Weed eater engine conversion

Let me know

I have a duropower unit (the whole mud motor) I built that is almost good to go. When it ran it ran great. Last year I could not get the motor to start. Wasn't the starter, wasn't the plug, wasn't the gas. Brought it into a guy to repair and he couldn't either. He believes it is the part that goes next to thr flywheel but isn't certain. Chinese motor parts for this motor aren't tough to find, I just don't want to spend the time to do so. If you are interested, let me know what this might be worth to you.

Mark

 

For Jobber

if you want a long shaft air cooled the easy way is just get an old 4 hp longshaft outboard and stick a briggs and stratton mower motor on the top
the photo is of a 4 hp Suzuki with a bs

 

Mark I wish I had known you were having a problem with your engine. Those motors are fairly simple to service. If it has spark , compression and fuel, we can make it run. Let me know if all three are present and we will go from there.

 

A duropower question for john

John, it appeared that you were working diligently on your duropower conversions, but then switched over the the greater HP longtails from SouthEast Asia. Was the duropower just not enough power for your needs? Do you still recommend the duropower unit as a very workable setup? I seems like everyone that was so jazzed about this unit has moved on to other solutions.

Thanks in advance,
Ed

 

It was getting fuel, it had compression but it had real weak spark. I think this is where the problems is.

Mark

 

as a help to everyone ...an HT spark in air must jump 1/4 inch if it is to jump the plug gap under compression.....its no good just taking the plug out and seeing if it jumps the gap....and the colour of the spark makes no difference its only the metal particles from the electrodes that colours it ....

 

What are you saying ?

We did take the plug out and look at the spark. It was haing a difficult time even jumping the gap of the plug without being under compression. REplaced the plug with a new one and saw no difference. Not being a mechanic, I did take enough of the motor apart to see where the plug cable terminated. There was a black box that was similar in radius to the flywheel on the motor. I assumed as the flywheel turned it created the spark when a certain part of it passed through this "box" I was thinking the "box" might be bad.

This motor went bad right after the pull start broke. When replaicn ght epull starter, I cracked a part of one of the mounting bolts for the starter. Didn't affect the integrity of the motor and the compression checked out OK for me to confirm this. Fors some reason, the motor will not start.

I would sure love to get this thing running again. Any suggestions are appreciated. Maybe I can post pictures.

Mark

 

provided the gap between your " black box" and the flywheel is minimal then there is little you can do to increase the voltage other then fit a new box. check there is no deris ..iron fillings etc between the box and the flywheel . gap about 5 thou of an inch box core to flywheel
The box is in fact a magneto coil with electronics instead of the old contacts . they are ususully reliable. the only other thing I can think of is that you have moved the flywheel on the crankshaft but this is not usually possibe as it has a keyway ..and I dont think you removed the flywheel when you did the starter cable ....
The look of the spark has nothing to do with it ..its how far it will jump in air that counts

 

Mark,

Thanks for giving me the option. I will think about it and let you know. Thanks again.

Chris

 

another question

I could have moved the flywheel. When I was trying to remove the old starter (the part on the shaft after you remove the pull start cover) it was difficult to remove. This is when I cracked one of the mounting bolts on the casing of the motor. It was a superficial crack and did not destroy the integrity of the motor but a crack none the less. I was cranking on the bolt hodling the starter piece in pretty good. when I was told to stick s rope with a knot in through the spark plug hole and then remove the starter mechanism bolt, it came right off.

Could I have moved the flywheel on the crankcase? It was immediatley after I did this that the motor would no longer fire. How do I check and then fix this problem. Is it possible. Sure would love to get this motor running again.

Mark

 

Mark; That particular motor uses a removable steel flywheel key. It only goes in one way. I seriously doubt if it sheared or changed it`s correct index. Here`s how to check it . Put a couple of screw drivers behind the flywheel and exert a pressure onto the flywheel as to remove it . After removing the retaining nut hit the end of the shaft with a hammer , the flywheel will pop loose. Check that the key is in the key way slot on the shaft. If everything is OK reassemble. Now to set the air-gap on the magneto/coil assembly. Loosen all the bolts that hold the mag in place. Now place a standard business card over the magnets on the flywheel and rotate the flywheel around until it is directly under the magneto/coil unit. The magnets in the flywheel will pull the magneto down onto it with the business card sandwiched between . Now tighten all the retaining bolts. Remove the card and the air-gap is set. If it still wont start I would suggest purchasing a new mag/coil unit from a supplier. Let me know I have a list of them if you need it.

 

You may want to use a brass hammer or put something soft between the hammer and the shaft to prevent distortion of the shaft by the hammer blow. I'm just sayin'...

 

i have been very interested in this but i dont see how you are attaching the the shaft to the lower unit? i have seen the ways some guys do it but they have vibration problems. How did you attach the motor shafts together?:?:

 

oh thats easy ..the end of the shaft down to the gearbox is splined so .take the crankshaft out of the old engine and chop off the end with the female spline inside it ....maybe turn in lathe or otherwise register with the end of the b/s motor crank ( maybe shorten the shaft on the b/s) and weld it in place ...make colar ..use keyway etc whaterver you have facility for ....This means you can lift the b/s on and off as you make your adaptor block ...take the water pump bits out ..... 8 inch pitch is about right .

 

ohh so i would take the crank out of the old motor, then baiscally adapt it to the lawm mower motor. i get it thanks.