Honda Spree and Elite 50 Forums

cf_z wrote:but boost is more fun, guys.

make it happen and you will be a hero

You cant make it happen for reasons already explained, you might see boost at the manifold/crankcase but no pressure will build in the cylinder BECAUSE THE INTAKE AND EXHAUST PORTS ARE OPEN AT THE SAME TIME ON A 2 SMOKER. Now a power valve setup changes things but I have never heard of any peds using one.

cf_z wrote:but boost is more fun, guys.

Personally I'd prefer a finely tuned all motor setup over a FI setup anyday. Granted the spike in power can be fun in the straights there's no fun or skill involved in cracking open the throttle wide open on the straights, any goof can do that. The real speed is in the sections where turns are involved, and I've never, not once, ever seen any bike that's on boost that was faster than a ultra high revving all engine unit.

i say turbo! dont do the supercharger way to much drag on the motor.these motors have a very light rotating mass not good for a charger. the best setup would be to ditch the carb and run a small throttle body. the fuel injection would be controlled by something like micro squirt. that way you could tune it properly.

http://www.sdsefi.com/features/apr00stool.htm

wheres the power valve on this?
http://www.youtube.com/watch?v=GGXcM9evUpo

biggest problem would be finding a turbo small enough. you would still need a bore kit to get the dissplacement up enough to have a shot at spooling the smallest turbo you could find.

Kenny_McCormic wrote:You cant make it happen for reasons already explained,

im not really sure where you got this in your head (not saying its not credible to some extent...), but the most powerful engine(s) in the world are 2 stroke turbocharged diesels.

i need to find a turbo that size losthope!! then im game!

Upon further thinking you might get SOME boost to the chamber if its got a fairly small exhaust outlet(tuned pipe, you would be pressurizing the pipe, that probably how the vespa is getting the gain it does).

The turbo 2 stroke diesels need the turbo to clear the exhaust out. They are a completely different animal compared to the 2 stroke gas engines we are working with. Some searching around found this little bit of info on them

The 2 stroke GM turbo diesel in the nuke plant I worked in had a single exhaust valve at the top of the cylinder and ports at the bottom of the cylinder bores for intakes. Thus the intakes were only open when the piston was near the bottom of it's stroke. The turbo was clutch driven to develop "boost" during start up.

I have been told you can get small turbos made for nitro RC applications, although I would rather just buy some glow fuel and a beater spree to see how long it can hang on(jetted properly of course)! Can you imagine 20-40hp out of a spree?

Kenny_McCormic wrote:Upon further thinking you might get SOME boost to the chamber if its got a fairly small exhaust outlet(tuned pipe, you would be pressurizing the pipe, that probably how the vespa is getting the gain it does).

the turbocharger IS the restriction in the exhaust, so it will almost be compating itself to slow the exhaust leaving, and still force air into the chamber during BDC.

i think it'l work

That does make sense, but all automobile turbos are too big for our purposes. I'm told a smog pump makes a good briggs flathead supercharger(and they fit nicely on the ones from the 70s with delco starter/generator motors) using the stock carb in a pull through setup, still probably too big for our purposes.