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Also to make air from the flywheel blow against the governor vane.

Yeah, I wasn't trying to say it would be a big deal, I just mentioned it out of curiosity to where it puts the wheel edge in relation to the deck edge.. Have a good one, Doug!

To help other LawnBoy fanatics like myself, I keep a downloadable LawnBoy Service Manual on my website: LawnBoy Service Manual

Have you seen an improvement doing that? This moves the wheels outboard the thickness of the washer. That, along with the extra ~1/2" shoulder length will come close to making the wheels contact trim before the deck does, which would limit how close you can trim. Do you get that issue...

Are you certain about the diameter? I just checked a new commercial (bearing) wheel against an NOS 603441 wheel bolt (i.e., made for plastic wheels) and it was the correct diameter, 1/2". The shoulder does need to be longer for the commercial wheel, approx. 1/2", maybe a little more. The...

Sorry, but I have never heard of a place where you can get new rubber tires put on used lawnmower wheels. But as a builder who has messed with both, I say switch to non-bearing wheels. Regular LawnBoy wheels have grooves that you fill with felt washers that keep dirt, etc. from getting to the...

Rivets: Thank you for the complete reply. I'm sure it will help others to understand how a carburetor works. I was actually wondering how such a small change in water column (gas column here) could make a detectable change in fuel/air ratio. It just doesn't seem like it would make enough...

As long as the float is keeping the jet in fuel, how does changing float level change fuel:air ratio?

Yes indeed. And I haven't forgotten where ithis great tube tester came from! : )

I looked at his posts and don't see this as a duplicate. His previous post was about carb leaks, this one is about float part numbers, Did I miss something?

Well, I went there, Rivets. Heh heh...and you're right, as usual. The colors are shown. And don't you find it interesting that because of how generic these parts are, none of the color/length combinations are available? Just make your own and ignore the colors! : )

One goes to CDI and the other to ground, right?

ON-OFF switches don't have polarity. With only two leads it doesn't matter electrically if you swap them. The correct wiring is therefore going to be the easiest way to hook them up, Also, Lawn-Boy sometimes uses different size terminals on leads to enforce which way you hook them up (even...

Ah! You were referring to post #7 (also mine): This is a larger issue for me to understand than just this engine. My 'daily-driver' crankshaft has been migrating up slightly so the flywheel is starting to "ting" against the pull-starter assembly on top. Not continuously, but when I hit a bump...

There are so many posts in this thread that I don't know for sure which you are replying to, but it sounds very interesting. Could you give some more info?

I don't have a service manual that new, but I my 1992 manual shows an inline filter built into the inlet of the Walbro carburetor. Have you checked to see if yours already has one? Or is there another reason you are thinking about an inline aftermarket filter?

Rivets: You mean an inline filter in the carburetor inlet, right? That's where I see them.

Wow. Hope your shoulder is feeling better and you got that Super Z done.

"Peoples persecption[sic] of quality is usually corrupted by price & marketing" I could "pedantic" you on that one, but I see what you mean.

StarTech: I was unable to send you a message. Do you have messaging shut off?

"I have troubles when some one starts talking about high quality engineering but can not understand how a ball bearing can locate a crankshaft & control end float ." Who is it that "can't understand how a ball bearing can locate..." ? Certainly not me, I understand it just fine. The issue...

Fascinating Australian small engine history you know, Bert. Though I read it carefully, I didn't see any mower engines with four (or five (counting the thrust bearing) ) needle (or ball) bearings. Which of these engines were on mowers and were better than Lawn-Boy in reliability and/or weight?

F-engines have roller main bearings at the bottom and top ("top bush"), needle bearings on the connecting rod at the crankshaft and at the wrist pin. Where would you put more bearings? Ball bearings would not be better. Neither ball bearings, nor straight needle bearings affect end-play, they...

Ah...ASSUME,.. What does that stand for again? Heh heh...just kidding around. I hope that in the future someone else fooling around with a Lawn-Boy engine reads this thread and saves themselves a ton of trouble! Thanks for sending me down the right road and have a great day! :)

I missed your reply initially. Sorry about that. I have a printout of those spec sheets, and depend on them a lot. And the end-play spec is just what you thought it was measuring, rather than what I thought it was measuring. Here's where my error was, and I'm surprised that no one pointed it...

I took photos of the cover's crank-sides to show the difference between the bottom (i.e., blade end, left photo) and the top (i.e., flywheel end, right photo). As you can see, the bottom end is shiny from the crankshaft rubbing on it and the top end not so much, apparently rarely contacting the...

StarTech: I watched a B&S video that included checking and setting instructions for crankshaft end-play. I don't see how it could more different than Lawn-Boy. 8^S On the B&S, crankshaft end-play has a .002 - .030 spec and the engine splits axially, so you set crankshaft end-play by changing...

Rivets: It's an F-engine, but I'm pretty sure we aren't talking about the same thing. .006 to .016 is surely the connecting rod endplay on the crankshaft, right? I'm talking about how far you can slide the crankshaft back and forth through the main bearings, as shown in the photos above. If...

