i've herd of guys using the air pumps meant to push air into a car's exhaust for emissions as mini turbos. they can even combine several in series.

Yonuh, I grew up in the era of ram air and big pistons. It worked well, so I believe ram air or maybe a small supercharger might work. The turbo works better IMO with fuel injection. What you are proposing sounds more like an electric supercharger. One thing's for sure. The hp gained wouldn't hurt the lower end of the 650.  To get some good info just Google "Go Kart Turbos". Pricey. 

The idea of an electric fan boost is a good one and is being pursued by some major companies.  The usual application now is for direct injected 2 cycle engines.  The electric fan supplies air for scavenging and once the rpms of the engine get up a turbo takes over the duties.  The two cycle engine is close to making a come back.  They want to bring in clean air for combustion and leave the oil in the crankcase where it belongs.

It takes a powerful fan to create positive pressure at high flow rates.  Axial flow fans like those in cooling applications produce a lot of flow but very little pressure.  Even a furnace blower or bathroom exhaust fan has to be centrifugal just to overcome the resistance of the duct work.

But it's worth thinking about.  If you Google with something like "latest 2 cycle designs" or "direct injection 2 cycle" you will find lots to read about and some of it will mention the electric blowers.

It won't work because it will make the carb tuning out of whack. The fan can't compensate for throttle movement. It will obstruct air.They make air cleaners with little fans in them that does boost air flow into the carb. Its shaped like a funnel, but it doesn't do much because you can air lock the carb. When you slam the throttle closed. where is all the air trapped in there (under pressure) gonna go?? Into every hole it can find! Guess what happens when you pressurize the bowl of a carb??
Thats why you have sealed air boxes that encases the entire carb on accessory mount (blow thru) superchargers on carb equipped engines. They also have a pressure dump/compression release when pressure builds in the box that the engine doesn't want or can use.

A better idea would be to make a longer intake manifold to give it more runner length and get the carb out into the wind. Or make a split manifold and use 2 smaller carbs....Kinda like the manifold on a Solex twin throat carb....

justin_o_guy2 wrote on 03/27/11 at 19:02:50:

No, it needs to be able to flow faster than the the cylinder can fill. My stock SE air cleaner on my 1200 Sporty has twice the area than the 2"x4" filter I run now. The advantage to my air cleaner is that it acts like a secondary venturi and actually moves more air. No stagnant areas that allows the movement of air flow to slow down or hinder flow in any way.
I ran one of these...



Which I made a mount and bracket that left the carb throat unobstructed and seems it should flow lots of air. Well, it does, but it also creates lots of turbulence.

So now I modified and run one of these cheap $12 Mr Gasket air cleaners with a K&N filter....It made 3hp and 4.7ft/lbs. It also took out a rich issue I had between 3400-4100.


And it also gave me more leg room...this crowded me pretty good. Hopefully I'll get some pics up of of by before and after...all these are before

ditch the air box for pod filters, yes.  Most upgrades for bikes start with either an air box mod or deletion.  Leave the fans for radiators, oil coolers, computers, air conditioners, and hair dryers......