I had a very similar problem with my 175 this Summer. Started running like that and I gave it a standard tuneup.
New points, plugs, condenser etc. Ran good for a couple of hours, started again. Pulled my hair out for about a week,
rebuilt the carb, adjusted and readjusted the timing, replaced everything from the Distributor back to the battery.
Nothing helped. It would idle good sometimes, but above 800 rpm it sounded like yours. Thought maybe the advance in the distributor was worn out. Maybe?
Finally went back to my local tractor mechanic for help questions.
After a bit of yes and no questions, he said they had found several bad condensers from their supplier (Tisco) returned by their customers.
Go to NAPA and get a good one. I did that, and it has ran like a stripped snake ever since. Never thought of the condenser being bad out of the box.
Might be one place to look. Also make sure the wire from the coil to the points, isn't grounded where it goes through the distributor.
All electric connections clean and tight. No wiring grounded.
New points, plugs, condenser etc. Ran good for a couple of hours, started again. Pulled my hair out for about a week,
rebuilt the carb, adjusted and readjusted the timing, replaced everything from the Distributor back to the battery.
Nothing helped. It would idle good sometimes, but above 800 rpm it sounded like yours. Thought maybe the advance in the distributor was worn out. Maybe?
Finally went back to my local tractor mechanic for help questions.
After a bit of yes and no questions, he said they had found several bad condensers from their supplier (Tisco) returned by their customers.
Go to NAPA and get a good one. I did that, and it has ran like a stripped snake ever since. Never thought of the condenser being bad out of the box.
Might be one place to look. Also make sure the wire from the coil to the points, isn't grounded where it goes through the distributor.
All electric connections clean and tight. No wiring grounded.
