My 5hp Robin Build

M

midwestmayhem

New Member
Hey peoples, Merry Christmas. Still kinda new here

As said in my first thread in the introduce yourself part of the forum, I've uploaded so build pics of my 5hp Robin powered bicycle. Cylindar is towards the front, so the motor runs the opposite direction it should. But instead of going with a friction drive, I used a spring loaded tensioner from a truck, used the bike's crank as a jackshaft, looped the chain around the two, and ran the clutch on the outside of the chain. Then to the rear derailer on rear wheel.

I have ridden it a few times with no issues. Never rode it in any higher than the lowest gear. I have checked the chain spacing in high gear, no rubbing :)

I plan on re-working the drive system. Think I'm going to keep the same general idea but add a jackshaft, an idler, a freewheel adapter and a few other goodies so I can peddle again. Got the whole thing figured out, just have to start workin' scratg

I'll do my best to attach some pics to this thread, but I have more pics in my albums. Feel free to check them all out. Comments welcome
 

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I have seen a few pieces of lawn equipment where they reverse rotation by running the belt in the same fashion you have there but never thought about a chain working in the same manner. Way to think, as rc said awsome!
 
Woah, That's an amazing bit of "out the box" thinking. Excellent way of reversing output to have the moror cyl foreward, which looks so right. Makes the carb and exhaust easier to deal with too.

It always amazes me when people come up with such inovative ideas.
 
Thanks for the comments everyone, It's nice to be able to get others opinions on a project.

I'm afraid re-doing the drive sestem will have to wait a little while. I want to get my custom shift kit for 66cc kit bike done first. I don't suppose anybody knows the dimensions for the plates for sbp's first and second gen shift kits. Does a measurement of 5 9/16 from the center of the screw to the center of the jackshaft seem right?
 
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I feel naked without mine in my pocket.IMAG0151.jpg

tn.jpg

I can't build these without one.DSC_0705.JPG

LOL sorry about rambling on your thread.
 
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That's alright wayne :D

I realize the question about the jackshaft plate probably requires a new thread on the 2 stroke section of the forum. :p

But it is suprising how sometimes it's the more simpler, older tools that seem to work the best.
 
Yea ain't it funny? I mean if it dosnt break don't make it better! But people can't seem to get that throught their sculls. Wow wayne that's a very nice staircase, good work :)
 
I like the do it yourself job here. I know you’re talking about a shift kit and that may be a kit part, but mainly homemade!

Is it that maybe I don't know the lingo, but I get the idea that the shift kit requires more width between the rear fork and you are planning on widening that area? I've seen a few ways of doing this and some don't require cut and weld.

I have a small shim that allows a v-belt pulley clearance on my current build and it is about a quarter inch. It is under an amount of tension fitting it now, but bending it as it is now, would require cutting two places and lengthening these small cross pieces that are by the top two pair and bottom two pairs of tubes. That is they are near the seat post tube top and bottom.

I already tried to bend without the cutting of the braces and it just springs back to original shape.

Measure Twice
 
Hey MT, when you tried to spread the frame, did you put something like a allthread and nuts in the dropouts?

When I jacked my frame out for sheave clearence, It started with 3.5 " between the frame and 4.25 between the dropouts. I captured the dropouts with an allthread, nuts/washers so it couldn't spread.
I then screwed out the jack till I got 4".IMAG0151.jpg
Then I Tightened the allthread's nuts until the dropouts were 3.25 inches apart, to pre-stress the the bend.
When I released everything, it only sprung back 1/8 "

Edit: Oops Sorry MW, for jackin yer thread again, I'm been tryin out that Crown Royal I got for christmass LOL
 
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lol, that's ok wayne, I might need to spread rear forks sometime. This info will come in handy. :D

I already re-posted my question about sbp's shift kits on the 2 stroke part of this forum. It doesn't look like as many people visit that part of the forom, but I imagine someone who knows will run across it and answer it.
 
Mayhem, what size is your engine chainring and the sprocket on your clutch?

Are your rear sprockets 11t/32t and how many gears are you using?

I'm slowly working on my 6hp Robin install. Power will prolly run thru the rear cassette and shift kit.
 
Sorry it's taken me so long to reply,
The clutch is your regular ten tooth, #41 chain clutch
the multispeed freewheel is an old 5 speed, 28-14
I'm making some changesto mine, like I previously said. I plan on adding a jackshaft, a second freewheel adapter, and a couple other things so I can peddle again(basically a 2 cycle shift kit).
I've also plan on swapping motors to a 212cc Preditor that I picked up at HF for $100.






Keep the wheel(s) spinnin
 
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