Advantages of longer rods in Nortons

hobot said:

No replacement for displacement only goes so far Dances especially boosted hi rpm, though don't ya know I looked at 1007 and sealing options years ago with M.A.P. Cycles. If Peels base 920 JSM rod engine is good for 80 hp and Drouin only adds 50% instead of advertised 58% more Drouin power that's ~140 hp around 7000. Do ya think with Maney cases, welded light nit-fried crank, JSM kit, Norris D cam and proven out of tach sight valve control head, Peel could stand 8500 and not just friction burn out? If so might top TC's nitromethane fueled 850 stocker engines. I expect Peel base line closer to Steve Maney's 100 hp 920's at 7200. Combat head flow and stock valve size is the weakest power link mystery. May be more than I can handle regardless and that's all I want any way.

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You will get further off topic here....surely the point of turbocharging or supercharging is to develop additional power throughout the rev range, meaning you can pull higher gearing and not rev beyond 7000 and still pull up tree stumps......

With a normally aspirated engine you need to rev higher to develop the power....different plan...

The 1007 works on the dyno, but precious few have had sufficient advantage on the race track, not just against other Nortons, but against the whole field. You need to be able to use the power, within the limits of the frame, suspension and tyre technology. It was said that at one point Gary Thwaites pulled in on the 1007 with a suspect puncture, but in fact it was moving around because the tyre was becoming chewing gum due to the torque.....

Races are won on more than sheer grunt, its a package.....including the rider....few riders have the measure of Gary on any bike....

I suspect that even if you do achieve 100hp at 7200, and why shouldn't you, you will be having so much fun at 6000 you will rarely go to 7200.....

[/quote]

THINK YOU PUT IN ENOUGH NITRO BOB?

Dances with Shrapnel said:

acotrel said:

With a short stroke motor, the valve train has to keep up with much higher revs, and often a harsher cam.

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Not necessarily, the Commando head flows pretty good. Depends upon if you want ultimate power or just more power. We are only raising the redline from 7,000 to 8,500 which is a 50% increase on acceleration forces. The Commando valve train (with some work) can handle more. Really a non issue, even with a harsh cam.

acotrel said:

The lack of torque ...........................

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Your assertion above is without a solid basis. If you had a lack of torque on your short stroke, you were doing something drastically wrong. What you loose in crank moment arm on a shorter stroke you gain in bigger piston and more force.

acotrel said:

I presume that with your 750, short stroke refers to about 82mm like an early Triumph twin - not what I would call short stroke ? The later (70s) Daytona T100 at 65.5mm is short stroke.

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Ahem, we are talking Nortons here. My 750 USS Norton is 81mm bore by 75mm stroke. Runs like the wind with gobs of torque throughout the range. Very trackable and very fast.

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To my mind, in a big vertical twin motor 75mm is the ideal stroke, you would still have enough torque to tide the bike hard around tight circuits, and have plenty of go at the ends of the straights without really needing a 6 speed box. My Triumph 500 with the 63mm stroke was unridable when it had 4 inch megaphones and it destroyed a much better rider than myself. A close friend rode it at Bathurst in the late 50s. With its really strong top end, he reached the end of conrod straight going extremely fast, and had to make the decision to either take the escape road or turn left into Murray's corner to continue - either option was potentially a really bad crash. He somehow got around, and continued until he got to the top of the mountain where the bike bounced him off the Armco fence at Skyline corner, broke his arm and leg. He did not race for twenty years afterwards.
When I started racing the bike, I was a pretty good rider, and it turned me into an instant dud. I rode it at Phillip island and on the big fast stuff it was superb towards the ends of the sweepers, it would pass the other guys like they were stationary. I was using a drum brake which both locked then dragged on occasion, it chucked me off onto the non-skid at about 90 MPH, and steered me off the track to two crashes. Four times in one day is my record for a single race meeting. I eventually got on top of the bike, however in the end I could choose where I would lose a race - gear it low and blitz them around the tight stuff, but get blitzed at the ends of the straights. Gear it high and blitz them on the fast stuff, but crash in the corners. I rode it in later years after I had sold it back to my mate who had crashed it in the 50s. He'd fitted straight pipes, good tyres and a 5 speed box. It was fairly decent, however I still got it sideways in a corner. With the good tyres, I simply rode through the problem, however it was still a nasty piece of shit.
I never have anxiety riding the Seeley 850, it is a whole different world for me - just so fast and so easy.

