• If you like antique engines, vintage tractors or old iron, please register and join us. When registering, please provide your CITY and STATE as your location!

Bump start explanation?

Tom Jamboretz

Subscriber
Last Subscription Date
08/04/2019
After viewing the Hercules bump start videos I got to wondering. Why is it that it is relatively easy to do on large engines but not small engines? Even though I have a 2" bore scale model of a Domestic sideshaft that will start with that method. TJ
 

MCanady

Subscriber
Last Subscription Date
07/11/2019
I have bump started Witte 2 hp headless , 2 Hp Series S Jaeger engines , etc.. I think you have to experiment with the engines timing to be successful . Merton
 

David M. Lyon

Subscriber
Last Subscription Date
12/12/2020
There is also a big difference between bump starting against a Wico mag or just an igniter VS starting with a Webster with a starting lever. :brows:
 

Rich Mueller Sr

Subscriber
Last Subscription Date
07/10/2019
A whole lot easier starting something like a 6-12 Mule bumping the igniter than whipping the 40"+ wheels over, once you get things dialed in!, Some day I will get a lever for the 21/4 Galloway and try that on the Webster......
 
Last edited:

Odin

Subscriber
Last Subscription Date
07/13/2019
I could probably get my 1 3/4 horse Nelson Bros. to bump start. Its using a Wico EK, and from time to time the crank jumps out of my hand when backing it off before a starting attempt.

It probably would be a feature of timing and mixture. The engine has to fire before crossing the top dead center, and has to do so with enough power behind it to get over the next compression and fire again.
 

Rich Mueller Sr

Subscriber
Last Subscription Date
07/10/2019
My little 13/4hp xk economy will do it , in fact easiest way to start it, in the manual I found in Dads junk , it states the way to unflood it is whip it backwards real fast and it will fire and then open the exhaust valve and clears the cyl. If you don't whip it real hard it will take off running, sometimes if not flooded, I found out by accident one day....
 

GearlessJoe

Registered
Bump starting kind of got started with many workers in the oil field with engines that had hot tubes that they would kick the engine backwards with the fuel mixture right and would usually start right up. The main item to consider is the type of ignition. If it is a hot tube unit you always have a ignition heat source and if it's a battery and coil with igniter and you can trip it by hand at the right moment you also have a ignition source. As far as I know the Webster magneto unit is the only one that can be made to trip by hand at the right time as you roll the engine over backwards with primed fuel inside cylinder. I don't think it is the size of the engine matters as much as what type ignition methods the engine has. I have a old McVicker 5 H.P. engine that has a piston tripped igniter that I used to start by rolling over center but now because of my age I just prime and bump start with very little problems. I am pretty sure that many owners of engines over the 4 H.P. range would love to find a much easier way to start their engines as they get older.

Joe
 
Top