Commando 2A Sensible mods

Hi Andrew - I too have a Mk.2a (converted to 920cc). I have an Alton starter on it that works well. The Pazon electronic ignition system has an 'anti-backfire' feature as does the Tri-Spark 'Classic Twin' system that I have fitted to my machine - it works well and I have never experienced any sprag clutch problems. The Alton system (by default) retains the original triplex primary chain drive. There is also an electric starter system available from Colorado Norton Works (cNw) in the USA. The cNW system comes with a new primary belt-drive with it which is a separate modification I have on my Mk2a (the system on mine is an RGM) this enables you run the primary drive 'dry' (i.e. no oil) which greatly helps with reducing clutch slip and reduces oil leaks etc. The Alton and cNW systems are similarly priced (at source) however importing the cNw system into the UK may cost a fair bit due to import duties, VAT etc. - best do some calculations first ... .

I also fitted (some years ago) an RGM Grimeca front disc brake upgrade which is well worthwhile.

I have also fitted a Dave Taylor head-steady (also from RGM) - easy to set up and much better than the original bent-metal effort.

I have fitted a single Mikuni carb replacing the original twin Amals - there are numerous single carb 'kits' available - some more sophisticated than others. The simplest (and cheapest) is a single Amal Mk1 Concentric which still retains the tickler and original choke/strangler system. The Mikuni and Amal Mk2 conversions negate the need to 'tickle' the carb as they have a 'proper' cold-start system - they are more expensive however. Given they way these bikes tend to be ridden these days, the very slight reduction in performance with the single carb systems is outweighed by easier tuning, smoother idling and a (possible) slight improvement in fuel economy.

Suffice to say, these are just my thoughts - the list of 'possible' improvements is pretty extensive - it's down to your requirements and the depth of your pocket!

HtH

I agree, a single carb is much better for most people as the twins only really have an effect at the top end. On my 850, I started with a single Concentric Mark 1 32mm which was good, tried a DellOrto which I could never get jetted right, and ended up with a Mark 2 Concentric which worked very well.

I had Boyer ignition which suffered from the usual intermittent connections to the pickups - sorted out by making proper joints instead of the daft preinsulated crimped things.

Front brake - I had the floating disc with a Lockheed caliper which gave excellent braking. The caliper adaptor plate I had from RGM was rubbish however, with a crack from new so I made my own.

I found the bike most comfortable (Interstate) with rearsets and standard type bars.

Never needed an electric start but I was younger then!

I installed a Norvil-type headsteady at a time when the Dave Taylor type was still a twinkle in Mike Taglieri's eye â it takes you back to shimming for clearance, by which I also mean you'll want to install the adjustable, Mk3-type front and rear isolastics, but it's easily done and cheaper. The handling is noticeably improved. The front brake was mentioned, the main thing there is to get the master cylinder sleeved down, or buy such an item new from Andover Norton. As important, in some ways, as a more powerful brake is a more powerful horn, especially while you've got the whole bike apart. Maybe consider how to incorporate a pair of Fiamms, like their AM80S kit, which comes with a relay.

You could get Norman White to do his Mk3-style fix on the swinging arm spindle, and if you go for a belt drive then you might get him to spigot the gearbox too, for secure alignment â Norman does a good belt drive. If you go for a CNW electric start, you won't need anyone else's belt drive but you'll need to lose the plastic airbox; but you can keep it with the Alton kit. A snag with the Alton kit is, if you have a belt drive, you need to make up a spacer to keep everything on that end of the crank where it should be â Alton supply the details â I'd be surprised if Norman wouldn't sort you out with that too. Depends where you are in the world, I suppose.

An uncontroversial mod, I think, is to fit relays in the headlight circuits. It takes the load off the handlebar switch gear, and unsurprisingly makes your headlight noticeably brighter by boosting the juice. And I'm hoping that we'll hear before too long from a UK member of this forum about a comprehensive wet-sumping fix, akin to but better than that in the Mk3 â i.e. between the pump and the crank. Similar work is done in the US by AMR.

Hi Andrew, ref the Alton with belt drive. I had mine fitted about six years ago when they were fairly new to the market. Alton had produced the 'standard' system for the chain primary drive and stated that they intended to produce specific kits for the numerous belt-drive Commandos. Mine was the first in the UK and Alton (quite rightly as it transpired) insisted that the fitment be performed by a professional workshop. The work was carried out by 'The Motorcycle Restoration Company' in Safron Walden (great guys BTW) but it took them circa 24 hours to fit it due to the numerous modifications required. I remember commenting to Alton that there are about five different belt-drive systems for the Commando (or there were then) and producing a kit for each variant might not be commercially viable. I note now that their instructions are only specific to the chain-drive systems but they do give advice ref the modifications, spacers etc. needed for fitment to belt-drive bikes (they provide specific advice for the RGM and Norvil belt drive systems).

