I think its a 100mm three jaw stanley brand from supercheap. Cost me less than $50 if i remember right. Does a good job.
If you modify the heels on the hooks on the end of the jaws slightly with the ginder it will even do the victa bosses on the short shaft Tecumesh motors.
Ive got a bigger two jaw I do most stuff with, but that stanley has done a good job. Guy at the mower shop told me it was the one to get. Its never not got a boss off that I have tasked it to remove.
Go and buy a couple of spare 3/8 UNF bolts. 2" & 2 1/2". If you have a lathe, drill a point into the top of the bolt head to locate the nose of the puller shaft. If you dont have access to a lathe you can do the same with a drill press reasonably acurately. You could do the same with a hand drill too i suppose. It does not have to be real deep just enough to stop the puller walking.
Put the bolt in the crank and wind it in a fair way. Ring spanner on the head of the bolt. Put the puller on. Then as you wind the puller the spanner will hit the arm of the puller and stop the bolt winding in any further.
It has been posted on here that another option is to clean up the cranksahft above the boss, the drive the boss up the crank, clean where it was on the crank the slide if off by hand.
Ive had limited succes with this, works well if the shaft is in fair shape. If not its a hell of a lot of work.
Cheers, Bob.
