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Good day fellas!

I have a Kaw FC420V that needs a rod which I'm getting ready to replace and I'm curious if I can use a Rod from any FC420V or does it have match the last 4 revision(?) letters of the model. In this case BS02.

I can't seem to find any used ones on the bay. I would rather not drop a full $65+ on a new Rod if not a full rebuild of the engine. Just going to replace the Rod if the crank journal is fine as well as de-carbon it and do a valve and gov/carb adjust (Surges at idle).

Thanks in advance.

Normally not the BS02 describes the variation from standard.
Usually this will be things like a different crank end, different filters or even just decals on the blower housing.
My parts list down here shows 13251 for all engines.
If there has been an upgrade to a part, kawakasi give is a suffex , generally a letter and number shown this 13215-A1.
FWIW I can not find a FC420v-BS02 listed. the closest is FC420V-S02

Gotcha.

Yes, the Only part that I've seen with a variation the 13251 is an a after it and that's an undersized for crank rod journal correction.

Okay, so 13251 will fit all of the FC420v's That's good. That opens up my options quite a bit. I would assume that the S02 and BS02 would be the same being that the site that I'm looking it up on which is scag oem parts O c o m... And it's not showing an xS02 for any other revision of the FC420V from -Axxx through -Kxxx.

Thanks a ton for the reply and info! Great site!

I get into the kawakasi portal via either one of my wholesalers.
One goes to the USA portal via the Australian one and the other connects directly to the USA site.
AFAIK Joe Public can also access kawakasi direct if they have a USA or Canada url

Would that be the best place to get a new rod?

Also, are these rods aluminum or steel? If I have a knock are the chance high that I'd need a crank as well? I know the only way to really tell is to check the rod journal on the crank with a Mic.

What's your experience with it though? I'm not looking to fully rebuild the engine.

My opinion is to open it up and have a look before you do anything.
It could be a large number of things and you won't know till you have a look .
If you don't have a manual they are available from here http://www.mymowerparts.com/pdf/Kawasaki-Service-and-Repair-Manuals/.
I run a repair business so I get them through my trade suppliers but expect to pay more than you think, Kwaka parts are expensive which is why you pull it down first.
Then if it needs machining or more work than you are comfortable with you can sell it as is.
There are lots of backyard mechanics who will be happy to pay a reasonable amount for a dead engine that they can repair and in many cases these people will have a source of cheaper parts so you won't get value for the new parts you have bought.

Oh I hear ya. I was just preparing myself for the possibilities of what could be going on. Wisdom has taught me to pull the trigger to fast on purchases until you know what the problem is.

The engine runs great overall and it's had this slight knock for the last few years. It would make sense to pay double the shipping on a crank and rod if I bought the rod without pull the oil pan and micing the rod journals first. Which is the next step for me.

I'd be better off waiting to see what the issue is and then buying a used crank and rod/ piston set of the bay from a low hour well maintained engine.


That's the repair manual for FC420V? Thanks for that. I will definitely need that when reassembling it.

The kwaka manuals are fairly good.
The JD kwaka manual is even better but a lot more expensive than a free pdf download.
If you were running on premium fuel the knock could have been a combustion knock and not a loose rod.
Usually the rods are really good.
What gives most problems with singles is the counter balance mechanism.
The rod is shorter and turns a shorter arc so wears more and the bolt holding the 2 halves on Briggs & Kohler engines is what usually gives way first.
Got a lot with a good crank and a counterweigh through the side of the block.

That's good to hear on the manuals. And very crazy about the crank and counterweights through the block. Yikes. Seems like I;ve been lucky for this engine being a 1988 SW52-13BV. smh

Near 20 years out of a mower engine is doing well.
So fair to say that engine owes you nothing.
Mower engines are fairly robust when used within specs but no noe can properly test or simulate years of use and the most complicated part of engine design is vibrations.
And vibrations is what does the damage.

Okay, so I have finished my 1988 Scag mower restore...

Before...




After...






now, I finally got a chance to tear into the engine to find out what that knock is. With some research I'm almost wondering if its the counterbalance making the noise. It's not terribly loud and it seems common for the counterbalance bearings/ bushings to wear to the point of allowing it to make noise.

Is there a way to check the counterbalance for wear? WITHOUT Tearing it apart and mic-ing clearances?

Okay, so I tore the engine apart and have MICed everything that I could that could be the issue of the knocking.

Piston Pin Hole is over on specs with visible signs of wear and the connecting rod large bore is as well. Everything else is within specs per the manual.

Now, I a;ready found a new Piston and have that on the way and I'm looking for a new connecting rod #13251-2063..

