I'm think of putting a Mega ZX-26 Sport w/ pull-start in my MBX-5, will fit??
What do you think about this engine??

I think you should get a starter box and a better motor... Most likely the pull start sticks down too much to get it on the lower mounts that are included in a Pro-level kit.

It will fit, though you may need spacers for the reason mentioned by Foamy. Never heard of the engine though so its most likely a piece of crap. I can give you a list of decent pull start engines if you wish or you can get a starter box and use anything you wish.

i have had a pullstart in mine u will have to cut of half of the end off the engine mount to allow the backplate to fit.

Mega engines are from Serpent, because of that i suppose they're not bad.
And they are produced by Picco.
But of course i prefer a RB C6BB or a O.S. Speed.......huahuaha

i would say, if you don't want to race and just want a bashing engine, a Hyper engine would be gd. Or, if you want to go cheap, a leo engine. http://www.justengines.unseen.org/Leo.htm