Morini Newby / cambelt question

[Andy_C]

Hello, a quick introduction.

My name is Andy and I am based in Somerset. I have just acquired a Morini 3 1/2 Strada, and plans are to use it as my summer "old bike" so will be used mainly on bike runs and weekend rides.

The bike was bought unseen apart from a few videos of the bike running that the vendor sent me along with a few pictures - it seemed to run OK and the price was reasonable so I decided to buy it.

I have been told by many that these are little gems, and I wont be dissapointed, previousley I have had a lot of Kawasaki Triples so I am accustomed to high revving engines.

Anyway, back to the bike, I have the whole Autumn / Winter to go over the bike, one of the first things I have decided to do is replace the cambelt - although the vendor said it had a new one, I like to be certain.

The issue is that with the dot on the camwheel aligned with the dot on the cases, the dot on the crank wheel cannot be aligned with its dot on the crankcase - the keyway in the crank aligns with the dot on the crankcases.

As far as I can see the dots on both wheels should align with their dots on the cases - although I have seen one article that says align the crank keyway with the dot on the crankcase.

Prior to removing the belt the engine seemed to be running fine - easy to start, settles to a good consistent idle etc, so my question is should I just fit the new belt in the same position as the old one, or is there an issue with the timing that needs to be sorted - I notice that the wheel on the crank appears to have multiple splines in it so could be removed / re fitted in a different position, but obviousley I dont want to mess about with that as my knowledge of these engines is virtually non existent apart from what I have read.

Any advice appreciated.

P.S. Not a club member yet, but I will be joining shortly.

[3potjohn]

Congratulations on your recent acquisition. These are fine motorcycles.
First: have you got a copy ( electronic or hardcopy) of the Blue Book Morini Manual?
Second: Normally the dots should align. This is covered on pages 66-71
Third : Recently a number of folk have found the crankshaft pulley to be loose or worn.
As a result various types of loctite were needed to enable a secure fit of the crankshaft pulley. Thus far my experience has been that the pulleys on both my bikes are a tight fit, however in view of these recent experiences I shall look to using loctite in future.
Some one else may be along to help you...I have some electronic versions of i fo I could email if necessary, and of course if you become a member then the documents library will be available.
John

[mbmm350s]

Hi,

Welcome to the joys of Morini ownership.

Can you post a picture of what you think is the problem please.

The dot on the upper cam pinion should align with the 12 o'clock notch at the crankcase. Then at TDC front cylinder in Italiano Punto Motore Superiore or PMS1 the crankshaft key way should align with the dot on the crankcase in 2 o'clock position. There may be a mark like a dot on the lower cam pinion, this should also align with the keyway it might not if.
1. As you noted the cam pinion is adjustable so has been put in another vernier adjustment position after a valve timing check or to facilitate belt installation.
2. The lower cam pinion has been removed and incorrectly replaced, or even slipped in service a rare event but does happen and very recently to a Devon section member
3. The lower cam pinion was a replacement from another engine which might have different markings.

The workshop manual gives all the details as to how to do the valve timing check and align the pinions if needed.
This can be downloaded from the members area of the club free download.
By the way rotate the engine in its normal direction to remove any backlash due to a sloppy belt, a few degrees error is not important but one whole tooth error in the lower pinion will lead to about 20 degrees ignition timing error which is uncorrectable.
If the ignition pickup is at either end of the adjustment slots then this could be the case and should be fixed.

Cheers
Mark

[Andy_C]

John / Mark

Thankyou both for your replies - I do have a copy of the Blue Engine Manual but not really dug into it yet.

The crank pulley certainly cannot move, and it does not rock on the crank - it seems to be pretty secure.

I have not taken a look at the ignition pickup yet - but Mark I note your comments.

If you look at https://www.real-classic.co.uk/2015/08/ ... video_002/ and at the caption labelled "When the new belt is fitted, check that the top pulley and crankcase mark are still lined up, and that the keyway is in line with the lower crankcase mark." that is exactly how mine looks - keyway lines up with the mark on the crankcase, but the dot on the pulley is one tooth away from the mark.

WRT your comment Mark "If the ignition pickup is at either end of the adjustment slots then this could be the case and should be fixed." I take it that that would be as a result of the crankshaft pulley being out of position. I'll take a look.

[mbmm350s]

If you look at https://www.real-classic.co.uk/2015/08/ ... video_002/ and at the caption labelled "When the new belt is fitted, check that the top pulley and crankcase mark are still lined up, and that the keyway is in line with the lower crankcase mark." that is exactly how mine looks - keyway lines up with the mark on the crankcase, but the dot on the pulley is one tooth away from the mark.

Nothing to worry about, the lower pinion has probably been moved to facilitate belt fitment as described in the manual, really they should have removed or obscured any previous marks and made a new mark on the pinion to align with the crank keyway.
I doubt if there is anything wrong with the ignition timing.
Strobe timing ANT1 at 6000rpm would confirm.
Cheers Mark

[Andy_C]

Thanks Mark, I'll press on and re assemble and the strobe the timing at 6K.

As I say the bike starts / runs / revs / idles fine so would have been surprised if the vavle timing was out - not ridden it yet so cannot comment on power, but given how the engine runs statically I dont expect any issues.

Many thanks for your help - I have an electrical question next for which I wil start a new thread.

Cheers,

[Vitesse]

Nothing to worry about, the lower pinion has probably been moved to facilitate belt fitment as described in the manual, really they should have removed or obscured any previous marks and made a new mark on the pinion to align with the crank keyway.
I doubt if there is anything wrong with the ignition timing.
Strobe timing ANT1 at 6000rpm would confirm.
Cheers Mark

This.

The marks on my 3 1/2 lined up perfectly so when I did a belt change on the Kanguro and they didn't I initially panicked, doubted my own competence, etc. As I removed the old belt it became clear that the bottom pulley had merely been put on with a different groove aligned with the woodruff key, probably to use a groove that had no wear. I put a mark in the pulley by the key and lo and behold, it lined up. Panic over!

[SupermotoDave]

If you put the bottom pulley on with a different grove “ because the original one has worn” you are adjusting the timing. Count the number of external teeth and compare to the number of internal groves. It gives a form of vernier adjustment.