Regarding the 920cc conversion - I have noticed no increase in vibration. The motor produces more torque than the 828 motor. I increased the gearbox sprocket to 23 teeth from the 22 teeth previously fitted and this makes for a nice 'lazy' cruise at 70mph.

One other somewhat cosmetic change I made was to replace the pea-shooters fitted to it when I bought it in 1989 with the RGM pseudo 'straight-through Black-Cap' silencers available from RGM. They sound and look good - the fit is excellent and the chromework is high quality.

I rebuilt the gearbox about six years ago and took the opportunity to rebuild it with the RGM 'toughened-up' gearbox case (with more 'meat' around the mainshaft and layshaft bearing housings. I don't think it's listed by RGM any more - at the time it was circa £120 which didn't seem too bad at the time ... .

I forgot to mention that when I bought the bike, it was already fitted with the Mk.III Isolastic vernier adjusters. I can confirm that these make adjusting and maintaining the 'vibe-free' nature of the bike far easier - I had a 750 Roadster in the '70s which had the original shim adjustment system - a right pain!

HtH

You could also add Ikon shocks at the rear & the late John Bould's Lansdowne Conversion at the front for compression/rebound damping (now available from madass onthe AccessNorton site). Then add Avon RoadRiders, I use 100/90/19front & rear (some prefer 90/90/19 on the front).

You could also add braided steel brake lines

There's some really cool stuff available if you has the money - Fullauto head, Maney, flat slides - Belgian chapon AN building a lovely 920 beast with big valves

By the way, I was thinking â always dangerous, I know ... If you do still have the plastic air box, make sure the rubber venturi on the lower intakes are gone; and, if you stick with Amals, you want 260 main jets, cutaway spray tubes and 4-ring needles. The main jets are probably smaller, but the others should already be present. Also you can pretty much assume that used needle jets need replacing (106). And, just so you know, I got a great improvement from switching to no. 3 slides, mine are anodised from Amal â something to bear in mind, maybe. Stay Up floats with aluminium needles from Amal are good too, although I had trouble setting mine up for an acceptable fuel height â but you wouldn't believe how helpful the people at Burlen are if you really get stuck! And an old bugbear, give the pilot jets a poke with a 0.016"/0.4mm wire or drill bit and flush with carb cleaner. Still assuming you're sticking with the Amals, a tip I've found works in keeping them in balance is to secure the cable splitter to the frame to stop it moving around. But of course, there are other solutions ...!

Hi

I have just bought an 850 also which is in need of total refurbishment, and doing the same, sorting out what mods to consider. so a very interesting read.

Is there a roller bearing swing arm available for the 850, I have a new one for a 750.

I will change my interstate panels and tank to roadsters.

If originality is not a requirement, I'd strongly suggest replacing the standard twist-grip, splitter and associated three cables with a twin-pull twist grip and two cables (which means you only have to carry one spare instead of two).

Previously Colin Peterson wrote:

Still assuming you're sticking with the Amals, a tip I've found works in keeping them in balance is to secure the cable splitter to the frame to stop it moving around. But of course, there are other solutions ...!

I'd say these are essential .

Previously mike_sullivan wrote:

You could also add braided steel brake lines

Previously Julian Wells wrote:

If originality is not a requirement, I'd strongly suggest replacing the standard twist-grip, splitter and associated three cables with a twin-pull twist grip and two cables (which means you only have to carry one spare instead of two).

There's also this option from madass140 on the Access Norton forum: https://photos.smugmug.com/One-cable-kit/i-Ccr7FnS/0/cf8cd06c/S/onecable%20002-S.jpg

I know of someone here in the UK who's invested in this kit and is very happy with it, and it retains the single-cable twistgrip. It's obviously superior to the tip I previously gave, I've just been too tight to try it for myself.

Better pictures here: https://www.accessnorton.com/NortonCommando/one-throttle-cable.23116/page-4#post-342273

Previously john_neely wrote:

Hi

I have just bought an 850 also which is in need of total refurbishment, and doing the same, sorting out what mods to consider. so a very interesting read.

Is there a roller bearing swing arm available for the 850, I have a new one for a 750.

I will change my interstate panels and tank to roadsters.

Yours is also a MK2A? Do you want to part with the Interstate side panels ...? If they're black I'd be interested!

Hi it' red and been in an unheated shed for 30 years. The bike is not with me yet.

Previously john_neely wrote:

Hi it' red and been in an unheated shed for 30 years. The bike is not with me yet.

Thanks for responding to that John â good luck with the bike then, those side panels seem to be pretty hard to come by and I could use a battery-side one that's in good shape, maybe a rattle-can of gloss black paint would sort it out for me if that's not sacrilege! Cheers.

Just a point to note. If fitting a dry belt drive to an electric start bike. The sprag clutch likes lubrication. I have seen the effect of a sprag seizing, makes a nice mess of starter motors. They don't like being spun at at 3000+ rpm.

Paul