Vintage Motocross Premier Open Twin Commando

Hello, My name is Robin Hannah. I'm a guy,53 years old,from Napa Calif, and I race Vintage Motocross. I am an Intermediate. Not Novice, not Expert but right in the middle, I am on a Moto-Quest, which started 5 years ago when my Stepfather past away and left me an SL125 Honda. Which I converted to a serious MX racer. I Won 2 AhrmaNorthwest Regional Championships on it. In 125 Classic Class. Then I ecided to race a Yamaha CT1 175 in Early Sportsman Stock 250 Class andHistoric250in Ahrma's Post Vintage Program, both which I also won. The same year I was sponsored on an 82 Husky 500cr and raced the AVDRA National series which I won. I never Dominated any of these classes, just kept going to the races and making the podium. So, at the beging of last season I was sitting on Championships in 125/250/500cc Classes. That was when I got the Idea to see if I could win Chapionships in all the major engine sizes, So for this last season I raced 100cc on an Sl Honda 4 stroke. I raced the AHRMA Northwest Regional Series in both 100cc sportsman and Just for fun +40 class in which I gave up 10years (being 53) and 300cc's (as most guys race 400's in age classes) I won the 100cc and placed 3rd in +40. I raced the AVDRA National Series and raced the Same Classes. Winning 100cc and +40 on the 100 !! This got me thinking what if? What if I could be the first guy to win all the major engine sizes? 100/125/250/500/Open Twin. That is why I am here on this site. I would like to build a Premier Open Twin Vintage Mx Racer on a Norton Commando Platform. It seams to me to be the best choice. The Commando Has the Reynolds 531 frame (light and strong) a very powerfull engine, close ratio transmission and hey they look and sound GREAT!!! As far as the state of tune,I want it to be mild and reliable. Tourqey with good throttle respose. So I'll need some advice from you guys as I am putting the Commando MX together. Thanks for your time. Robin Hannah #960

Greetings,
Congrats on your wins. You did not say whether or not you presently have a Norton, but if you are looking for one check out Ebay as there are typically a half dozen or so on there at any given time.
However, due to your intended use I think you would be better served if you could find one of the Norton hybrids (IE P11 Ranger). Hopefully someone more knowledgable about those models than me will comment and give you more info about them.

GB

My respects to have time and means to get all that racing in. The rough and ready stuff is a big interest of mine but just for fun. Would like to see example of the events you run for idea of what a bike must endure. I've made some mods to a isolastic 750 Commando that still allows it to disappear vibration wise but eager and able to out zig zag and run down freaked out deer, encountered at times playing with MX and trials bikes in raw woods or narrow loose paths, stuff you must fully commit to with power and momentum to carry on or else splat.

One thing that surprised me and the MX guys was the grip/hook up my Commando had on mostly street tires vs their full knobbies. I mention this as I think its the isolastics acting as power pulse dampeners. Really adds confidence and thrill to climb out ravines with headlight in groin and fender near face standing on pegs while vertical to gravity. 750 engine and frame is way to go as more nimble than 850 stem angle and power band. I held back doing full over head MX swing arounds and back down steep hill side because I didn't trust the street tires on greasy brush to stop the slide in time nor brave enough to hit speeds I didn't need to lean much for rear to sling around on its own. No good when tire traction so low throttle cuts takes a while to be felt.

Almost no one races an isolastic Commando outside its almost stock mates and other brands d/t the hinged handling when leaned long accelerating. With rod links all around I've not been able to get my Cdo to hinge or do anything but stay neutral angle and aim on changing throttle or shifting gears, even sliding rear some w/o crossing up to prevent fall downs. My Ms Peel is my tool of choice to tear up THE Gravel paths, whether thin layer on glass smooth hard base or lumpy and rutted with a few layers of up to fist size stones. Dirt/clay/sand is luxury I only get a few 10's of yards worth of here.

