Valve timing issues

[G3L1946]

Goon morning to all,

Part of my ‘total revision’ ( due to running, starting problems ) of the G3LS (1955) I have removed and inspected the timing cams. They both appear to be correct (and undamaged) for model and are marked H for high lift ( correct according to F.W Neil’s maintenance manual ). The exhaust cam, see picture, has a shim, the inlet does not. Is this correct? I can not find reference to a shim in any books I have.
I set the timing up as per 1955 manual using dots 2 for exhaust and 3 for inlet . Now, trying to turn over engine with kick start to check all is correct, it will no longer turn over and is ‘locked’. What have I done wrong? I slackened off the tappet clearances prior to refitting.
However, I can turn the cams by using a spanner on the nut securing the timing pinion?
What baffles me is that with cams out kickstart will turn engine but when replaced locks.

Thanks for any directions, I’ve probably overlooked the obvious!

Steve

[Duncan]

Hi Steve, the shims are added as required to take up end float in the cams to prevent them from becoming noisy.

Are you turning the engine over with the outer cover on?

If not it may be that the cams are not running square and locking.

If the cover is on either the shim is too much and locking the cam this could be if the paper gasket has been omitted if previously fitted, alternatively the end of the spindle could be hitting the flywheel check they are the same length and the available depth to the flywheel (usually the big end nut).

[SPRIDDLER]

The exhaust cam, see picture, has a shim, the inlet does not. Is this correct? I can not find reference to a shim in any books I have.

It's a shim to take up end float. The shims are listed on page 10 of the '55 spares list and can be fitted to both camshafts if necessary. Too much end float will generate a 'clacking' sound as the cam turns. On initial assembly the inner camshaft bushes are moved in or out to set the end float but that's not possible once the engine is assembled as you need access to inside the c/case.

I set the timing up as per 1955 manual using dots 2 for exhaust and 3 for inlet . Now, trying to turn over engine with kick start to check all is correct, it will no longer turn over and is ‘locked’.

in addition to Duncan's suggestions......

Since you can rotate the engine with a spanner on the pinion but not with the kickstart I think what you may possibly be experiencing is the common result of the kickstart quadrant teeth not registering exactly with the 1st gear teeth when operating the k/s. It does happen on all g/boxes from time to time and you just have to repeat the k/s movement gently a couple of times. I've found that putting the bike in gear and rocking the bike to and fro helps to line them up or pulling in the clutch and trying the k/s also sometimes frees it for some inexplicable reason.
You will find techy articles that suggest grinding down the first tooth of the k/s quadrant for a more permanent cure.

[G3L1946]

Hi Duncan & Spriddler,

Thank you both for your replies. Duncan , yes without cover on but I was watching carefully. Have now replaced cover and gasket and will turn over with kick start. It still locks at times but, as Spriddler notes this could be common problem with kickstart quadrant. Incidentally, I have discussed this problem before and have checked that first tooth on quadrant has been filed down. Maybe a go at tooth number two in the future?
I’m about to double check values using a timing disc to see if open and close values are correct.

That’ll be interesting!

Thanks,

Steve

[G3L1946]

Hi Spriddler,

Thanks, shims found where you said!

Steve

[ajscomboman]

Hi Duncan & Spriddler,

Thank you both for your replies. Duncan , yes without cover on but I was watching carefully. Have now replaced cover and gasket and will turn over with kick start. It still locks at times but, as Spriddler notes this could be common problem with kickstart quadrant. Incidentally, I have discussed this problem before and have checked that first tooth on quadrant has been filed down. Maybe a go at tooth number two in the future?
I’m about to double check values using a timing disc to see if open and close values are correct.

That’ll be interesting!

Thanks,

Steve

Gearbox kickstart locking is a common feature on Burman boxes, the ideal cure is to replace the ratchet gear and the quadrant at the same time. Only issue now is all the new gears have gone! Whilst quadrants are available they're pretty useless if the ratchet is screwed beyond use. Your suggestion of looking at the 2nd tooth is the best way to go and try to form a better leading edge. I've had to do the same to a bike that came in recently with the worst example of locking I've ever run across! No amount of playing about would cure it so I had to use one of my better ratchet gears and grind the teeth on the quadrant to forma lead into tooth no.3 and that worked a treat. Rather than locking up every time it'd only do it every now and again and once I worked out the sequence I could avoid it completely so had to teach the owner.

[jackstringer]

Maybe a drawing could be put together for the gear as it's not beyond the abilities of the club to get some more made. I know I was looking into Pistons but learning CAD was getting on my nerves.

[G3L1946]

It does seem that there is quite a problem with this quadrant. I’ve spoken to few local owners who have experienced the same issue. How would we, as club members, go about commissioning a quantity to be manufactured? Could it be economically and practically achieved? Or, a redesigned item that does not suffer from this issue?

Steve

[ajscomboman]

It does seem that there is quite a problem with this quadrant. I’ve spoken to few local owners who have experienced the same issue. How would we, as club members, go about commissioning a quantity to be manufactured? Could it be economically and practically achieved? Or, a redesigned item that does not suffer from this issue?

Steve

It's a common fitment that Ariel and Vincents etc use in their boxes. Draganfly have a few items that we're already in on. Yes the club could get some made but there are several other items that are more pressing and we simply don't have enough money to go round.

[G3L1946]

Fully understood. I might make some local enquiries with the many small engineering works nearby.
Rally sport is very big around here with workshops catering to their needs. I have a friend in the sport who might have some ideas or contacts.

Steve