I raced my 500cc short stroke Triumph for about 12 years in Allpowers C grade. In the end the opposition were riding Z900, and kitted H2 Kawasakis, and RD 350 Yamahas. I couldn't beat them however I was never last - always mid field. I used an AJS 7 R drum brake when most other were using discs, and I could still outride most of them on a tight circuit. If I'd had the Seeley 850, the story would have been very different. It is really a very bloody good thing - a substantial weapon.
Have a look at the photo to the right of this post, it was taken at Mount Gambier in about 1972 - the other bikes were mainly two strokes.

the One007 is a l o n g s t r o k e , the Royal Oilfields 93 mm or suchlike , which had a 71mm bore , at 750 cc .

Then theres the 89 stroke .

The SHORT STROKE Norton in the 750 is the 850 bore with a 80 mm stroke , as per P. U. 500 Triumph . The Pre Unit ' R 's were redlined at 8000 rpm too .
At 77 x 80 , its still not square . So still almost ' long stroke ' .

An 81mm stroke pre-unit 500cc Triumph will cop 8,000 RPM all day, an 82mm stroke 650cc Triumph will not. My 63mm stroke 500cc Triumph used to regularly cop 10,500 RPM without blowing up - the only reason I ever persevered with it. It had a billet crank, and the short stroke meant it did not shag the cases or bearings. Every 650cc Triumph which raced in historic races in Victoria in the 70s and 80s has blown up with only one notable exception. It is a Triton, and the motor was built for torque and never revved over 6,300 RPM. It is now a 750 with the usual one piece Triumph crank, and extremely fast.
In the 80s Triumph brought out a 650cc Thunderbird with a 75mm stroke crankshaft. That shaft would be ideal in the appropriately sized 500cc or 750cc motor using early 650 Triumph parts - or even in a Norton. I don't believe many were ever made.

worntorn said:

I think the Norton engine works quite well as designed, that is as a low rpm high torque engine. With the updated bearings it makes a great road engine. If the desire is to turn it into something it is not - a high rpm race type engine, then it needs a major revamp, or as Steve Maney and Kenny Deer both decided, a complete redesign.

It was mentioned that a long rod ratio is used in Formula one race engines. There does seem to be a consensus that the longer rod ratio works best with very high rpm engines of this type.
I don't see the Norton engines as having much in common with that type of engine, nor would I want to attempt to remake my engines into high rpm Screamers, invariably at loss of low and midrange punch.
Best to start again for that.
Or buy a litre Sport bike and watch the tach go effortlessly to 12 or 14 grand without vibration or risk to engine.

Glen

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A. MEN. BROTHER.

So far going by the success of the UK 1007cc racer the best combo for Norton power and rpm character is longer stroker engine with longer rods, sheeze. Pretty much topped out in bore sizes. I've tried the sports bike route but it just don't satisfy me and now see em as just flashy bait fish to snap up to get around.

hobot said:

So far going by the success of the UK 1007cc racer the best combo for Norton power and rpm character is longer stroker engine with longer rods, sheeze. Pretty much topped out in bore sizes. I've tried the sports bike route but it just don't satisfy me and now see em as just flashy bait fish to snap up to get around.

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ONLY because (wait for it.....) they are usually piloted by squids!! :mrgreen:

Yep soft bodied animals with jet propulsion that don't live long, though are pretty smart and colorful being mollusks. This powerful engine stuff is not just academics to me as I don't like being out powered in open waters by the fat tire moderns. My hobby was/is seeing what I could press hardest on power thru turns so surprised to high heavens nothing took my breath away like a linked Combat. My goal is proving an ole clunker can hook up more power on leans and not get caught back up with in time before some more leaning involved.

hobot said:

So far going by the success of the UK 1007cc racer the best combo for Norton power and rpm character is longer stroker engine with longer rods, sheeze. Pretty much topped out in bore sizes. I've tried the sports bike route but it just don't satisfy me and now see em as just flashy bait fish to snap up to get around.