Here's a recent forum post with bad ass paired down off tarmac Commandos.
Not a single one is isolastic protected, I want someone to find out besides me
what they are missing out on with a tri linked isolastic wonder.
dirttracker-t7881.html

More examples in Phantom OIler by Davenport a friend of mine that lived on a P11 with rubber honda handle bars. He is the one that lead me to Bob Patton and his rod link wonder.
http://www.vintagenet.us/phantom/

Maybe see if you can find a P-11, or baring that you would be IMHO much better off racing dirt on a Yankee 500 twin 2-smoke (real vintage and hard to find), or a Harley XR 750 (still competitive), or a Dave Aldana (style) 750 Triumph dirt tracker. With the dirt oval bikes all you'd need to do is fit a front brake and change the gearimng in the final drive.

I love Nortons, I have two, and I respect Hobot, but maybe with a Track Master frame? The isolastics would get beat to hell in a proper MX and give you mystery handeling (BTW Hobot, one of the links you offered shows a Norton set up like a dirt tracker with velocity stacks, not air cleaners---what gives??)

RS

The Commando power plant has a good history in Motocross, but mainly in sidecar racing in special frames (Wasp I seem to remember) I think it would make a great power plant in a solo for historic Motocross racing, but not with a standard or even modified Commando frame. There are a couple of guys in the UK remaking the Rickman Metisse chassis for a number of applications and as others have mentioned a P11 or even a G15 chassis might get you started, although I'm not sure about the geometry for serious MX racing, the P11s and G15s were campaigned in desert races with some success. but for MX I would probably want something that turned a bit quicker. If you do a 'Google images' search for Norton P11 there are a number of photos that might give you some ideas. Keep us posted and take some photos. I raced Motocross for many years even representing my (very small) 'country' in The MX Des Nations.

Hi Robin, as they say the Commando frame was made for the road not the dirt.

Unless, of course, you have a hankerin' for goat meat. :mrgreen:

Sorry, I couldn't help myself. :wink:

Ok I admit I'm a princess on a pea when it comes to the sense of engine or chassis vibration oscillation noise, but boy howdy I'm out to prove nothing can handle differing traction in differing tire directions like a good ole rubber baby bumper Commando tamed by linkages. Please remember my very first m/c was pure P!! champion dragster with two lights tacked on, nothing else. Exactly same as these 'desert racers' but with front lowered 2". I loved to off road it, once I got brave enough to just blast through surface humps that tended to snag-drag hi centering. I learned too well the limits of regular iso Cdo off road with pasture surfing or Gravel commuting - jeeze lousie it dances a jig under you while jarring to the teeth. After fabulous 3 linked Peel I now consider dedicated MX bikes same unstable jouncing platforms with too touchy a power response and delay. Its handy as hell to have torque on tap to twitch tire spin just so-right now and no more then hook up getting it on in best line, yum. To summarize my findings what ever I did that worked better for the rough and ready also worked better on tarmac, a lot better! I"m depressed others don't claim same handling with their Cdo's.

P11's Ranger Cheetah 45's are rather rare and expensive and known to destroy and tear off everything not essential. But they are the model that got the chrome alloy frames, not plain ole Commando's with mild thin steel, not even up to a hot Norton power plant - until over lapped with the engine/cradle stiffness.
Its not hard to do if starting from raw frame to build up a reliable racer. Torque response is way more important than hp if top speeds possible with the hp are not needed very long. Commandos are regularly built up to still be real pullers at 100 mph. World class like Woods or Axtell likely pull hard another 20 mph before reducing about wheel lifting acceleration further on.

A rear linked Cdo don't feel like anything else, it don't wiggle/wobble like regular Cdo's do on far over leans accelerating, it don't ring and jitter out from under like solid mounts do, it just articulates storing the energy and unwraps it back into tires just as they are about to lose it for spikes in traction and aim control.
I well know how to hold a Cdo in the half crashing state right up to point of no return, but to even a tad faster all hell breaks loose in positive feedback. Racers on isolastics must always stay just shy of this or else, me too. The best place I test and practice this is THE Gravel sweepers, I spin up rear before tipping in then keep accelerating till the front fights to go outward while rear fights to go inward and swing arm slaps stem/forks which wiggles front tire just as chassis is twisting and untwisting, woohoo ride em cow boy. If I don't back off on un-tamed Cdo its get out of control. On Peel that just a sign of phase transition in handling which needs more power to blast past the flip into straight steering and new level of steady state as long as you can keep accelerating with rear in slight slippage-best hook up till path gets more open. Timed right its like riding right into a crash that crashes into upright balanced aim out of there. Ahh.

