21hp I/C Twin Hard Start and Surging

[cruzenmike]

UPDATE::

Yesterday I finally got around to working on the old Craftsman mower. I went ahead and replaced all of the carb and intake gaskets, along with a replacement (aftermarket) carburetor. I did also do a static governor adjustment when I had the intake removed. When everything was put back together I went ahead and adjusted the idle speed and top no load rpm. I could not find any specific information on the recommended engine RPM, so I set it to 1800 idle and 3300 top no load. The mower idled just fine, but when I increased the throttle to full, I feel as if it is still surging a little bit, but definitely nowhere near as bad as it was. I am thinking that maybe the springs in the governor may be part of the problem. I know that these can get weak and go back over time, and being 20 years old with no other engine work being done, I know the governor to be original.

With no fuel or air leaks anywhere, would these springs be the last thing to look at replacing?

 

[Scrubcadet10]

I had to buy a new bell crank for the opposed twin one time, that's what the governor link is hooked to, and there was an extra spring in the kit that said to install on the governor arm to the bell crank if high speed surging happens.

 

[cruzenmike]

I had to buy a new bell crank for the opposed twin one time, that's what the governor link is hooked to, and there was an extra spring in the kit that said to install on the governor arm to the bell crank if high speed surging happens.

I will have to look into this. Thank you for the advice.

 

[Scrubcadet10]

here is the mentioned spring,

https://i.ebayimg.com/images/g/v4sAAOSwt0FZChkI/s-l400.jpg