make your own torque pipe

[SuperDave]

Yes! That is almost EXACTLY like I was thinking! I hadn't thought of waffling the intake tip but that might help with decibel levels.

I figured if I had thought of it so could someone else.

 

[SuperDave]

The bike is now running but just with a bir of silicone hose from my car as the header extension as i havnt gotten around to getting some pipe to weld in yet.

The low down torque is great especially with the shift kit but because i have the shift kit id like some of the power up a bit higher than you would on a single speed, would a shorter header move the powerband up a bit?

any idea what length i should use for decent top end power but not losing too much low down torque?

Sweet setup! If it were me, I'd dial up the motor for low end & midrange grunt, you got gears to keep that thing in its powerband.
As fun as my bike is, I've really no wish to spill at 60. I'd feel different if it had a suspension, but a rigid frame with all that top heavy unsprung weight does effect handling the faster you go.
But Jaguar's right, Start long, say 28" and ride it. Cut 2" off and ride it again. Repeat as necessary until you find your sweet spot. The longer the header, the lower the hit. That's why racing pipes have a short header, some even come directly off the port itself.

I'm no engineer, but I'd have to guess that thing you have with that long header, expansion chamber & gears would have enough torque to yank the front tire! If you get that thing dialed in, I'd hang an intake extension on it and pick up some more low end grunt.

 

[Deleted member 12676]

the belly stinger is welded shut at its beginning so as to not receive any of the strong front of the sound wave. The entrance to it is via 4 holes drilled in its side at the beginning of the tube. I think its a good design. I just need to measure the difference once I find or make the time.

 

[fx-2]

Well I just did it . About finished with the pipe . Bike should be running in about two weeks .

 

[Deleted member 12676]

should be a torque monster when you're through! I like that intake extension as well. Head looks trick. Any other important modifications you want to tell us about?

 

[fx-2]

Well lets see . I built motor last summer . It's Jet 66 cc . New crank bearing a wider upper rod bearing .Mild port work , case matched to cylinder . Piston cut at intake port a little work on top at transfer port . Puch 70 cc hi compression head , It's cheep an more cooling . Rt carb on a 6 inch self built manifold , Jaguar cdi and now the pipe .

 

[MikeyMotorBikey]

Hey jaguar First off thanks for all the FREE information you share and all the long meticulous reasearch you have done. its Been the ONLY reason I have done any mods to my motor cause its not just your opinion you are scientifically going at this. I went ahead and made a Torque Pipe, was very skeptical as i was making it as to the benefit but WOW my bike is actually very fun to ride now! AMAZING! It is loud i went with the belly stinger. Im not getting what you did here quoted below.

the belly stinger is welded shut at its beginning so as to not receive any of the strong front of the sound wave. The entrance to it is via 4 holes drilled in its side at the beginning of the tube. I think its a good design. I just need to measure the difference once I find or make the time.

 

[Deleted member 12676]

There's two types of belly stinger; 1) the stinger runs along-side the pipe with its source being a hole in the side of the belly, 2) a stinger pipe running inside the pipe, originating inside the belly (see drawing at post #50 in this thread) with it accepting pressure not from the beginning of the tube (which is welded shut) but from holes drilled in the side of it.
#1 gives the most torque but #2 is more silent

 

[MikeyMotorBikey]

Muffler placement

For the muffler would you just weld it to the end of the stinger? what type of stinger would be better belly or internal or does it matter?

All the pipes sold for these engines are made for pocketbike racers, not for low rpm single speed street bikes. A racing pipe only enhances top rpm power (if the header length is correct for the engine specs and top rpm). My latest design enhances low rpm power without detracting from top rpm power. I´m giving the design away here. Pipes arent too hard to make. Just takes patience and determination. The sheet metal ideally should be steel of .7mm thickness. Someone told me that the steel from a water heater is just about right. If you buy a sheet then it should be the kind that rusts since it is easiest to weld. You can use tin snips to cut the pieces out. A computer program can printout the pieces on paper that you can use as patterns. I use a rubber mallet, pliers, and needle nose pliers to bend the pieces. I use a bicycle fork to bend the pieces onto by hammering the piece while it rests on the fork. Other metal cylinders of various diameters can also be used. You will need to find someone with an oxyacetylene welder to weld it together. Emphasis to them that it needs to be lightly welded so that little "slag" extends inside the pipe. For an upswept pipe you can cut off the std muffler for the first section. Second section is only the curved header pipe from a standard muffler, 6.5" long (centerline). This sets the correct tuned distance for around 6000 rpm max. For a muffler you can make a cylinder with removable metal scouring pads inside it. Just put small holes in the end of it. Less holes is less noise.
There is no feeling equal to having your own handmade expansion chamber on your pipe and feeling the difference it makes. I knew nothing about making them but I just dived in and did it. Anyone with one brain and two hands can make one.
I used my newly created Excel files to come up with these dimensions. Click here to read about how expansion chambers work and how extending the last cone (the baffle) extends the pipes powerband.
enjoy
View attachment 45123

 

[SuperDave]

For the muffler would you just weld it to the end of the stinger? what type of stinger would be better belly or internal or does it matter?

Yes, weld muffler to end of stinger end.
Internal stinger is quieter, but external(belly) stinger makes a bit more torque. Which is better depends on what is more important to you, silence or power. Loud pipes attract cops, if they are on foot then the extra torque might help you outrun them, but if they are in a cop car then you're screwed. I prefer silence myself, but I've been told that I'm weird.