JsMotorsport Maney 850 85bhp motor!

jseng1 said:

AlColombia said:

What would one of the new manfactured and flowed cylinderheads add to the picture,if anything?
Al

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Ports, pipes and intake track length make a significant difference but I don't have numbers.

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So this "JS lightweight Medium C.R. pistons, longer rods, flatslide carbs, stage one cam & lightweight lifters, beehive valve springs" plus a cylinderhead and pipe-should more or less give us a 70bhp motor that the gearbox and clutch can handle? Cosentini +Maxton suspension should produce a reliable and fun useable classic motorcycle!
Al

AlColombia said:

jseng1 said:

AlColombia said:

What would one of the new manfactured and flowed cylinderheads add to the picture,if anything?
Al

Click to expand...

Ports, pipes and intake track length make a significant difference but I don't have numbers.

Click to expand...

So this "JS lightweight Medium C.R. pistons, longer rods, flatslide carbs, stage one cam & lightweight lifters, beehive valve springs" plus a cylinderhead and pipe-should more or less give us a 70bhp motor that the gearbox and clutch can handle? Cosentini +Maxton suspension should produce a reliable and fun useable classic motorcycle!
Al

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Toss on a Full Auto head and you might have some serious problems. :mrgreen:

swooshdave said:

Toss on a Full Auto head and you might have some serious problems. :mrgreen:

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That seems a very ambiguous statement.
Care to explain further....

Al sorry to hear your surfaces are worse though the video is more recent times after some repaving, thank goodness. Like everyone I don't like bad surfaces and only forced to ride THE Gravel which forces on panic states for nothing to lose anitcs to save - maybe- maybe not.

Nothing replaces displacement is an ancient motto in naturally inspired engines. Jim Comstock told us that the longer the stroke the sooner its friction is nullified by further rpm so take that into account to gear up a big block. One of the advantages of Norton is enough torque not to be peddling gears as much as hi rpm bikes so can gain a some during their shifts. That's balls to the walls play though and I may never do that again in public. The more power response the faster ya can go in less space till you go about any speed ya dare about anywhere. I don't think an AMC box could stand all a 1007 could dish out w/o thoughtful throttle control, which is fun if just to prevent wheel spin but sucks to prevent parts snapping. In public the hardest thing is not over doing it everywhere. I'm really worried about some us posters discipline. One thing no one seems to mention is the big block advantage for slow speed stunts, get sloppy on throttle and you may learn hi speed stunting or maybe not?

Best engine money can buy today might be Maney 1007 crank and cases and exhaust, JMS rod/piston/ BSA liters, Bee hive springs plus big valves with a hot Norris grind for a FullAouto or other good head and Comstock's EFI that can feed like 175 hp perfectly and PowerArc programmable ignition and TTI gearbox, cryo temper, ceramic coat and dry friction treated. Or get Bruce's Drouin on a more Norton parts engine OR put it on the hi money engine combo and get pilots G's force suit instead of just leathers.

This thread reminds me of the guy in England who asked the forum about touring the world on a Commando, weeks of heated debate.
The guy kept comming back and back,saying he was going to do it,and it didn't matter if forum members told/advised he should or should'nt.
I the end the guy turned around and said " I HAVE CHANGED MY MIND"

This tuning old engine's went out with the ark, [the japs where here] making sensible mods using modern products is good, but only to increase the realiability.
A good rider with the best rubber is worth more than extra hp, At the I.O.M i came up behind a old feller on a Vincent Twin, i was two up on a ZZR 1100.

Me thinking i will destroy the old pair, well i had another think comming. He used on comming traffic to good use, and matched the Kwak in the twisty bits.

I was still behind him at the Castle town meeting, after parking up he strolled over , Grining " ya not the first son to be shown the the way, i have owned this 50 years and know how to make them go"

I think i could have passed him, but i was smileing to much at the old dueo , anyway that just proves a point 45 BHP in the hand's of a good rider can put up a good fight against 147 BHP....had there been money on it..proberly a differant story.

So true john robert bould, so true.

Back to my comment about a 125 cc GP bike. Reality checks all the time.

Back to my original comment that a 1,007cc is the best route to get this type of reliable power. If not constrained by displacement then why bother going through the troubles of developing a high strung motor that is really straining many of the components.

To get a good compression ratio on a 750 cc or 828 cc the combustion chambers become more difficult to form and less ideal whereas upping the compression ratio on the longer stroke 1,007cc is relatively easy. You could probably run with stock rods but I would certainly go with the JSMotorsports rods and pistons to reduce vibraton and free up some extra torque. You would not need to rev the 1,007cc that high for boat loads of torque thus friction loss due to high piston speeds is not a significant factor.

Most other components (cam drive, oil pump, covers, miscelany) could come right off the stock 850 motor and the balance of the stock motor parted out to help fund the build.

Taking this a step further, building a solid 920 cc would be considerably cheaper; keep the stock barrels, crank and rods and get the head work done. Achieving 85 BHP would be more of a push but assuming this is not a race application, you would not be stressing the motor that often. So a 920 cc would probably be the least expensive route for reliable power. There is no replacement for displacement rings so true here.

What is Nortoneers sense of what Ms Peel's 920 potential is at say 7500 rpm?
Octane no problemo, just heat dumping.

Taking this a step further, building a solid 920 cc would be considerably cheaper; keep the stock barrels, crank and rods and get the head work done. Achieving 85 BHP would be more of a push but assuming this is not a race application, you would not be stressing the motor that often. So a 920 cc would probably be the least expensive route for reliable power. There is no replacement for displacement rings so true here

A 920 with a Fullauto head! Maybe 70bhp is a more realistic number and shouldn`t break the bank!

70 at the crank 60 at the rear wheel from a 920 might be realistic if tuned properly, and the trans would have a better chance of standing up to this amount.
A good mk 3 bottom end with its strengthened cases and crank would be a starting point.
I have one of RGM's 920 kits, was planning to use it on my MK3, but reconsidered since the engine is working very nicely as is.

When I purchased the kit I asked Roger what kind of power increase should be expected with the 920. His answer was "Most guys end up with less power". From what he explained, the typical owner who would do the 920 conversion would also do a mismash of bad porting, high rise cam, carb and other changes, which often resulted in a bike with less power on the road than the original 850 they started with.
Couldn't accuse him of hardselling his 920 kit!
An 850 with open pipes and a skinny head gasket runs pretty strong as is.

Glen

Thinking out load (and dreaming) a little bit here but:

920/828=111%

So that's a simple 11% increase in swept volume. Say a stock 828cc makes 50 RWHP so with appropriate tuning you have a potential 55.6 RWHP.

One advantage to increasing the bore diameter is yielding more space for a larger instake valve. A larger intake valve and some judicious blending of the throat and bowl plus an exhaust, improved (say 34mm) carbs, bump up the compression ratio a bit and a moderate performance cam (Megacycle 560-020) should easily bump you up well beyond 60 RWHP. Might even be able to exceed 60 RWHP w/o the larger valve and porting.

Edit- corrected decimal place on percentage.

Dances with Shrapnel said:

920/828=1.11%
So that's a simple 11% increase in swept volume. Say a stock 828cc makes 50 RWHP so with appropriate tuning you have a potential 55.6 RWHP.

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920/828=1.11% ????

What precisely is "1.11%" ???
828 to 920cc may be an approx 11% increase, but thats not what you have written there ?!? :mrgreen:
(surplus decimal point, or % sign ?)

Its been discussed here before that a stock 850 usually makes around 42 or 43 rear wheel horsepower, so even 50 here is somewhat of an exaggeration.
(That 60 hp in the brochure was pure marketing speak ?). The 850 was said to give more torque everywhere in the rev range, but didn't really rev as hard as the combats of old, so max hp at the back wheel showed as a bit less. And it says somewhere there that 5800 rpm is max sustained cruising rpm, something not to be ignored... ?

Oh the horror, oh the humanity! I knew I screwed up somewhere as that was before my morning coffeee - well that's my excuse. Thanks for the catch - my original post has been corrected.

How I get 50 RWHP for an 828 cc is through a careful yet painful process of extracting it out of my derrier.

I never dyno'd a stock 850 but have owned and ridden enough to know what their about. I have raced a 750 Commando with a Megacycle (560-020 cam), stock pipes with open reverse megaphones, stock head, 9.5:1 compression ratio and worn out out stock AMAL 32mm carbs and it dyno'd at 50 RWHP in a fair state of tune. My gut is telling me an 828 cc Norton Commando stock is probably around 50 RWHP give or take a few.

So even at 43 RWHP at 111% gets you close to 50 RWHP (47.73 RWHP) once the other enhancements "free up that displacement potential". Add on pipes, carbs, larger intake valves, minor porting and blending, higher compression pistons, a 560-020 cam and some tuning and as Bob is your Uncle you should be well within the +60 RWHP range.

Thanks for catching the error; there's enough confusion on the forum and I don't need to contribute to that.

As for the caution of "maximum sustained cruise is 5,800 rpm"; I do not recall ever reading that but it certainly sounds reasonable. I wonder if this was a distinction of the 850's or did the 750's receive the same cautionary statement. Only differences I could see are maybe the 850's had heavier pistons (more crankshaft loading) and more combustion forces due to a larger bore (again, more crankshaft loading).

There was a Norton Tech note that 850 were good up to 5800 sustained. Never heard of alerts for 750's but I bet Norton wished they had for excuse to reject warranty claims. I suspect the cast iron flywheel was biggest concern.
past thread on 850 redline...
850-rpm-redline-t7897.html

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5/5/2002 2:43 PM

Hi Steve
All my long stroke motors peak around 7200 rpm in race tune so I don't rev them past 7500 rpm this is way fast enough for a 89mm stroke motor.

I have seen standard 750 road bikes on the dyno they typically produce some 42-45 bhp at the back wheel this equates to 52-55 bhp at the crank, if revved to 7000 rpm for any length time they do come apart,

My 920 race motors typically produce around 100 bhp at the crank (last time at the dyno my own bike showed 100.4 bhp at the crank)

So it doesn't take much to imagine what would happen if I built one of my engines with the standard crank, crankcases, cylinder, etc.

To sum up, the mean piston speed of a 89mm stroke engine is ok up to 7000 rpm, when you use my engine parts you will be able to raise the power output considerably without risking mechanical disaster.
Steve

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Maximum rpm continuous cruiseing 5,900 rpm .

http://classicbike.biz/Norton/Brochures ... ochure.pdf 1974 Brochure . Avea lookat the lower RH side , P 8 . 9left for above )

12.00 @ 114.68 quater , october 6 1973 . ( someone mayve been fiddling with it . )

Croink shaftts , would think ' theyed vary , a bit ' being produced manually , without quality being paramount over cost .

The Boreing of the Big Ends ( internally 0 being a point , would Lampredi or Columbo stood by the ' throw a drill bit down the inside '
approach there . The irregular surface & sharp edges being a no - no in terms of quality of production machineing , for a Racing Engine .

Wonder if theyre all like that , hardly a model of smooth contuors and refined finish . Dimensional accuracy , if not all identical , would mean some were more equal ( to the task ) than others .

This is where Maneys attention to detail would transform from archaic to avand garde the multi piece crankshaft assembly . Not to mention the flywheel .

Cast Iron seems not as secure as the eupherism implies , unless its cannonballs . But they have no extended service requirements .

A 750 as per dance's specs should put down 60 hp as equally as a exxcess 11 puts down its 80 . Which puts a 750 equalling a Yam in context .
Power to Weight , 60hp + 400lbs Vs 80 hp + 600 lbs ( or do the Japs claim 90 ) whadeva , the XS isnt a mountain road sportsbike .

The momentum wont help dealing with the unexpected either . Cant imagine a hyabusa is any better regarding the laws of physics in that respect either .

I dont think the stock carb to head manifolds are particularly ideal . A smooth continuous transition from slightly downdraft carbs , without kinks , by itself
is worth a few horsepower . Let alone when it comes to ' ram effect ' . The standard kinked constrictive manifolds would inhibet this ( pnematic ) action .

Ignition & carburation are fundamental to performance , without excellance there , its lost before its started .

Unrestriction in Carburation means the carb isnt a limiting factor ( at peak power ) therefore the 34 ( 750 ) if you cant find 33s ! & 36 for the 828 ,
if Concentrics , or 32 / 34 Mk II Amals see the thing working there .

