79cc Dyno #2 Build

[MotorBikeFab]

Another 79cc Dyno build.

What I learned here:
Use a solid rod in the seat post to minimize vibration (I am going to try making an extended seat post that goes to the bottom of the seat tube)
Allow the centrifugal clutch to "float" on the crankshaft, in other words, do not tighten the grub screws (I understand that this allows for the best sprocket alignment)

I got the jackshaft to glide smoothly in both pillow blocks by slowly tightening the mounting bolts and tapping the pillow blocks gently as I tighten. The axle glides smoothly back and forth with no binding.

I may mount a disc brake to the jackshaft...instead of at the rear wheel. Not sure yet.

Next up:
Fabrication of the intake and exhaust manifolds
Make a fiberglass gas tank

 

[curtisfox]

WOW! Kool work is great, but unless you are going to change the sprockets and pulleys, you will be geared to high. Your jack shaft sprocket need to be way bigger..........Curt

 

[MotorBikeFab]

You are correct
I was thinking to get a 36 tooth #41 sprocket for the jackshaft
Should end up with about 12:1 final drive ratio
What do you think?

 

[curtisfox]

Sounds good, should be ok then. is the rear pulley super-teen belt also? I will be using a super-teen on mine, with a 24" bike rim on rear wheel.........Curt

 

[Venice Motor Bikes]

Killer looking bike!!!!

Hit up James at Ghettobike... He might have a tank for that frame laying around the shop.

 

[MotorBikeFab]

Sounds good, should be ok then. is the rear pulley super-teen belt also? I will be using a super-teen on mine, with a 24" bike rim on rear wheel.........Curt

Looking good Curtisfox.

I filled the larger composite pulley with with epoxy and wrapped the belt around it to try to "make" ribs in the pulley and hoping the serpentine ribs would transfer from the belt to the pulley...even with a release agent on the belt the epoxy "ribs" stuck to the belt. So I have a flat surface in the larger pulley. I hope it works and that the belt will stay in the pulley instead of riding up and out. I am not sure the composite pulley will hold up. I should know in a few weeks when the build is running.

If that fails I will go to a sprocket and chain system.

I may get one of those 15" Whizzer sheaves for a future belt drive motorbike.

 

[MotorBikeFab]

Killer looking bike!!!!

Hit up James at Ghettobike... He might have a tank for that frame laying around the shop.

THANKS!

I always thought pillow blocks are on the crude if effective side. Thinking about making something out of a 4 or 5 inch alu angle and the kind of pillow blocks that mount to the side.

Thanks for the hit-up to James at Ghettobike...I just have this itch to make my own fiberglass gas tank(s). I have the foam for the sacrificial mold and got some epoxy that is supposed to be ethanol friendly.

And I found this brass vented gas cap:
http://www.bungking.com/brass-vented-filler-cap-and-weld-in-bung/
Kinda pricey but vented and brass.
And this far less expensive one that I can drill a vent into:
https://www.fillernecksupply.com/2-billet-aluminum-anodized-weld-on-bung-and-fill-cap-pro-werks/

Cheers!

 

[curtisfox]

There is also garden hose cap and coupling. Mr.B shows how to vent it https://motorbicycling.com/threads/excalibur-09.37011/ .

How about flange mount bearings

I have the first on my snow blower drive on my tractor, one bolt is stationary and one has a slot for some adjustment. Local farm store has them. Just some thought's ........Curt

 

[curtisfox]

picture didn't come through.

 

[MotorBikeFab]

Maybe like this?

 

[curtisfox]

Yep! Looks good, round the corners some. There is also round flangers bearings, do a search for flangers mount bearings. Like your idea, maybe cut the outer channel lip down some more.................Curt

 

[MotorBikeFab]

Had a change of heart on the design of the bike.
Going back to a much more original look.

 

[MotorBikeFab]

Made a lay back seat post yesterday.
Also added some length so it will go all the way down inside the seat tube. They say it helps reduce the effect of engine vibration to fill the seat tube with a solid rod...but I am hoping this will help with the vibration without all the weight of a solid rod.