3 1/2 - 500 cranckshaft balance.

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rrr1980
Posts: 3
Joined: 08 Aug 2017 14:36
Location: Italy

3 1/2 - 500 cranckshaft balance.

Post by rrr1980 »

Hello everyone,

I would like to share with you my balancing experience on engines of 3 1/2 and 500. You can find here the instructions (written in Italian).

http://www.morinispecial.it/joomla/foru ... -OPERATIVA

The method works fine, I hope you can translate them into English.
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Ming
Posts: 798
Joined: 01 Aug 2014 16:32
Location: France
Location: Central France

Re: 3 1/2 - 500 cranckshaft balance.

Post by Ming »

Wow - very thorough (I used Google Translate on the web-page).
I hope I will never need to use those instructions, though!
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72degrees
Posts: 1549
Joined: 31 Aug 2007 21:24
Location: West Midlands

Re: 3 1/2 - 500 cranckshaft balance.

Post by 72degrees »

Ming wrote:Wow - very thorough (I used Google Translate on the web-page).
I hope I will never need to use those instructions, though!
Agreed. It's only after getting back on a wee vee after riding the ER6n (180 degree crank with balance shaft) that I realise that they do vibrate more than I remember when I first had a Strada. That was after an AJS 650 31CSR though and all things are relative ("four inch handlebars")!

Putting a 350 in a 250 frame seems to allow the vibes to reach the parts (mainly the handlebars) more - possibly because of the front engine mounting being only 3 point rather than 4. The project engine is a little smoother than the 375; as it should be considering it has a reground crank and all new bearings, but perhaps the 'big bore' pistons affect balance very slightly. I do wonder if I should have the 375 apart or simply take the bottom end to NLM for their ministrations - but I'm not sure my wallet could stand the shock of either scenario. It was rebuilt by the late Phil Smith so long ago that I can't remember what it was like just after that. It's OK bumbling along but if forced to keep up with motorway traffic for long, despite having bar end weights on the OEM 2C adjustable bars and 'decent' supagrip grips, it does get the fingers a bit tingly. Being a Morini, however, one strategy is to just grip the bars very lightly.
Butch
Posts: 94
Joined: 15 Oct 2016 16:47
Location: Essex
Location: Mid Essex

Re: 3 1/2 - 500 cranckshaft balance.

Post by Butch »

Interesting to read thoughts on 'buzz' here. I'm new to Morinis and finding my Camel quite vibey at higher revs. Cruising at engine speeds approaching the red zone particularly so.
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