Author Topic: Which spins faster - kickstarter or starter motor??  (Read 1622 times)

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Offline puppytrax

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Which spins faster - kickstarter or starter motor??
« on: February 03, 2007, 04:13:23 PM »
OK; I've been discussing magneto ignition conversions with several members, as well as magneto rebuilders. Most 4-cyl mags as made by Fairbanks Morse for stationary engines, tractors, etc, use an impulse advance unit attached to the mag shaft, so that when the engine starts up "It gives the magneto a quick snap over for better spark for starting and also retards the timing." There are weights to draw the advance back in when running. Pretty much just like a distributor advance.

Anyway, I have owned two Triumph ARD magneto conversions using the FM mags, and they did not use any impulse advance, or any advance unit at all. I never had any problem kickstarting my Triumphs.

Now I'm wondering what the big difference is between kickstarting a Britbike, and electric starter-motor starting a tractor/stationary engine. If the stationary/tractor engine actually *needs* a retarded ignition, is it because the electric starter motor spins the motor over much slower [RPM] than the kickstarter gearing??   ???

BTW: As an example of a stationary engine, I used a power luber in the military to grease trucks. It had an opposed flat-four gasoline engine with a magneto ignition, but an electric starter motor. These mags are still showing up on eBay, and I may try to use one on my Honda magneto conversion.  ::)

So...Does a Honda kickstarter spin the motor faster than a starter motor?? Is that why I had no problems kickstarting a mag with no advance??
 
« Last Edit: February 03, 2007, 04:19:01 PM by puppytrax »
...stock 1972 CB500 '500 Four' undergoing re-assembly...
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Offline Jonesy

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Re: Which spins faster - kickstarter or starter motor??
« Reply #1 on: February 03, 2007, 04:48:41 PM »
I believe the starter motor (with a fully-charged battery, mind you) spins the engine over faster.

I've seen 4 cylinder outboard engines use magneto igniton. I've got a 60 HP V-4 Evinrude with a self-energizing magneto (it has a magnet rotor to power the coil and the entire unit was self-contained with the points and all) and it is belt-driven from the crankshaft at a 1:1 ratio. This engine has both an electric starter and a pull starter. In this engine the electric starter spins the engine waaaaay faster than the rope. With the monster compression this motor has, pulling the rope turns the engine very slowly, but it is still enough for spark. I read somewhere that this type of magneto puts out around 50,000 volts at cranking speed (I'm assuming with the electric starter), but even turning it very slowly will make spark. I knew a guy who was working on one of these behemoth motors and reached for the magneto assembly on the workbench. He grabbed the plug wires and pulled it towards him, and the belt pulley dragged on the benchtop enough to turn it. He got a nasty jolt to his hand!

However, I'm not sure if an outboard engine is a good example since the throttle is partially controlled (or in the case of small motors completely controlled) via the ignition timing. The timing is usually advanced some when starting, and there is no sort of automatic spark advance mechanism, other than the throttle control that is manipulated by the operator.

Not sure if this helps you or not, but this is where my experience has been...
"Every time I start thinking the world is all bad, then I start seeing people out there having a good time on motorcycles; it makes me take another look." -Steve McQueen

juanclos

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Re: Which spins faster - kickstarter or starter motor??
« Reply #2 on: February 03, 2007, 05:49:40 PM »
Not an expert on this but since the standard magnetos by ARD were advanced pretty nicely they did try to kick back at you when you start your bike. This is main reason my bike has the kick starter broken at the shaft.  They tried to start it without giving it a couple of soft turns first and they busted the starter shaft.
They can be started that way though, my bikes just happened to be an 11:1 compression bike with a 915cc kit.  I've spoken with plenty of guys with stock bikes that kick start their bikes with ARD magnetos.

Good luck

Offline puppytrax

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Re: Which spins faster - kickstarter or starter motor??
« Reply #3 on: February 03, 2007, 06:04:44 PM »
They tried to start it without giving it a couple of soft turns first...

Yes, I'd forgotten that...You did have to bring a piston up on compression, like you said..."a couple soft turns"...   ;D

And they could kick back...After a while, you learned how to let your leg absorb the kick...   ;)

Well, that convinces me...no advance!!!   :o
...stock 1972 CB500 '500 Four' undergoing re-assembly...
...Stock 1972 CL450 'Scrambler' also being re-assembled...

Offline Jim F

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Re: Which spins faster - kickstarter or starter motor??
« Reply #4 on: February 04, 2007, 07:32:27 AM »
just like starting my KTM 500 2 stroke,
give it some gentle loving before you try and start it
and it starts on the third kick everytime.......


And it has kick back and ripped the sole off a pair of
SIDI boots too
« Last Edit: February 04, 2007, 07:34:56 AM by big-jim »
2002 RC51 1000 (SP2)
1983 GS1100EC Suzuki
2002 998 Dukati (Customers Bike)
1992 KTM500 2 stroke
1975 CB750/836 Honda
1978 GS750/840 Suzuki