3hp Flathead Briggs won’t start

Joined
Apr 9, 2018
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#1
Think the motor is from 1988 but it’s on a rupp minibike. Cleaned the carb and all jets seem to be clear and the float needle is working. Has spark and plug is wet. I am baffled why it won’t start. Ran when I first brought it home but one day refused to fire. Seems to have good compression and has oil.
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Btw this site flips pictures on the side for some reason idk why.
 
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RAT RYDER 101

Active Member
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Jul 12, 2017
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#2
Check the coil. Also the gap on the mags> some spider guts might be in there.... (carry on) Rings might be loaded to. Just sayin.. I have that exact carb on a 10 horse Briggs cast block mounted on a SPEEDX from the early 60s.
 
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#4
It was weird I sprayed carb cleaner into the spark plug hole and it still wouldn’t start. The jet on the bottom of the carb? The only thing I could think of valves need adjusted.
 
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#6
The spark is a bright white, not blue I don’t know if that could be the problem. It has an old fashioned killswitch- a metal tab bolted to the head.
 

darwin

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#7
Notice the stickers saying easy spin. My ass, those motors were the original Bow flex machines.
 

darwin

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#8
The spark is a bright white, not blue I don’t know if that could be the problem. It has an old fashioned killswitch- a metal tab bolted to the head.
Adjust the point gap, make sure the cam rider [plastic piece that rides on the cam] is good so the points are opening and closing. Bad/weak spark could be a condenser problem too if it's old and can't hold a proper charge.
 
D

DRK

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#9
Flywheel could have a light coating of rust on it from setting. Sand the rust off the flywheel & coil magnet. Set the gap by sliding a business card between the magnet & flywheel, hold down on the magnet & tighten the 2 screws. Pull out the business card. Also looks like that one has the points setup. The points could be burnt or corroded. Use a fingernail file to clean the points. Slide the file between the points, push down on the points & pull the file through the points. If it still has weak spark, as Darwin said, condenser could be bad.
 
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#13
I have taken both the pull start covers off and both the motors have magnetos, no points. Maybe you were thinking about an earlier model briggs? I personally think the screw on the bottom of the carb just needs adjusted also the motor needs an oil change. Well I'll need a new chain and tires if I want the bike to be in good shape. It's fun to ride around on it but the other day the chain came off and I thought I could take a link off but the chain wouldn't fit.
 
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May 13, 2010
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#14
The points are behind the flywheel, it has to be pulled to get at it. Points and condenser are around $10.

If it is a newer motor they have CD's on the magneto, identified by a small bulge on the side of the coil, and a separate magnetic pickup on it. If the engine has been overheated it will fry the CD, so you need a new one. Hope this helps...............Curt
 
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#15
I have taken both the pull start covers off and both the motors have magnetos, no points. Maybe you were thinking about an earlier model briggs? I personally think the screw on the bottom of the carb just needs adjusted also the motor needs an oil change. Well I'll need a new chain and tires if I want the bike to be in good shape. It's fun to ride around on it but the other day the chain came off and I thought I could take a link off but the chain wouldn't fit.
have you checked the valve gap? it could be possible that the valves are worn and the gap is too large or too smal). ( check the gap with a feller gauge it should be less than .009, but more than .003)
does the kill switch work? try to unplug it to see if its bad.
good fuel?
hope this helps
 
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#17
Killswitch is a metal tab, looked behind the flywheel and don’t see anything just the shaft and ribs that come off the side cover. I know if it had points it would have a separate cover for the points and I can’t see a seam. I’m talking about the green engine which is the same as the copper. Was going to post pics but it has been saying file is too large for some reason.
 

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