A work in progress

[carpespasm]

Hi all, After lurking for some time now I finally ordered a 60cc 2 stroke kit and am building up a boardie-style bike to put it on. I've chopped up an old beach cruiser which used to be my mom's and have stretched the frame by about 8cm and flipped the handlebars. I'm planning on cutting the bars a bit shorter, and will will be adding a rear motor mount and middle frame tube once I have the motor positioning like I want it. Here's some photos of the build thus far:

After cutting the frame in two I welded a couple of plates to the front half's tubes so I'd know they were square, then cut the bit of top tube out of the way so I could fit in a new one. Then I clamped both halves between bits of 1x4 and shimmed both sides with a couple of small wrenches for shims to fine tune it. This method of keeping it all square worked better than I expected.

New top tube welded in place with splints still holding bottom together.

After getting the frame back in once piece, I tossed it together for a spin around the block. Not too bad.

After about 10min of putting bits together from the box. I was surprised how much was left unassembled.

Motor rough fit

I'm not sure I'm happy with the straight addition to the down tube since it makes the motor seem to ride a little high for the middle tube to clear the spark plug and throttle cable. This is my first build of this kind, so if anyone has any good advice I'm all ears.

 

[harry76]

Your top tube is looking real good, but you need to redo a whole new downtube imo, this will lower the motor which will help with handling and also help you level that motor out so your carby is horizontal..... are you going to mount a fuel tank inside the frame?

 

[carpespasm]

Agreed. The more I look at the downtube the less I like it. Having that weld in the middle and no curve to part of it kinda kills the aesthetics even if the carb would work at that angle. Any idea how to bend tubing into a curve or where to snag a donor? The top tube came from a handle on a broken down hand truck I had around. I tried making a press with a 1/4" steel plate, some galvanized pipe, and a bottle jack, but the plate bows before the tubing bends.

I am gonna fab up and mount a tank inside the frame, which I guess gives me all the more reason to find a more suitable down tube.

 

[harry76]

Ask shops for scraps, try metal recyclig yards. And last resort buy a length of new tube. And have a look on here for down tubes you like, they can either curve and follow the front wheel or come straight down and have a drop loop on the bottom. If you arent confident bending the downtube try a mendrell bending place for a quote or get some scrap and practice

 

[carpespasm]

Well, I've made my with the top down tube not having a curve to it, and have mounted my rear sprocket and made up a motor mount for the rear mount. I'm still not sure I'm happy with the peanut gas tank, but it's at least decently matching to the bike as it is now. Just need to mount everything up tight, get the cables, hoses, and chain straight, and I'll give it a whirl before getting ready for paint.

 

[carpespasm]

Got it all set up and running today. I was pretty surprised how easily it started up and how quickly the motor seemed to loosen up. Just took it for about a 10 minute spin around the neighborhood. A front brake is definitely on the short list of things to come.

 

[silverbear]

Good that you moved the motor back. My suggestion would be to ride the heck out of the bike this summer and be on the lookout for a girls bike... a girls Schwinn would be good or something with a similar curved front down tube. It makes a perfect donor. Then when winter comes, modify your frame with the swooping down tube, weld in the lower top tube and fabricate your gas tank. Then you'll have your board tracker. You might also be on the lookout for a donor bike that has a front V brake. I cut the V brake setup off of an old mountain bike and modified it a bit to fit on my Schwinn springer fork like yours. With cool stop shoes it is a very good brake, close if not equal to a drum brake in stopping power.
SB

 

[harry76]

What Silverbear said..... plus if you are going to run the motor at that angle, you may need to level your carby so its vertical. Otherwise good work and enjoy the thing. They are so much fun....

 

[carpespasm]

How do you level the carb if the motors at an angle? Is there a differently angled intake manifold? Does it matter if it seems to be running alright as-is.

 

[harry76]

If it were me, id remove your motor, cut off your rear engine mount and remount the engine. You could mount the motor directly to your seat tube and make and your engine mount for the downtube. That would get the motor where it should be and carby level.

If you dont feel like doing that you could modify your inlet manifold, or make a new one. Im not sure if they sell them. But resetting the motor would be easier IMO.

Good luck bro

 

[carpespasm]

I'll definitely keep those things in mind, but like I said, there doesn't seem to be much issue with the carb being at the angle it's at right now. If anyone knows of a problem it might pose that I'm not noticing I'll definitely remedy it though.

Anyway, I kinda got tired of seeing red white and burns this morning so I took some of the hardware loose and hit the frame with a coat of flat black just to make it a uniform color for now. After the motor gets broken in in a tank or two of gas I'll strip it down to the frame and paint it properly with a nice hunter green.

I also shined the wheels up with some 000 steel wool. Purdy.

Close-up of the rear motor mount. Had to grind a fair bit of material off the left side of the stock mount plate to keep the chain from touching it. How would you go about using this without cutting it out of the way? Part of my choice in mounting angle perhaps to blame?

Close-up of my fuel feed and spark plug line. I went with an automotive wire and a plug that has a round top rather than the stock one's threaded top. It's also a bit shorter overall. The fuel feed is ethanol-rated hose, a plain barb on the tank with teflon tape to keep a good seal, a new fuel filter, and a cutoff valve. It takes about 200 meters to run the carb dry when I want to kill the motor for parking.

I'm gonna take it out in a bit to pick up a speedometer for it so I make sure to not rev it to death too early.

 

[cobrafreak]

Agreed. The more I look at the downtube the less I like it. Having that weld in the middle and no curve to part of it kinda kills the aesthetics even if the carb would work at that angle. Any idea how to bend tubing into a curve or where to snag a donor? The top tube came from a handle on a broken down hand truck I had around. I tried making a press with a 1/4" steel plate, some galvanized pipe, and a bottle jack, but the plate bows before the tubing bends.

I am gonna fab up and mount a tank inside the frame, which I guess gives me all the more reason to find a more suitable down tube.

Hello, nice effort! Motorbikes are great. I agree about the down tube. Here is what I did:

When I built my 1911 Indian I made two down tubes so I could use one as a pattern for myself for a second bike if I ever did one. Go to a steel fabrication shop or somewhere that has a "radius bender". Show them this picture. The measuring tape shows 14 1/2" from inside to inside, and the long end is about 3 feet long. Cut off your down tube, cut some of the "J" off, and weld it on your crank bracket from the bottom so the "U" is like the Letter "U". On the long strait part you will need to do a small bend right where the front tire gets closest to the tube, and weld onto your steering bracket. You will now have a vintage "drop loop" frame. You nailed the top tube perfectly! Then if you get the urge, you could lengthen the rear triangle a couple of inches to elongate the entire wheelbase. Good job so far!

 

[carpespasm]

Thanks for the input cobra. Since these motors are a little on the small side compared with their 1920s brethren I'm a not so in favor of the drop loop but when the time comes I'd definitely be looking for someone with a radius bender. I have seen some with mounting plates filling some of the area under the motor which looked pretty nice though. I tried an electrical conduit bender at first, but it just kinked the tubing. Getting a nice swooping curve otherwise seems to be an exercise in madness .

The frame is already stretched by about 6 inches, so using another ladies bike frame for the down tube seems out of the question unless I butt two of them together and take what I need from that.