This spring i bought what I thought was a decent Garden tractor at a good price. 2000 JD 445, has 2100 hours came with a cab and the spare engine. Bought it with a governor that was "out of adjustment". If I pushed up the throttle it would spin up until it floated the valves, governor was not working. After a little headache and some research I thought that the governor and flyweights had failed inside the crankcase and having no real history on this engine figured I'd yank it and replace the governor, oil and water pump. After opening up the case I found a pristine governor, completely intact and functioning. I was already in there with parts on the bench, I swapped it all out anyway! Now I need to find out why the governor wasn't working. BTW this is the only governed engine I have any experience with.
Thru the initial headache and research I did try to adjust the governor. This is where it gets tricky. The guy I bought it from made mention of swapping the engines. I ASSumed that a FD620D is a FD620D, maybe not the case. What was happening was the gov. rod was spinning in the gov arm. It appears that the original JD engine has a larger 1/4 to 5/16"gov rod with a machined flat that the gov arm grabs to help keep the arm and rod locked together. The engine that is now in the tractor has a smaller maybe 1/8-3/16" gov rod that is perfectly round. I have "clearanced" the gov arm and cranked it down TIGHT to the gov rod. With the gov spring that came on the tractor it strips/spins until the governor has no authority to slow the engine and it will rev until the valves float. To combat that I bought from ebay a 425 gov arm and spring (couldn't find one for a 445). After installing the 425 gov arm and spring now the idle hunts or bounces from max rev assuming 3500 to idle. Thinking that the internal governor is identical in both the 425 and 445 I have chased my tail in a complete circle.
I have serviced and eliminated the following: short fuel line in the tank (replaced), fuel press 28psi, pulled heads after failed compression check and did a basic valve job and it now has about 175psi on one side and 170 on the other, sprayed a who can of starting fluid around checking for vacuum leaks.
The whole governor assembly I think has been monkeyed with and the factory 445 governor springs are not available. The spare engine has a had the starter motor mounting ears broken off, I would just swap it in if it were usable.
I'm hoping a member here has at least a picture of a functioning 445 governor arm and spring. I think I have a good (spring that came on the tractor) governor spring but it is too stiff for the smaller round gov rod??
I have a suspicion that the injected 445 needs the stiffer spring and the card engines can use the smaller springs??
Any advice or pics would be great.
Sorry for the poor intro.