I'm thinking of going with 4 stroke setup.
I am also checking in to a shifting kit.
I am 51 years old and guess I'm crazy for wanting one of these but oh well.
Keith
Hi Keith, welcome to the forum.
WARNING! These machines can be addicting!
I was ~50 when I built my first one and couldn't stop, to the point of making it a full time business.
A 4-stroke is a good choice if your anything like me, I
might be able to pedal a mile if my life depended on it but I'd just as soon not.
You have to pedal to start a 2-stroke and if it's stubborn you find yourself worn out before you can go anywhere.
The $100 49cc Husashengtaishan (HS 142) 4-stroke is a Honda 50cc knockoff and what most MB kits use.
Since the EPA was shut down for awhile the engine has no 2012 EPA so they threw a sticker on saying it is for off-road only to get them imported.
There things put out far less pollution than EPA required so don't worry about it.
Most parts are interchangeable and meant as a cheap replacement for Honda Portable Generators and lawn equipment and such.
Keep the oil fresh and they will run all day for years.
The hard decision is what bolt on clutch & transfer case to choose for motorized bike use, or if you want to venture into making your own.
There are 2 engine types:
One has a short shaft with the clutch on it.
This takes a transfer case with the clutch bell attached to the transfer case.
The other has a longer shaft with no clutch.
This takes a transfer case with a big hole where the clutch bell goes and you mount the clutch and bell to the shaft yourself.
There is more to it than that but I find the Grubee 4G with 80 tooth freewheel belt pulley that fits on the 142 with a clutch to be best.
Phantom Bike still has a couple I think for ~$350 for the kit.
Next up would be the 7G ghost, it has a crap clutch bushing and no freewheel but it is adjustable, quiet and cheap at $200 for the kit at gasbikes.net
I have built a bunch with both.
You'll want a nice big beach cruiser and you will have challenges getting the motor where it needs to be but that's half the fun.
To shift or not to shift...
I have built both ways and hands down with the 49cc with a 3-speed shift.
It adds $200 but replaces much of the junk in the stock kit as well.
In fact you can just the transfer case you want, by the correct engine for and the SickBikes 4-stroke shift kit all you need is a throttle and gas tank to build a bike.
The thing is it's like $20 difference in price to get all the other parts so I do, and end up using them eventually.
If you want some close up big pics and info on some of my builds this link shows my 4-stroke Shifters
http://kcsbikes.com/KCsBuilds.asp?motor=4-stroke&Drive=Yes
And this shows my 4-stroke Direct Drive builds.
http://kcsbikes.com/KCsBuilds.asp?motor=4-stroke&Drive=No
Bolt type work well, gears just make them more fun and efficient.