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So this afternoon I was working on fitting the new numberplate to the bike now that she is fully registered and taxed and at long last ready for the road. The bike had been laid up all winter with all the major work complete, or so I thought. It may be worth knowing that the bike has not had any real road time other than 1-2 mile test runs on my local country roads since I started to restore it.

The problem is that at idle the bike sounds good but once the engine picks up above 2k or so there appears the sound similar to a bearing that is spinning too fast or is worn. It comes in and does not build to that sound and it stays through the rev range but once the bike returns to idle it disappears. The sound is metallic just like a fast spinning bearing that is too dry or worn as if the inner bearing race is slightly off centre. Hard to describe but anyone that has heard this will know what I mean. The noise has never been there in the past but just started after the first start after the winter.

What I don't understand is what would be spinning in the engine at those sort of speeds. Could it be a vibration and not a rotation causing the noise? I don't like it and don't think I should run the engine much more before getting some advice or input from other learned members.

Mr Compton if you are out there, do you have any clues for me?

I'd recheck the rocker gear for end float and clearances as a starting point, and try running with the small clutch cover plate off and the generator side casing off to try and pinpoint it. Far be it for me to suggest not wearing a skid lid.
I had a terrible noise on my A65 (I know what you're thinking!) and it turned out to be a metal strip on the tank vibrating, so it may be something like that,there may be a witness mark to prove it. Hope you don't have metal in the oil.
best of luck.John

Have you checked if the noise stops or changes when you pull in the clutch lever? In my experience those kind of noises are more often associated with the clutch, gearbox or primary, so it's worth a few experiments to try to see where it's coming from. Also try it de-clutched but in gear. Good luck!

3potjohn wrote:I'd recheck the rocker gear for end float and clearances as a starting point, and try running with the small clutch cover plate off and the generator side casing off to try and pinpoint it. Far be it for me to suggest not wearing a skid lid.
I had a terrible noise on my A65 (I know what you're thinking!) and it turned out to be a metal strip on the tank vibrating, so it may be something like that,there may be a witness mark to prove it. Hope you don't have metal in the oil.
best of luck.John

I had an awful grinding noise at certain rpm on my T140 Bonnie, turned out to be a loose front mudguard stay. Up to that point I was convinced it was coming from the exhaust camshaft!

I did check that. No difference with clutch in or with bike in first or second gear. It does sound like it could possibly be a vibration, resonance noise but it sounds close to the engine.

First thing to do is check the engine mount bolts are tight, it's probably not that but it's easy to do and it's a step on the journey of discovery.

All the obvious things are done. I have ordered a mechanics stethoscope to try and locate the source of the noise. Any and all help is welcomed.

I had a noise that only came when the engine revved, turned out the rubber at the rear tank mount had moved and the tank was vibrating against the frame, sounded like the engine though.
Alan.

Bison beat me to it, I had that after the rebuild of my Strada, it only kicked in at higher frequency and took a fair bit of padding to resolve. But scared the sh*t out of me on the first proper run.

So I thought it would be a good idea to close this thread with some good news and some advice for other like minded fettlers of the Morini. Yesterday was the first available and dry day I have had to take the recently completed 350 Sport for a proper run. The noise in this thread was still present even after much investigation so I decided to take the bike for a proper run and heat everything up properly, test everything properly and generally see if a decent run would put an end to the noise.

My first (close to home roads) run was about 7 miles and everything went well. I returned home to hop off and check all bolts, pipes etc. Two things had changed during the run. Firstly the slightly rough rear carb which up top this point always seemed a little lean was not happily idling and the bike would sit running. Secondly the 'noise' had gotten a little worse. Concerned I stopped the engine and again started to look. Nothing appeared wrong. After a cup of tea I wanted another go so I kicked the bike, she started perfectly but I caught my jean leg on the kickstarter and held it down by mistake. The 'noise' got worse. The penny dropped and with a 13m spanner and a little adjustment, all my worries vanished.

You guessed it, I had put too much pre-tension on the kickstart lever when I last fitted it and the position was such that it was only just trailing and causing the noise. Something so simple. Tea drank, noise removed I headed out for an hours fun on my new lady. The bike is so light, manoeuvrable and fun to ride but then you already know this.