same sort of general feeling for the Commando as you do. Great bike that needs modernization of the engine.
He went so far as to build his own strengthened crankcases (drive side) to handle the extra power. He built quite a few of his 880s and they were fast. Not nearly modern 600 cc sport bike fast but substantially faster than the stock Commandos.
But they also liked to disintegrate after very few miles.
In the end he decided that the original Commando engine should not be pumped up in power, just leave it as it is and enjoy the torquey power delivery and sound.
So in the quest for a modern Norton type bike he embarked on a new design using modern ideas while retaining the looks of a cafe racer from the 60s/70s (Norton 952, now the 961) That is an ongoing saga.

I suggest you do an internet search on Dreer 880 Nortons. There is a lot of hop up history there and equal amounts of blow up history as well.

You mention that you don't want to change the brakes. This is one area of the old bike that was pretty weak, not a match for the rest of the machine, it really is worth making a change of some sort there, not hard or expensive to do and there is really no downside.

Glen

swooshdave · May 12, 2015

In case you missed LABs post on the first page...

http://www.jsmotorsport.com/

Lightweight pistons and rods to match. Someone has already done the hard part, now you just need to pay them the money. Unless you think you are a better engineer...

cjandme · May 12, 2015

chipdossjr said:
......... as if I were hot-rodding back in 1975....... what sort of problems I could face by attempting to put a modern piston in this bike. From what I've read so far, things I will need to take into consideration aside from obvious piston dimensions: skirt length, if the crank can handle it (I figured a new one might have to be made), cylinder axis, rod length, cooling. What else am I missing?

Welcome chip, there are tons of upgrades available now that wern't available back in the day, so your lucky there. Jsmotorsports has the pisto ns and longer carillo rods that your looking for and I think that Nourish has the one piece crank. I think that he was just bought out or taken over by family but it seems like I remember reading that they are still in business. Search info about the yellow peril race team, also look for info on a shop in germany that has done a bunch of work with nortons....I seems like they came up with or build a 905 that is along the same lines as what your talking about, but I forget their name at the moment. Search this forum for "920 picture" (IIRC) and it should bring up the thread from fellow forum member named matchless, who has rebuilt his bike out of the ashes of a blown motor. Fullauto in Australia makes the new meatier replacement cylinder heads, and TTi in New Zealand has the new gearboxes to handle the extra horses. Again welcome and post lots of pictures of your build as you go along

we all love seeing them :mrgreen:

72Combat · May 12, 2015

Interesting, I find the engine on my Combat pretty good, its the brakes , riding position and suspension that I'm spending on

Fast Eddie · May 12, 2015

worntorn said:
chipdossjr said:

Woah, you guys. I don't think most of you are really understanding what I'm going for here. I don't want a new bike. I love the Norton. I love engines which are brought out to the fullest of their potential. I'm leaving the chassis, brakes, everything else that isn't the engine untouched. I want to live as if I were hot-rodding back in 1975.

I don't need to be told that I'm blaspheming the machine or that my efforts are hopeless. I'm here to learn. Tell me what I would have to do to make it work, not that it shouldn't.

What I'm asking is what sort of problems I could face by attempting to put a modern piston in this bike. From what I've read so far, things I will need to take into consideration aside from obvious piston dimensions: skirt length, if the crank can handle it (I figured a new one might have to be made), cylinder axis, rod length, cooling. What else am I missing?

Click to expand...

Not hopeless but perhaps heading in the wrong direction. We could all cheerfully agree with your plan and send you off into the land of misfortune, but that wouldn't really be fair would it? It might make you happy right now and not so happy in the future.
Kenny Dreer had the same sort of general feeling for the Commando as you do. Great bike that needs modernization of the engine.
He went so far as to build his own strengthened crankcases (drive side) to handle the extra power. He built quite a few of his 880s and they were fast. Not nearly modern 600 cc sport bike fast but substantially faster than the stock Commandos.
But they also liked to disintegrate after very few miles.
In the end he decided that the original Commando engine should not be pumped up in power, just leave it as it is and enjoy the torquey power delivery and sound.
So in the quest for a modern Norton type bike he embarked on a new design using modern ideas while retaining the looks of a cafe racer from the 60s/70s (Norton 952, now the 961) That is an ongoing saga.

I suggest you do an internet search on Dreer 880 Nortons. There is a lot of hop up history there and equal amounts of blow up history as well.

You mention that you don't want to change the brakes. This is one area of the old bike that was pretty weak, not a match for the rest of the machine, it really is worth making a change of some sort there, not hard or expensive to do and there is really no downside.

Glen

Orright Glen you got me now... reading the above text would seem you suggest the 'standard is best' approach...

How are we to balance that with your personal 1360cc nuterbastard Vincent approach...!?!

Rohan · May 12, 2015

Using all Steve Maney parts can build a similar hotrodded Commando engine.
Although perhaps not to the same extent.

And a lotta shekels for a street engine, that still can't keep up with any of the current crop of hyperbikes...

worntorn · May 12, 2015

Fast Eddie said:
worntorn said:

chipdossjr said:

Orright Glen you got me now... reading the above text would seem you suggest the 'standard is best' approach...

How are we to balance that with your personal 1360cc nuterbastard Vincent approach...!?!

Click to expand...

Click to expand...

I sure wouldn't recommend trying to make a 100+ horsepower Vincent from a nice standard Vin like your or my Rapides.
I think the engine would shatter into many pieces somewhere well before 100 HP, many have tried and failed.
The 1360 was a complete new bike and engine, so no Vincents were harmed during the making of that bike.
Since it was all new stuff and the plan was for big power, I used some greatly uprated components such as

- Crankcases heavily fortified around main bearing areas in engine and trans and other known weak areas ( trans cam pinion boss)

-Quaife 5 speed rated for 200 bhp according to Rod Quaife

- One off Bob New by clutch with thin plates and extra plates. Said to be OK to 140 HP. Holds OK but just.

-crankshaft with oversized mainshafts, oversized bearings and oversized main pin. Main pin has 3 times the surface connection to the flywheels that the standard crank uses and has a 14 ton interference fit rather than 5 ton as for standard.

- the cylinders and heads look just like a standard Vincent but have approximately 35% more cooling fin area to deal with the increased horsepower.

- two start oil pump delivers twice the volume of the standard pump, and is a "must" according to Terry Prince, who supplied many of the steroidal parts.

There are other changes such as forged Pistons and rods and on and on.

With all of that it is a bit of a silly experiment as far as longevity. It would be a wonderful outcome if the engine stood up as well as a standard Vincent engine generally does.

No reason that one could not build a big bore big stroke Norton engine/trans in the same way. I the Norton engine/trans(TTI, 6K) would end up costing 20 or 25 k US$ , maybe more with assembly labour.
I think Jim Com stock has one almost together, he must have a good handle on what it would cost to start from scratch and build such a power train.

As far as hopping up a stock Norton engine, I have been mightily tempted and have had 920 kit in the drawer for years now.
The more I learn, the more I think it is not such a great idea, unless you start completely from new with beefed up parts hopefully capable of giving years of reliable running at the new higher power output level.

Glen

Engine Modernization

Fast Eddie

Fast Eddie

Rohan

john robert bould

lrutt

worntorn

Hobot

1up3down

L.A.B.

Moderator

chipdossjr

Mark

john robert bould

Fast Eddie

worntorn

swooshdave

cjandme

72Combat

Fast Eddie

Rohan

worntorn

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