79cc build from scratch

[banjotinker]

Been awhile since I’ve last posted (gokart rebuild) life got in the way and then I started my classes towards journeymans papers as a machinist. Will eventually post an update on the gokart when I go back to Oklahoma.

Doing a build mostly from scrap material at work. Have my frame mocked up for the most part still designing the swing arm and a few other components have been killing brackets during my lunch at work so here’s some pictures. Played around a bit with design and layout not entirely sure I’m satisfied yet. Picked up the gas tank from a coworker but don’t have a cap or petcock for it. He says it’s from a Honda z50(r?) mini trail. Made a template for the seat base in the last picture scored some black vinyl out of a scrap bin for a couple bucks so I’ll be sewing that too.

 

[landuse]

Looks good. I like the tank

 

[madprofessor]

Not understanding what you'll do with a swingarm. Are you planning to pivot it on the jackshaft? That's the only way the swing motion won't affect chain tension, slacken/tighten as it travels up/down.
Attaching pics of the jackshaft/pivot setup on my kart, before/after slicing the shaft into 3 pieces. No point in spinning pivot bearings along with the jackshaft.

 

[banjotinker]

Not understanding what you'll do with a swingarm. Are you planning to pivot it on the jackshaft? That's the only way the swing motion won't affect chain tension, slacken/tighten as it travels up/down.
Attaching pics of the jackshaft/pivot setup on my kart, before/after slicing the shaft into 3 pieces. No point in spinning pivot bearings along with the jackshaft.

That’s exactly what I’m planning to do. I just have spare parts sitting on the bench in the pictures

 

[banjotinker]

So it’s been awhile, work during covid got hectic, then we moved cross country and that was hectic but it’s basically final form now. Gonna clean everything up change the front forks completely. We put the final exhaust setup on (not in picture) did a few last runs before we were going to add the finishing touches to the frame and our clutch went out on us. So throwing on new clutch and we’ll be back in business until we start work on the final forks. Our top average speed is around 18 mph and that’s with majority hill climbing.

 

[txluke]

That turned out amazing.

 

[madprofessor]

Our top average speed is around 18 mph and that’s with majority hill climbing.

That helps explain the clutch burning up. Kudos on the build, looks great, really like that frame. Seat stitching very stylish too.

 

[banjotinker]

That helps explain the clutch burning up. Kudos on the build, looks great, really like that frame. Seat stitching very stylish too.

Right?!

Thank you! We had the machine all packed up so I was doing the seat by hand.

 

[pearl111]

That mini bike turned out looking really good.

 

[Denny]

Really sharp looking!

 

[banjotinker]

Thanks for all the kind words! Slapped on the new clutch and took off the front forks. Hopefully when I’m not working this week I’ll have time to get pictures of that progress.

Took the forks off of a shineray 200cc dirtbike that we grabbed for $50 and I’m making wider triple trees for it. Luckily axle size is the same on the forks. We also stripped the brakes off the dirt bike so we’ll get to adding front brakes to the mini bike.

In the shorter gaps between work I’m making a custom kill switch to 3d print and mount. Considered using the one from my zn700 but uh until I get new controls for that they got to stay on.

Also started working on the back rack and rod holders for my fishing gear but that’s less a priority. Once we test it with the new set up I’ll start cleaning the welds and rounding off everything sharp and prep for paint.

 

[madprofessor]

I’m making wider triple trees for it.

I'd like to see how you do that to the trees. Picture in my mind is only showing me a pair of slices in each plate, with splices welded in, or newly formed and drilled out plates altogether. Has to be an easier way, looking forward to finding out.

 

[banjotinker]

I'd like to see how you do that to the trees. Picture in my mind is only showing me a pair of slices in each plate, with splices welded in, or newly formed and drilled out plates altogether. Has to be an easier way, looking forward to finding out.

My original plan was to mill them at work however I have since moved, changed trades and do not have immediate access to a mill. One of the other carpenters on our crew has a mill I’m hoping to utilize otherwise it will be turning locks on my lathe tapping them for threads and then split those and weld to new plates.

 

[banjotinker]

Temporary kill switch mount, the final one will have wire harness on the backside and have a cleaner shape. Then I’ll solder the wires.