Hey,

I'm fairly ok in electronics and have this gas engine lying around. I know its possible to take the pull start off of it and replace it with a push start. Kits that do this can be costly and I was wondering does anyone know of a circuit that i could build that would do the exact same as a starter box?
I dont know the actual process of how the started box works and I have searched online for plans...but with no luck. If anyone has an idea or clue or a step by step thing to guide me I would apprechiate it since i am in a bit of a rush. Again thank you for your time.



Thanks

 

Hi Kosoz,

What gas does this gas engine use ?
Some gas engines have to be warmed up by
starting on petrol or diesel first.
Special precautions usually have to be observed
for running on gas, especially compressed gas.

And 'pull-start' is that where you pull a cord
to spin the engine ?
Surely it cannot be that ...
no electronic circuit could replace a pull-cord.
So what is it then ?

If you want to fit a starter motor onto an engine
that doesnt have one, then have a look at other
similar engines that do have starter motors and see
what is involved.

I do not know what a push start means to you, but
here we get our freinds to give us a 'push start' if
our car battery goes flat and cannot start the car.
It involves people pushing the car from behind until
the engine fires and runs. That is what we call a
push start.

I doubt very much that this is what you mean, maybe
you mean a press button that would engage the starter?

Such a circuit would be fairly simple, the difficulty
would be the coupling between the starter motor and
the engine. And of course un-coupling it when the
engine starts. This mechanism is probably the major
part of the kit you mentioned, and cannot be replaced
by any kind of electronic circuit.

As to a 'starter box' i am afraid you have me stumped
on that. I have no idea what you might mean. I vaguely
recollect the term 'starter box' from somewhere, but
i'm not sure its anything to do with engines.

John

 

Hi Kosoz,

I think a 'starter box' was something we used to use
on model air-planes. It had a spinning flywheel that
we would offer up to the prop and make it spin until
the model air-plane engine started, it was just a
fricton coupling and we just removed it when the
engine started.

Maybe you mean something like that ?

John

 

Ok the engine i am using is basically the same as a small gas engine. Maybe 18 cc or 22 cc. Now i remember reading what John had said about the flywheel and model airplane. Lets say this engine will be used for a purpose such as mounted on something...lets say a bike for instance. Pulling the rope to make the engine start will not kill me...but i would like to be able to take off the pullstart and put a pushstart (starter box) kinda in place if it is possible. That is exactly what i ment. Opening it, taking off the whole pull start mechanism and replacing it with that starter box. Ya John.....something that will start the engine rather then pulling...an easier alternative basically.

 

Basically thats what i mean...pressing a button to engage the engine in starting.

 

It's pretty pointless asking this in an Electronics forum, it's a mechanical problem - with perhaps a slight bit of electrics, but no electronics at all.

From what I understand you want to add a starter motor to a small engine, like cars added many years ago to replace the starter handle. The problem, just as with cars, is how to disconnect the motor when the engine starts.

I would suggest your best chance is radio control model groups.

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Hi Kosoz,

With such a small engine,
it might be possible to have the motor fixed to the crankshaft,
and allow it to spin with the engine running,
unless of course this is a model aircraft.

That way you don't have to concern yourself with engaging and
dis-engaging the motor, maybe it could double as a charger for
the battery when the engine is running.
That would mean some kind of change-over circuit.

I am assuming a standing engine setup.

Does this engine have a use or function?

Regards, John

 

This motor is going to be positioned on the back of a scooter, gas tank will be relocated and such. It will have the function of either ( a chain, or gears) connect to the back wheel. The motor will be controlled with acceleration controls.

The thing im wondering is...can the motor be modded to just pressing a button to start it. Stopping it is no problem since it already has a Stop button. Stops the engine right away.

 

Basically the motor will be driving the back wheel. The thing is..i dont want to have to go down and pull start this thing if it keeps cutting out because of the braking system, which stops the engine....i would prefer a "button" to be pushed to make it start the engine.

 

The basic question i am asking....if the motor is mounted completly...can the PULL mechanism be converted to a "Push" Button Start? I know its a mechanicial problem...but it does include a small bit of electronics....

 

HMmm ...

I would suggest a kick start assembly might be easier to make.

Those little scooters with tiny engines could have a small
hand operated clutch which could be used to engage the engine
to start it while you're scooting along.
That might be a lot easier.

John

 

ic....

well about the push start...i read up more about it

as soon as the button is pushed the connection is engaged and a motor turns the "shaft" where the pull mechanism would be. Same as starting a motor by pulling it. Do you really think a small lets say 12 volt motor could turn the crank enough to get the thing started?

 

Basically i need the most cheapest and easiest way of doing this....so if you got the idea and the plan..im up for the challenge. Ty for the help...btw do you have msn?? Easier to chat that way.

 

Lets see have you seen starters on motors before theres a nylon gear
that when the starter turns raises or pushes out by centrifugal force and
and hooks itself upto a larger steel gear on the flywheel, and when the
starter stops it pulls itself down.The gear is a couple of bucks at most
lawnmower shops.

I would say buy a lawnmower starter. And a gear if your flywheel dosn't
have one which i asume it dosn't. Then align and mount it on the chassis.
Wire it up to a switch and 12v motorcycle battery. That would be the
easiest way I could think of.

It mostly will be pricy. Especially if you don't get the electric motor to pull
out when the lawnmower starts. Starters are not meant to be turn for
long periods of time they wear out, then you have to replace the brushes
and all that good stuff. And the gear will wear out to. I just recently
replaced my lawnmowers starter gear it's not hard but getting the gear
off the starter is a pain.

 

Would this work....... Lets say once you take off the pull start and everything you are just left with the shaft right? Then mount a Tight Spring Loaded Gear...So that the gear can move the shaft to the end and then the spring would let it go. Just like you pulling the cord to start it and then letting it go? Just using a 12 volt motor and a trigger. Basically once you press the trigger the motor moves the gear/shaft to the pulled out position and then the spring puts it back. Basically the same effect as pulling and letting go. Will that work? That seems to be easier