Mighty Boy Gearbox

[peterg]

I have recently purchased a Mighty Boy. It has an F8B motor and manual gearbox. The gear box is jumping out of third gear. I have another gearbox but I'm not sure if it is from a 543cc engine or the 800cc engine. Is there any difference in the gearing of the 500 or 800 gearboxes? If there is, are you able to tell on the outside of the gearbox what the difference is between the 2 gearboxes? Thanks.

[KEVIN]

Yes there is a big ratio difference between the two boxes, can be very hard to identify check the forums it has been well covered. Also check for worn linkages to make sure it is properly selecting gears. Best of luck.

[Brayden]

Besides worn linkages, worn out engine mounts can also cause the gearbox to jump out of gear or make gear selection more difficult.

[peterg]

Thanks for the Info. I was able to figure that my spare gearbox is from an 800. The engine mounts are good. Something definitely wrong inside my current box. I have only had this car about 6 weeks. The last owner didn't love this car much. Certainly not like his Ebay description. It is really fun to drive. The engine seems really good. I would like to know if there are any tips to get any more power out the 800cc motor. I Don't want to try and turn it into a killer. I just want to get it running as best as it can. I'm going to go to Albury for the Mighty Boy cruise. I hope there are plenty of Mighty Boys there.

[Brayden]

I would like to know if there are any tips to get any more power out the 800cc motor.

The simple mods are a better carby and bigger cam. Beyond that, bang for buck tapers off very quickly. Forced induction is the answer if you want a decent kick in the pants.