ET: Engine (Twin) Grosset Electric Starter Installation

Phil Mahood

VOC Hon. Computer Officer
VOC Member
Following is a recent article I wrote with photographs on the electric starter. François will also be posting it on his site among his other support documents.

The following goes through a real, live installation of Francois Grosset’s increasingly popular starter kit for Vincent twins. First, thanks go to Bob Williams, member emeritus from Ottawa, Ontario, Canada for giving me the opportunity to carryout this installation on his Series C Black Shadow. It was one of the most interesting, and intricate projects I have tackled in a while.

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The electric starter goes almost un-noticed. That’s it peeking out at about 7 o’clock below the exhaust pipe.

The Business Case
The complete kit from Francois Grosset is very well-engineered and manufactured. At over1,700 Euros, it is not cheap. But it is a quality piece throughout. Alas, you’ll need to add a solid 12V charging system, (Alton recommended) and a large capacity battery. Nevertheless, this should add value to the bike. But, see a recent Lone Star (Texas) newsletter. People are putting these kits on right, left, and centre. The reason is to enjoy the bikes for many more years. Investment seems not to be a consideration. The people doing this have no intention of selling. They want to ride.

Is This a DIY Project?
My intention in doing this article is not to imply criticism of the Grosset kit or the instructions. Both are fine. Instead, I am hoping these pictures and words give the reader a feel for the nature of the job so that you can answer the above question for yourself. The right answer depends on your facilities, mechanical aptitude, and temperament.

Installation involves modification of many of the original Vincent starter and shifter parts. The design is such that the kick starter remains operational – a very good thing! But, it means everything has to be precisely modified and fitted. Lathe operations are part of this. Several of us have lathes and good shops. Even if you don’t have a lathe, Francois provides good drawings. Any machine shop could handle that part of it for you. With an angle grinder, and plenty of patience, you may well be able to handle the rest.

The kit comes with very detailed instructions. There are six pages of written material and seven pages of diagrams and illustrations. This can be heavy going. It took me several readings to get the general idea. At the end of it, I still had to go back to the instructions repeatedly once I had the actual parts in hand for each step. It is not simple.

Most of the complications in the instructions come from variations in the standard parts over the different Vincent Series. Extensive experience has alerted Grosset to several gotchas from variations in parts supplied over the years. Instead of a straight read, the instructions are interrupted frequently with warnings to check this or that, grind here or there. The design of the kit is such that it just, and only just, fits in among the other
standard bits behind the kick start cover. It is tight, but does go. Attention to detail is critical. As you go, you must manually test each piece through its full operating motion.

In the case of Bob Williams’ Shadow, things went relatively smoothly and many of the warnings did not apply – just a lot of checking to make sure. So, let's get into it. The biggest design objective was to give you a starter but to retain as much of the original appearance and function as possible. Extra bits and pieces are obviously needed. The whole trick is to make room for those bits without affecting too much. This is done brilliantly and everything is reversable. The key is a trick new G50 plate that actually moves all the original kick start bits inboard by about 1/4” while keeping the gear shifting mechanism as original. That done, plus some trimming here and there, and you have created room for the electric starter bits.

Getting Down To Work
The foundation piece of the kit is a new G50 plate allowing the mounting of the starter below the transmission. The other key components are a sprag (one-way) clutch, the starter motor, heavy duty electrical cables, a relay switch and hardware. There is a longer battery strap for the bigger battery and an extension piece to move the battery rod out. They thought of everything.

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The instructions start right in with an easy step to get you warmed up. The G22 cup on the counter shaft sprocket needs to be removed and made shallower. I squashed it in a press. The G52 felt is then narrowed by half. I used a serrated kitchen knife for that.

After removing the exhaust system, and all the shifter and K/S parts, I placed a jack under the engine. This takes pressure off the swinging arm pivot and facilitates removal of the old G50 pate and installation of the new piece.

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Note that the new plate is milled out to allow the old kick start quadrant to sit further inboard than standard.

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Starting from the inside out, all components from the old G50 need to be removed and mounted on the new plate including the shifter shaft bearing and kick start bushing.

The new plate comes complete with the starter gear train assembled. There is a grease fitting on the gear housing. You need to load that up before using the starter.

