choppin n weld'n another 'junk yard' frame

Jan 17, 2015
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Decided I need a bike to mount the snowboard saddle on. So, here I go. Gonna make 2" slide out extensions so I can move seat location back to make up for my bending of the seat tube so my feet don't get behind me. Bent seat tube for more room and for a flatter future seat spring mount.
 

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cannonball2

Well-Known Member
Oct 28, 2010
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Colonial Coast USA.
Holy freakin mackerel Scratch I thought I was bad addicted building stuff. If you have a room full of nearly but not finished stuff because you are building something new then you are as bad as me. I have learned to scatter the unused parts around. If they get stacked too close together I can usually see the beginnings of another build.

Nice to have company!

Like the looks of this build already!
 
Jan 17, 2015
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LoL....yep,, I look around and find the next sacrifice. That was all this started out to be...just a visual..then the cut off grinder jumped in my hand and the cuttin was on! I wanted to just heat the seat tube and do the bend...but only a map gas torch...ran out of patience. The look isn't bad. I did a head tube job also...which was just to be an attempt to see if... and it does work. I tacked the head tube before I cut it up. I like that it lowered the seat height 3". Gotta strip all the paint off tomorrow.
 
Jan 17, 2015
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Anyone lookie lew'n...have you ever tried this(pic) I like that the cylinder is seen. Reason for this thought is not having an exposed fly and cup. I would end up hurtin myself.
 

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cannonball2

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Oct 28, 2010
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Seen that done with the little 49cc HS engine.

I removed the recoil on a 5hp Robin flattie in a build I did, Ground off all the flywheel fins then made a start pulley out of a lawn mower deck idler and moved the starter rope notch inside. It was all smooth. If yer pants got in it not much happened, just let you know it there. Gotta live on the edge some time!

Just don't leave your start rope at home, it was a long push back!

pic. http://motorbicycling.com/attachment.php?attachmentid=47832&d=1336601541
 
Jan 17, 2015
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That is a nice way of doing a rope start. I'm runnin the alum flywheel. I don't know for sure if the cast would work with the mag. I took mag and flywhheel off a 4hp mower, put em on my 3.5 and worked great. If the cast fly works, how do you remove the fins. I've got a couple to practice on! I don't want to do the alum one because, if you don't do it right, it will snap back, as you mentioned. At first I thought the engine gained heck a compression..till you told about your experience with alum fly.
 
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cannonball2

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Oct 28, 2010
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Colonial Coast USA.
The flywheels should interchange. We ran 3hp flywheels on 5hp engines just by making a drop for the mag.

Lathing the fins is the best way if $$ isn't a problem. As crude as it sounds on the Robin I knocked the fins off with a hammer then ground the stubs down. The fins were fairly delicate. As I remember on the Briggs the fins are quite stout and may not knock off so easily. You can grind em just takes a while. I left just a faint trace of the fins so I was sure I hadn't ground into the flywheel itself, not a good idea.


Check with Msrfan I believe a lot of his builds may be finless.

Remember with no or even your cut shroud you have to be moving to cool. Probably not a good idea if you sit idling for long periods.
 
Jan 17, 2015
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Well I will probably just keep the pull stock. I took the curve out of the seat stays buy cutting them loose from the top tube. I wanna go ridin, but its so cotton pickin windeeeey.
 

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msrfan

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Sep 17, 2010
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Looks good scratch. You may have to support what's left of the top of your shroud so it doesn't distort when pulling the rope. A fast idle helps cool the engine when stopped by lots of oil splashing.
 
Jan 17, 2015
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Hi msr, the cover was to see the possibilities..and yes it could work. I put it on the shelf to gather ideas of how to finish the idea to where it doesn't have 'scratchbuilder's' look to it. thx
 
Jan 17, 2015
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No more drop outs! I'll take the time and make, what I call 'slide outs'. For now I'm on the single gear pineapple sprocket along with a coaster wheel. I haven't had the experience of this set up...yet...
 

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Jan 17, 2015
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I agree, I hope the next one resembles this one... I glad this hobby found me. I hopped on one of my bicycles for a trip to the donut shop...i kinda miss ridin my peddlers....but I like gettin there quicker ..
 
Jan 17, 2015
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Might have to make a toolbox/battery box behind seatpost. A lot of space there. Like I could make something like that..prolly be flat shaped piece of alum...lol. One of the 'things' I was after was,getting the engine lower and I did. Seeing that I'm going to spring saddle this bike, I'm thinking ,cut out the seat tube, bend one for a better look.
 

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cannonball2

Well-Known Member
Oct 28, 2010
3,662
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Colonial Coast USA.
I dunno Scratch. Put a good weld on the front and it will smooth out by grinding a bit. If you are going to run a flat mount from the bottom bracket area to the front down tube it will already have an angular look. Don't think the seat tube will look all that out of place.

How far back is the SB seat going?

Move that gas can before you weld!!
 
Jan 17, 2015
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Patience pays in the end. I'm going to replace the seat tube. Mm coming along. Js placement now needs consideration. Ice got to get the down tube and mm done before cutting seat tube.
 

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Jan 17, 2015
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I moved my "cleaning solvent"lol...yeah that's plan on the mm. Then do something like wrap the flat mount with 1"or 1 1/2 band. I'll get a pic of seat position.