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No doubt that the 1007 in question works as a Seeley Commando....but I will repeat, ridden by an exceptional rider....

If the whole field were 1007s he would still have a very good chance of taking the win.....

However, the bike is, I think. still up for sale, so with the CRMC season starting tomorrow we will see what happens this year....

My own prediction is that there will be few 1007 Nortons to emulate the Watson bike and that the overall race win will be a multi cylinder bike and the leading twin will be of less than 1000 cc and may not even be a Norton...think Weslake!....I shall in any case watch with interest as I hope to join them on a 750 short stroke by year end (though I don't expect to be troubling anyone for the race win!).

Don't put so much on the race results of one rider on one bike....

I can sure appreciate the part of pilot skill and balls play in pecking orders but it don't take much of a pilot to just nail extra power exiting turns to leave the best bike/rider behind. Can we get much bigger badder Norton-ish Twin than this 1007 with longer stroke and longer rods and light enough pistons for decent redline? I well know what the liter rockets can do - once they ease up on any leaning. Only path I know while sticking with clunker engine is big block factory stroke with boost and anti-detonation fluids - but not if the whole package can sustain the heat loads long enough to matter. Up torque and gear up but who knows what the rev limiter should be set at...

Btw I also know how wheelie limited moderns are compared to hard to lift Commando so when the going gets hand to hand close quarters combat them moderns can't plant and hook up as much get go G response leaps as a hot Commando, till Commando hp runs out of course. As fuel cells come on line all combustion cycles will fall behind in a flash, unless of course they have innate power handling when leaning good.

SteveA said:

No doubt that the 1007 in question works as a Seeley Commando....

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The Seeley Mk2 can only accept up to a certain width of rear tire to handle the greater torque of a 1,007cc. Even before you get to that tire width limit one would be diminishing the nimble quick handling characteristics of a classic Seeley Mk2. As Keith Stephenson warned me, go too wide with the tire(s) and the fine handling characteristics of a Mk2 Seeley are spoiled. Big motor and carefully control throttle driving out of a turn with a narrower rear tire is fine (like driving on razor edge of traction but then you loose the opportunity to use that torque to drive out of the turns and it becomes more of a straight line machine.

I have some breaking news for ya - all fatso tires spoil all motorcycles fine handling to point of becoming corner cripples. I found out slightly fat skinny tires are a secret weapon against balloon tires that get too unpredictable loose for my kind of jerking around. There ain't much patch area difference but boy howdy there's important differences in patch shape, especially on edges. One the best things to me on Norton power character is ability for fine control of tire spin out instants at lean limits so avoid long lingering heating of narrow tire band. Heat handling is the main advantage of fatso tires but life on THE Gravel teaches ways to avoid that while preserving tire surface mileage. When ya get to maxing out beyond tire planting level the innate weakness of modern construction concepts gets in the way of pressing down harder on rear patch as they just vibrate off the path. Rigid is as rigid does but too floppy sucks even more so only two of 5 phases of power steering considered by rest of the world expect for ice spiked speedway racers and MX bikes horizontal in vertical dirt ruts.

Dances with Shrapnel said:

SteveA said:

No doubt that the 1007 in question works as a Seeley Commando....

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The Seeley Mk2 can only accept up to a certain width of rear tire to handle the greater torque of a 1,007cc. Even before you get to that tire width limit one would be diminishing the nimble quick handling characteristics of a classic Seeley Mk2. As Keith Stephenson warned me, go too wide with the tire(s) and the fine handling characteristics of a Mk2 Seeley are spoiled. Big motor and carefully control throttle driving out of a turn with a narrower rear tire is fine (like driving on razor edge of traction but then you loose the opportunity to use that torque to drive out of the turns and it becomes more of a straight line machine.

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I agree, however I recently asked the question on this forum whether anyone had ever hi-sided a commando. It does not seem to happen unless the drive train breaks. My Mk3 Seeley has greatly reduced trail and tightens it's line considerably in corners, if gassed hard when laid over. It has never moved even when given the biggest squirt, however I do run very high overall gearing with a close box. I never raced with decent rubber in the old days, now with my Seeley I often gas it extremely hard and think 'this must step out and try to launch me' - it never happens. I don't really believe this stuff about 'excellent riders' - if the bike does a lot for you, you look really good. I don't believe I am a good rider, however I do know how to survive.

Dances, I have found there is a problem if you don't have enough gears in an AMC close box. If you gear high enough for a decent ride, first gear can be too high for a clutch start without really cooking the clutch, and possibly bending the mainshaft. I still haven't got around to testing my bike with the 6 speed TTI, however I believe it should be much better, though I might still have to buy a lower first gear.
I still don't understand this stuff about angle of lean in corners. I never consciously lean the bike - it just happens when I go in fast and if I start to get too much, I climb off the side a bit and keep the bike almost in the same attitude. I believe that if you pull the bike down and push it very hard in a corner, you don't gain much except increased risk. My Seeley is very easy to ride, except you have to anticipate where it will end up as you are coming out of corners, if you are riding relaxed.
Recently I found that a bolt under the seat had been touching the rear tyre, so I wound the shocks up one notch. Next time I ride it I will have to find out where it is going as it comes out of corners. The rear end is not so soft, so the steering will change slightly. It is interesting to ride, I really like it.

Getting back on topic:

Dances with Shrapnel said:

For clarity:

Stock Commando rod - 5-7/8" or 149.225mm
Stock Norton Stroke - 89mm

Rod/Stroke Ratio
149.225/89 = 1.68

Long Commando rod - 6.40" or 162.56mm
Stock Norton Stroke - 89mm

Rod/Stroke Ratio
162.56/89 = 1.83

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and

lcrken said:

And just for fun, the same for the factory short stroke 750:

Rod - 6.200"/157.48 mm
Stroke - 80.4 mm

Rod/Stroke Ratio = 1.96

Ken

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For a Steve Maney 1,007cc with 6.40" rods:

Long Commando rod - 6.40" or 162.56mm
Steve Maney 1,007cc Norton Stroke - 93mm

Rod/Stroke Ratio
162.56/93 = 1.75

For a 750 Ultra Short Stroke with 6.40" rods:

Long Commando rod - 6.40" or 162.56mm
750cc Norton Ultra Short Stroke - 75mm

Rod/Stroke Ratio
162.56/75 = 2.17

From what I have seen, a 2.20 R/S ratio is roughly the upper limit to normalcy in modern IC engines. There are higher ratios but they are the exception

hobot said:

No replacement for displacement only goes so far Dances especially boosted hi rpm, though don't ya know I looked at 1007 and sealing options years ago with M.A.P. Cycles. If Peels base 920 JSM rod engine is good for 80 hp and Drouin only adds 50% instead of advertised 58% more Drouin power that's ~140 hp around 7000. Do ya think with Maney cases, welded light nit-fried crank, JSM kit, Norris D cam and proven out of tach sight valve control head, Peel could stand 8500 and not just friction burn out? If so might top TC's nitromethane fueled 850 stocker engines. I expect Peel base line closer to Steve Maney's 100 hp 920's at 7200. Combat head flow and stock valve size is the weakest power link mystery. May be more than I can handle regardless and that's all I want any way.

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hobot,

Are you sure you want to run a cam as hot as a Norris D+ grind in your forced induction engine? Cams typical for such applications exhibit much shorter duration and relatively wide lobe separation. A stock Commando cam, which is a strong performance cam in it's own right, at ~ 247 deg at 0.050" cam lift, would be more typical of the desired duration, vs the Norris D+ which is huge, having 285 deg duration at 0.050" cam lift (yes that's +40 degrees in duration!). All other things being equal the Norris D+ would provide ~ 2X the overlap area of a Commando cam, which you don't want (too much time to blow the IN charge out the EX). And as you separate the lobe centers on a Norris D+, to perhaps 110-112 deg in order to minimize overlap, this long duration cam yields opening/closing timing that will be way, way out of whack, not to mention the possibility of valve/piston contact.

I hope we are talking about the same cam above, i.e., your Norris D is a Norris D+.

