The Electric Start Question (again)

The conversion was sold to me on the basis that it is a fitandforget sort of job. Another benefit was supposed to be a lighter clutch action. I don't know how true that is.

It does eliminate on potential oil leak!

One counter comment comes from Nick Hopkins of Andover Norton; the triplex primary chain is very robust and, if necessary cheap to replace.

Peter - I am doing the same sort of thing at the moment, so bear with me for a minute...

I literally am doing the job almost as I write!

My sprag clutch has been detroyed - probably by a back-fire caused by low voltage supply to the the Boyer Bransdon transistor ignition during start-up, due to battery drain caused by the starter load. Consequently this has mis-timed the engine, causing a huge back fire. I am only surmising and may be entirely wrong, however it was most certainly good-bye spraggy...

The outer bearing case of the sprag clutch is physically broken in two places and a few of the "teeth" are most certainly not where they should be, or correctly oriented. It is very badly damaged, but fortunately has not fallen to bits.

The bearing surfaces on the shaft and internal face of the sprocket are worn, but you would expect that and they do not seem to be too worn - however it seems ipossible to measure them accurately without stripping the engine (anyone got any ideas?)

So, after a little research and a chat with the chaps at Andover the other day, I will need to replace the sprag clutch, firstly ensuring that I fix the root cause of the original failure.

To me this means that I will need add Pazon ignition in place of the Boyer Bransdon - which I believe times accurately down to 6 volts or so); retain the final drive chain (to reduce cost and improve resilience - in place of the Boyer Bransdon which I believe does not; replace the sprag clutch; and finally get the 4 brush ES conversion "kit" from Norvil (I think).

This should give me a reliable working electric start at a cost - ouch. Expensive lesson eh?

You will need to check whether your belt drive system can be modified to work with the ES.

I used to have an ES with the same mod as yours - worked well but ate a couple of belts.

I have a 1975 ES with the original 2 brush starter that works perfectly every time even from cold in winter, below are listed the steps I took to get to this point

1. Installed new bushes & brushes in starter , make sure it spins free with no rubbing.

2. Installed Lucas Rita ignition reliable spark advance down to 6 volts Pazon should work.

3. Installed heavier starter cables to reduce voltage drop under load.

4. Removed battery tray and installed new bigger sealed battery.

5. Installed 3 phase alternator this will keep battery topped up when riding with lights on and at moderate RPM around town

I made these changes over 5 years ago and haven't had to kick start since then. Good luck with your bike, I am now 72 and had hip replacement and knee surgery so these changes make it possible for me to ride my bike anytime anywhere!!

Teaticketony Lockwood

Peter,

I only have experience with the Lucas Rita however the Pazon literature claims their unit gives reliable ignition retardation at low volts. Of course you could use the orignal points with good results. Check out Dynodave's analysis of the Boyer problem.

Tony

Peter,

I have stripped it all down now, and have also found noticeable wear in the crank gear bearing surface (putting it out of useable tolerance) and the thrust washer (possibly allowing undue lateral play under load). So I will replace those as well as the sprag clutch.

Apparently there is a Honda needle roller bearing that can be installed in the Prestolite end cap to replace the phosphor-bronze job, a useful upgrade apparently - requires a bit of machining.

I like the sound of Tony Lockwood's mod's. I may well give that a go as my old Prestolite seems to spin, and it will save me £250 for the replacement! Thanks Tony.

Tell me, when you upgrade the the 3 phase alternator, do you need to upgrade the rotor or anything?

So in short I will be replacing the crank gear, sprag, thrust washer, Boyer ignition and upgrading the starter with the needle roller bearing, cables and big battery! Ouch.

Adrian - if the sprag and starter set up is left as standard when the belt drive is installed; it would indeed seem to operate through the belt.

Surely though if the the belt can take the whole mechanical engine load throuhgh to the gearbox and final drive, wouldn't the mechanical starting load be much less that that?

I think that the drive belts are a bit tougher too, as they are taking full engine load as opposed to just turning the cams.

Peter,

To upgrade to 3 phase you only need to replace the stator your original rotor will work if it is in good shape . You will of course need a new regulator and also keep in mind that your assimlilator does not work well with 3 phase. Check Al Osborns web site for all your needs aoservices.co.uk I think In place of the assimilalator you can use one of his battery status monitors. Finally the sprag clutch drives the cranshaft directly so the belt primary is notloaded in the starting process , hope this helps

Teaticketony Lockwood

Yep - re-assembled it and had a proper look now, and of course the sprag drives the crank gear directly from the starter via the anti-backfire mechanism - nothing to do with the primary drive really. Sorry for any confusion caused, thanks Tony - thank god that at least you know what you're talking about!

Can you advise what battery to use?

Gents,

I am surprised that no one with a belt drive has responded to this question.

As far as I know, and I have spoken to a few belt suppliers, and have decided against it, you CANNOT use a starter with belt drive. This is because, the engine sprocket that the belt runs on is totally diferent to one that has a chain on it, and the starter gears wont fit.

Also, in reply to the writer who trashed his sprag, the innergear and outer race have to be in perfect condition for the sprag to bite properly and once the damn thing has eaten itself then you need to replace both. Very expensive and Nortons excuse is to always blame the Boyer ! Another good mod to iomprove the standard set up is to fit a Leyland Mini starter solonoid, it will fit where the old one goes.

I hate to think what would happen if a primary chain gave way ! A flappy bit of rubber wouldnt trash both your casings, clutch, alternator etc

Go well

Hans Taylor

Hi,

RGM (www.rgmmotors.co.uk) do a belt drive kit:-

BELTMK3SMBELT DRIVE KIT FOR FOR MK3 COMMANDO WITH SPECIAL TENSIONER AND SPECIAL DESIGN OF FRONT PULLEY WHICH ALLOWS THE RETENTION OF THE STARTER MOTOR

Have not tried it as there is nothing wrong withthe chain setup. When did you last hear of a triplex chain breaking on a standard road bike ?

You can get a GEL battery that is a bit bigger than standard but does make life easier, I will have a look tonight as to what it is and take a picture to show how it is mounted. You have to cut the end lip off the battery tray.

Tony

Previously wrote:

Yep - re-assembled it and had a proper look now, and of course the sprag drives the crank gear directly from the starter via the anti-backfire mechanism - nothing to do with the primary drive really. Sorry for any confusion caused, thanks Tony - thank god that at least you know what you're talking about!

Can you advise what battery to use?

I like the Odyssey PC625 it is a sealed unit and spins my motor just fine. I bought it from Battery Mart in USA don't know if it is available in UK I have used a Panasonic unit in the past and had good results for 3 or 4 years

Teaticketony Lockwood

I am interested as to how you fitted the Odyssey PC625, did you remove the standard black box air box ?

I have the Yuasa NP18-12B mounted on it's side And this ends up filling all the available space.

Odyssey PC625 170 x 99 x 175

Yuasa NP18-12B 134 x 89 x 166

Regards

Tony

I use a single carb with K&N filter in addition I removed the original battery tray and have the Odyssey battery installed 90 deg from original ,

Teaticketony

Apoplogies, I must be out of date with the Mk 111 belt drive issue. The last time I enquired they didnt exist.

Cheers

FAO Roy Edwards, I am interested in your RGM belt kit if you want to part with it?

Louis Carey

Hello,

Igniton BOYER MK3 it is not recommended for ElÃ?ctric start,PAXON or Trispark are best.

J have do like Tony to my 850 MK3 and it is very well since four years,also the winter motor cold.

Francis,french member.

Regards