Can I put this engine on my bike?

Hey all,

I have a 2 stroke china girl from bikeberry.com with a bunch of aftermarket parts like the piratecycles sprocket, etc. The engine is losing compression and idling really high. I'd prefer to just switch to a 4 stroke at this point, but I don't want to part with all my aftermarket accessories that I put on my current build.
I had a conversation earlier with some people on this board about whether I could switch to a 4 stroke and re-use some of the parts, and many people insisted I couldn't. But I noticed the drive chain is the same (415) on the following: http://www.rawmotors.com/Bicycle-Engines-Only/HuaSheng-49cc-Engine-Only-4-stroke-p241.html
If I took off my 2 stroke engine, and popped this on, would it not work? Is it not that simple?

Look forward to hearing your input

-VT

Here's an old pic of the set up. Basic china girl setup. A few things have been upgraded, but this should give you the basic idea:


Here's a pic of it now, minus the engine:



Here's the pics on postimage . org in case those aren't accessible:
http://postimg.org/image/if4rnqqcf/full/
http://postimg.org/image/5j9uxsbjr/


Thanks,

-VT

Yeah I love the Del Mar. The fenders don't hold up real well, but I've heard most fenders are garbage anyway.

But anywho, do you know if I can just buy the 4 stroke engine by itself (minus the kit) and install it in place of my 2 stroke? (Meaning, can I use the same sprocket, same chain, etc.?)

Thanks,

-VT