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1972 Commando running issues - pls help a new owner.

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Re: 1972 Commando running issues - pls help a new owner.

Posted by Fritz Wettstein at April 16. 2017

I have at least two right ones.

I can send you one for cost of postage, about £15.––, to be sure I have to weigth it first.

Please contact me by email if you're interested.

Fritz

Re: 1972 Commando running issues - pls help a new owner.

Posted by richard_chan at April 16. 2017

Thanks again John and Fritz.

Yup, will post luck as soon as i have time for the bike.

Re: Fritz - I'll send you a message here with my email either way first. My bike is a combat with 32mm 932 Amal.

Thanks guys. Hope you're having a good Easter Sunday! I just made a killer Lamb chop on the BBQ for my wife and little 2 yr old, was a winner :)

Re: 1972 Commando running issues - pls help a new owner.

Posted by richard_chan at April 19. 2017
Hi everyone, Here are some images of my carbs. There is a small hairline crack on the right carb as i remembered, but it's not huge. Opinions?  http://i.imgur.com/NI7mfpe.jpg As for the conditions of the slides. Left carb:  http://i.imgur.com/DlSUeHb.jpg  http://i.imgur.com/FssIK6y.jpg Right carb  http://i.imgur.com/QjbMbRb.jpg  http://i.imgur.com/jevZvNs.jpg Since taking the carbs off and installing at Amal Stay Up Floats (due to leaking right carb), the bike will start, but it won't idle constantly. It almost sounds and feels like it's not got fuel, but tank is half full. I had to re-adjust the screws by turning in 1/4-1/2 to give it more rev to stay idle. Suggestions? And finally my bike put back together. No test rides yet, but she is definitely the prettiest bike I've owned.  http://i.imgur.com/wZZFoZA.jpg

Re: 1972 Commando running issues - pls help a new owner.

Posted by john_holmes at April 19. 2017

That crack looks very like the casting defect that is close by and possibly not a crack at all, I would take some emery paper to it to level it off and follow up with a polish. If it still shows as a black line after the polish its a crack, if it has disappeared then it was a casting defect.

The slides look worn, they need replacing but if the bodies are ok then new anodised slides will stop the rapid wear, if the bodies are worn then resleeve.

What exactly do you mean by won't idle constantly, are the revs wandering say 900 to 1100, 900 to 1500, or does the engine die completely.

Re: 1972 Commando running issues - pls help a new owner.

Posted by richard_chan at April 19. 2017

Thanks John for your reply.

Firstly, I made a few changes today. 
Aml Stay Up Floats - both sides set to 2mm bowl edge to the tip of the bowl when the needle is pushed down.

Secondly - Clutch cable - had to install a new longer version, as I had new handlebar installed which needed longer cables.

Thirdly - new braided Rocker Oil feed line. I checked, oil is running through it. 

I bring these up it's because only since I made these three changes, the bike has not idled consistently. Took a few good kicks to start, which was expected, as I had emptied the carbs. But when it started, it idled really low, so I let it idle for a bit while I was claeaning etc, but it started idling lower and it died. 
Kicked it over again, idled ok, let it idle, it stayed idled for a bit, then died. Then I turned the idle screws on both carbs, turned it in 1/4 - 1/2, it idle ok, a bit on the high side of around 1500rpm, which is over the 900-1000rpm recommended (from memory).

I then proceeded to turn the throttle cables out a bit, as it had too much play, but that still didnt fix it, it juts made the revs go up more.
I took the bike out for a quick up and down the 20 meter path outside my garage, but when I got to the other end in 1st Gear, stop, clutch in etc, the bike decided to die. No cough, no back fire. But it kicks over and starts first kick. 

It's almost like it's out of fuel, but it isn't.  

I'm a bit lost here tbh... could it be the new clutch cable freeplay which i HAVEN'T adjusted as yet (mainly because I can't get the nut loose, and I'm way to sacred to use the electric impact gun on a smallish nut).  The new cable is much tighter than the old one of course.  And perhaps the floats are set too high? the manual recommends 0.21" from top of bowl to float when it's sitting? 

Thanks for any suggestions.

Rich.

