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.

 

[FurryOnTheInside]

I would go for a geared electric motor wheel on the Kona if it has the old standard 10mm x 135mm vertical dropouts. A not too powerful hub to use a cheap torque arm kit, maybe 750W Bafang, peaking at 1500W so no complicated custom work needed on the dropouts. Battery inside the frame triangle. Plug n play, pretty much. The rear hub motor is a serious weight but so much lower down than a rack mounted engine, and as long as the wheel survives the impacts it should be more reliable than having carb/chain/belt taking the vibrations and impacts and the strain on the rack from mounting an engine out over the wheel. Imho. I don't know if you could get all the flex out of the rack for using it as a mountain bike should be without fear of chain coming off/ jamming. Imho.

A bottom bracket mounted electric motor kit would be best, but they are much more expensive and I don't know if it definitely clears all the suspension parts, though it looks like it probably would.

 

[Captain Rainmaker]

Good job! A shift kit is a nice thing to have. How wide are those tires? You might want to switch to street tires.

They are 26x2.1s. Fortuitously, I found a set of Continental street tires on sale for 25% off, so I ordered those.

More progress today. Got all my wires and cables routed and everything else fit up. Had to shorten the jackshaft to stop it fouling on the left crank arm and take some meat out of the rear mount so the engine chain would stop rubbing. Stripped one of the stock head studs (thank you, Chinese hardware) so I'm on the lookout for new ones. Also waiting on a new rearmost chain and the tires.

Did the shifter too. My engineering genius knows no bounds.

In all seriousness, does anyone know of anything off-the-shelf that would let me mount the grip shifter to the frame like that? Preferably without drilling or welding on the frame, in case I ever decide to take the bike back to stock. I have a few ideas for something homebrew, but if there's something commercially available that won't look like I hacked it together, I'd rather do that.

 

[Chainlube]

What about a handlebar stem, just clamp it to cross bar instead of handle bar. Cut off excess.
https://www.amazon.ca/Raleigh-GNJ11...32000&sprefix=handle+bar+stem,aps,194&sr=8-32

 

[Captain Rainmaker]

What about a handlebar stem, just clamp it to cross bar instead of handle bar. Cut off excess.
https://www.amazon.ca/Raleigh-GNJ116-Short-Handlebar-Fitting/dp/B004KW6NZ0/ref=sr_1_32?crid=2HP4DGR4MNMV2&dchild=1&keywords=handlebar+stem&qid=1585532000&sprefix=handle+bar+stem,aps,194&sr=8-32

Genius. Thank you so much.

 

[Chainlube]

Cheap enough too.

 

[Chainlube]

Genius. Thank you so much.

Ha ha, I surprise myself some times.

 

[Captain Rainmaker]

eVeRyBoDy NeEdS a HeLpInG hAaAaAnD

Also put the new shoes on today. Just a few things left on the list, then she'll be ready to go.

By the way, can someone please explain to me why none of my local hardware stores carry metric threaded rods?

 

[FurryOnTheInside]

Very nice. Going to be an exciting ride!
Gear shifts will be a thrill!

So when are you going to take the bar ends off?

 

[Captain Rainmaker]

Very nice. Going to be an exciting ride!
Gear shifts will be a thrill!

So when are you going to take the bar ends off?

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.

 

[FurryOnTheInside]

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.

Fair enough.