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Discussion in 'Motorized Bicycle General Discussion' started by motorbikes, Sep 9, 2012.
How does a pull starter work? What happens once it turns on the engine?
It's magic. Nobody knows how they work.
i just watched something on them and still cant tell you exactly how they work lol
its pretty simple. When you pull the rope, a mechanism inside spins the crankshaft. when you release the rope, the mechanism sort of opens up and allows the crankshaft to move on its own. with our two stroke engines, engines that come with pull starts usually have a centrifugal clutch. but you can use a pullstart with a manual clutch as well, you just have to pull the clutch in and start the engine in neutral. you need a wider crankset to use a pullstart. standard width pedals will not clear a pullstart.
When you pull the pull stater, the centrifugal force acts on the pawls in the mechanisim. They swing out and engage a sprag clutch of sorts and that's how you turn the engine with the rope/spin the engine over. Once the engine is turning, it free wheels over the sprag clutch. That's why once the engine starts if you keep the rope out you hear that sound (ratcheting).
Did that help, or were you happy when you thought it worked by magic?
What Joe said sounds good but, it's just theory. No one knows how they work.
I thought it was the spirits from dead China girls past, coming back through reincarnation.
Anyone have a good set of instructions for re-assembling? I am in process of changing the color of my Greyhound 79cc from blue to black, and I tore the pull starter totally apart to paint the sheetmetal. Problem is, when I removed the nut on the center of the pull start shaft, the whole thing sprang apart. Thus I was not able to see exactly how it was assembled to begin with.
What he said. (but for a HF 6.5 engine)
Hit it with a juju stick.
Works every time.
I know how they work.
You pull it. It breaks. You throw things. Repeat as needed.
Make sure it's a "juju stick"........a "mojo stick" looks very similiar, but has completely different results.
I tried the mojo stick and it didn't help at all. I found an old juju stick I hadn't used for a long time so I didn't think it would work but it fixed it jest fine. Thanks for the help guys.
Just throw that ugly mess in the scrap heap (along with plastic fan) get a pulley, grind a rope notch and carry an old-style pull rope. Go one step further and make a nice cover for the whole rotating assembly.
Or, go electric start... Get a high torque battery drill or impact (sort of smallish) use the proper socket for fly-wheel nut, now that's magic! Carry in a cool vintage tool box.. On package rack, tank mount, or fake battery box... Wow your friends!
If you want a pull start and automatic (centrifugal) clutch just buy a 4-stroke as the 2-stroke add-on ones are a joke.
As for 'Juju or MoJo' sticks there are indeed different sticks, I hollowed out my 'Bad Mojo' stick and stuck it on the end of my expansion chamber to make my ride sound and perform more like a Harley than a weed wacker ;-}
no no no no you should have an exorcism .LMAO
There are videos on Youtube showing how to install a new spring, that should show you what you need. The flat springs wind very tight into a small circle, very hard to keep flat and concise under the extreme tension. You can make a winding board out of a piece of scrap wood with short nails placed appropriately to help you while you wind the coil and hold it flat. Each spring is different so you just have to experiment with what nails are needed to assist you.
If you are going to try to rewind the spring I would highly recommend wearing safety goggles and heavy leather gloves like Wells-LaMont Buck Skins. I used to assemble spring wound gyroscopes and every now and then a spring would slip on a technician and go flying. Pays to be careful. That's the magic part!
just wanted to add here that a few years back I ran one of the pull starts for a while, as they are from china they're junky and clunky, I took mine apart and put a very strong small dia. rope in it in place of that stupid cable idea it came with, it never failed on me once, another thing that is a must on the pull starts is that you dont jerk them when trying to start the engine, you should get hold of the handle, lift until there isn't ant slack in the rope and then with a good even pull just use it to spin the engine over, and they do ok, but if you just grab the handle and start yanking the ever living crap out of it, they will fail shortly, you cant get to rough with themsince there poorly constructed.
just thought I would share my personal experience with the pull starters, also had same experience with the pull starters on some of the Chinese made 6.5HP GX200 Honda Clone engines.
Rubber side down ya'll