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Motorcycle Discussions => British Bikes => Topic started by: nickjaxe on April 12, 2017, 07:24:29 PM

Title: Bantam B175 Crank re-building.
Post by: nickjaxe on April 12, 2017, 07:24:29 PM

I think my big end maybe on its last throws....the engine vibration that normally comes in at 50...is now coming in at 40mph and harsher.

I have found a guy that will re-build it but he cant balance it...is balancing strictly necessary on single cylinder crank.

I have a tool to measure the clearance in the conrod bearing without stripping the engine..12mths ago is was ind 2 thou inch...3 months later 4 thou...now its 8thou inch...I suppose its possible the needle roller bearing in the little end...that was new 6 months ago...will take a look at the weekend.

Nick.

Title: Re: Bantam B175 Crank re-building.
Post by: iansoady on April 13, 2017, 10:13:19 AM

It shouldn't need rebalancing as if it's just rebuilt it will have the original balance factor.

If you really have .008" on the big end you should hear it clattering. Even more so if t was the little end.....

Title: Re: Bantam B175 Crank re-building.
Post by: nickjaxe on April 13, 2017, 07:03:34 PM

Hi Ian...haven't noticed a noise but Bantams arnt quite.

The tool I use to measure things take a reading off the con-rod both ends combined...so between the two ends there is 8 thou clearance.

Of course it maybe the small end torrington needle roller bearing that give up...I hope so...I will take the barrel off over the weekend and get a better idea.

Its possible it may have to have a new conrod fitted so I believe...so would this erect the balance.

Nick.