KICK START BEVEL DRIVE

The bevel gear is the output from the kick start unit and meshes with the gearbox to provide drive to the crank shaft during starting.  It is housed in the kick start outer cover  (at the top of the picture)
The kick start bevel gear is in constant mesh with the clutch and crank bevel gears and so is rotating all the time the engine is running.  With the engine stationary the kick start  leaver brings the quadrant into contact with the quadrant drive gear which in turn rotates the kick start bevel and thus the engine.  If the kick start leaver is held down with the engine running the ratchet comes into play.  With the lever released the quadrant returns to it's parked position out of mesh with the quadrant gear and the bevel gear rotates freely.

PARTS

1   The kick start outer cover
2    "O" seal  (fitted on cover)
3   The bevel gear and shaft
4   Washer (not shown, I forgot to take to out of the casting)
5   Cir clip
6   Spring

7   Quadrant drive gear  - note the three ratchet teeth, earlier   models had six.

8   Quadrant gear
  

9   Bevel gear Cover plate and bearing

The bevel gear and shaft have and oil return spiral cut into the bearing surface in order to minimise oil escaping from the gearbox.
I'm not sure if the gear box oil level reaches this high or if the gear is lubricated by splash alone. Any oil that finds it's way along this bearing will eventually get onto the quadrant and the kick start shaft.  Since the kick start shaft has no means of preventing oil escaping  this is what I may have been experiencing. However I favor my problem being caused but the damaged "O" seal and possibly over filling.  We shall see.

The Service Book says if the bevel gear is meshed too tightly with the clutch bevel it can produce a whine when the engine is running in neutral.  Backlash is provided by fitting paper gaskets between the unit cover and the gearbox casting.  I note that mine had two gaskets fitted, apparently you check the slack through the oil filler hole.

Now for the new shaft and putting it all together again.

 

INSIDE THE KICK START UNIT

Before I could remove the original shaft I needed to release the return spring tension.  the "outboard" (nearest to the kick start leaver) end of the spring is restrained in a sleeve which is prevented form turning because it is resting up against the pillar that should be attached to the outside cover.  Since I don't want to cause an uncontrolled release of the spring tension I must look to the "in board" end.

At the inboard end the spring is restrained by a sleeve which has a pin passing through it and the shaft.  If I just used a punch to drive the pin out I would just end up with the punch being trapped as the pin was.  I needed some way of holding the inboard sleeve against the spring whilst the pin is removed.  I feel a tool coming on.


 




The tool is made from mild steel.  The pin and punch is made from a nail.  The pin is silver soldered to the side of the tube and the square bar welded to the top of the tube.

            Rough dimensions of the tool

The tool slides over the inboard end of the kick start shaft. The internal diameter of the tube is a good fit on the shaft in order to maintain alignment of the pin

There are two holes in the end of the inboard sleeve.  One is used to restrain the end of the return spring the other is spare, the pin of the tool is inserted into the spare hole.







By restraining the quadrant end of the return spring it is possible to use the tool to react against the spring.  This enables the pin to be driven out and still allow the punch to be withdrawn by adjusting the pressure the spring exerts on the punch.  With the pin and punch removed it is possible to release the one and a half turns of pre load from the return spring without loosing any fingers.

Note:    This operation would have much simpler had I not removed the M5 nut that retains the pillar to the outer cover.  I would then been able to hold the outer cover whilst using the tool to unload the return spring on the pin.

With the pin removed it is possible to take the return spring assembly to pieces. It consists of:-
1   The kick start shaft
2   Return spring
3   Cir clip  (broken)
4   Washer
5   Outer sleeve
6   Inner sleeve
7   Locating Pin (not shown)

Having read in the Service book that there was a version of the pillar that had flats on the base so that a spanner could be used when tightening the M6 nut I decided to modify mine.
I found that if I filed flats for a 12mm spanner I still had sufficient material left. 

REMOVING THE KICK START ASSEMBLY

I had been told that the kick start assembly could be removed as one unit by removing the  securing bolts for the cover and then pulling the cover away from the gear box casing.  Sounds simple enough, it just a case of how hard to pull.

Firstly there are five M6 bolts that secure the assembly,     1, 2, 3, 4, and 5.  1 and 4 are nuts on studs.  Note the cable support clip under nut at position 1

The triangular cover plate at the top of the cover is still retained by the two M5 bolts, 6 and 7







When I tried to pull the assembly from the gear box case I experienced significant resistance.  Not really knowing what to expect I removed bolts 6 and 7 and nut 8 in the hope that this would help.  It didn't, and the cover plate still refused to move.  

I was loathed to try and  force something between the cover and the casing for fear of damaging the gasket or the gasket surface.  

