79cc Dyno #2 Build

MotorBikeFab

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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

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curtisfox

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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
 
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curtisfox

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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

 

MotorBikeFab

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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

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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

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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

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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.
LBSP_2186.jpg
 
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