stuck motor old briggs

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motor_head

motor_head

New Member
Dec 18, 2008
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iowa
well i found a cool old motor it's a wmb briggs and stratton made in '57(think thats
what the tag said).
i have gotton the crank freed but the piston won't budge all i can do is rock the crank back and
forth a little.so i was wondering what the best thing to try to free it with is

hoping to put it on a bike on a website it says 1/2 hp but it was probably rated pretty modestly
and with a better carb should put out 1-1 1/2 hp in todays rating
 
Elmo

Elmo

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Sep 3, 2009
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Try some Marvel Mystry oil down the sparkplug hole. I bought an 8n tractor with all 4 pistons stuck, used the MMO let it sit for 24 hrs tried to move it, no go. Added some more and 24hrs later it came free. The folks on the 8n board swear by it and have seen several posts where it worked on stuck tractor engines. Can't hurt to try it.
Elmo
 
D

dmar836

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Jun 23, 2009
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KC
I have a 1948 WMB. What carb have you considered? The vacuum carb on there isn't good for much........ and there is no real throttle. They were designed to operated at more or less one RPM to power washers, etc.
Mine wouldn't run as the valves were stuck open from carbon. Runs now but again that carb won't allow easy starting without considerable priming.
I have read it is actually rated at 5/8 HP. With it's design, it has more torque than an equivalent Chinese 2-stroke. Could work on a belt driven machine - my plan.
I did read about the carb swap but can't remember what might work. Do you know?
Let me know,
Dave
KC
 
bairdco

bairdco

a guy who makes cool bikes
Aug 18, 2009
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living the dream in southern california
i had an old suzuki RV90 trail bike that i got with a seized piston. with the head off, i just poured some regular motor oil in the top, till it filled up. let it sit for awhile, and the oil seeped in and loosened it up.

same deal with the mystery oil, but cheaper.
 
GearNut

GearNut

Active Member
Aug 19, 2009
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San Diego, Kaliforgnia
I have had excellent results soaking the piston/ cylinder with straight diesel fuel. I have read that a 50/50 mixture of diesel fuel and kerosene works better yet.
 
N

noco

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Sep 9, 2009
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fort collins colorado
the best penatraiting oil ive ever used was pb blaster....soak it in it....by the way it might be a blessing....they make bigger cranks and cams for these and ive built these to run alcohol...wapwap...funfun
 
motor_head

motor_head

New Member
Dec 18, 2008
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iowa
dmar836 said:
I have a 1948 WMB. What carb have you considered? The vacuum carb on there isn't good for much........ and there is no real throttle. They were designed to operated at more or less one RPM to power washers, etc.
Mine wouldn't run as the valves were stuck open from carbon. Runs now but again that carb won't allow easy starting without considerable priming.
I have read it is actually rated at 5/8 HP. With it's design, it has more torque than an equivalent Chinese 2-stroke. Could work on a belt driven machine - my plan.
I did read about the carb swap but can't remember what might work. Do you know?
Let me know,
Dave
KC
Click to expand...
i realy haven't given alot of thought about a carb to put on it only thing i can think of for a
motor this small would be the carb from a weedeater,the carb on it is no good
if i can free it then it will probably have to be belt driven
 
D

dmar836

New Member
Jun 23, 2009
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KC
Yeah but carbs from a 2 stroke can act different than those for a 4 stroke so..............
 
Tom Bartlett

Tom Bartlett

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Jul 13, 2008
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Motor Head,
Played with many an old stuck motor, and recently found (invented?) a new technique. I was trying to help a friend with a stuck 1967 Sears 165 motorbike. He had given up...I thought, PB Blaster didn't work, diesel fuel didn't work, so I carefully degreased the engine and while holding pressure on the kick starter, gently heated the head fins with a propane torch. I never let the torch stay in one spot, just kept moving (the fins will really disperse the heat) when LO and Behold! the engine kicked over. A few spins and we sprayed some Hot-Start into the cylinder, replaced the spark plug and it fired! Happy shouts and a sigh--we saved another old bike.
 
motor_head

motor_head

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Dec 18, 2008
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iowa
i really don't think 2 stroke carbs are very different from 4 stroke carbs, i saw a setup were a guy ran 2 weedeater carb into a Y adaper on a briggs (5hp??) and it ran fine, better actualy, since there were 2 small carbs instead of one large one

the torch idea is a good idea, but will probably only use it as a last resort, i would also have to be carefull because i have an acetylene torch and they burn hotter than propane
 
motor_head

motor_head

New Member
Dec 18, 2008
107
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iowa
well since the piston is on the to of it's stroke had to pour in the diesel for the bottom side
hopefully i can free it up cause it will make a cool motor for a bike
i just used strait diesel no kerosene cause i can get diesel out of the tank at home but would have to go get kerosene so will see how it works
 
a_dam

a_dam

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Feb 21, 2009
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Momence, IL
Let us know if that soaking with diesel does the trick.

Turning the crank alone might not be the best way to yank the piston free. I'd try putting a length of wooden dowel rod through the spark plug hole, sitting on the piston's top, and tap it with a hammer or whatever. Preferably while someone else is torquing on the crank to make sure you're not stuck at top-dead-center.
 
Bikeguy Joe

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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up north now
a-dam said:
Let us know if that soaking with diesel does the trick.

Turning the crank alone might not be the best way to yank the piston free. I'd try putting a length of wooden dowel rod through the spark plug hole, sitting on the piston's top, and tap it with a hammer or whatever. Preferably while someone else is torquing on the crank to make sure you're not stuck at top-dead-center.
Click to expand...
That's a good way to ruin a piston, if you could tap the crown by doing that on a flat head engine, but I don't think you can.
 
civlized

civlized

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Apr 28, 2009
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Alabama
I have a compression testing kit that I have used to inject air into the cylinder. I sprayed a lot of pb blaster into the spark plug hole, let it sit for a day, then pressurized the top of the cylinder with air. This worked for me. A little turning on the crank and it freed right up. It did seem a little dangerous, but it worked without having to take the engine apart.
 
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