Commando Newbie

I'm a newbie here - this is a great site. I recently picked up a very nice early 1973 750. Just over 18,000 miles, all original and in very good shape. Apparently I'm the third owner of this bike. The short riding season and dry climate in my part of the world has preserved this bike very well. The engine was blue printed at 10,000 miles and has not been apart since. It was a strong runner when parked two years ago in a heated shop. It is leaking badly from the kick start and gearshift shafts, over two litres of oil has wet sumped into the crank cases but otherwise appears to just need some cleaning up, new rubber and should run. I have a seal and gasket kit on order.

This is the first British bike I've ever owned. I've been into bikes for years, restored several bikes, mostly Ducati singles and Yamaha TZ racebikes. I will be looking to the expertise on this site when questions pop up.

Does anyone have any pointers on re-commissioning a Commando that has sat unused for two years?

Thanks.

Derek.

Welcome to the forum Derek,

northern750 said:

Does anyone have any pointers on re-commissioning a Commando that has sat unused for two years?

Click to expand...

Change all the oils and brake fluid, and fit a new spin-on oil filter, fit new spark plugs, and check all ignition and vave settings are correct.

Here is an online pdf copy of the factory manual: http://www.classicbike.biz/Norton/Repai ... mmando.pdf

Remove the fuel taps/petcocks, flush the tank out and clean the tap filters, and check them for adequate flow, flush out the oil tank and clean the gauze tank strainer.




The carbs will definitely benefit from being dismantled and cleaned, and the float heights checked and adjusted as necessary (see Bushman's link). The pilot system passageways can become blocked,-especially the pilot jet (pilot bush) so make sure they are clear, as well as the two tiny mixing chamber drillings into the carb bore. The Bushman's info here should help you?: http://www.jba.bc.ca/Bushmans%20Carb%20Tuning.html

The rubber brake hose (presuming it's got a front disc) probably needs changing if it is old?

Before attempting to stat up, remove the exhaust rocker covers and add a cupful of oil to the cylinder head to give the cam lobes and followers some initial lubrication.

Once you are sure you have an oil and fuel supply to the engine, start it up, (if it will?) and check the oil tank to make sure the oil is returning, and loosen one of the rocker feed banjos to check oil is being pumped to the valve gear. Always check the engine oil level after the engine has been run for a few minutes, and don't top it up more than about halfway between the high and low marks on the dipstick. Connect a temporary gauge to check the oil pressure, if you are able to.


I'm sure our other members can think of a few more things to add to the list?

You mention bad leaks from the shifter and kick start shaft. Replacing the stock seals with lipped seals is a popular modification. It requires machining but is available from AMR in Arizona and others. If you've never ridden a Commando before then the Isolastic system is about to become a big deal for you. They shake like crazy at low rev's then settle down at about 3000rpm. It will never handle like a TZ.
Where in the Yukon are you from? Been up there a few times. Loved it.

Thanks, L.A.B. - great information. The fuel was removed from the tank and carbs before storage so I don't have gummed carbs to deal with but I will check the float height in them.

Bob - the previous owner said the exact same thing about the vibration, said it was happiest 65-75mph. I live in Whitehorse, good motorcycle country from May through September...


Derek.

I've spent a fair bit of time cleaning up my bike, ordered a few parts that I need to get it running and am having a great time with it all. New rubber boots for the air intake, tires and a few odds and ends and I should be ready to go.

I will have a series of dumb questions for Commando Vets but please bear with me...

The ignition system on my 750 Roadster (10/72 manufacture date) is an early electronic point-less ignition. There is a small 'brain box' between the coils labelled "Lucas AB11 Electronic Ignition Amplifier 47270A" The parts manual that came with the bike, listed as through 1973, shows a conventional points ignition.

So, do I have an early aftermarket upgrade? What can anyone tell me about this ignition - tuning or setting tips, since my service manual doesn't cover it...?

Thanks.

Derek,

The RITA is the Lucas aftermarket electronic ignition. Check out Michael Moore's site

http://www.eurospares.com/elec.htm

and Dave Comeau's site

http://atlanticgreen.com/index.php?opti ... e&Itemid=1

Dave's is mainly about Boyer systems but it shows the curve for the RITA, and why he prefers it to the Boyer. Michael's has the setup instructions for the RITA.

P.S. also http://www.britcycle.com/help.htm

Derek,

It looks like that could be for a negative ground '79-'87 Triumph twin. Are you running negative ground?

bpatton said:

It looks like that could be for a negative ground '79-'87 Triumph twin. Are you running negative ground?

Click to expand...

A RITA box can be wired for positive or negative ground.

The RITA electronic ignition is a good one. The cost was considerably higher than the Boyer in the early days and the pickup required the squarish points cover so some did not like it for aesthetic and cost reasons.

It was used on the Norton factory race bikes and is still a good option for working electric start bikes. Unfortunately the company that made them (Mistral Engineering) in later years has ceased production. I have collected a couple of new units and a few spare parts while waiting to see if any of the newer style units on the market provide good service with electric start models.

If you have the AB11 amplifier you actually have the later design. I have an early AB5 amplifier in my cafe racer that is still sparking and firing up on the e-starter!

