Crank end float

Hi John,

As there hasn't been a response yet to your question, here's the information from the factory manuals.

Please note the different specification for the Mark 3 electric start model compared for the earlier 750/850's. Second photo is for the electric start models.

You can worry too much. I would just carry on riding it. It's clearly working just fine.

John Hudson reported that he often came across newly built Commando engines with up to 40 thou of end float in their crankshafts. 

If the engine has twin roller mains fitted, the potential problem can be that the 6 start oil drive worm can push the crankshaft side-ways. This in turn can lead to premature wear of the crankpin corners if the big-end shells rub against them. Also  the engine can emit a clicking sound if the inner roller race strikes the rollers themselves. This sound is similar to a loose pushrod end or worn conrod small end.

My first Commando which was an original low mileage bike way back when, had around 40 thou end float but it never caused any issues. I fitted an Alton to my present Mk2 years ago and don’t remember even checking the end float. Looking through my Alton instructions I can’t see any mention of checking end float unless this is a recent update, therefore I wouldn’t think you have anything to worry about with your bike but why not check with Alton to be sure anyway.

Best regards, Al.