Here's the beginning of the parts pile for the Bird. I started with a frame that had been cut in half. I added 6" in the backbone and front downtubes. Here's how it looks for the start of the build. Not sure on the engine yet. I'm waiting on a flathead Tecumseh from my in-laws now, and depending on the HP, I may use it. I may add suspension to the front, and possibly the rear. I'm hoping for a low rider/chopper/boober/dragster look, while still looking somewhat like a Bird. May end up looking like a dirt bike with a funky front end and street tires. :hack::grind::hammer::weld::thumbsup:
Minibike Build Off jimh's Bird
- Thread starter jimh
- Start date
Jimh is gonna start a debate here...
If the bike is gonna be ridden by adults, you can't beat the comfort provided by a 6" frame stretch...
Most of the old minis were sized for kids, and too uncomfortable (even dangerous) for an adult to ride...
My knees usually intefere with steering on a stock frame...at 6'4", there's a bunch of them I can't physically ride...
The purists/restoration guys are gonna cringe, but I like the stretch, and I love the 'twisted' top tube...
If the bike is gonna be ridden by adults, you can't beat the comfort provided by a 6" frame stretch...
Most of the old minis were sized for kids, and too uncomfortable (even dangerous) for an adult to ride...
My knees usually intefere with steering on a stock frame...at 6'4", there's a bunch of them I can't physically ride...
The purists/restoration guys are gonna cringe, but I like the stretch, and I love the 'twisted' top tube...
Before the debate starts, I would like to add that I didn't cut the frame. It was so sprung that it would have been next to impossible to fit it back to stock. I consider what I'm doing to it now as upgrades. I'm going to add a torque converter and a couple of jackshafts to go to right hand drive and change my gearing, another twisted bar between the downtubes, and possibly an inverted, upside down, bass-ackward springer front end.
Have not had a lot of time to spend on this lately, but I managed to get my tires mounted without pinching the tubes. The rims are aftermarket alloy CT70rims. The tires are 3.50x10. I got my engine. It's a ported, shaved headed, ungoverned H70. Despite it's ugliness, it sounds great. My late brother-in-law saved it from a crashed kart. It had a stripped spark plug hole. I had the in-laws ship it to me a while back. I helicoiled the hole, put in a plug, hooked a fuel tank to it and it fired up. I ordered a new carb which should be here soon. I'm going to leave the block in natural aluminum and paint the sheet metal to compliment the frame. The black engine is a HS50 for comparison between small block and big block Tecumsehs. The big blocks have a mounting plate that bolts to the bottom of the block, allowing it to be mounted in the typical small engine slots. I put my plate on backwards to set the engine to the left in my frame, so it doesn't hang out the right side so much. I had to use 5/16 spacers between the block and the plate so the flywheel cover would clear the plate.
Pulled some parts out and started loosely mocking things up. trying to get an idea what this is going to look like. So far the shape of it is about right. Long, low, and bobbed looking is what I'm after. I may go with 3" risers for the handlebars, and raise the foot pegs 2 or 3". I still have to make mounts for a jackshaft torque converter. I have aother H70 on the way, and possibly a H60
too. One of the 3 engines will end up on here.
too. One of the 3 engines will end up on here.
Got a little done in the past few days. I decided on an engine. It's a 5hp Briggs. After putting one on the Boonie and the black clunker, I decided to put one on this one too. This one had a bad crank and rod. I had another one with a broken mounting ear on the block, so I robbed the crank and rod from it. I bought a new piston, rings, piston pin, intake valve and gasket set.
I removed all the casting slag from the rod and polished the beam with Mothers.
It's all back together and all seems well. I also rebuilt the carb. I polished the intake runner of the carb with Mothers and cleaned the ridges and slag from the ports. I still have to make an exhaust for it.
I bought a comet 20 series drive clutch and painted it with BBQ Black. The driven clutch is a Comet 21 D-7. It's a 7 1/4 size. with the small rear sprocket and 10" wheels, I figured I might need a little help taking off. This should do the trick. :thumbsup:.
The lef spring on the left will be the rear seat spring instead of shocks.
The seat brackets are painted.
I also built some more bearing blocks for the jackshaft. The same style I made for the Boonie. The deal with the two little extra holes is they can be bolted to different length bottom blocks for different width bikes. Or if I weld them together, I can thread these and use them to mount chain/belt guards.
At the beginning of the build I said it would have a reverse upside down springer. I was just trash talking.....
BUT, after trying on the original forks and another set,I decided I would go ahead and build it. I'm going to modify the original forks, using flat bar,bronze bushed bolt holes, hardened shoulder bolts,and my own design.:grind::hack::weld::hammer::smile: The fun is just beginning.:biggrin:
I removed all the casting slag from the rod and polished the beam with Mothers.
It's all back together and all seems well. I also rebuilt the carb. I polished the intake runner of the carb with Mothers and cleaned the ridges and slag from the ports. I still have to make an exhaust for it.
I bought a comet 20 series drive clutch and painted it with BBQ Black. The driven clutch is a Comet 21 D-7. It's a 7 1/4 size. with the small rear sprocket and 10" wheels, I figured I might need a little help taking off. This should do the trick. :thumbsup:.
The lef spring on the left will be the rear seat spring instead of shocks.
The seat brackets are painted.
I also built some more bearing blocks for the jackshaft. The same style I made for the Boonie. The deal with the two little extra holes is they can be bolted to different length bottom blocks for different width bikes. Or if I weld them together, I can thread these and use them to mount chain/belt guards.
At the beginning of the build I said it would have a reverse upside down springer. I was just trash talking.....
BUT, after trying on the original forks and another set,I decided I would go ahead and build it. I'm going to modify the original forks, using flat bar,bronze bushed bolt holes, hardened shoulder bolts,and my own design.:grind::hack::weld::hammer::smile: The fun is just beginning.:biggrin:
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That frame looks awesome! Has just the right amount of stretch IMO and should be very comfortable with the extra leg room. OOPS, there goes my mind racing again, thinking about yet another project. Every time I look at what all you guys are doing it sparks new ideas in my head for my next mini
I gotta go.......................:hammer::weld::hack::grind:
ut:
I gotta go.......................:hammer::weld::hack::grind:
ut:Got a little more done lately. I removed the scrub brake tabs. brake pedal rest and return spring tab. Made some plates from 1/2" X 1" flat bar to set my engine 1 3/8" to the left. This gives me the space to run the driven clutch outside the frame. There's no way it would have fit inside without the engine hanging out the right side. This centers the engine more in the frame too. i made some small slotted brckets to be welded to the frame. The bearing blocks for the jackshaft will be bolted to them,with the slots allowing more belt and chain tension adjustability. I'm planning to tack them on tomorrow and mock up with the engine and drive system installed.:hack::grind::weld::hammer: :smile: