Honda Spree and Elite 50 Forums

So heres my set up. 2000 elite with phongeer exaust, #80 mainjet, vaiator + weights, and a derestricted airbox. I had just installed the new exaust yesterday and lost a ton of low range power, yet gained allot of power once it hits 20-25. the spark plug seems to be fine. Iam not sure what to do to get it back. should i put in a bigger or smaller main jet? or a bigger/smaller secondary jet?

clutch springs will help keep the motor in its powerband, variator tuning should help too. are you talking about the pilot jet? if the motor stumbles, hesitates or bogs between 1/8 and 1/2 throttle and then takes off at WOT, first try raising the clip on the needle, then start looking at the pilot jet...if its just slow taking off in general, some tranny tuning is in order.....

Right now it does have tighter springs and heavier weights, but I have a keli variator that i will put on. and yes the pilot jet is what i was referring to.

ouch dude, you should have researched some more first!
thats a 90cc pipe, you put that on a 72cc and you get ok take off. you put that on a 50cc... well you know what happens.

problem is not enough back pressure. Im not sure how you could fix that...

Let me get to the point quickly by saying this. If your bore is 50cc (stock bore), you're going to lose a ton of power so the easiest things to do is...
1. Take off that pipe and run the S pipe (which isn't a bad pipe)
or
2. Upgrade your bore to 72cc.
The PG pipe is a high rev pipe even for a 72cc bore.

Technical Info:

2 stroke motors differ from 4 strokes in such that in 4 strokes, exhaust back pressure is never a good thing. Forget about all the myths about how you need backpressure on 4 strokes to generate torque, the dynos don't lie, not a single car or motorcycle for 4 strokes make more power with more backpressure.

2 strokes on the other hand are a little different, during the power stroke (piston starts its downward movement), the first port to open up is the exhaust port. What's also happening is the crankcase is pressurizing so that when the piston is near the bottom of the stroke, the intake port is uncovered and a fresh intake charge is pushed into the cylinder.

For a moment, both the intake and exhaust ports are open and part of the fresh air-fuel charge is blown out of the exhaust port. Using a pipe that's designed for a much larger displacement motor only makes this issue worse. The exhaust port for 2 stroke engines are open a lot longer than on 4 strokes which means there's a lot of potential for "too much" of that intake charge to be blown out.

Pipes like the PG are tuned for specific applications. On a smaller displacement pipe (like the stock S pipe), the pipe is designed to have a little more backpressure so that the amount of fresh intake charge doesn't bleed like * into the exhaust. (Imagine pouring a liquid into a funnel with a small hole versus one with a much larger hole). The large portion of the funnel is like your exhaust port on your cylinder, the narrow end of the funnel represents your exhaust pipe. The liquid poured into it represents the fresh intake charge (which is supposed to remain in the cylinder) that is getting blown out the exhaust port into the pipe. The stock S pipe is like the funnel with a small hole, it takes longer for the liquid to move through it which allows more of the intake charge to remain in the cylinder. The PG pipe is like the funnel with a wide opening on the narrow end. The liquid will flow through it too fast meaning too much of the intake charge (on a stock engine) will fly out of the exhaust. This is why you feel that huge loss in power. A small amount of fresh intake charge (from a smaller cc engine) is taken in and too much of it is being blown out the exhaust because the exhaust is "too" free flowing.

The internal parts of the stock S pipe "fills up" sooner, pressurizing the pipe, limiting the bleed and eliminating turbulence inside the pipe which allows for a more controlled (smoother) flow. The PG pipe in your application is allowing more fresh intake charge to flow into it (getting wasted) and since it's a higher flowing pipe, it takes a lot more rpms to pressurize that bigger pipe. When a pipe takes longer to pressurize, the interior is experiencing turbulence which is the enemy of flow.

the leovinci sp-3 pipe is the best for a standard 72cc setup!

your problem is your springs and weights you will need to up graded your clutch srpings to polini yellows or blues and change your center spring to a 20% then you will need to change your weights to 45gm I think that you may have 8 or 8.5gm weights that come with a kelly pulley also you should change your ramp to a SEF or daytona2 pg pipes needs lots of rpm to get low end hope this helps