Anyone have any leads for one shipped for <$60???

Also, is there a cross reference list for the connecting rod to see if other rods will fit correctly to open up the range of potentially available rods?

Thanks.

Mastiffman said:

Good day fellas!

I have a Kaw FC420V that needs a rod which I'm getting ready to replace and I'm curious if I can use a Rod from any FC420V or does it have match the last 4 revision(?) letters of the model. In this case BS02.

I can't seem to find any used ones on the bay. I would rather not drop a full $65+ on a new Rod if not a full rebuild of the engine. Just going to replace the Rod if the crank journal is fine as well as de-carbon it and do a valve and gov/carb adjust (Surges at idle).

Thanks in advance.

Click to expand...

Hi! I would question your diagnosis. If you have an engine that has had a slight knock for several years and it was a rod knock, it wouldn't have made it this far. By chance, do you run Regular unleaded fuel? That engine design along with low grade fuel will create an excessive amount of carbon build-up in the cylinder head and ultimately it sounds like the rod is ready to go, but in reality, the cylinder head just needs to be de-carboned and replace the gaskets.
I would look at that before I would pull the engine for a complete teardown that it may not even need. If I am correct, start buying better grade fuel.

Good Luck!

Thanks for the reply.

Too late! lol

I am familiar with carbon deposit build up and yes for a 1988 engine, this one wasn't too bad inside compared to some of the Onan's that I've dealt with in the past.

I did tear everything down to the block, puled the crank and all. I had to know what was out of spec and what wasn't. I found that everything that could be making a knock (Counterbalance and connecting rods, piston, wrist pin, connecting rod and crank) was well within proper operating spec and nothing right on the verge of needing to be replaced. The cranks piston pin (Rod journal) was completly round as well. EXCEPT, the large bore of the connecting rod... It is supposed to no more than 1.6169" and was 1.6175" running the length of the right (top to bottom) and was 1.6155" 1.6160" side to side. So that bore was oval shaped. A tell tale sign of Rod Knock... And out of spec.

The small bore was right on the cusp of needing to be replaced @ .8685"-.8690" The piston pin was in great shape and perfectly round the length of it @ .8665". BUT the pistons wrist pin holes were over the Max .8676" @ .8690"-8.695"...

So between the large bore on the Con-Rod and the Horrible piston pin holes, that's where the knock was coming from. I have a new piston and rod coming and will most likely hone the cylinder and put new rings in as well.

Okay,

SO I have the new parts ready to go. Piston, Rod and Rings.

I'm going to be honing the cylinder today and hopefully start reassembly.

Any Tips?

Mastiffman said:

Okay,

SO I have the new parts ready to go. Piston, Rod and Rings.

I'm going to be honing the cylinder today and hopefully start reassembly.

Any Tips?

Click to expand...

I have to hand it to you, you have done an awesome job restoring this unit. It looks magnificent! Engine wise, I wish I had more techs that would take the time to spec out the components like you did. That is the right way. I am still blown-away that the rod was oval for that long and didn't fail. That's one for the record book.
I think you are more than capable of rebuilding this engine to better than new. Not sure what tips I could give unless you're never honed a bore before, but I have a feeling you're pretty experienced. Do you have access to the torque specs? If there is anything I could assist you with, let me know. I have full access to the service manuals, etc.

I hope you plan on posting picks of the completed unit. I know my friends at Scag would be impressed as well.

Thanks a Ton for the compliment and encouragement. That means a lot to me.

I put a lot of hours into this restore and I'm just about done... This was my first honing believe it or not. So I have one under my belt now. Won't be the last. I do a lot of reading, watching videos and looking at repair manuals, becoming familiar with the parts and seeing just how available potential replacement parts are before any disassembly. I have rebuilt an old 1970 Onan Generator engine. So this didn't seem to hard. Just a bit different in design. There was no way that I wasn't going to MIC everything that I could to find that knock. This is the first of a few noises within my small fleet of machines that I'm going to be taking care of.

I Got the engine back together late last night with a small bottle of assembly lube, some rags, parts cleaner and some 9mil gloves. I set a goal of honing and getting it rebuilt for the day and didn't want to go to bed until I did everything that I could. Today I've sprayed my last two parts. The PTO pulley's underneath. I had to weld a crack in the bottom of the exhaust manifild that was spitting carbon on the old paint finish so that was a must to fix. Got that fix and mounted the engine on the engine deck. Finished with the initial throttle, choke and carb settings. I need to fix a couple of raw rubs in the wiring harness, get a few 2.5" mounting bolts for the new (used) oil filter bracket an oil filter, oil, lube everything up an the last touch I'm going to pickup today... DECALS...