Thanks for the info. My bike is negative ground. Sounds like I lucked out with this ignition system...

Derek.

Well, the new battery arrived today. I installed it and the bike fired up on the third kick...Thanks to all the tips from you folks.

I can't go for a ride quite yet, the new tires aren't in yet, nor are the carb to air filter boots - which are essential in the dry climate up here.

I'll post photos soon.

Derek.

The carb-airbox rubber boots arrived last week and with some difficulty, I got them on and did the final checks on my 750. This past weekend I did a few short trips around the neighborhood and all seemed well with the bike, no oil leaks even...

This evening I went for a 60 mile ride and all went weel except that when I pulled over after about 30 miles at 70mph, the bike was idling at just over 2000rpm. I thought the throttle cable or slides were stuck, that didn't appear to be the case. I backed off the idle adjuster screws on both carbs and got idle down to where the tach was bouncing just below 1000rpm and it seemed fine for the duration of my ride.

Any theories on why idle speed was up like this after a good, long run rather than short runs around town? Did I just blow the cobwebs out of the carbs and it's doing what it shoud do? I'll try again tomorrow and see what happens.

Will take and upload a photo as soon as I get batteries for my camera...

Derek.

Derek,
just make sure the slides are not starting to stick in the carb bodies. With that mileage they may need a resleeve. I have 9,000 orig miles on my 6/72 combat am considering this for next riding season. If it doesn't do it again no sweat but be familar w/ where the kill switch is on the handle bar cluster in case you need to shut her down quickly. When I first got my bike back on the road one cyclinder was cutting in and out? Finally blew itself clear. Probably old junk in tank passed through the jet. I was at 70 mph when it acted up and I must have been moving well enough to evacuate whatever was the culprit. They will do this from time to time. A Norton Commando is like a doctor/patient relationship. Get to know the patient as best as you can.

The amal mk1 carbs are noted for wearing badly in the slide to bore department. This is because they chose to use zinc alloy in the construction. Also on a Commando there is considerable suction pulling the slide onto the engine side of the bore. Add to that a lack of lubrication and engine vibration and you have a less than ideal arrangement.
This is the reason I feel your bike idles fast when warm. Set up your idle after a good ride when hot and see how you go. Of course you will not idle when cold.

If your idle remains intermittent you have 3 options:-
Re-sleeve your current carbs using brass or chrome slides.
Buy a new set of carbs.
Install a mikuni single carb conversion.

Many folk on this forum seem to suggest the Mikuni option is the way to go.
I went for a new set of amals.
My idle was fantastic on day one but 3000 miles later and already it is not as good....

Stu

Well, I'll stir up the pot a little. If you're feeling vibration through the footpegs or hadlebars at anything above about 1200 rpm, the Isolastics arean't working the way they were designed to do. That's how the prototypes were set up and it was the Coomando's biggest selling point. Once you're in gear and above idle, there should be no vibration except in the eegine/transmission "pod".

If the after-market Isos can't be adjusted for that, it's a shame.

bigstu said:

Many folk on this forum seem to suggest the Mikuni option is the way to go.
I went for a new set of amals.
My idle was fantastic on day one but 3000 miles later and already it is not as good....

Stu

Click to expand...

The good news is that you can still sleeve the Amals and get them working great again.

I went on a 70 mile highway ride this evening and all was well, I did not have the fast idling again - I must have set the idle speed before the bike was fully warmed up.

I am geting somewhat used to the quirks of this particular machine. The iso-elastic mounts are great, it's a very smooth ride for a bike of the early 70s. The kickstart pedal inteferes with my ankle a bit on the footrest, but nothing really uncomfortable. The brakes are ok - the front disc takes a firm pul but the rear is ultra sensitive, easy to lock the wheel.

I will have a bit of work to do on the bike in the near future. A previous owner put a new chain over worn sprockets; the right side petcock lever is broken off; and I will put a K&N pod filter on it, the stock airbox is not very user friendly and appears quite restrictive. The bike runs quite rich but I won't mess with the carb until I've installed the K&N, I'm hoping that will help lean it up a tiny bit.

All in all, it is great fun to ride, by far the most enjoyable streetbike I've ridden in a long time. The sound coming from those exhaust pipes under acceleration is fantastic.

The stock aircleaner may be a little restrictive but one really good reason to put on a K&N is that the rubber bellows have a habit of cracking on the inside pleat, which you cant see. In the land of pumice this could be very bad. Great looking bike, and you're right peashooters rule in the sound department.

northern750 said:

I went on a 70 mile highway ride this evening and all was well, I did not have the fast idling again - I must have set the idle speed before the bike was fully warmed up.

I am geting somewhat used to the quirks of this particular machine. The iso-elastic mounts are great, it's a very smooth ride for a bike of the early 70s. The kickstart pedal inteferes with my ankle a bit on the footrest, but nothing really uncomfortable. The brakes are ok - the front disc takes a firm pul but the rear is ultra sensitive, easy to lock the wheel.

Click to expand...

Maybe the rear has AM4 "Green" linings fitted.

northern750 said:

The brakes are ok - the front disc takes a firm pul but the rear is ultra sensitive, easy to lock the wheel.

Click to expand...

The master cylinder mod should fix that front brake issue.