Cam Belts

[Papa Lazarou]

I've read on the Dutch site that cam belts can vary slightly, from loose to very tight. The one the Strada is new-but very, very tight. I'll cut it off, as it isn't budging.

So I've ordered a selection of different makes. The cheapest worked out as the Contitech from RS, with generic examples coming from BearingBoys, BearingsRus and Bearing Station costing a little more. I'll post up how each fits.

The saga of the Woodruff key continues. After three days soaking in penetrating mixture and then Plusgas, it still won't shift. I'll have some micro chisels delivered soon and give them a go-if not, I'll use the idea of locating a ball bearing in a hole in the key to locate the flywheel.

[72degrees]

The OEM belts were graded A,B or C to match the pulley size (which is marked). Presumably the generic versions will be about the same as a 'B'. So long as isn't way too loose I suspect it isn't a big issue. A tight one is unlikely to affect bearings like an over-tight drive chain, just tricky to get off - as you have found.

A pity about the key. Perhaps also do as Evguru suggested. Drill for the ball and then file the remnants of the key down flat so that you can lap the taper in well.

[Papa Lazarou]

Thanks for that-I wondered what the A, B and C meant. I've checked mine and it's an A.

The micro chisels have arrived. No movement still. Rain is on its way, so I'll leave it till tomorrow.

[Ming]

When you do get the 'old' belt off, I suggest a thorough clean of the pulleys, then a dusting of talc on them and the inside of the belt to help it slide on.
I've also heard of this method of changing the belt: slit the old belt longtitudinally, so that it is in 2 halves, cut the outer half and remove it, push on the first half of the new belt, cut the inner part of the old and remove it, then push the new belt fully home. The idea is that you then run no risk of pulley(s) moving and affecting the timing.

[Papa Lazarou]

When you do get the 'old' belt off, I suggest a thorough clean of the pulleys, then a dusting of talc on them and the inside of the belt to help it slide on.
I've also heard of this method of changing the belt: slit the old belt longtitudinally, so that it is in 2 halves, cut the outer half and remove it, push on the first half of the new belt, cut the inner part of the old and remove it, then push the new belt fully home. The idea is that you then run no risk of pulley(s) moving and affecting the timing.

good tip.

[EVguru]

The OEM belts were graded A,B or C to match the pulley size (which is marked)

Not quite.

The belt length would have varied most due to production tolerances. Without a tensioner, Morini had two choices; Have the belts selected for ones that were the right length, or have them graded into length groups. The former would have been very expensive, the manufacturere would have been left with belts that were all longer or shorter than nominal. It's much easier to hold close tolerances when machining metal, rather than moulding rubber, so Morini almost certainly had pulleys made deliberately under and over-size to make use of the A and C graded belts.

You'd really have to struggle to fit a belt that's really too short. Over-tensioning cambelts is usually only a problem on engines where there is a manually adjusted belt tensioner and over-tensioning puts the belt at risk of failing due to fatigue.

It sounds like the Woodruff has been peened into the crank. There a couple of tricks that work to get them out.

Use a Dremmel blade of smaller radius than the key to slit the key down the middle, which would release the tension.

Run a TIG bead down the length of the key (no filler rod). That should shrink the key.

[Butch]

A woodruff key should be soft - in part so that is will be sacrificial in the event of some kind sudden catastrophic failure. Personally I would not consider replacing it with a hardened steel ball - if that is what has been previously suggested.

[Haboola72]

I thought the old ball bearing trick might prove divisive!
With no key, I ran my bike with no locating device at all for months. The tapers were true and the flywheel solid, we're not in Briggs & Stratton territory here..
I only fitted something , and the 3mm ball bearing came to hand, because of a crankshaft seal leak which meant removing the flywheel a few times.
Its the taper that fixes the flywheel on the shaft, not the key! The key will only give if your taper is butchered or you haven't tightened the flywheel properly.

I suppose you could use a nylon ball instead if you were losing sleep over it..

The crankshaft seal leak turned out to be a main bearing on it's way out. Now that the cranks on the bench the old key was easier to winkle out.

[Papa Lazarou]

The plan is to use a Dremel mini grinder to cut out the centre of the key-if that fails, either a ball bearing or no key at all. I'll be lapping the flywheel to the shaft after that.

Waiting on some mini grinding discs (the standard resin ones won't do) and a day without rain.

[Mepstein]

I would hit it with heat. We use MAP gas all the time to loosen up seized parts. Get it nice and hot and then touch some wax to it. Wax won't burn away like penetrating oil. It flows into the cracks and helps the process.

[Papa Lazarou]

I would hit it with heat. We use MAP gas all the time to loosen up seized parts. Get it nice and hot and then touch some wax to it. Wax won't burn away like penetrating oil. It flows into the cracks and helps the process.

Won't that damage the crank seals?

[Mepstein]

I would hit it with heat. We use MAP gas all the time to loosen up seized parts. Get it nice and hot and then touch some wax to it. Wax won't burn away like penetrating oil. It flows into the cracks and helps the process.

Won't that damage the crank seals?

Depends what your goal is.
People are using dremel stones to cut in key ways. Maybe the right sized stone can grind out the key.

[Ming]

I think you can do more than you'd think with a Dremel - if you are careful and aware of the risks. The MZ I have referred to in another post had a siezed carburettor slide, which I could only remove using my 'Dremel-alike' fitted with a fine cut-off disc. I succeeded, without damaging the bore of the carb, and it's now running again.
I would say that the key is a more easily accessible than the interior of a 125 carb, so that you could use a cut-off disc down the middle of the key to collapse it, or the previously mentioned grindstone.
Good luck anyway.

[Papa Lazarou]

Yup, Dremel is the way. I don't think I'll use heat as I don't intend to strip the engine...

[Papa Lazarou]

Dremelling today. Yippee. Sort of.

On the cam belt delivery-RS delivered theirs within a day, with Bearing Station, and Bearing Boys arriving within 4 days. No sign of the one from BearingsRus, so won't be using them again.