I also sometimes like to do the flat tracker crossed up slide, where space permits but I don't put a foot down, Peel is so neutral she can slide w/o changing lean angle! Also its so rough I've gotten scared and slammed boot down to have it jerked under tire or almost to my head hitting rock knobs or big stones. I have had Peel hit extra loose spots and wet slicks mid turn but tip over delayed enough so far I can jerk back up with a stab on rear brake. I have to add power or extra steering to get her to *trip* out on purpose to get extra sharp handling into decreasing radius turns. Slides are fun but not fastest-funnest way as can't keep accelerating forward until hooked up good. Wider is longer way around too.

A real Cdo could be made to easy keep up with the main pack, so may well bring an over all win plus an extra big feather in boy racer cluttered cap! Doing it on a comfortable road going Snorton Commando. I think recent So. American long tough event was won by a real Commando. I say boy racer with respect as above my level of involvement and getting off to think of a dirt tracker Commando taking the podium time and time again.

Thank you for all your replies. First of all No, I do not have the Norton yet. Secondly this is a hobby for me I am a working class guy. I'm not wealthy, I have built every single bike I raced from the ground up, cutting every corner and stretching every penny into copper wire, not really, but you get the idea. The thing I have learned is what ever bike I have built, (make sure everything works together) simple as it sounds, this is the biggest mistake people make,when building a race bike. The best part in the world for one use, could be the worst for your situation. Too large of diameter head pipe comes to mind, when I built the first Honda, I welded up this really cool looking custom exauhst pipe. I take the bike to my first race and the thing has awsome bottom and midrange but soggy topend. I played and played with the jetting to no avail. Finally a friend hooked me up with a sponsor who does (Real time computer, exauhst emission,Dyno tuning) The technitian there told me the head pipe was too large. I went to a smaller diameter head pipe and with their help I was able to extract enough HP from the little thumper to be competitive with the two strokes. My sponsor is salivating at the chance to tune a Norton twin for MX, and tust me I am anxious to get on something with good power after spending the whole last racing season flogging a 100cc fourstroke. I will look into the P11 also. Is a P11 a Hybrid? If so what bikes is it made of? Which Norton engine is it? what chassis does it use? Come on guys I have a feeling you know this bike is something I need to know about. Robin Hannah #960

P11's was an evolved Norton Hydrid made for desert racing, once non essentials removed themselves or thoughtful owners so some original do dads exist. Only made '67-68. Knowing users found it better than the famous Featherbed chassis.
Mine had world class engine and built up by motorcycle shop to race into mid 10 sec 1/4 miler via 4" flat slick and 3 rim clamps to hook up the grunt.

Here long aritcles + teaser to wade through to P11 back ground and details of issues and solutions.
[R click view image to see all and click on image for full size detail]

By the late sixties, the rise of light yet powerful two strokes spelled the end for big four-strokes in America off-road sport. But the P11 also made an exciting street scrambler, offering lean and rugges looks for the youthful road rider. One of the Norton's strongest selling points was its ability to out-accelerate every car on the highways of America except AC's 5-litre Conra.

Click to expand...

http://www.motorbyte.com/norton/hybridpage.html
http://www.motorbyte.com/norton/hybrid.htm
commandos-whose-daddy-cheetah-t7076.html?hilit=P11
http://en.wikipedia.org/wiki/Norton_P11
http://motorbike-search-engine.co.uk/cl ... allery.php

Finally a steel tank was designed with rubber mounted clamps and this solved the problem. As mentioned earlier the oil tank was the only problem - as long as all ancillary parts were removed. If the machine was used hard, the headlamp, side cover and few other minor items would become loose and fly off into the desert. Contemporary road tests show that in America the P.11 where it was called the 'Cheetah 45' because of its tremendous acceleration) was very highly rated and some testers were not at all concerned about how much lighter the machine felt after a rugged test. Of course it can be said that the machine was never intended to be jumped with all its ancillary equipment in place. After all it was fitted with coil/capacitor ignition system so the machine could run without a battery. One of the most absurd statements made about the P.11 in this country, where wisely the machine was not available, was that handling of the P.11 was not to "Featherbed standards".