The only thing I don't like about the CDO cam for this application is its low lift. I wish there existed a cam ~ 245 deg duration at 0.050" cam lift that provided ~ 0.400" total cam lift, as I think this would be a great blower cam for you. But that desire leads us to the age old Norton cam conundrum - no such cam exists because the valve train design (heavy components with minimal rocker ratio) will not tolerate the acceleration/velocity/stress profiles conveyed by such a cam design. It's no big deal to do it with a 1.5:1 rocker ratio, but 1.13:1 has it's limitations.

Apologies for steering from R/S ratio to cams, but was curious about the Norris D in this application. Perhaps should be a new subject altogether.

Wow WZ its refreshing as depressing to read someone who grasps the straws Ms Peel's experimental engine is hanging by. The cam is from Jim Schmidt labeled Norris D but seem close enough to warrant the +. I asked the late arthritic crooked old Norton drag racer Duncan Campbell of Joplin MO with blown and unblown Norton photos on his wall, bored to death with life literally leaped off his stool in the shade into blistering summer sun hollering jumping about slapping his knees like a crazy man for over a minute till finally made sense of his exclamations *(* NORTON LOVE THE NORRIS D+ CAM** A year later hunting parts I phoned him and happened to ask about cam options and the bugger got so excited again he dropped the phone hallowing and hopping around yelling NORTONS LOVE THE NORRIS D+ CAM in the background about a min before recovering the phone. Hm don't ya know I want what he had too. Dunan sold his shop stock while I was there, 2 big trailers of everything Commando I assume went to Baxter's warehouses piles as one the few set up to take on that much at once.

Peel must operate at least on light throttle with 87 octane with static CR 10.5 so when I did the math on cam to get dynamic CR below 8 the Norris D plus popped to the top. I could not resist. I want wimpy response off idle so don't care if what little boost is being made then gets passed through, just hope the slight blower flow helps will feed enough mixture to idle and not stall lugging around on the big cam's other wise low intake compression. After that is should act like a potent big block torque till mid range 4500-ish when piston speed and mixture blown inertia should start packing in trapped mix of drag cam so should behave like a normal big block coming on cam way sooner then just gets out of sight after that. Its against the grain but for a few examples existing of big blocks with hi CR low boost such as the Mercedes Kompressor engines and private outlaws. They say it gives the big displacement punch down low and blower more that fills in breathing issues that would otherwise lower torque level hp. Driven snail type centrifugal blowers cam needs conflict with positive displacement compressors and heat driven turbos so takes lots of reading between the lines to come up with likes of Peel's deal. I want to be able to dive into a nice sweeper at full lean front barely holding traction near the ton to hold a line then light the rear up for upright series of drag sprints snap downs and still more on tap for heading into the opens. There are some timed hill climbs I want to try too besides the airport land speed events though I expect the parking lot stunts to be most fun. I cut my teeth on a P!! that was always traction limited and couldn't lean. If I wanted max possible power and didn't want to use everywhere all the time I'd lower CR with non over lapped cam and put a big compressor or tubro on it. Boosted engines like longer rods.

https://www.google.com/#q=high+compress ... gal+blower
https://www.google.com/#q=high%20compre ... ow%20boost

SteveA said:

No doubt that the 1007 in question works as a Seeley Commando....but I will repeat, ridden by an exceptional rider....

If the whole field were 1007s he would still have a very good chance of taking the win.....

However, the bike is, I think. still up for sale, so with the CRMC season starting tomorrow we will see what happens this year....

My own prediction is that there will be few 1007 Nortons to emulate the Watson bike and that the overall race win will be a multi cylinder bike and the leading twin will be of less than 1000 cc and may not even be a Norton...think Weslake!....I shall in any case watch with interest as I hope to join them on a 750 short stroke by year end (though I don't expect to be troubling anyone for the race win!).

Don't put so much on the race results of one rider on one bike....

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Gary Thwaites is a fantastic rider - of that there is no doubt. And the 1000cc Nort probably wouldn't have won the championship without him. But it takes the bike and the rider to win. The amazing thing about that bike is that it won every race and never crapped out. The only time he pulled in was because of a melting rear tire. You have to give credit to Gordon Humphrey for his wrenching expertise and the choice of lightweight internals that helped keep everything together. There have been plenty of other big bore Nortons that shook themselves to death and DNF with the heavy pistons they used.

Gary Thwaites in center below.