Yeah, it figures that I would end up with one that has an oddball size insert. Might have to go to a 3" bell like you said. It works pretty good. I have it set up with 14 3800 mah nimh batteries. It started my Echo 58cc single ok, and does really well on 20 to 45cc engines, but it won't start my homemade Echo 48cc twin cylinder engine. I think the batt's are getting a little tired though. I've been thinking of picking up a couple of cheap 2200mah 3 cell Lipoly batteries to run it. 14 of those nimh batteries weren't cheap!! But.... I need to find a new insert. Good thing all my engines start fairly easy by hand. I just like to have the electric starter as a backup in case one gets stubborn and I run out of patience...

AV8TOR