The removal of bolts 6 and 7 allowed the triangular cover to be removed.  By inserting two M5 blots into the threaded holes I had something I hoped would give me something to purchase on.  By "careful" use of a couple of blocks of wood resting on the casing and a couple of leavers I was able to use the bolt heads to slowly pry the cover away from the casing without damaging the gasket.  (Note there were two gaskets in my case and I have subsequently read that sufficient gaskets are added to ensure correct meshing of the kick start bevel gear).

Once the gaskets have been released the only resistance is due to the "O" seal around the bevel gear ratchet mounting.  

Looking at the condition of the seal I have hopes that this damaged seal is the cause of my leak.  I don't think this seal is under oil and only has to withstand oil splashed from the gears.  Hopefully a new seal will solve my problem.  If the seal works then the only other way oil could get to the kick start shaft is via the bevel gear shaft.

This is the outside cover with the triangular cover removed and showing the bevel drive gear and ratchet.

Note that I have removed the M5 nut 8.  Not a good idea and not necessary once you understand what it does.  My excuse is that I didn't and I was finding the cover difficult to move. Next time I will know.








 

This is the Kick Start return spring and quadrant.  The removal of the M5 nut from position 8 enabled the spring retaining pillar (which is fixed to the return spring outer end mounting) to move round until it was stopped by the quadrant.  
It would have been much simpler to remove the return spring one and a half turns pre load had I left the spring retaining pillar in the front cover.  Too late now.  The service manual implies that you just remove the M4 nut that secures the return spring outer end mount to the pillar and let it fly!
Oh yes? Not for me thanks!

RENEWED ENTHUIASM?

Back in November  2011 I had started to think about the fitting of the kick start leaver.  Was the original shaft really as bad as I thought? I had a go at fitting the leaver to the shaft and tried to tighten the pinch bolt.  No matter how hard I tried I couldn't stop the leaver moving on the shaft.  This wouldn't do and to cut the leaver to help improve the grip was not acceptable as it would potentially destroy a good kick start leaver.

I reluctantly came to the conclusion that the shaft should be changed (something that should have happened during the rebuild of the engine).  Patrick agreed to send me a new shaft (£36) so I could check that it fitted on my leaver, if no better than the original one I could return the new shaft and decide what to do next.  As soon as it arrived I fitted it to the leaver and was relieved to find it fitted much better 

original shaft

Not too surprising when you look at the difference between the splines at the end of the shafts.  The old one has certainly seen better days

new shaft

Having shown that it would be worth fitting a new shaft it only remained to fit it.

THE RETURN OF THE ENGINE

At long last, encouraged by Tim, I had to agree that it was time to refit the engine (leak and all).  I have so many problems to sort out the leak is only one and until I can assess the size of the problems I wont know which to do first.

It was good to have Tim to help lift the engine into place.  I still placed a jack under it to take the majority of the weight.  Holding and engine out at almost arms length get very tiring very quickly.  The bottom mounting pin went in quickly and we were left with the fitting of the torsion bar link to complete the job.

After all my deliberations on how to remove the front link pin without doing damage to the needle rollers only to find my link had a plain bearing I felt that refitting should be easier.  Assuming that the torsion bar arm was in the correct position when I received the scooter I only had to replicate this position.  As I said previously I had only removed one end of the torsion bar so it was easy to find the original position.  With everything set up it was time to fit the front link pin.

I had forgotten about the offset cam tool to pull the bearing hole on the engine into alignment with the link bearing.  I had previously thought I would make one as it's a simple operation but it was too late now.  I resorted to the simple alternative - a large "G" clamp

























This "G" clamp method has dangers.  It involves two pieces of packing which want to jump out at the first opportunity.  Because of positional constraints the "G" clamp bar is dangerously close to the to the cooling fins of the flywheel.  (My flywheel already has part of one of the fins missing, not me I promise).  Some specific shaping of the font block where it fits onto the engine casting helps to reduce the risk of it slipping.  The rear block which presses on the torsion bar arm only needs to be cut to length that enables the clamp to operate.  With everything in position the clamp can slowly be tightened, watching the blocks all the time.

The torsion bar arm only needs to be moved forward about 8mm before the holes are in line.  The link pin can then be inserted from off side of the engine.  It's a bit fiddly because there are two spacing washer to be fitted, one either side of the link and these keep wanting to fall out until they are retained by the pin.  The dilemma is when to hit the pin to drive it into the link and on into the nearside mounting lug.  Apparently it's all too easy to break a lug during this operation.  I guess as always a bit of caution is required.  Eventually things seemed to line up and we were able to drive the pin into its final position before fitting the cir clips.  Release the clamp.  Job done.