Pit bikes/vehicles

We call our minibike "Death on Wheels".  It's a janky old minibike frame with a booger weld front fork repair and a 6.5 hp Harbor Freight 'Predator' motor on it.

Sucker will pull a wheelie at 25 mph if you're not careful.

What's a chain guard?

Kidding...

Actually, this is old enough that it was probably made in the USA.  But the booger weld is scary enough my crew chief won't even try to ride it.

tSoG got on it and it tried to kill him.

Hell, it tries to kill me regularly.

We were pitted by track out, sitting there trying to relax when we suddenly hear a screaming engine and a loud banging sound. We turn to look and there is tSoG straddling this deathmobile laying on it's side. We went back to our conversation. Typical Lemons.

And that's probably why I need to remove the flywheel cover on the pull-start side and bang out some dent or something.

I fired it up Sunday morning and it was rattling and banging like something had come loose in the engine compartment.

For the record, though, we did warn him.

That's what I assumed too, but nope, fuel in the floats. It has brass floats, which after a while will leak and slowly fill with fuel. Happened to me on my XS500. There wasn't a lot in these yet, but enough that they weren't closing the valve fully before the level was over the overflow tube. I adjusted the tab over the needle and no more overflow. Should work until I get a few float.

What he said.  Had to do this on untold number of UJM's...was the second most popular repair in my college years when I flipped bikes for beer money.

I am surprised the Honda XL125 has not popped up here?  Growing up in Oklahoma you could get a daylight license for 125cc or smaller bike at 14 so those things littered the streets.  Street legal.  Able to hit 55 is the rider was not too aerodynamically challenged.

I think you will find that the Chinese have a different idea of "interchangeable parts" than the Japanese. They also seem to think the numbers on the jets have something to do with numerology, and not the size of the hole, from what I have heard lately about their aftermarket jets. The Chinese version of the carb may not have parts that will work on the original.

Anyone who has seen us in the last few years has seen the "widowmaker".  It is the jankiest of the janky, some mongrel of the back of an old square tire mini bike, with the front of a bicycle welded on it.  Has another bike handlebar as the pegs, which effectively moves the brake pedal about 12 inches from where your feet are.  Front tire looks like it might be from the carter administration, and it is squirrley as all get out.  There are few who will get on it.  I love to bring it, because if I need it, it's always there.  It has only tried to kill me once, a couple of years ago at Autobahn when I missed the brake and ran my own foot over.  No real harm or foul, but I did gain a whole new respect for the bastard at that time.

Has anyone built a beach cruiser moped using a Chinese moped kit?  If so, please share.

This is a perfect place to post the picture of what I found while trying to solve a similar issue on my CB750. While some people will suggest you check the vent in the fuel cap, and also the float bowl vent I was pretty sure that wasn't my issue. I drained enough gas out of the tank to take the petcock off and this is what it looked like

I suspect you will find something similar in your tank.

I've built a few of them.

I currently have two in my garage: a 26" direct drive / single speed and a 29" multi speed jack-shaft. The multi speed jack-shaft sounds cool in theory, but it's only a few mph faster than the single speed direct drive.  You end up using only one or two gears as the torque band of the Shanghai Special is wider than the gear range of the bicycle.

Also, the single speed is a more raw visceral experience.  It's loud, vibrates like crazy and reminds you that it may come apart at any second.  It's the perfect primer for a Lemons car.

The single speed tops out at a very dangerous 31 mph while the jack-shaft bike can hit an even more sketchy 36 - 37 mph.  This sounds like a cool pit bike, but the down side to these bikes is that they don't like to go slow.  Anything less than 15 mph, the single-speed starts lugging down and surges.

My recommendation to anyone building a bike like this, don't waste your time with the "rag joint" (sprocket that uses a rubber gasket which attaches to the spokes) and instead spend $20 on the sprocket mount that bolts directly to the rear hub.  It's almost impossible to get the rag joint perfectly centered, and an un-centered rear sprocket will play havoc on drive chain tension which will eventually break the chain.

Single-speed direct drive:

(original wheels / rag joint)
 

(fatter rear wheel with solid hub mounted sprocket and lemony laid-back seat post)

Multi-speed jack shaft: