Some fun with another Briggs 3hp
- Thread starter Thepaetsguy
- Start date
You don’t have to true the crank or anything it’s fine for just a junker to mess with. As for shaping the lobes it’s not Important either. I have a big box of polishing stones. I think when said and done getting the lobes more like a glass surface with the stones is probably the most important thing. Next to the valves not touching the head. And the cam not touching anything inside the case.
do not do this unless your buying a billet flywheel.. once that flywheel has been acquired push them as far as you can.. Also to tell you the truth I took a grinder to the crank with zero fear of the outcome. this little 3hp spins up hard. I love snapping it to full throttle with no load. I can’t believe the WOT blasts the thing has already taken. the rod inside this engine is a trooper. Edit: A good 20% of the left crank weight is gone to clearance the lobe.
here is a 5hp cam I welded up and ran till the rod broke. if the engine is a throw away do whatever you have to to make it work. it’s not ok to grind on a crank and not balance It I understand that. I haven't noticed any difference in vibration before or after the cams though... a lot of stress heating/welding the cam grinding the crank. didn’t seem to bother much of anything.
I recently had a similar problem with the same type of carb on my old Briggs.
The engine would start on the first pull, idle just fine, but die when the throttle was opened.
After removing the carb, replacing the diaphragm and spraying Gumout throughout, still same symptom.
The fix was taking the wire from a bread tie and cleaning out the port on the right.
The engine would start on the first pull, idle just fine, but die when the throttle was opened.
After removing the carb, replacing the diaphragm and spraying Gumout throughout, still same symptom.
The fix was taking the wire from a bread tie and cleaning out the port on the right.
This carburetor had been disassembled completely cleaned and had quite the amount of work done to it. Those ports are what you drill/slot before you screw in the drilled out methanol jet. And I knew to check those before assembly. the only thing that changed was a pump cover swap and new diaphragm from the 5hp. Truing up the pump cover made a world of difference.
Hey Man, Have you put a tach on that 3 horse when you ran it wide open with no load? I had a 5 horse with a 3 horse billet flywheel that we welded up the cam and we didn't get the tach hooked up before it threw the rod but it was REALLY screaming fast when that rod let go! I'm glad it was my buddy riding it when it let go. We estimated he was doing about 7000 RPM and 50 MPH when the back wheel locked up and sent him into the grass.