PGO T-rex 50 to 90cc build?

[sunia]

Hello everyone, this is my first post here but I’ve been lurking around for a bit, and was just wondering if anyone had any advice on whether this project would be feasible or not. So my neighbor recently gave me an 06 PGO T-rex with a long case horizontal minarelli motor. I have split the crankcase apart and removed the stock crankshaft, and the diameter of lobes measure out to 72mm , with the cutout in the case measuring to 74mm in diameter. There is only 4mm of meat in between the case holes and the inside of the case 5 would probably break into the holes. I just wonder is it realistic to try and stuff a 44-45 mm stroke crank inside this particular motor? I’m willing to take the time and spend the dime (but hopefully not spend too much money lol) to see this project through if it is even possible at all. I truly appreciate your time and for reading this.

[190mech]

Lots of info here;
49ccscoot.proboards.com/thread/10392/cutting-cases-accept-cranks-matching

[sunia]

Thanks for the link, I’ve looked through a few of the builds on that topic before, that’s how I came to making this thread in the first place. I guess I was hoping someone would give me a simple “yes or no” answer (silly me). After reading through some more of the 90cc projects last night and sleeping on the whole idea I realize there’s so much more that needs to be taken into consideration than just crank clearances. Me having 0 experience fabricating or machining anything I don’t think it’s wise for me to try clearance the cases myself although I really would love to take up the challenge. Even though I got this scooter for free I would hate myself if I ruined the engine and I think that with my lack of experience it is a risk I just shouldn’t take atm. I was planning on replacing bearings and the stock crankshaft anyways with something a little more stout so that’s why I have the cases apart. It’s worth mentioning this is the first time I’ve ever split a crankcase before, I’ve installed an 83cc big bore kit on my qmb139 scoot but that’s about it. I’m not sure if I should continue this thread or not because I think I’m just going to get some decent made to fit the parts and get the T. rex back on the road again. It would be nice to have a documentation of the process for myself and anyone else who might be interested but this project now seems like it’s gonna be a lot more tame and lame compared to a 90cc!

[aeroxbud]

Start a build thread in the build section. A lot of builds on there started out very tame. But over time they take on a mind of their own.
It's always useful for other owners to see how a build went. And the end results.