Click to expand...

Also a few vitals to be aware of when owning/building Nortons in their 1960's transition zone to the Commando power plant.
http://www.motorbyte.com/norton/hybrid/G15OIL.html



[video]http://www.youtube.com/watch?v=ZgpUn6O2VO4&feature=related[/video]
[video]http://www.youtube.com/watch?v=nQ0HEqjrG3M&feature=related[/video]
[video]http://www.youtube.com/watch?v=3oC2yg16LnA&NR=1[/video]

This Bike looks like it could be a lot of fun!

Mark one of these can fun ya back to juvenile states. Piciture it 2" tucked so no wheelies! Fenders are most civilized thing to have on if really living on one of these. Mine just had seat and tag I attached for some mud flap help. A mirror is nice but its mostly for after the fact to watch zoom away of traffic as no need to look for anything about to pass ya. Running w/o a battery is touchy balance to light both road and sparkplugs with brake on for intersections or loose slopes.
But I've tasted isolastics now so no more solid bone shakers for me. But I ain't going to give up nothing in the paired down handy get go department thank you. As I've reviewed, I think my linked Cdo can take on the likes of these and so intend to.

no wheelies????
PFFFT!

Dear Mark, do not mistake lack of Wheelie as lack of power for forward G's.
In my P!! case it was not mean for road so down tubes lengthened an inch and forks shorten an inch. This allowed me to decide if I just sat in place through 4 gears or feathered power a tad and floated front wheel 2" level all mass on rear tire expect of an instant of front tire touch as kill button tapped to cut torque as tranny snatched next gear at WOT. I learned how to do wheelie on this drag bike though. I had to get to like 40 mph minium then de-clutch then rev up some and drop clutch.

My dad ordered me to sell the P!! so 3 bad boys on bad ass Triumph triples showed up, so I gave em a show ripping back in forth in front of them, then decided to wheelie at least once so left some smoke till 50's mph then slight clutch slip on throttle and leaped up and forward like a whip lash and flashed past nearly 100 mph then began the serious braking to turn around. They were gone when I got back, my roman general like dad was both frowning and beaming at same time, telling me - Son they didn't say a thing just got on and left, I think that thing scared them too much.

What sold me on this tiny bike was on test ride in tight housing area I came upon a couple hundred yard straight path that was a steep down hill ending in line of homes. I actually passed it and stopped and backed up wondering how it would be on just one cylinder speed, so opened up to max I could stand ~3/4 throttle - just as I cried Uncle and was letting go of throttle about 65 mph
COIL DRIED OUT BOTH PLUGS FIRED >>> BIKE LEAPED STRAIGHT UP JERKED MY FEET OFF PEG- SLUNG ME OUT LIKE A FLAG IN THE WIND- WHICH TWISTED TO FULLFFFKING WIDE OPEN- AS MY BUTT SLAMMED SEAT SO HARD IT RIPPED FRONT SEAT FASTENER OFF AND SLAPPED ME IN THE FACE TO BLIND MY VIEW AS IT REV'D TO NEARLY 9000 RPM.

Wheelies mate'? I HATE WHEELIES!

hobot said:

Wheelies mate'? I HATE WHEELIES!

Click to expand...

I like your avatar. :mrgreen:

My avatar is my 1st Combat, about .03 seconds prior to another reason I HATE Wheelies! I think I got so adrenlaized my body reflexes though I was on the P!! which would have spanked that 1200 wheelie bar'd Sportster in next lane ass.
A friends HD, cam too aggressive to enjoy on road, would out hp my well tuned factory Combat after 80+ mph 10+ seconds but I showed him up to then prior.
New Peel tucks front couple+ inches under factory stance before I let her hair out.

Under 11 sec 1/4 mile push rod beast in public is something I never got over.
I just don't care to do it on a water cooled buzz bomb balloon tire appliance.
What would you rather die on? [rhetorical ok it don't matter by then]

Hi Dave, Ididn't know you were into Nortons. Could someone explain linkages to me? The ones you said would tame the handling of a Rubber mounted Commando???

