How to make a small engine preform better?

[Bikespot]

As a curious guy i would like to know how to get a small engine to preform better. What i mean by a small engine I'm talking about something around 50CC possibly a pocket bike engine. Something for my scooter.

Also should i put a exhaust pipe or muffler on it? Or would that just reduce the power the engine will put out?


:cool2:

[TEK]

Way too generic. Need more data.....:waving:

If its a 2-stroke an expansion chamber is way better than a straight pipe.

[Bikespot]

It's a 2-stroke

[BlatantAnomaly]

boost it if you want to get really crazy.

[Joe H]

boost it if you want to get really crazy.



http://cgi.ebay.com/144-Whip-Cream-Chargers-Nitrous-Oxide-N2O-Whip-it-FS_W0QQitemZ170138986617QQihZ007QQcategoryZ14310QQ ssPageNameZWDVWQQrdZ1QQcmdZViewItem

There you go, those should do the trick!

Just don't inhale ALL of them:laugh: :laugh:

[Vicoor]

2 stroke engines are very sensitive to air/fuel ratio.

any mods to the exhaust or intake require proper jetting to realize significant gains.

just throwing on a pipe or expansion chamber could result in a loss of power or worse, you could damage the engine.

I would suggest searching the web for more details on this type of modification

[Me!]

use a 4 stroke....

[e_racer1999]

i have an '85 honda spree that we disassembled and are in the process of putting back together (49cc).

a few of the mods that I have done include cleaning up the nasty casting on the "intake manifold", we modded the carb up a bit so that it ran a little richer. i haven't welded YET, but i will be making an expansion chamber to the proper specs. there's a program somewhere on the web that takes all of the measurements for your engine and gives you proper dimensions....

[Rick Moran]

To increase MOST factory 2-strokes performance, you need to increase the flow, in and out. You can't just run a straight pipe though. 2-stokes depend on the "plugging" effect to reverse-pack the cylinder for each stroke, more so in piston ported type intake design. Having no valves on a 2-stroke, their problem is keeping the mix in the cylinder. The piston crown and skirt act as the valve opening closing off the ports. They have a tendency to be an inefficient motor because they waste fuel blowing it clean through. The expansion chamber cones set up a reverse shock wave effect that actually packs a bit more into the cylinder before the piston completely closes the exhaust port. Reed valve motors are a little less sensitive to this action and case-reed induction design can draw air anytime they want.

In contrast, 4-stokes depend on the "scavenging" effect, or complete extraction to get a fresh mix each power stroke. Thats why they are more sensitive to drag pipes when combined with the correct cam/valve timing, carb (of course jetting) and ignition timing.

I have been building 2-stokes for a long time and presently have a toy, a 50cc an '82 Honda Express that I modified for more power, just for fun. I put a Yamaha YZ 80 carb, a Honda 90ATC intake manifold to clear the shock tower, I manufactured a custom, one off, 4-reed manifold to replace the stock little 2-reed and modified the crankcase to accept it with everything ported. I also put on a 70cc big bore kit. There happens to be a market for the the 50cc Hondas and I bought the cylinder and pipe from a place in Hawaii that specializes in scooters. It used to do 23, now it'll go 46mph. I have some nice close up pics of the setup on my work computer I'll post tomorrow.

I graduated from American Motorcycle Institute (AMI) in Daytona Beach in 1977 and I know that things have changed a lot since then. These are generalities of the nature of 2 & 4 stokes engines.

[Rick Moran]

Here are the pics of my vintage scooter I described in the previous post. I took off the saddlebags for the pics. I bought it from an old guy who used it for skeet shooting and had it rigged to carry all his stuff from his car to the range. I use it for a local "market flyer" and to take camping.

I got the used dirt bike parts off ebay. Some specifics for if your interrested are: The air filter is a K&N because I could no longer use the original air filter box. The standard carb is a 16mm and the YZ80 carb is a 22mm. The 4-reed petals were off a Yamaha DT-100 (2 1/2"X2"), The stock Honda 2-petal reed ssytem was 1"X1 1/4") . The manifold is off an old Honda ATC 90. The pipe was made by Proma and has a forestry approved spark arrester/silencer on it. It starts 2nd kick everytime, as dependable as if Honda designed it that way.

I found the place that I got the cylinder and pipe from and I believe they have parts for other scooters. They do a lot of transmission tuning stuff, clutch spring and counter weighting for quicker starts.

http://www.vtcycles.com/main/parts-spree.htm

[MicroZone]

Hit it with some pray and spray power - nitrous!

http://www.callieskustoms.com/CalliesKustoms-Mower.html

[MicroZone]

Here are some funny ones:
http://www.youtube.com/watch?v=psyb38Qk8us

This one is the best:
http://www.youtube.com/watch?v=GL1tA8FXmkg

[fordman]

boost it if you want to get really crazy. You cant boost a two cylce, your effectively boosting the crankcase, which will blow the seals like a motha!! :laugh:

[river rat]

A lot of go-kart guys (WKA Yamaha heavy) build the exhaust with a slip joint between the downpipe and the can. This allows you to change the length of the exhaust system by a few inches. Changing the length effectively rotates the torque curve, shorter = more up high/less down low; longer = more low end for tighter, slower tracks. Once you pick a good can, you can use the slip pipe to tune your scooter to where it runs best for you and your intented uses. You can do the same thing on your car. Changing the length of the collectors (not the primaries) on your headers will rotate the torque curve so you can match it to your shift points or take some out of the low end on a slippery track.

[crl283]

(2 Stroke Wizard) expansion chamber design software. Awesome Program... $40...


www.buildandclick.com

[crl283]

Just some more illustrations. an expansion chamber would definitely help...

[William McCormick Jr]

2 stroke engines are very sensitive to air/fuel ratio.

any mods to the exhaust or intake require proper jetting to realize significant gains.

just throwing on a pipe or expansion chamber could result in a loss of power or worse, you could damage the engine.

I would suggest searching the web for more details on this type of modification


The real problem with a two stroke is that you cannot adjust the timing easily in most cases. If you could adjust the timing you could raise it, advance it, and then add more fuel, jet the carburetor, and if you can, get more air. Often you can get more air with a simple bonnet, that creates a funnel effect above the mouth of the carburetor.

That is what we used to do with car engines when we were younger. We used to drill out our brass jets in the carburetor. We would jet the carburetor and advance the timing to as much as 40 degrees before top dead center. The torque goes up a lot. You have to lower the idle because the engine is just so powerful, that it does not slow much under a load. Like when you put it into drive.

It is like a whole new car. Much more peppy too.


Sincerely,


William McCormick