What limits the B&S end-play? Do they have a separate thrust bearing? Or conical bearings that lock them axially? I added photos to my above post so you can see the difference since, as I understand it, you don't work on Lawn-Boys.

I took some measurements on crankshaft axial end-play. Since the bearings do not lock the crankshaft axially, crankshaft up and down movement is limited by physical contact between the crankshaft and engine case. I got 0.1625" full travel (See "Crank Down" and "Crank Up" below). Gravity and...

Thanks. I wasn't thinking about engines where there's no split along the crankshaft combined with cylinders that aren't separate.

I bought a Lisle brand ring expander. Made in USA and <$10. It worked great, and thanks for the heads-up on that.

Try as I might, I can't mentally picture an engine where you have to put the pistons in at the same time. What kind of bike is this??

StarTech: It's not just the Lawn-Boy you looked at. Unless I'm mistaken, there aren't any Lawn-Boys with pins on the piston rings. Nothing to prevent them from rotating. Bert: What are "ratcheting pliers"? I've used large wire crimpers that ratcheted, but not pliers. Is this what they call...

How is that apparent? Does it have anything to do with how to get the piston into the cylinder? Please don't assume that, when talking about how to get the piston into the cylinder, I didn't read other parts that don't address that concern - like staggering the rings. The interesting part of...

For those in the future looking for advice on this: Following Bert's advice on grit, I got a180 Grit Silicon Carbide Flex-Hone, Part No: BC21218. This was the perfect size for a Lawn-Boy cylinder (2-3/8"). I spun it at ~400 RPM. After a couple of iterations (sorry, I didn't time them), the...

StarTech: As I said in my original post ("Following the tips in the service manual") I was already well aware of all this. Note that the only thing it says about piston installation is: "Apply oil to piston rings, wrist pin and cylinder. Carefully slide piston into cylinder." and it shows a...

Thanks for the link, Hammer. I can't say it wouldn't have worked, but the principle doesn't look much different than the hose-clamp suggestion that I saw and tried (but forgot to mention in my previous post). If I had it, I'd try it.

The crankshaft on one of my self-propelled mower's engines has a thrust bearing and washer between the radial bearing and crank. This mower had a pully on the crankshaft to drive the self-propelled assembly. I don't see anything in any of my service manuals about a thrust bearing, even on...

I tried a whole bunch of ways to get the piston in and finally got it. I bought a Lisle ring compressor and that was a total waste of money. Packaging said it could get down to 2-1/8", but at that size it was not going into the cylinder. Even worse was the fact that it was designed to push a...

Thanks for taking the time for that detailed write up. Just FYI, Bert, Lawn-Boy piston diameter is 2-3/8".

Are you suggesting a tool that expands the diameter of the ring larger than the diameter of the piston so it can be removed all at once?? Just pulling one end over the top edge and working carefully around a little at a time (i.e., so the ring was never larger than the diameter) was enough to...

Following the tips in the service manual, I was as careful as I could be removing the bottom ring from an F-engine piston and broke it anyway. Anybody have a good tip to keep from breaking these? Maybe heating the ring? Freezing the piston? Some sort of magic lubricant? I'd really like to...

Bert: Yup, that's why I'm going with the flex-hone. I have a stone hone with long stones, but still the flex hone is safer. Rivets: Checking at several stroke positions and radial positions seems like good advice. They sell special honing oil, I don't have any, but I do have several...

Thanks, Rivets. I'm not trying to resize either of the cylinders I've got laying on the bench right now, just wanting to clean them up and put a nice cross-hatch on them to go with new rings. Looks like I'll go with a 180 grit 2-1/2" BRM Flex-Hone. My micrometer didn't reach in very far...

I'm going to hone at least two of my F-engines (I have at least six to mess with). Looks like a flex-hone is the way to go. I can't find a spec for what grit to use, though. Any of you guys have experience with different grits and what worked the best? BRM has flex-hones in 120, 180, 240...

Wow, that seems like a strange failure. I'm not familiar with that kind of carburetor. By "choke shaft" are you talking about the shaft that the choke plate is attached to? Is the housing plastic?

Since it's tapered, at first I only drove down about half way. At that, I could barely get it started. I went after it some more - too enthusiastically - and when I tried it again it went all the way and didn't tighten until it hit the hex part. Which leaked, as I related. I wasn't about to...

Yeah, those are just suds from the soapy-water spray, there's no leak on this iteration. I tapped the plate for 1/4-NPT, but the plate is way too thin to get a good seal by itself. I tried an O-ring/washer combination and that leaked to the tune of a 2 inch bubble every 10 seconds or so. Not...

I spent the last couple days on-and-off making test flanges out of steel. They work great and don't leak like the wooden ones I whipped up. This test equipment buildup should make leak checking go super-fast in the future. I duplicated my previous check to verify it all works well with no...