ORIGINAL: HerrSavage

I know your problem well.. I'm also running a Mach engine from a Muggy..

The problem is 2 things - the stupid Hyper mount, but also the Mach backplate, which is just ridiculously big.. You must have a ridiculous number of washers to make it fit...

Basically, these are your options:

1.) Go with a starterbox.. This is what I did.. I only use my Hyper for the track though, so the whole starter box hassle is just part of the deal.. For bashing I understand though - boxes can be kind of dumb.. The Mach is an awesome engine IMO.. To do this you need part number SWK8057 (type it in at www.amainhobbies.com , and you'll find it..), and yeah, the box with batteries.. The closed backplate bolts right up, no modding, and then your Mach will fit the engine mount perfectly...

2.) Convert to rotostart. You can do this - theoretically - with the rotostart backplate for the XTM 247 engine.. I have this backplate too, but have never tried it..(And don't think I ever will.. My LRP OWB is slipping like crazy - and it gets annoying..)

3.) Get a new engine.. LRP Spec 3, Picco 28, etc have smaller pullstart backplates than the Mach.. I made a Picco fit, but it still needed washers..

Anyway, my advice is just do the starter box.. It's kind of a pain to transport, but ultimately it does eliminate the hassles of a pullstart - it breaking, or a slipping one-way bearing.., and is just all around more reliable.. You'll get a few more RPM's out of that Mach too.. Then later, when you replace the Mach, you'll have many more engine options, cuz most engines nowadays are for starter box anyway.. Good luck..