Maximum obtainable Comp. Ratio will give V small % ( a few , say 2% gain in optimum figure , say per 3/4 of a place , ( 9.5 to 10.25 = 3/4 )
HOWEVER correctly contured / configured induction can induce ram effect to increase charge density to match or exceed actual Cylinder Charge Volume .

Therefore , around 9:1 with its increased flexibility / broadness of powerband , ( with suitable ignition curve ) can still when ' Cammed Up ' provide a more
useable powerplant than one produceing the highest peak at a intractable range requireing closer gear ratios , and more . Not that were not short of one
already . Gearing @ 23 tooth ( or higher ) output leaves first not entirely suitable for traffic , to the point you need to leave a gap in front before engageing drive. So as not to run into them with the clutch disengaged . The habit of slideing it in these circumstance will not increase its service intervals .

By the time the things going at this rate of knots , not everyones convinced the frame is entirely ridgid in all respects either , or ' brakes ' is entirely the
right term in respect to their function . At least that , also , is correctable . After all Masseratti 3500s cost more than Fords . Vehicals are more up'speced
these days .
wheres my trabant . :x :!:

The early 650SS was rated at 49hp, crankshaft. I have seen the same ratings for the later model with larger carbs and also a 52 hp rating.
There is not a great deal of difference in design(as far as engine tune is considered) between the 650SS, the 750Commando and the 850 Commando. If a skinny head gasket is used on the 850, then all three have the same compression ratio. They all have essentially the same cam (other than the Combats)
So if the 49 crank hp rings true, a 9 to one cr. 920 cc version of the 650SS ought o produce 920 ÷650x 49 hp or about 69 crankshaft hp. If the later 52 hp figure is used, then the result is 73 crankshaft.
This would be without radical tuning, just following on from the 650SS which is a very tractible motor at low revs but has a surprising whack of power between 4,000 and 6,500.rpm.
Of course there are some variables not considered with this simple equation, the big one being engine breathing. If breathing is maintained at the 650ss levels, then the result should be in the 70 hp at crank ballpark.

Glen

'This would be without radical tuning, just following on from the 650SS which is a very tractible motor at low revs but has a surprising whack of power between 4,000 and 6,500.rpm '

I'm amazed how much torque my 850 puts out, I've found it very difficult to gear for and very deceptive. I've actually geared up considerably to keep the revs sensible, and the bike just goes faster once it is rolling, but in a clutch start it becomes hopeless. I've always believed that short stroke is the way to go for a fast motor, however I'm not so sure any more. For all of it's bottom end problems the 89mm stroke commando motor still does the business. I've found that with that much torque, my Seeley only ever inspires confidence in the rider.

Alan I love your posts and similar surprise what our ole clunkers are capable of. Ms Peel had extraordinary Combat power form accidental expedient combo just for initial 1000 mile easy break in being very careful and timid as my first ever engine build. When I first gave er the gun in scared state she'd blow up, instead I ended up on grab railing, so in unbelieving shock gripped harder and set butt in seat and tried it again, to again have bike shoot out from under so hard I again ened up on rear of seat and tingling how close I almost got left behind to have bike hit the bluff face or topple off edge into crap w/o me. This happened in 1st and 2nd with 21 tooth final drive ratio. The way this played out in real life contests was with a hot sports bike and me aiming into next turn I could shoot ahead of them as I notice their front lifting so they'd back off some but Peel getting even better power band range left em bike lengths behind by time apex reached and another shift ahead by time they were raising up leaving apex. I hated waiting on lag in 3rd > 90 to 110+ mph till I could snick 4th and feel the torque effectively pull harder again. Peel was geared high enough [850 2nd ratio] she could only reach 6000 in top but that showed over 130 on my speedo and didn't get left behind in opens with the sport bikers telling me they saw similar 135 mph indicated on their digital meters, which all read about 2 mph faster than actual ground speed. If I only had two gears to play with Peel torque - 2nd and 4th were enough. This implies I'm going to buy wide ratio 4 spd TTI someday not 6 spd narrow power band bikes need. My sense of what limited Peel was the 34 miki carb too small. Maybe two 34's or one bigger 36 or 38 might press hi end torque higher.
Next Peel has single 40 mm feeding.