1988 Scag w/ Kaw FC420v-BS02 and slight knock but runs great!

[Honda Tech]

Ha ha. Thanks. My wife calls me "obsessed"! lol

No pulley yet. I wanted to make sure that it was running well before fully hooking it up. It's definitely inside the engine.

Well, from as thorough as you have been, I'm at a loss. I assume you replaced the cylinder head gasket. Was it a Kawasaki gasket? I have seen were the wrong head gasket was installed before and the sealing ring ends up exposed to the combustion chamber, allowing the piston to contact it and making a definite knock.

There is no play in the crankshaft at the bearings?? Just grasping for straws...

 

[Mastiffman]

Well, from as thorough as you have been, I'm at a loss. I assume you replaced the cylinder head gasket. Was it a Kawasaki gasket? I have seen were the wrong head gasket was installed before and the sealing ring ends up exposed to the combustion chamber, allowing the piston to contact it and making a definite knock.

There is no play in the crankshaft at the bearings?? Just grasping for straws...

Thanks for the reply. The head gasket is ultra thin to begin with. Plus the knock sounds like it's coming from the crank case.

I did mic the crank bearings and crank and all are well within tolerances. I even double checked them today. It's baffling to me.

Could the 20w50 really be causing it? Would the fram filter get clogged with the zinc or something? Maybe the flow of the filter is too low? IDK...

 

[Mastiffman]

Okay....

SO I'm beginning to think that this is exactly the way that it's supposed to sound and I technically never should have even rebuild the engine. Every video that I watch on youtube this exact engine it sounds identical to mine. Even people claiming that they have a great one!

Even the 540v sound like it. I believe what I' hearing is the snap of counterbalance back and forth.

Take a listen to any one of these videos and you'll hear it at idle and WOT. But mine you can't hear it at WOT so I'm done I think. smh.. lol

https://www.youtube.com/results?search_query=new+kawasaki+FC420v

 

[Honda Tech]

The 20w50 oil is an approved oil by Kawasaki and recommended in their newer engines, but that shouldn't have anything to do with it. The Zinc is added to the oil because it used to always be present, but the manufacturers have slowly removed it.
I'm not a big fan of Fram filters, but that shouldn't be an issue as long as it is a comparable filter. Even if it did plug, they have a by-pass.

Since you are quite sure it is coming from the lower end, I can only guess and assume it is the counter-balance also. Per Kawasaki min/max allowable on the conn. rod/crank journal, they allow up to .0056" and you are well below that. I'd like to recommend just removing the counter-balance, but with that design, I'm not so sure it can be done without causing issues.

If you want original labels yet...56030-2324 Recoil Starter Label. 56031-2191 Air Cleaner Label. 56031-2238 Before Starting/Oil Label. 56038-2504 Kawasaki FC420 Label.

I'm not sure what else I can recommend, so if, when you figure it out, I would like to know what you found.

Best of Luck!

 

[Mastiffman]

I'm done... I haven't heard this thing run in well over a year and Im used to listening to my 20hp 2 cylinder Onan engines and 12-14hp Kohler Engines...

I was chasing something that wasn't even there.

https://www.youtube.com/watch?v=aqbGBmdOifQ

 

[Mastiffman]

I'm done... I haven't heard this thing run in well over a year and Im used to listening to my 20hp 2 cylinder Onan engines and 12-14hp Kohler Engines...

I was chasing something that wasn't even there.