So far only hobot has tasted a rear linked Cdo with its 2 extra helper linkages.
Others have put on a top and front links but are not besides them selves in transformation of handling wild loads, especially when traction is lost on purpose!
I know of 2 other Commando's being configured to follow Ms Peel's lead but are not yet completed to road test. Rod links are easy - rest of a Commando takes awhile. I can't get scared on tarmac anymore so mainly have to go off road for the adrenalin glee shakes. Having tried both paired down solid chassis and the flexy flyer Nortons, plus famous sports bikes = all corner cripples to Ms Peel.
Here's some forum threads to entertain and make ya restless.

As you learn more about Norton 360 twins you will come across both crank balance factors and solid mount engines/chassis, all because standard frame breaks when solid mounted and shakes pilots hands off bars to the teeth or rubber mounted turns into fish flopping off the dock. Full linkage solves the 4 decades long quest to extend Commando handling up to what its power plant can fast shove ya into.

Basically ties frame and power unit together as over lapping articulated load storing and releasing device that can take more tire direction conflicts than any thing else while feeling like huge loaded down GoldWing of inertial smoothness.
IN maxed out states only the rear patch grip and effect gets through, nothing else to worry about as so neutral no matter what pilot only needs wrist control. I need race track to explore further as too deadly to enter 10 mph chicanes over 50 mph and come out over 60 while still sticking to inside road edge with cliff face or guard rails inches away and still have reserves to dodge on coming flying wide of their land in total blind turns. Peel could take more I could not.

Photo of Ms Peel's key linkage - i don't know if other versions as good or better yet. I have not found full corner limits yet, as so far are 3 other phases of handling that I found possible on other fast bikes. Only 2 things have shown up far for to freak me out, fuel slosh of 4 gallons when 2 gallon space, on a reversed slope decreasing radius double hook back- as front hi sided up one way the fuel hits and knocks forks the other way. Other is ground effects lift/drop d/t both wind gusts and fork slider eddies inter reacting when so low no room to get knee tight off tank and about to run out of rpm in 1st or 2nd 60-90 mph.



post66581.html?hilit=watt%20linkage#p66581
post67138.html?hilit=watt%20linkage#p67138
post70896.html?hilit=watt%20linkage#p70896

Okay, I'm not an engineer but I think I'm getting the Linkage concept now. It is rather ingenious, it allows some movement of the engine/ powertrain but at the same time keeps everything in a straight line, very cool, kudos, well done!! I knew nothing of the 360 configuration of the engine and hence the necessity for rubber mounting. Do you see my headlights are on and I am leaning?? Okay if you would pretend that you are an inhabitant of the planet Norton and a well meaning bumbleing Allien has just landed from the far off planet of VMX. I am him. I promise not to destroy a restorable classic Norton, I have more respect for motorcycles in general to do that. My plan is to find a "roach" and make the powertrain running, reliable and responsive enough to be Motocross track worthy, this is NOT SuperCross like you see on TV, but here in the U.S. some of us race Vintage Motocross,which is more like Scrambles used to be, back in the Sixties in Europe and England. Our suspensions are limited to 7in front and 4inches rear Travel. The courses are tame using natural terrain, to accomidate the old bikes and older riders. If I can not find a P11, I will probably use a Commando and I think your likage system will be a must. I cannot be dancing on the razors edge in oversized rubber boots (gum boots?) I'll most certainly end up in more that one piece(ouch) Thank you very much for taking the time to school me I do appreciate it Robin Hannah #960 Here is an example of the tracks we race http://www.youtube.com/watch?v=hDG9Faz8NI0

