Hi guys NEW here and got a question about engine sizes.
 

Hi all! I have a 2011 Tomos nitro 50cc currently with a 80cc bbk. And i was wondering what is the biggest cc size engine i could drop in this without any modding of the frame, basically just a drop in. And has anyone tried the 100cc longcase complete motor from scrappy dogs? if so how fast did you go and what bike did you have. cause i might get that. My goal is a cruise speed of 50 but not to have it wot so maybe a max of 60.

Firstly, Welcome to the Forums. :cheers:
Tomos' are nice bikes.
As for a BBK, 80cc is the biggest you can go to without actually having to machine the case bigger. If you get a stock 90cc case, you could go to 115cc.
For better top speed, go for a larger Variator face, change your Varo weights, and get an unrestricted CDI.

You can go to the 100c kit, but with a stock crank your actual size is 81cc with the 100cc kit. These kits commonly fail because of the high compression, matched with a correct 100cc head and not a re-machined 50cc they do great, I usually get about 50mph out of a 100cc bbk, With the stroker crank from Scrappydog you can get 87 true cc's, and it is much better quality than stock Chinese parts

I don't have experience with the 100cc long case engine but I do have the 80cc short case (147QME) in a TaoTao T3. I dropped it in and not broken in yet I have gotten it to 48mph with my 6'1" 235lbs tail on it.

I have the 50mm bore a9 cam with 69mm valve with ported head