First build: Two stroke 80cc mountain bike with jackshaft

Hey guys! Glad to have found this place.

This week, I started my first build, a Wildcat PK80 with a Sick Bike Parts jackshaft kit. The base is a 1997 Gary Fisher Mamba that belonged to my mother...she was about to throw it out, but I saved it from this grisly fate to give it a second chance. Right now I'm waiting on the right size chain breaker to show up; in the meantime, I plan to hang out here and pick up whatever tips and tricks I can.

Eventual plan is to add a complete electrical system with headlight, brake light, speedo, and horn, possibly with a dynamo. The grip shifter dangling off there will most likely become a tank shifter.

 

[Chainlube]

They're staying. My mother bought this bike brand new in 1997, and it was handed down to me as my first real bike, so it has a fair amount of sentimental value. I want to keep it looking as close to its original form as possible, and those bar ends are just too iconic to get rid of.

So, are you going to cut off the end of the throttle grip?

You'll have to look into a bolt supply house to find your metric threaded rod.

 

[FurryOnTheInside]

Is ebay no good for hardware there? I am in a supposedly metric country but there are no proper hardware shops, only consumer product outlets, so I am always turning to the evil bay for nuts n bolts, and everything. The post office makes a lot from my hobbies.

 

[Captain Rainmaker]

So, are you going to cut off the end of the throttle grip?

You'll have to look into a bolt supply house to find your metric threaded rod.

That's exactly what I did. Lopped it off with a hacksaw and filed it smooth.

And that sucks about the threaded rod. My dad knows a guy who owns a machine shop here in town; maybe he could just turn me up some new studs.

 

[Chainlube]

If the throttle binds against your bull horns you can always color the end of the grip with a standard pencil, the graphite lubes the rubber and doesn't make an oily mess.

 

[Wrench]

You live in CA. Ace Hardware has metric threaded rod or can order you some.
Ace always has metric threaded rod where I live in SO CAL.

 

[Fast Shag]

Your shifter can go between grips and brake/clutch lever. Hard to shift down there....

 

[Captain Rainmaker]

You live in CA. Ace Hardware has metric threaded rod or can order you some.
Ace always has metric threaded rod where I live in SO CAL.

Unfortunately one of the stores I visited was an Ace. The only thing they had was 100mm lengths of 8mm rod, which wasn't long enough. They did have 5/16" blank rod and an 8mm die, though, so there's that problem solved.

Your shifter can go between grips and brake/clutch lever. Hard to shift down there....

It's going to have a shift lever eventually. A guy who runs a local bar has a 1940s Harley with the shift lever next to the tank and I think that's the tightest s#!t ever so I want to replicate that.

 

[Captain Rainmaker]

Well, tried to take her for her maiden voyage yesterday, but it didn't go so well. Couldn't get it to start, so the first thing I checked was the mag. Everything looked alright, but then I noticed it wasn't spinning. Tried tightening the clutch, but that wasn't working either, no matter how hard I cranked on it. So I pulled the head and cylinder off the engine and found out it's seized up real good. Quite the buzzkill if I do say so myself.

I don't have the need or desire to tear into this today so I'm gonna just walk away and pick it back up tomorrow.

 

[Fast Shag]

Does the mag spin freely? no keyway? Does the motor spin? Sometimes the clutch will stick from factory. Loosen it back, hit it with a hammer to release.

 

[Captain Rainmaker]

Does the mag spin freely? no keyway? Does the motor spin? Sometimes the clutch will stick from factory. Loosen it back, hit it with a hammer to release.

That's the thing. I know the clutch isn't stuck because all it does is slip when I try to engage it, even after cranking on the flower nut as hard as I possibly could. The mag does not spin freely; I put masking tape on some slipjoint pliers and tried to use them to turn it, with no luck. I then pulled the top end off the motor and the piston off the rod, then tried to spin the crank by pulling and pushing on the connecting rod with a small helping of brute force and ignorance. For love or money the thing would not even so much as budge, even with the clutch plate completely removed.

As soon as I can muster the craps to give, I'm going to unmount the motor and tear it down. This was a brand new engine that had never run before, so I'm guessing a piece of swarf or something broke off and jammed itself in the works.