I couldn't find the pull starter decal anywhere so I carefully removed the three decals and ID tag from the cowl and designed my own decals for the top of the cowl and pull starter on my computer software and I go to pick those up in a few! Hoping to get it started before the night is over.

More Pics...



















More to come later...

P.S. I also have tear down and repair pics if anyone would like to see how bad the deck really was... Put it this way, The only reason I spent half of the build time with repairing it was because I couldn't find an other one. But she's solid as a rock now. New bearings and bushings and all. I took the spindle completely apart as well a the drive wheels and their pulley's and the levers that move them. It's all tight again like new. It's going to be hard to sell this thing, if I can bring myself to do it.

Okay,

So I'm fully stumped. I literally mic'd everything that I could initially and second and third time now. This engine has a new piston head, rings, con-rod, counterbalance link rods and everything else literally MIC's well within allowed tolerances...

Initially I honed the cylinder, put new piston, con-rod and rings together with the old wrist pin as it was perfectly round the length of it and within spec. I added an oil filter adapter which I initially blew out with carb cleaner and compressed air and used Fram PH4967 as that's what I found for a cross reference online to the original Kawasaki filter. It was recommended by a local small engine rebuilder that I use Valv. F1 high zinc 20w/50 for all small air cooled engines. Put it back together and there was still a knock noise. Pulled it apart and realized that I MIC'd the small bore of the Link Rods wrong and they were actually over by .002". So I replaced those thinking that would be the end all issue.

Back together with the same oil and filter. Runs great BUT Knocking starts about 30 seconds into running STILL. Sounds like a Rod Knock!? I pulled the entire engine apart minus pulling the piston, again this morning and MIC'd the crank journal and connecting rod large bore after torqued and I'm no more than .001" clearance between rod and crank. Checked the bearing per manual recommendations, the cam journals and bearings and the weight pin hole and pin as well as blew out the oil passages on the crank and checked to make sure the Rod Oil passage was clear. All is Good...

I purchased an oil pressure gauge from O'reilly's and I'm getting 45+ PSI at the top access hole of the filter adapter.

Where the heck is/could this knock coming from? I didn't check the axial measurement as I didn't change anything related to it.

Could it be a combo of the oil filter and high Zinc 20w/50???

I'm stumped... I thought about taking the oil filter adapter completely off and running the 20w/50 in there or straight 30w and see what that does. But when I disassembled the engine the rod journal was dripping with oil.

Mastiffman said:

Okay,

So I'm fully stumped. I literally mic'd everything that I could initially and second and third time now. This engine has a new piston head, rings, con-rod, counterbalance link rods and everything else literally MIC's well within allowed tolerances...

Initially I honed the cylinder, put new piston, con-rod and rings together with the old wrist pin as it was perfectly round the length of it and within spec. I added an oil filter adapter which I initially blew out with carb cleaner and compressed air and used Fram PH4967 as that's what I found for a cross reference online to the original Kawasaki filter. It was recommended by a local small engine rebuilder that I use Valv. F1 high zinc 20w/50 for all small air cooled engines. Put it back together and there was still a knock noise. Pulled it apart and realized that I MIC'd the small bore of the Link Rods wrong and they were actually over by .002". So I replaced those thinking that would be the end all issue.

Back together with the same oil and filter. Runs great BUT Knocking starts about 30 seconds into running STILL. Sounds like a Rod Knock!? I pulled the entire engine apart minus pulling the piston, again this morning and MIC'd the crank journal and connecting rod large bore after torqued and I'm no more than .001" clearance between rod and crank. Checked the bearing per manual recommendations, the cam journals and bearings and the weight pin hole and pin as well as blew out the oil passages on the crank and checked to make sure the Rod Oil passage was clear. All is Good...

I purchased an oil pressure gauge from O'reilly's and I'm getting 45+ PSI at the top access hole of the filter adapter.

Where the heck is/could this knock coming from? I didn't check the axial measurement as I didn't change anything related to it.

Could it be a combo of the oil filter and high Zinc 20w/50???

I'm stumped... I thought about taking the oil filter adapter completely off and running the 20w/50 in there or straight 30w and see what that does. But when I disassembled the engine the rod journal was dripping with oil.

Click to expand...

I know you have more patience than me. Are you running the engine with the pulley and clutch installed?

Honda Tech said:

I know you have more patience than me. Are you running the engine with the pulley and clutch installed?

Click to expand...

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.

Mastiffman said:

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.

Click to expand...

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...

Honda Tech said:

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...

Click to expand...

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...

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

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!

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

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.