Re: johnson HD-20 2.5hp parts?
JB, I think what I said is that they are more finicky than the 3hp that replaced them. We all know how the 3 is such a sweet running motor, that you just pull the rope and go, and it runs perfect without any fiddling once you set the carb one time and forget it.
The 2.5, first of all is a 3rd port motor with a rotary valve added. The internals must be in good condition for it to run right. Not such a bad deal, but it takes some understanding the system. In reality, it has two carburetors, though it doesn't seem that way. The main carb feeds the high speed through the 3rd port and then there is a second induction system at the rotary valve that supplies idle fuel. Again, it is not such a bad deal, just different. The idle needle has to be precisely adjusted, and there is considerable interaction between it and the high speed adjustment so if you are not aware of the peculirity, you will spend all day trying to get the dang thing adjusted. I know, I'm sounding like a broken record, but it's just different.
Depending on the year of the HD-25, it may have "Maverick Spark Suppressors". So when you run up against those things, you will say what the heck...? Once you understand, it's no big deal either.
It has a wobbler type water pump. That's good, but did I mention different?
I'm sorry if I came across as saying the HD is a POS. If it was, they wouldn't have been able to sell so many of them. In fact, in good mechanical conditon and some loving tinkering, they will do very well.
One thing about it, you will never run a HD hot. At the first hint of overheating, the fuel boils in the carburetor and the motor quits, and you will tear your hair out trying to figure out why it won't keep running.