The kickstart bushing flange must be machined so that it does not protrude outside the plate surface. Ditto the #39 countersunk screws. In this instance, the screws had to be trimmed on the lathe and shortened by one thread.

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All this is to enable the quadrant to fit as close as possible to the recessed plate and move thru its arc without snags.

Your kick start mechanism is moving inboard. Shown here is the extra-long kickstart shaft supplied in the kit needed to compensate for that repositioning. The shaft is also long enough for the crank to clear the exhaust pipe, which is an issue with the latest generation of Vincent twin pipes. This another example of the
thorough engineering in the kit.

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The original starter ratchet (G46) needs to be narrowed overall and recessed. The bushing (G101) is machined flush to the back of the gear. The recess is large enough to locate the spring (G48).

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On the other side, the ratchet teeth O.D. needs to be reduced so it will work without chewing up the clutch grease seal. The bushing (G101) is narrowed to stay below the ratchet teeth on the back of the clutch.

I needed to grind a little off both faces of the kickstart quadrant so that it just slips between the plate and the back of the clutch.

Next, put the clutch on with the supplied circlip. Then check the operation of the kickstarter in its new position. The ratchet should work and the quadrant should return without resistance, as before. If not,
find out what is binding and deal with it. There is a long discussion on this in the instructions.

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Tip: Kick start bushes should be line reamed and not loose. To keep this all trouble-free in the long term, shim the kickstarter shaft so that the end float is nearly nil. This reduces wear and keeps the quadrant from travelling outward and fouling the clutch some day.

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Here the sprag clutch is shown in place.

Hidden behind it is the starter ratchet pinion and spring. Now the starter pinion can be spun with either the kick starter or the electric starter gear train.

On top goes the shifter arm. This too must clear the front of the clutch. If not, get out the angle grinder! The shifter return spring (G70) needs to be trimmed so that, on full downward motion of the shifter, it does not foul the clutch.


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This shows the modifications need for the kick start cover. The bottom of the cover needs to be cut out to allow the starter gear case to go through.

A fair amount of material must be removed from the inside of the cover so that it too clears the sprag clutch. Be careful not to break through!

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Finally, trim G49 as shown so it too clears the clutch.

If you are still with me, you’ve figured it out. Yes, this entire exercise is all about making room for that darn sprag clutch.

All you need to do now is mount the starter motor and wire it all up. The wiring is easy to integrate with the standard wiring harness.

Final words:
Heed all the warnings about getting the engine in good tune before using the electric starter. If in doubt, remove the starter motor. Start the engine using the kicker until it is right and there are no backfires. Backfires can cause expensive damage to the gear train and/or the sprag clutch. The only protection from this is a sheer pin on the starter motor pinion (1 spare provided). But, even this may not protect the clutch.

If you have the work done by a professional, still read the instructions. It is important for the owner to understand how this system works and what could go wrong. It is a good system that is working successfully and delighting hundreds of Vincent riders.

Take your time, have fun, good luck!
 

stu spalding

Well Known and Active Forum User
VOC Member
Has anyone considered building up a small tooth of weld on the sprag clutch body to machine the inside of the kickstart cover while gently tightening the screws? It's an idea I had after I'd fitted my kit which included a lot of laborious grinding, assembling and stripping. It should be OK as long as not too much heat is put into the sprag clutch. Any takers? Cheers, Stu.
 

BigEd

Well Known and Active Forum User
VOC Member
VOC Forum Moderator
Thank you for posting this excellent article.
Just to emphasize a few points: There is very little that can not be done using hand tools. Creating space and checking clearance is key. You need to check and double check for clearance as Vincent parts and castings can vary. e.g. My kickstart cover is an early one and needed hardly anything taking out inside. It could have been done with an angle grinder. Your cover may need more work. The cut out in the cover for the transfer gearbox can easily be made using a hacksaw and file. The modification to the kickstart ratchet gear is most likely the only part that might need some simple machining on a small lathe.
I have found the electric start to be very good and reliable. Having confirmed my confidence in the system I removed the kickstart lever, kickstart quadrant, shaft, return spring, etc. (My right knee has been reminding me that I have been abusing it with a kickstart lever for too many years.) I fitted an aluminium bung in the shaft hole in the cover. If you plan on removing these parts it also means that some of the modifications are unnecessary. If you are prepared to pay a little extra when buying a battery, lithium iron batteries have great capacity for their size and the one that I have used fits inside a dummy battery case so no mods required to the battery platform or strap. It also retains the original look if that is a consideration for you. (It wasn't a consideration for me. ;))
A 12 volt charging system is more or less essential but that brings the added benefit of easily available lamp replacement and better lights. As a side note, at least one person in the Coventry Section has retained his dynamo converted to 12 volts and that seems to satisfy the needs of the electric starter.
 

