Jackshaft kit?

Dirt Road Cowboy said:

Hey KC - That's a nice looking exhaust setup you've got there!

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Thanks ;-}
It's an SBP X-chamber, I just plumbed the parts different.
I didn't want it the standard way, with the chamber under the BB so by assembling the parts different I got it to go above the BB but the silver muffler was pointing up at the back of my seat like this.



So you can see how it's plumbed with all the SPB X-chamber parts...



Note the long straight piece of copper pipe...
These pipe come tuned for a low end power band boost on a 48cc motor.
You move the power band boost up by cutting that piece shorter.
I moved mine up to 3/4 throttle on my 66cc by leaving only 1/4" of that straight pipe showing once connected.

It was just too loud with that pipe pointing up so I added that big glass pack.
What is important to note is the pipe tuning is also dependent on the final exhaust back pressure as well so I had to keep that intact.

It looks like this on the inside.



I just took that aluminum silencer off (pop the two front rivets) and cut the end cap flair down some, then I just stuffed the inside perforated tube and it's fiberglass up into my custom 2" diameter curved end section.



By directing the final X-chamber exhaust out in to a secondary glass pack it not only muffled the sound volume, it changed the pitch by drawing out the sound pulse with the wider pipe yet it doesn't hamper the flow.
The result is a pitch more like a 4-stroke motorcycle than a weed eater, and I pass people walking on the sidewalk (me on the road of course) @35MPH and they didn't even hear me coming.

Just some last words of wisdom...

'How FAST will it go?' is always the first question out of everyone's month when they ask me about my bike. Top speed is just a dumb measure like comparing a Lamborghini to a Ferrari, who cares if they can 200MPH when you can only get away with maybe 100MPH in a car on an empty highway for a few miles?

In my humble opinion from building and riding these for awhile now, it is all a simple matter of getting up to cruising speed quick, and then being able to maintain your comfort level speed safely, comfortably and reliably on a given roadway for as long as you like.

Other than a couple of other bikes I built or helped build that can run with mine, nothing I have ever ridden or rode with fits that bill for my riding taste like my bike, but that's what it's all about right?

I guess my point is don't get caught up in 'high score' numbers.
Build to suit your own 90% riding time and get the things you think would make more enjoyable and comfortable.

KCvale said:

Who is THEY?
They may be talking about using the 'Basic' JS kit, I would tend to agree with that, the freewheel is light duty and won't take much, I don't know as I have always used the HD kit on every build.
The only real difference in the kits is the HD freewheel, that sucker is $65 more than the light duty one and the big difference in the kit price.
But the slant head thing? That makes no sense at all.

I have been running this 66cc slant head putting out over 3.5 HP to a NuVinci hub via HD JS for over 500 Miles now and built 1/2 a dozen other 66cc JSed bikes and just ordered another kit this morning for yet another 66cc build.

Yes, the pedals turn the motor directly the same as the rear wheel does on a direct drive, in both cases you just lock the clutch in to pedal without the motor.

Starting a JS'ed bike is different from a direct bike however.
With a direct drive bike you pedal up to speed and when you drop the clutch you have the bike momentum to help you start the motor.

JSed bikes all have freewheel back wheels so you get no bike momentum, in fact you can roll your bike forward with the clutch out all you want.
To start your bike you have to use the pedals much like a motorcycle kickstart.

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My tfr kinetic and peugeot 103 were exactly like that. You had to turn the pedals to get the motor cranking. So does this essentially turn a bicycle into a makeshift moped? Thanks for the incredible knowledge here, very awesome thread guys

TheRealDune said:

My tfr kinetic and peugeot 103 were exactly like that. You had to turn the pedals to get the motor cranking. So does this essentially turn a bicycle into a makeshift moped? Thanks for the incredible knowledge here, very awesome thread guys

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Wow, way old thread, I've built 40 or more shifters since that shifter rebuild in 2011.

Any SBP shift kit motor shifting is done by the bicycles back wheel not the Jackshaft, if you don't have pedal gears you won't get JS gears and front chainring sprockets don't count as all of that gets replaced with the freewheel pedal crank arm assembly and it's two sprockets so the pedals don't beat you to death when the motor is powering them ;-}