Previously john_holmes wrote:

That crack looks very like the casting defect that is close by and possibly not a crack at all, I would take some emery paper to it to level it off and follow up with a polish. If it still shows as a black line after the polish its a crack, if it has disappeared then it was a casting defect.

The slides look worn, they need replacing but if the bodies are ok then new anodised slides will stop the rapid wear, if the bodies are worn then resleeve.

What exactly do you mean by won't idle constantly, are the revs wandering say 900 to 1100, 900 to 1500, or does the engine die completely.

Re: 1972 Commando running issues - pls help a new owner.

Posted by john_holmes at April 19. 2017

On the floats I would set the actual fuel level in the middle of the carb (as the carb is at a 10 angle its the level in the middle in line with the main jet that is important) and not rely on the float setting as that is derived from the fuel level.

The correct fuel level for all Mark 1 Concentric carburetters is 0.21” plus or minus 0.040” below the top edge of the float bowl. Thus when the needle valve is being held shut by the tangs of the float, the level of the fuel will be between 0.17” to 0.24” (4.33mm to 6.35mm) from the top of the bowl.

https://andover-norton.co.uk/en/shop-details/20569/fuel-level-checking-kit-amal-mk1-mk2

As you changed the fuel levels than you need to also do the pilot/idle tuning from the start again, your base line is new so you start all over again. Do not just blindly change settings as you may be going the wrong way.

So back to Bushmans

http://www.jba.bc.ca/Bushmans%20Carb%20Tuning.html

900 to 1000 is too low especially as you slow down for traffic lights with the back brake plus headlight on, best aim for 1100.

As for the clutch the worst you can do is strip the thread in the clutch spring center, so carry on and do your worst.

Re: 1972 Commando running issues - pls help a new owner.

Posted by richard_chan at April 19. 2017

For the float height with the Stay Up Floats, i set it to 2mm as said in the Bushmans guide.

I measured the "regular" floats and they were easily just over 5mm.

I'll try and reset it back to the Andover's instruction tomorrow and see if it is any better and set idle at 1100 if i can. It was really idling great last week before the new floats. Back to the drawing board.

And for the nut, yeah, I'm going to give it a go as well, i guess I've gotta do it either way, as the cable is pretty tight.

Thx again.

 

Re: 1972 Commando running issues - pls help a new owner.

Posted by David Cooper at April 19. 2017

I can't help feeling that now's the time to get out and ride it and don't worry so much about a reliable slow tickover.  It's not as if you need to leave the bike ticking over on its stand for very long.  If you have two carburreters, there are all sorts of reasons why tickover might not be as steady as it is on a modern fuel injected machine.  Any slide or body wear will make it a bit less reliable.  If the throttle cables don't have smooth lines, they might change it each time you move it.  Are the adjuster lock nuts on the carb tops tight?  If they move a bit by themselves, all the careful balancing you might have indulged in will become suspect.  A  bit of slack in the timing chain is a good thing - but too much and the cam won't spin evenly.  There might be wear in the drive to the ignition.  Most of the above won't matter a lot on the open road (if, of course, you can find an open road in the UK...)

New carbs should be better than old - but that does not mean that a different type is necessarily all that much better than a new version of the original type.  And it's a lot of money if the problem lies elsewhere.

Are you a UK member, and is there a branch near you?  Direct assistance might then be possible.  And most of us carry on without messing about with float levels which are not really intended to be adjusted anyway.  My only issues with float levels have been due to dirt in the petrol upsetting the float needle on its seat.

Good luck and enjoy it!

Re: 1972 Commando running issues - pls help a new owner.

Posted by christopher_winsby at April 19. 2017

Previously richard_chan wrote:

For the float height with the Stay Up Floats, i set it to 2mm as said in the Bushmans guide.

I measured the "regular" floats and they were easily just over 5mm.

I'll try and reset it back to the Andover's instruction tomorrow and see if it is any better and set idle at 1100 if i can. It was really idling great last week before the new floats. Back to the drawing board.

And for the nut, yeah, I'm going to give it a go as well, i guess I've gotta do it either way, as the cable is pretty tight.

Thx again.

 

Have you got the brass viton tipped float needles. The light weight ones can leak with engine vibration

Re: 1972 Commando running issues - pls help a new owner.

Posted by richard_chan at April 20. 2017

Thanks David and Christopher for your reply.

 

No, I'm a German member, i have been in touch with the two very nice gentleman from NOC, who has given me some very good advice along with with members here.

Fritz has 2 right carb bobies i can purchase, but I'm going to give it one more go today and tune it as much as i can and take it out for a test ride if weather permits.

As for the float needles - they are the brass ones. But since the new stay up floats, the carbs have stopped leaking.

Back in a few hours of fiddling with result hopefully.

Re: 1972 Commando running issues - pls help a new owner.

Posted by richard_chan at April 20. 2017

So figured out what i can.

Clutch didn't need adjustment after all, as i slackened the cable from the bar end, and the adjuster on the right side had a good 3mm play.

Redid the floats accordingly to the Andover info sheet. 0.17" when floats needle is closed.

Bike idle well between 1200-1300 at the moment.

Took it out for a test ride and it wasn't great.

Right exhaust is back firing constantly. And when I'm in 3rd gear, at 3500rpm, the bike seems to just gain life on its own and accelerate like it should have more power. But it pops even more in the right side.

On idle at traffic lights, the right pops as well.

I'm not 100% sure when in 3rd gear, the clutch is slipping, I've loosened the clutch cable so there is a good amount of play, but it didn't help.

Any ideas anyone why the rev shoots up in 3rd? The bike feels like it should have more power, but at the moment, it just bobs along ok.

Thanks everyone for being so patient with me and my newbie problems.

Rich.

Re: 1972 Commando running issues - pls help a new owner.

Posted by david_evans at April 20. 2017

I would agree with John that your crack looks like a casting mark, also I think your slides look pretty good, If you are happy with the cleanliness of your pilot jet and passages, I would set the air screws 1.5 turns out and see if you can get a pair of carb balancers to sort out the height of the slides. It takes all the guessing out of the balancing issue. (Morgan Carbtune are good and money well spent) rig up a small fuel bottle to feed the carbs while you have the tank off. this will give you good access to the carb cables to get both slides lifting together. Just check that you have a good supply of fuel getting into the float bowls.

Re: 1972 Commando running issues - pls help a new owner.

Posted by david_evans at April 20. 2017

There are a couple of used (though not much) Morgan Carbtune on eBay at the moment. It's the way ahead with twin carbs IMHO

Re: 1972 Commando running issues - pls help a new owner.

Posted by Julian Wells at April 20. 2017

Dear Richard,

I see what you mean about the images -- they didn't look like that when I was downsizing them in my picture editing programme ...

On the needles, bear in mind that the annulus through which the fuel is flowing has a tiny diameter; any wear or other blemishes on either needle or corresponding jet will have more effect than you might imagine. In my case, dropping the worn needles from bottom to middle groove only gave a slight improvement to hopeless richness. New jets, and new needles in the original, lowest, groove put everything to rights.

On the slides, regardless of what it looks like, the real question is "how much do they rattle?" Mine were fairly rattly, but evidently the carb bodies weren't badly worn, as new hard-anodised slides have eliminated any movement (except in the desired up-and-down direction ;) ). Subjectively they also provide much smoother action (assessed by direct manipulation in the carb, not at the twistgrip, where it would be harder to claim an obvious improvement in feel)

 

Previously richard_chan wrote:

Thanks for the info Julian.

I checked your link and picture. Unfortunately, the pictures are super pixelated, especially on the slide image, can't really make out the scratches. I'm viewing it on my phone, but i cant imagine pixelation caused by a smaller screen. I can see that the needles are in a bad state tho, mine are bad, but not as bad, mine does have score makes on it. I have tried to clean it some what with carb cleaner, but no help.

Re: 1972 Commando running issues - pls help a new owner.

Posted by richard_chan at April 20. 2017

Thanks is for your replies Davis and Julian.

 

One step forward and two steps back is the motto for the day.

I went back to try and balance the carbs again, found that the right side needle had fallen off the clip. Which could be why the right way on and off power.

But after reinstalling new clips, balancing and tuning it to stated, it ha s in fact worsened. It now back fires and shoots fire out the right exhaust.... Absolutely no idea why. Everything is in place as before.

The timing couldn't have gone out already. I haven't checked but I'm assuming no way timing is out as i only took the bike out 2 hours before and it ran okish.

Suggestions anyone?

Thx...

Re: 1972 Commando running issues - pls help a new owner.

Posted by richard_chan at April 21. 2017

Never mind.

The right carb needle fell of the clip, therefore causing erratic throttle and pops.

Timing checked and all good again.

New problem is that in 3rd gear at 3000rpm, at slow throttle towards 4000rpm onwards it's fine. BUT, if i do a quick throttle twist at 3000rpm, the bike doesn't want to move, but the revs still climb up.

Clutch slip? It only happens in 3rd to 4th, and 4th gear as well.

Re: 1972 Commando running issues - pls help a new owner.

Posted by john_holmes at April 21. 2017

Sounds like clutch slip, you need to check the plates and probably roughen up the plain steel plates with a orbital sander. Stack height could also be a factor as the spring used has a non linear force to movement relationship.

Re: 1972 Commando running issues - pls help a new owner.

Posted by richard_payne at April 21. 2017

Have you replaced the wiring from the Boyer stator to the ignition unit ? I do this every couple of years (I use ordinary household 2-core with a black outer insulation).

 

'Hitting a wall' at 3000 rpm is pretty characteristic of a pick-up wire that has broken inside the insulation (where it does a double bend through the back of the timing cover, about 1.5" up)

It is possible to have an adequate end-contact inside the insulation at low revs but at about 3000, when the engine really starts to leap around, the contact will intermittently make and break.

It can feel like carbs. The first time that it happened to me, I spent several happy hours at the roadside diagnosing all the wrong things. The second time, I recognised it immediately...and now I replace the cable regularly.

Taking out the clutch plates and scrubbing them in solvent every 10,000km or so is part and parcel of Commando ownership. It's unusual to find severe wear on the clutch friction surfaces but drive teeth do wear.

Re: 1972 Commando running issues - pls help a new owner.

Posted by richard_chan at April 21. 2017

Thanks Richard for your input on the Boyer. And John on the Clutch.

Questions tho - why would it only bog down or hit the wall in 3rd and 4th gear? I would think if it's an electronic issue, it would apply in any gear and revs would be bogged down in 1st and 2nd? Did you also experience this issue in higher gears?

The strange thing for me was that it would accelerate IF i turned the throttle slowly, and acceleration is slow, but steady. BUT IF i really open her up, the bogging starts between 3500 -4000rpm, and it catches up again at around 5000.

I looked at the wiring going up to the box, and the connection to the stator plate is in decent shape, but i have thought about upgrading to a Surefire, as i have read good reviews on them, and Joe from Norton GmbH have said they are basically the same unit but with the small issues solved.

Regarding the clutch - thanks both for your info. I have never had to use a belt sander on a bike before, this would be the first...

There is a regular drip of oil coming from the primary side at the moment, i will have to resolve this anyways, so it looks like my next job would be the clutch while I'm there.

Thanks again everyone, i hope this thread is useful to someone else one day, because I'm learning a lot here.

 

Previously richard_payne wrote:

Have you replaced the wiring from the Boyer stator to the ignition unit ? I do this every couple of years (I use ordinary household 2-core with a black outer insulation).

 

'Hitting a wall' at 3000 rpm is pretty characteristic of a pick-up wire that has broken inside the insulation (where it does a double bend through the back of the timing cover, about 1.5" up)

It is possible to have an adequate end-contact inside the insulation at low revs but at about 3000, when the engine really starts to leap around, the contact will intermittently make and break.

It can feel like carbs. The first time that it happened to me, I spent several happy hours at the roadside diagnosing all the wrong things. The second time, I recognised it immediately...and now I replace the cable regularly.

Taking out the clutch plates and scrubbing them in solvent every 10,000km or so is part and parcel of Commando ownership. It's unusual to find severe wear on the clutch friction surfaces but drive teeth do wear.

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