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Electric start!

Submitted by mark_chapman2 on Sat, 20/06/2015
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Commando

Hi I have just aquired after a long wait a Mk111 comando 1977 and as she has been standing for a while has a few minor issues most of which are straightforward others not so! The electric start has been replaced like for like (original)with all new components and has had very little use was working fine but now spins but will not engage. battery is fine (but i will recheck) can anyone throw any light just where to begin. Also i have the original head steady and would like to replace views on preferences would be gratefully accepted.

Mark.

Submitted by Anonymous (not verified) on Sat, 20/06/2015

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I fitted the Dave Taylor item and think it is very good. Tony Ripley fitted one and took it off again after a while. That's not really very helpful is it? It might kick off a few other views on this option though.

Submitted by tim_harrison on Sat, 20/06/2015

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Hi Mark

regarding the starter, have you checked the sprag clutch, it could be that it has been fitted the wrong way round or is useless, it is a component that can require fairly regular replacement. Ideally you would change the sprocket as well and if your were doing that you would also change the rear sprocket - expensive! For the starter to work anything like efficiently you need considerably upgraded battery leads, you can make them up yourself of buy from Norvil. Finally the battery needs to be good and you will also find that if your ignition is taking a lot of the amps available, for example if a Lucas Rita electronic ignition is fitted, then the engine will turn over fine but not start.

Tim H

Submitted by mark_chapman2 on Mon, 22/06/2015

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Previously alan_sessions wrote:

Look at the oldbrits technical articles

https://www.oldbritts.com/ob_tech.html

in the gear box section for the correct assembly of the sprag and also the anti backfire assembly - Alan

Hi Alan andthank you. I am about to embark on the reading of the link however before i getstarted i thought itrelevent to mention that the starter only stopped engaging after a back fire? I was tuning the carbs with a lead off to adjust one side at a time and using the kick start to fire her up. She had a mild backfire so i chose to use the button and that's when she just span without engagaing so i am hoping that you have pinpointed the problem and that it is a simple and cheap solution.

Mark

Submitted by mark_woodward on Mon, 22/06/2015

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I too fitted a Dave Taylor head steady (available from RGM) a number of years ago and it works a treat. It's straightforward to fit and set up.

Submitted by mark_chapman2 on Mon, 22/06/2015

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Previously tim_harrison wrote:

Hi Mark

regarding the starter, have you checked the sprag clutch, it could be that it has been fitted the wrong way round or is useless, it is a component that can require fairly regular replacement. Ideally you would change the sprocket as well and if your were doing that you would also change the rear sprocket - expensive! For the starter to work anything like efficiently you need considerably upgraded battery leads, you can make them up yourself of buy from Norvil. Finally the battery needs to be good and you will also find that if your ignition is taking a lot of the amps available, for example if a Lucas Rita electronic ignition is fitted, then the engine will turn over fine but not start.

Tim H

Hi Tim thanks for the info.

By my own admission i am green on the Sprag Clutch workings. The chain case and starter motor are off and i can see no damage. All appears to be turning freely with no debis or swarf evident.

I have 13.3 volt on the battery. So i am at the mercy of those who know. I could start the process of stipping down to examine further but my gut feeling tells me that this is not a major mechanical failure as it is all new and i could be just missing something very simple. alternatively the simple aspect could just be me and the problem is the new sprag clutch.

Mark.

Submitted by david_evans on Mon, 22/06/2015

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To understand the workings of a sprag clutch, search on line and look at the animation on the reynold website. (The wickipedia details are sketchy to say the least) once you have done this the problems lie with a worn inner shaft, worn outer bore, or worn spragsor a selection of all of these. Each of the elements can allow the sprag to go past the locking point and fail to transmit rotation to the crankshaft. You could replace the sprag but if the inner and outer diameters are too worn it may work but not for long. As Tim H says, replacing the front sprocket deals with the outer diameter wear. Cross Morse make the sprags for Norton Rotary starters and I bought one direct from them a few years ago. It was considerably cheaper than any of the Norton dealers but still about £56 I believe it may be the same one fitted to Commando electric starters. Cross Morse are not really geared up for one off sales to pauper motorcyclists but it's worth a try if you need one. I'll see if I can trace a part number for you.

Submitted by david_evans on Mon, 22/06/2015

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Andover Norton's price for a new sprag is £73.50 I paid £47.26 for a sprag from Cross Morse 5 years ago (for a rotary, part Number 1310145) I can't guarantee that it's the same part though.

Submitted by mark_chapman2 on Mon, 22/06/2015

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Previously david_evans wrote:

Andover Norton's price for a new sprag is £73.50 I paid £47.26 for a sprag from Cross Morse 5 years ago (for a rotary, part Number 1310145) I can't guarantee that it's the same part though.

Thank you David now that i know what i am looking at i can at least make a start.

Mark.

 


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