Robin, If you went with a Commando frame for dirt riding I think you would be disappointed both with the handling and with the reliability. The Commando uses relatively thin-walled tubing that works well with the stresses imposed by road use, but I doubt it would last long even on classic style scrambles tracks. Looking at some photos of classic scrambles in the UK, those people running big twins seem to use Norton/Matchless brazed-lug type chassis, BSA or specials like Rickman, Cheyney etc. The fact that the Norton has a separate engine and gearbox requires a bit more space than many frames provide. The other thing you should consider is that a Commando engine is balanced specifically for the isolastic set up and if you opt to fit it into a rigid mount frame you should probably rebalance the crank shaft. The other option is to source an earlier G15, or Atlas engine. You will probably also find that the gear ratios are not close enough together for competition use, RGM Motors in the UK sell a close-ratio 4-speed gear set for quite reasonable money. My advise is to look around for a G15 project bike, you could probably get something fairly complete for one or two thousand dollars, especially since it wont be critical for your application that all of the hard to get things like battery box, tank, mudguards etc are intact on the bike. Actually your best bet might be to buy an old Flat-tracker and modify it for MX, you might not actually find a Norton, but would fairly easily find yourself a decent British twin of some description for racing.

I've caught a bunch of flak on how to describe Ms Peel's full rod-age.
Techically - Watt's like Helm's Joint/rod end triangulated elastometric linkage.

Commando's are 2 parts, the horse and the saddle and reins. Engine-cradle-grear box-swing arm are a unity called the Power Unit. Forks-frame-pegs-saddle are another unity. They OVER LAP by about 2 feet! Tie ends together plus each side rear frame tubes and both cradle plates and it more than doubles the front to rear stiffness, yet free to oscillate to take up engine bounce *and *and* and* and !!! the jerking type tire traction to power pulses in loose stuff *or* tolerating the upper harmonics of max traction 10% tire slippage on tarmac on fast toque rise hooking sprints.

Engine bounces up/dn at front iso d/t both pistons mass, but rear cradle/swing arm only pivots a bit on rear iso. Road suspension and tire pulses shove iso's fro/aft as much as engine blip up torque bounces the front comforting iso.
All the elite are looking for sideways suspension, pashaw that just adds to fish flop at higher freq the stiffer the rest of chassis is. Were talking ~1/8" max motion off of center, What happens is rear patch levers thru rear iso pivot to slap at the front mount which has to have some slack in it, this wiggles forks a bit, which wiggles back into the rubbers in cycles. A little bit is fine but its like a slow leak before the blow out. It builds till pilot is pushing one way to take up the wobble but by time the front tire reacts the vibes hit the other way and add up fast. I can no longer produce this on Ms Peel no matter how I've tired. She just twists up and un twists as needed like a dampened spring/shock combo.
Ok actually more like an anti sway bar.
This seem to allow front to follow road texture while also absorbing the swing arm side loads w/o feed back wiggle/wobbles into the rear tire that is really the one ruling the roost on aim with engine power backing its authority.

Even factory stock 'iso Cdo' can out turn about anything if the inputs are kept short enough and long enough apart, even rather worn out sloppy ones. I test this by fast zig zags in one lane and by dives into turns that only take a second till apex relief straightening back up. Only thing felt is a twitch as slack taken up, like an archery bow with a loose string, only loose till pulled on then don't stand in front if loaded, Its rings on release but no new loads to create positive feed back into fish flopping right off the dock. Trouble mainly shows up rather above legal speeds while accelerating in sweepers you stay at same lean for over a second or more.

This hinge handling is exactly what you seem to love dodging doing dirt type races. Front steered to outside of turn wanting to trip bike down and widen radius - while rear thrust is trying to lift bike up and turn it sharper. Bike starts to oscillate on its vertical CoG and if not backing off or really blasting rear out of grip for a crossed up slide- WooWooWOOSplat.

Its a schizophrenic state only a crazy Cdo chassis can really enjoy. The video was very educational, looking like luxury smooth deep soft dirt wide open no trees freeway to me and Ms Peel. A good spun tire there would make its own
rut instead of just rolling more on top of Gravel. Oh yes a tri linked Cdo would excel. Listen close to even those tiny 100's, they are backing off power to enter, youtube up ice spike racers and listen to them upping throttle before leans.
Listen to flat trackers powering up ahead of turns, look at them relieving loads by hardly keeping forward acceleration going, drifting wide and upright with front pointed away from where they want it to go, listen &* look close to ice spiked racers, see them using straight steering with harsh frame scape leans.
+Yeah man that's what I'm talking about w/o having to have superstar bravery.