Electric Start

Jasanabia

Jasanabia

New Member
Hi I have a 66cc raw motor on a gt mountain bike, Soon I hope to get a shift kit and maybe an expansion chamber later.
Heres my question,

So when you pull start an engine or use a starter motor, you are causing the magneto to generate electricity which goes to the coil, then to the spark plug.
What if I pulled in the clutch on my bike and connected an amount of voltage straight to the coil (blue and black wires)? Would that ignite the spark plug and cause the engine to start?

I know there would have to be fuel in the chamber but supposing it was primed

Has anyone been able to use an electric motor to start their bike? This dea sounds like it could damage the engine but I thought I would get some feedback
 
Probably not, as the piston has to be at about TDC to fire and have a useful effect in moving the crank. And pistons don't like to sit still at TDC with the clutch pulled in. The fuel must be compressed to fire correctly/

And why do you think an electric motor would damage the engine? No differn than roll starting in the engines pov.
 
The reason I mention this is because roll starting the bike skids through the back tire, I just had to spend 28 bucks on a new one, and switching tires isn't easy.
My bike won't run at all with the choke on so I cold start it without the choke and it take a bit of pedaling while the engine is engaged before it starts.

A starter motor would be so much easier and I already have a 12v sla behind the seat for my headlight.
 
If your engine won't run at all even cold w/the choke on - your fuel/air mix is likely far too rich. Check plug electrode coloration, it should be a brown/tan.

While an electric start would be nice, TBH by far the easiest solution & one ya hafta do w/a shift kit anyway is just keep pedaling as you let the clutch out. The 49-66cc engines have enough compression new that a pure roll/pop start (no pedaling) that most bikes will skid & a shift kit is freewheeled so you can't pop start them at all.

Shift kit owners get used to the technique of pedaling up to speed and timing the clutch release so it coincides with the downward power stroke of one of the pedals - kinda like like a kick starter. Doing this anyway with a non shift kit bike will defo help prolong tire life.
 
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I am actually installing a sick bike parts shift kit right now ( and having some trouble with the bottom bracket). I know the gas-air ratio is too rich because th engine runs great without a muffler. I have a muffler frk a weedwacker on right now and it seems to run better. I downt know a way to get more air som if you have any suggestions that would be great.

I have two ideas for electric starters:
1. You could have a car starter on a rear rack with
a chain going to the left side sprocket on the back
tire. I won't be using that sprocke with the sift kit.
Then get one of those kickstands that keep the
back tire off the ground.
2. Buy a pull start and take that apart. Pulling a
string just creates a spinning motion so I'm sure a
starter motor could be used with that somehow.

You said the easiest solution is tbh, what is tbh?
 
Also What does TDC mean.
Frozenveinz what I mean is that connecting voltage strait to the coil does no sound like a good idea.
 
Jasanabia said:
I am actually installing a sick bike parts shift kit right now ( and having some trouble with the bottom bracket). I know the gas-air ratio is too rich because th engine runs great without a muffler. I have a muffler frk a weedwacker on right now and it seems to run better. I downt know a way to get more air som if you have any suggestions that would be great.

You said the easiest solution is tbh, what is tbh?
Click to expand...

Adjusting the fuel air mix is done my moving the E clip in the carburetor: http://motorbicycling.com/f4/motorized-bicycle-carburetor-pictures-how-install-195.html

...and "TBH" = "To Be Honest" as in, "to be honest by far the easiest solution & one ya hafta do w/a shift kit anyway is just keep pedaling..."
 
Ok thanks, I'll need to take the carb apart where the throttle cabe is connected it sounds like.
Also when I turn the choke on the engine actually sometimes does start up very briefly, on for a short moment and then immediatly dies (cold start)
 
Ok here's the design:
Taking off the cover next to the engine sprocket reveals the governor and magneto. There s a nut on the magneto and can be turned with a socket. Because the clutch is on
the other side of the engine (on the crank case side) you
can pull in the cutch and start the engine by turning this
nut.
My idea is to have a starter motor beneath the engine in
the small triangular shaped spot, using a chain to go from the starter motor to a socket on the nut.
Not easy but I'll post updates if I get anything done
 
Still working on design but here's what is have so far

I will sandwich a sprocket in between 2 jam nut on a threaded rod, then grind down one end of the threaded rod so it's square and can fit into a socket. With the square peg secured with jb weld and some jb weld on where the socket fits onto the nut everything should hold up.
The problem is attaching a sprocket to a starter motor. Power tools like drills can't be used because the starter has to be able to spin freely while turned off. Since the chain will be continuously moving I'll need to make a chain guard. The motor can be held on with u bolts and battery can be anywhere on the bike.
If this works I'll make a diagram
 
when an electric motor is turned by something other than itself, doesn't that make it a generator? Is there some way you could use that?
could you not put the sprocket on a freehweel so it isn't nececesarily turning the motor after starting?
I'm pretty psyched about your project, keep us informed!
 
Yes exactly, but a permanent set up with some kind of switch on the handlebars. Unfortunately I haven't had time to work on this lately and I probably wont get to it for a while.
 
I found a stater form an atv, that's small enough to fit on the bike under the motor, the atv starter has a small sprocket on it, so it can be hooked into the chain.
Saying that you would need to have a stand on the bike like the old whizzer that put the rear wheel off the ground, then use the starter to start the motor, pull the clutch out drop the bike and go.
The other way is to have a centrifugal clutch on a jack shaft and put the starter in between that and the motor so the motor will turn free, then you can start the motor and it will idle until till your ready to go.
But you will need a battery, solenoid, voltage regulator to make all work, but then you can have a real lighting system on the bike.
 
Donbia, actually it's much easier than that, there are two covers on the side of the engine where the chain is. One covers that engine sprocket where the chain is, there is a slightly larger one next to it. Take of that cover and you can see the magneto and governor. There is a nut on there which when turned, can start the engine from a stop. Without the cover on you can drill start your bike just like the video of the lawnmower. The clutch still has to be in to start it, because you are turning the engine and therefore also turning the back wheel. Your atv starter would be the perfect thing to use for this.

What I'm saying here is that with the starter motor connected to this side of the engine you can have the bike sitting still with both tires on the ground, and turn a switch to start it just how you would a normal motorcycle.
You just need to have the clutch pulled in because these bikes have no neutral gear.
 
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Jolfstn, I never thought of using the starter motor as a generator as well, but I suppose you could set it up to power lights or charge a battery. I don't know much about freewheels but I think you mean like a bike freewheel where a sprocket can turn one way, but spins freely when turned in the opposite direction. When you start an engine you turn it the same direction it's going to be running so I don't see how that would work, unfortunately.
A friend of mine suggest sticking and angle grinder/drill over the nut, but it would never clear the pedals.
 
No the starter motor is not the generator, you have to have a separate generator as well, hooked into the chain with sprocket large enough to make it work. But not overly large. As far as the nut on the motor, It would take changing the motor cover plate to do it, and it would stick out from the motor and be in the way. but the stater motor I will be using is made to hook into a chain and just turns with the chain till you need it, further, with it between the engine and centrifugal clutch you could start on the fly, If the motor would die on you., because the chain on the clutch is not turning the motor if it stops running. Just freewheeling with the back tire. Plus you can mount it out of the way say under the motor and it will not be sticking out from the motor.
When I get my bike setup l will post it, I am not using a china motor. but is a american made motor. but still a 2 cycle. it can be mounted any way up or down because the Carburetor does not use a float. so that makes it easier to mount in tight places. it makes 3.5 horse and red lines at 9000 rpm. It is not a chain saw motor.
 
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