Phil Mahood

VOC Hon. Computer Officer
VOC Member
Thank you for posting this excellent article.
Just to emphasize a few points: There is very little that can not be done using hand tools. Creating space and checking clearance is key. You need to check and double check for clearance as Vincent parts and castings can vary. e.g. My kickstart cover is an early one and needed hardly anything taking out inside. It could have been done with an angle grinder. Your cover may need more work. The cut out in the cover for the transfer gearbox can easily be made using a hacksaw and file. The modification to the kickstart ratchet gear is most likely the only part that might need some simple machining on a small lathe.
I have found the electric start to be very good and reliable. Having confirmed my confidence in the system I removed the kickstart lever, kickstart quadrant, shaft, return spring, etc. (My right knee has been reminding me that I have been abusing it with a kickstart lever for too many years.) I fitted an aluminium bung in the shaft hole in the cover. If you plan on removing these parts it also means that some of the modifications are unnecessary. If you are prepared to pay a little extra when buying a battery, lithium iron batteries have great capacity for their size and the one that I have used fits inside a dummy battery case so no mods required to the battery platform or strap. It also retains the original look if that is a consideration for you. (It wasn't a consideration for me. ;))
A 12 volt charging system is more or less essential but that brings the added benefit of easily available lamp replacement and better lights. As a side note, at least one person in the Coventry Section has retained his dynamo converted to 12 volts and that seems to satisfy the needs of the electric starter.
Thanks for the comments. I agree, especially the one about most of it being doable with hand tools. It is nice to hear that the kit has been so dependable for you.
 

craig

Well Known and Active Forum User
VOC Member
If you are prepared to pay a little extra when buying a battery, lithium iron batteries have great capacity for their size and the one that I have used fits inside a dummy battery case so no mods required to the battery platform or strap. It also retains the original look if that is a consideration for you. (It wasn't a consideration for me. ;))

What exact lithium battery have you been using?
do you have photo of this installation?
Thank you
craig
 

greg brillus

Well Known and Active Forum User
VOC Member
If you are building up or rebuilding an engine and you are going to install one of these kits, it is worth trimming a small amount off the threaded/splined end of the output shaft G4 ...........Say one of two mm off the end. This will allow more room for the kick start ratchet, and it wont affect much as the shaft usually protrudes past the main shaft nut anyway. If you are not going to run any of the manual kick start parts then this mod is not necessary.
 

Phil Mahood

VOC Hon. Computer Officer
VOC Member
Craig,
On both your questions ...
It was not necessary in this instance to grind G66AS, so I do not have a picture. If you did have this problem, it should be obvious where material should be removed. I have seen this part in a few patterns and thicknesses. The originals were hardened and hence grinding the back face could be needed. On some more recent replacements you could use a good file. I find an angle grinder easiest to control and maneuver. But, you could do this with a bench grinder.

I wish I had a picture of the G22 cup before and after. Sorry. The instructions that come with the kit have a diagram of the desired result. The instructions say this can be achieved by cutting the outer rim of the cup or pressing it flatter. I put it in a press between two steel plates. I could have used a bench vise. Cutting could be done neatly on a lathe. You could also do it with a Dremel tool, a hack saw or, again that hand grinder. this is not a precision step. As long as the cup ends up with about a 1/16" gap between itself and the back of the new G50 plate, it is fine. The thinned out felt now will sit in that cup and press lightly on back of G50.

Graig, keep in mind I was not trying to provide comprehensive, detailed instructions. Francois Grosset's instructions do that. He also suggests many alternative ways of doing things where appropriate. My objective was to give people a feel for the job to enable them to determine which parts of it, if any, they could handle by themselves. The above two things can both be handled with manual tools that most of us have around. In summary, the work needed on the kick-start ratchet and bush are the only parts of the installation where precision machining (lathe work) is truly necessary. All the rest can be done with hand tools.
 
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