Mystery Commando

Hi, I recently purchased a slightly ratty 1971 Commando thats been mucked around with. The generator was toast , probably due to out of concentricity of the rotor. (Only 4 thou clearance on one side with new rotor and stator fitted.). Its fitted with Dell Orto carbs, PHF 32's. The bike ran dead rough but it did run. Amazingly I realised the carbs were fitted back to front! Does anybody have any tips on getting the rotor concentric,( 3 phase),plus views on DellOrto carbs? I spoke to a man at Dellorto who recommended the following: Main jet 125,idle,65,K5 needle, 35 pump jet, 75 start jet. These were the settings for a Ducati sport 750. He didnt have any recomendations for Norton Commandos. Does anyone have them fitted, and if so what settings do you have on yours? Other features of the bike is that the backbone of the frame has been cut off at the the back of the petrol tank, and blanked off. They did a good job, but for what reason? To get the seat lower?. Its also got fascinating double discs and calipers on the front that I have never seen before, that Nortons reckon are probably original Norton production racing brakes, 11 inches diameter, and not Norvil.
Anybody got experience of them? Lockheed calipers. I cant wait to get this bike on the road. I think it will either be a crock of s*** or go like the clappers.
Colin

Can only advise on the mag rotor clearance, 2 ways, one open up the hardened holes in stator or use old stator mounted to whack on to bend studs in the ally posts, which has most risk to bugger the laminates that hurt bend/break the ally posts. Only need a few 1000'th usually so I usually get bigger hammer to ease my mind.

That sounds like a very interesting bike and I know I am not the only one who would like to see some pictures.

I would get some .010" stock and place it in between the rotor and stator all around if possible. As Hobot said, you can tweak the mounting studs to fine tune. It doesn't take much.
Also, some resin in the stator can be relieved to offer some clearance and to remove slag, if you will, that is sometime presant.

Ugh Pete you listed grinding out stator ID which I had to do after Peel's over rev melted out resin and then metal globs on sparx 3 phase but worked a treat after wards on tiny 1.2 ah alarm battery so one of the simplest shade tree. Btw Peel lost a crank nut prior to over rev that fracture through the upper rear post so JBWelded back on no problemo, in the rare case like that. Interesting Cdo mods out the ordinary that got us bored with the normal all perked up to learn about your mystery ride. Cutting the spine down is common for chopper plans to look right.

Hi, people, thanks for the very quick responses! Only goes goes to show how many sickoes like us there are out there with nothing to do at work other than peruse items of interest on the company internet!! Only joking! I am very grateful!
I did think about drilling out the three mounting holes in the stator by about 1/32" . That way I could move the stator about a bit. Then put 8 thou shim in 3 places around the rotor, poke thin bits of wire down all the mounting holes to fix the position before putting the three nuts back on. Alternatively I could move the whole primary chaincase about on its three bolts, but it seems to be fairly rigidly stuck where it is. It could be because there is a boss in the middle to locate it it, or I failed to break the gooey seal I had there between the chaincase and the crank case.
I have now put the carbs back on the right way round and got it going. I must say it sounds a lot better now. Before, it had a strange slightly high pitched two strokey sound to the exhaust. At least it now sounds like a Norton should. Its ticking over too fast despite the slow running set to minimum. Could be the slightly shagged out looking cables. I will trot up the road when its cooler, this evening and see how it goes. The seller told me it went like the proverbial of a shovel. So it should go even better now, with the carbs the right way round! ( or was he lying?) Watch this space. No sign as yet of any demise of the new rotor and stator, despite the rather small gap of .004 on one side.
Cheers, Colin

exodice said:

No sign as yet of any demise of the new rotor and stator, despite the rather small gap of .004 on one side.
Cheers, Colin

Click to expand...

What is the gap on the other side?

If ya run up to crank flex rpm red zone level the rotor gets pushed into stator around the 7 o'clock area so if that the tight spot better open up gap but that's the hardest direction to hit and move mounts. If gap is biggest down in front then ya got a trick set up to run into red zone no charger worries. If really whacked into red zone the rotor can sweep all the way across stator bottom to 5 o-clockish zone so beepop accordingly rather than just centering. Below extreme rpms may just leave it proven as is.

