TOPIC:

Probably a silly question.............

I have just acquired a 1956 G175 from Italy. It has been previously restored but not used for some time. I've just had the wheels off to fit new tyres and am puzzled as to the correct procedure for adjusting the drive chain. The brake drum and sprocket are held on a short hollow stub axle secured against the swinging arm by a 24mm nut. To tighten the nut there is a hole in the inboard end of the axle for a tommy bar (to stop the axle turning as the nut is tightened). With the wheel in place on the brake drum/sprocket the main axle passes through the stub axle and swinging arm and is secured as usual. To adjust the chain the main axle is loosened along with the stub axle. However, the stub axle then turns when retightening and there is no way I can figure out to stop it.

Thanks,
Simon

It took me a while to figure it out on my 1957 G175. You will see that the brake plate also acts as the stay/torque arm and is secured by a set screw. This limits the range of rear wheel movement when adjusting.

I think the large nut on the stub axle does up pretty tight on mine but can't remember if it still turns, at least once once the spindle nut is tight.


I would check, but I'm out of action with a crocked hip at the moment.

Nonsense. I blame my medication. It's oddly the chain guard that acts as the brake stay I think. I suppose the question is the wheel secured tightly once the spindle nut is good and tight?

Sorry to hear you're laid up for a while and thanks for your reply.

The brake plate has a boss that locates in a slot in the swinging arm that acts a a torque arm. Having looked at the wheel spindle arrangement again, I think if the main spindle is tightened as usual it will secure the wheel even if the stub axle nut is only "finger tight".

Ah yes. Though as the chain guard is mounted on the brake plate I've found you have to loosen the screw at the other end in order to change the chain tension.

I got a new rear sprocket made for mine. No pattern ones to be found so I got an MX place to do an alloy one from dimensions. Even with a new chain I couldn't get the wheel as far forward as I expected due to the guard limiting range without modifying the slot. Might have another sprocket made with 1 more tooth as since I got the correct 2.50 tyre on the rear it feels slightly over geared.

Another question.
My G175 has a Dell'Orto MB20B fitted. I'm having issues with the bike not wanting to run without choke- spitting back through the carb. Is this the right fitment for the 175 as all the information I can find refers to a MB22B being fitted.
Thanks.