175 CS kick starter issue - MVAgusta.net
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post #1 of 13 (permalink) Old 03-09-2018, 01:39 PM Thread Starter
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175 CS kick starter issue

Hi,

Please could you help me ?
I have an issue with the kick starter of my 1954 CS that would not return properly.

I think the problem is in the ratchet system which is inside the engine and that would not correctly reset.

My question is : is it possible to part out the whole kick starter system from the left side off the engine, without splitting the main cases ?

All the best
Dominique

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post #2 of 13 (permalink) Old 03-11-2018, 03:43 PM
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Dear Dominique,

Yes, you can remove the kick start shaft, spring and drive ratchet from the left of the engine - no need to split the crankcases. However, I do not think you can remove the main kick start gear as it is too big to pass through the hole.
Please see some photos of my engine in the following gallery, including parts diagram extract:

MVAgusta.net - Mondello175's Album: CS175 Kickstart mechanism

I had my engine cases split to replace all of the bearings.

If the problem is only the return spring (item 27) then it will be easier to leave the shaft in the gearbox. The shaft can be taken out, complete with the ratchet assembly but it looks like it could be difficult to refit the parts correctly. There is a washer (item 26) behind the kick start gear (item 24) that needs to be positioned correctly and it looks like it could drop into the bottom of the gearbox. There is probably a technique to do this but I don't know it.

Please feel free to contact me if I can help. I'm currently close to finishing the assembly of my CS engine.
Regards,
Ron
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post #3 of 13 (permalink) Old 03-12-2018, 02:34 AM Thread Starter
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Hi Ron,

Thanks for the help.

The problem is not on the main return spring but on the ratchet that very often don't re engage correctly and then the kick starter works lose.

I think that the issue would be on the return of the small wafer in the ratchet (small spring ?)

If you have an idea of the reason of the problem, i would be glad to hear you

All the best
Dominique
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post #4 of 13 (permalink) Old 03-12-2018, 05:51 PM
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Dear Dominique,
I think your problem is most likely wear on the front edge of the ratchet, as this is the part that does most work. Normally the driven gear is OK as it has around 18 teeth, so it wears at 1/18 the rate of the ratchet.

My ratchet had some wear but I have not changed it as the kick start was working OK. You can see the wear on mine, in the photo below.

To change this you must remove the primary drive cover (drain oil first), then remove the 2 screws that hold the kick start plate.

Before removing the plate, I suggest you lay the motorcycle over on it's right hand side to use gravity to help keep the kickstart drive gear in position. There is a special washer behind the gear that hooks over a rib in the right hand casting to stop the gear from dropping - see photo below.

Next hold the kick start shaft in position whilst you remove the plate. Then use a long rod to hold the gear in position and carefully pull the shaft out. Leave the motorcycle on it's side to keep the large gear in position.

After replacing the ratchet, insert the shaft carefully back into the gear. You can use the ratchet return plate to push the ratchet back so it enters the gear - see photo.

I hope this helps but please PM me if you have any questions.

Ron
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post #5 of 13 (permalink) Old 03-13-2018, 02:29 AM Thread Starter
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Hi Ron,

Many thanks for your help.

That's clear with the pictures and your indications.
I'm happy to avoid splitting the main cases, it would be a more important work.

If i have some other questions, i will contact you.
On my part, if i can help you anyway, feel free to contact me.

All the best
Dominique
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post #6 of 13 (permalink) Old 03-13-2018, 04:56 AM
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Talking

Hi Dominique,
Here's one for you.

I've been setting my valve timing and find I'm short of cam opening angle, see attached image.

This is probably due to cam lobe wear. So the question is what do I use at the datum? Opening point, closing point, or set it in the middle (my current preference).

Thoughts? Anybody?

Ron
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post #7 of 13 (permalink) Old 03-14-2018, 02:17 AM Thread Starter
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Usually, i set the camshaft on the exhaust opening advance, i's easiest because there is only one cam on contact and this data is the one with very little variations on all models of cams for an engine.

If there is a lot off wear, you can play with the difference as you say , but i would favor the exhaust advance in the compromise.

All the best
Dominique

Last edited by GTW36; 03-14-2018 at 02:24 AM.
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post #8 of 13 (permalink) Old 03-14-2018, 05:06 PM
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Hmm.. interesting suggestion Dominique. But that's not what I've done and I'll explain why.

The standard cam timing is shown is the first image below.

If I set my cam timing on the exhaust opening spec of 70 degrees BBDC, then it closes at 3 degrees ATDC, rather than the spec of 24 degrees ATDC. And the inlet opens at 38 degrees BTDC rather than the spec of 33 degrees BTDC. So most of the valve overlap is happening with the piston still rising and this will reduce the suction on the inlet that draws in the next fuel charge, caused by the outgoing exhaust gases. See the second image below.

What I've done is balance the valve overlap is a similar ratio to the standard settings - 58% of overlap before TDC and 42% of overlap after TDC. Or at least as close as I could get. See the third image below.

I think this should give me the best performance available from a worn camshaft. Also If I use your method the inlet valve opens much earlier than standard specification and I'd be worried it could clash with the high compression CSS piston fitted to my engine.

But am I right?

I should have my motor running in the next few days and I'll let you know how it performs.

Of course the best solution would be a new camshaft - do you know where I can get one?

Ron
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Last edited by Mondello175; 03-15-2018 at 06:42 AM.
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post #9 of 13 (permalink) Old 03-15-2018, 03:53 AM Thread Starter
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Hi Ron,

I did not thought that your cams were so worn !!!
I think that the only real solution would be a new camshaft

I will be in Italy next month at the REGGIO EMILIA autojumble, may be i can do something for you ?

All the best
Dominique

Last edited by GTW36; 03-15-2018 at 06:38 AM.
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post #10 of 13 (permalink) Old 03-15-2018, 07:03 AM
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Hi Dominique,
I've measured the cam lobe lift and it's 6.0/6.1mm when I think the specification is 6.5mm. Obviously the opening angles will be bigger with the tappets set at the running clearance of 0.15mm.

I probably don't have time to do anything about the cam now, as I've entered the Motorgiro at the end of April. I did wonder whether it was possible to have the cam reground to remove metal from the opposite side to the lobe. Normally this would not work as modern cam shafts are surface hardened only but this cam looks to be through hardened (but I'd need to check).

I guess a new, old stock cam would be like gold but if you find one in Italy, then I'd gladly buy it. The alternative would be to have a new one made. A friend did this several years ago and added through cam oiling to overcome the wear problem.

Ron

PS Have you sorted your kickstart problem? I think I may have a spare used ratchet that you could borrow to have one made. It would need to be a good tool steel (like EN8) and hardened and tempered. I tried to dress mine with a needle file and it wouldn't touch it, so it's very hard.
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