Can we see the carbs reversed? :shock:

exodice said:

Hi, people, thanks for the very quick responses! Only goes goes to show how many sickoes like us there are out there with nothing to do at work other than peruse items of interest on the company internet!! Only joking! I am very grateful!
I did think about drilling out the three mounting holes in the stator by about 1/32" . That way I could move the stator about a bit. Then put 8 thou shim in 3 places around the rotor, poke thin bits of wire down all the mounting holes to fix the position before putting the three nuts back on. Alternatively I could move the whole primary chaincase about on its three bolts, but it seems to be fairly rigidly stuck where it is. It could be because there is a boss in the middle to locate it it, or I failed to break the gooey seal I had there between the chaincase and the crank case.
I have now put the carbs back on the right way round and got it going. I must say it sounds a lot better now. Before, it had a strange slightly high pitched two strokey sound to the exhaust. At least it now sounds like a Norton should. Its ticking over too fast despite the slow running set to minimum. Could be the slightly shagged out looking cables. I will trot up the road when its cooler, this evening and see how it goes. The seller told me it went like the proverbial of a shovel. So it should go even better now, with the carbs the right way round! ( or was he lying?) Watch this space. No sign as yet of any demise of the new rotor and stator, despite the rather small gap of .004 on one side.
Cheers, Colin

Click to expand...

DO NOT ride the bike with a 0.004 gap! Repeat, do not ride the bike until you have sorted this out. Before you drive it anywhere, make sure you have the required minimum clearance between rotor and stator (0.008" all the way 'round if memory serves) or you WILL seize the rotor to the stator and you WILL break your primary drive chain and you MAY very likely bend your mainshaft. If you do not have enough clearance all the way around, it will seize in 5 miles or so. A very expensive mistake and one that I will never make again. Ask me how I know..............

Easy to get Del Ortos turned the wrong way 'round. Flat part of slide towards the intake.

Hi all you fans out there kind enough to show an interest in this bike! Sorry to Concours,Ive already put the carbs back on so its too late to take a pic for you! Its actually now going but spits and bangs so I'm not out of the woods just yet. I worry that if someone who I'm told rebuilt the whole engine can be daft enough to fit the carbs on back to front, what else has he done? So Im going to check valve timing and also spend some time finding out the most likely combination of jets etc, just in case these carbs came of a jumbo jet. Its got Boyer bits on so there shouldnt be any ignition issues, although the coils look like they have been wearing a girdle due to some idiot over clamping them. To Tpeever: was your comment about it being easy to get Delortos back to front a subliminal confession?! I hear your comment about not using the bike without confronting the issue of out of true rotors. Its about 4 0r 5 thou at 5 oclock. What concerns me a bit is that under load the crank assy might possible be pulled back that amount. Somebody advised me that the "racing boys" (whoever they are) turn about 10 thou off the rotor diameter. I could do that although holding the rotor in the lathe is a challenge. I have no idea what that would do to the charging rate. Hobot suggests that problems would only start if you rev the nuts off the engine and the crank starts whipping around in different directions causing the rotor to start scouring the innards out of the stator. Strangely, now that Ive had the engine going and getting hot, the tighter sector seems to have eased slightly, so I will leave the primary case off for the moment and monitor the situation. Dont worry ,Tpeever I hear you loud and clear! I already have the previous stator,all burnt and withered internally and a rotor with ridges on.
Its amazing isnt it? If we had all had Jap bikes through the 50s and 60s and then Nortons had pitched up ,we would have all said what unreliable crap they were and laughed them out of court, instead of getting dewy eyed everytime we talk about them and paying silly money for shagged out examples. My friend recently sold a totally immaculate and perfect in every way, low mileage 1985 BMW 100 for £2500 and every body said how expensive it was. Talk about knowing the price of everything and the value of nothing...
sorry Im getting philosophical,I must go and get a hanky.
Cheers Colin
PS pics to follow once I discover how you do it.
Ive now done it!( or got my son to do it for me)Pics:
1 Showing modified frame. Actually you can just see the back to front carbs!
2. Another pic of the rear end of the frame.
3. Strange blanked off thing at the back of the timing chest, low down. Old pressure gauge tapping??
4. My amazing double brake discs (disks?)
Any info/advice gratefully received.
Colin

Pictures as promised:

OK forget my comment about the carbs.

exodice said:

3. Strange blanked off thing at the back of the timing chest, low down. Old pressure gauge tapping??

Click to expand...

Yes, but a strange place to put a gauge as that's the scavenge gallery and 'before' the pump, so a gauge would only work if it showed a negative reading.

exodice said:

4. My amazing double brake discs (disks?)

Click to expand...

Usual 'Norvil' kit by the looks of it? But there's more than one Norvil.

exodice said:

11 inches diameter, and not Norvil.

Click to expand...

11" or 11.5" ?

exodice said:

Its got Boyer bits on so there shouldnt be any ignition issues

Click to expand...

That's not always true.

exodice said:

although the coils look like they have been wearing a girdle due to some idiot over clamping them.

Click to expand...

If the coil casings are crushed then the internal windings can sometimes short to earth/ground through the coil case. Coils with dents or crush marks really ought to be replaced.

Somebody bought hobot's book on drilling for lightness...

Cleaver clean frame mod for a short inseam kicker so likely a shorter fella's daughter or kids Commando solution.
Strange welded on fitting was a brilliant solution for wet sump by just letting it drool into catch basin while stored then close valve and put back in oil tank for tool-less ease, duh. Also makes for more complete oil changes by draining the TS case puddle duh. Hm I want some level of wet sump on all my start ups so may follow in same extra nipple path so I can air pressure push a few oz in to splash things before starts, cool. Ya'all should know what those with an extra nipple like 007 are known for don't ya? Don't dish the extra holiness or may not be light enough to float up to heaven in the end...

Like LAB said, looks like Norvil PR brakes, but if you have dual disks with calipers behind fork on both sides, then you have at least some aftermarket parts. The original Norvil FIM 750 Production Racer kits only managed dual disks by having one caliper in front of the forks and one caliper behind. Later "Norvil" suppliers like Mick Hemmings and Fair Spares/Norvil later supplied the second fork slider to put both calipers in the same position. If it's original PR, it should have a Campagnola front hub roll-marked Norton around it.

I'm amazed that you could even start the bike with the carbs reversed! It never occurred to me that you could do that. I run a pair of Dellorto 34 mm carbs on a 750 Commando engine in a race bike, but I doubt if the jetting would be the same for the 32s you have. The jetting suggested to you from the Ducati setup sounds about right. It should certainly be close enough to get it rideable.

Interesting find.

Ken

My trick for rotor clearance is I made a spacer from a plastic milk jug, the width of the rotor and the length just shy of the rotor circumference, so the spacer can't overlap. Fit between the stator and rotor before tightening the stator nuts, and remove after tight.

ugh the issue is when ya can not fit a correct thickness spacer all the way around. My Trixie Combat won't clear a same width band all around but is fine up red line i touch now and then just because it feels so good now and then on a Combat. Checking after some partial rotation of crank can reveal some run out of centter to juggle spacing by brute force or material removal.

Looks to me that that frame is custom ready for Pete v tm40 pumper or twin tm36-68 pumper setup.

Hi everyone, I got the bike going but its still a bit rough and bangs a bit in the silencer, so I thought: I have to know the sizes of all the jets, needles etc to see if they co-relate with other peoples experience, so I have listed them as follows:
Carb: PHF32 AD
1.Main jet, 125 recommended by Dellorto for a Moto Guzzi 750 sport,: mine:175.
2.Idle jet 65, mine 50.
3.Needle,K5 ,mine K1
4.Pump jet 35,mine- cant find a number, but its basically just a check valve with a ball bearing in it to stop fuel running back into the float chamber.In fact maybe the actual jet is the piece that screw into the side of the carb where the fuel is sprayed in when the pump operates.
5 Start jet 75, mine 70.
So... K1 seems very different to K5 although D.O tell me that there are over 100 different needles available so maybe its not that different.
What I am hoping is that there is an expert out there who has these carbs on his Commando and knows his jets! Are these carbs enthused about or derided? I saw an American blog wildly enthusing on them.

This might not be a Commando frame. I saw a rare Norton race bike at Jurby (Isle of Man) during Manx GP week two years ago. The owner said that it was a factory framed race bike. It looked vaguely like a Commando and he was quick to put me right.