if the rope pulls back when you start the engine the timing key could be broken. even if you dont hit something perhaps the thick grass overloaded the engine to that extreme? pull the engine cover off, loosen the flywheel nut to the point where the nut is about a turn higher the flush with the top of the crankshaft. then using 2 scewdrivers pry upward on the the bottom of the flywheel while someone else hits the crankshaft nut with a hammer. your flywheel should pop loose and proably will see the key broken off underneath. as long as the keyway in the flywheel is not worn sideways just get a new key from a toro dealer or suzuki and start the mower. assuming its back in business then go back to the dealer who gave you the bad estimate and ask how that happend.

sounds like a broken flywheel key to me to although the key on this engine is very strong. i have seen the flywheel brake before the key does on this motor several times.

I have a Toro with the Suzuki 2-cycle and can anyone confirm that rumor about this engine having an estimated life of 30,000 hours as tested by Toro. I'm sure I heard something like that regarding this mower engine. Mine runs like a top after many many years.

Gene

With the rope pulling back, it's definitely timing, and almost surely the flywheel key. On the 2 cycle, it is a soft aluminum key (part #81-2370)that breaks very easily. However, don't use a hammer and screwdrivers to pop the flywheel, as the crankshaft and con rod are one piece, and the bearing can easily be damaged when pounding. Use a screw in type puller (toro #41-7650) with the holes in the top of the flywheel (threads are metric). Also, torque the flywheel to the proper spec (36Ft/lbs) to prevent premature shearing of the key. I bet that gets you up and running.

About the estimated life of 30,000 hours...I don't know the exact number but I'd guess it's up there. These engines were also used on the ~$900 ProLine models so they were no doubt spec'd and tested to take a lot of abuse. Maybe it's just me, but they also seem to have a larger than normal air filter. I have one from '87 as well and it's still running great.

Thanks for the helpful feedback folks. I will try to tear it down this week and check it out. I'm not much of an engine mechanic but it seemed to my semi-educated mind like an engine with skipped timing.

Maybe the mechanic wanted my 'zuki if I bought a new mower or something (grin)?

I think I have a plain puller or can borrow one - is that good enough? Or do I really need to buy a special Toro one (or maybe just take it to another shop)?

Thanks again to all for the help!

i looked in my repair book and a puller must be used to avoid flywheel damage. some can be removed using a prybar and hammer but this engine is not one of them.-i have one with around 10,000 commercial hrs on it . they will last a long time.

Thanks very much for the info, lawnmowerdan.

Do you think I can I safely use a generic puller or do I need to take it to another Toro dealer who has a special puller?

that i cant tell you as i have never had to pull the flywheel on any of mine

Do not use a regular jaw type puller, you will split your flywheel in half, and they are not cheap. The puller it calls for should not cost very much.

Good Luck, hope ya' get her going again ! The Suzuki GTS 2-strokes are very tough - I had approx. a 1981 model that refused to quit. I only discarded it because I could'nt find parts for the BBC, etc. Sold the engine alone on Ebay for about $60.00 - more than I gave for the whole mower used years ago. Too bad that no local dealers had a new Proline to replace it.

The Toro flywheel puller costs around $40. but you may find a generic copy for less. Just make sure the threads are metric, or you will strip the holes out. If you have a good relationship with a local dealer, he may loan it to you for a few minutes to get it done.

Well folks,
It took me until today to get around to getting the flywheel pulled. I made my own puller by using a small rectangle of 3\8" scrap aluminum with three holes drilled in a triangle to match the holes in the flywheel. I used the holes in the part of the pull-starter gizmo attached to the top of the flywheel as a pattern. I bought some longer screws and put the rectangle of aluminum on top of the shaft (after removing the shaft nut, of course ). I used a little penetrating oil, tapping, and slowly tightening each screw a fraction of a turn at a time, and was able to sucessfully pull the flywheel that way without damage to the flywheel or shaft or spending $40 on the Toro puller.

And yup, the aluminum key was sheared off, just like we had all figured, and the tapered hole around the shaft showed clearly that the timing had jumped from mowing the really tall wet grass. I don't care if it looks bad, I'll never mow tall wet grass again. I should've known better.

Well, I'll go to the dealer with the sheared key and flywheel (with the other half of the key still in the groove) tommorrow to buy or order a replacement key to fix my toro suzuki.

Should I wait until I've got it fixed to mention the mechanic misdiagnosed the engine problem and told me I needed a new short-block engine or a new lawnmower when all it probably needs is a new $2 timing key to get it going again?

I find myself wondering if the technician was just making an honest mistake, incompetent, or crooked and wanted my 'zuki to fix up for himself. He had pulled the muffler off and said the engine was shot. When I went back up to the store to look at it and talk to him about it, he pulled the cord while I watched the piston go back and forth... the ring on the piston looked fine, little or no scratching on the piston as far as I could see, but he said it needed a short-block engine to repair it. It didn't make sense to me, and made even less sense the more I thought about it and read a library book about 2-cycle engines.

Anyway, the tech sure was telling me it was up to me but I should really think about buying a new mower instead of putting $400 plus into an old mower. The service department counter guy looked kinda funny and perturbed when I went back and told him I wanted to pay the $20 "repair estimate" and take my mower home. The counter guy had to go in the back and find the estimate ticket because the repair tech hadn't turned it in like he normally was supposed to. Maybe that was normal - I told the repair tech I wanted to think about it before I decided whether to pay the $400 plus he said it would cost to fix it, or buy a new mower.

What do y'all think?

Anway, THANKS for all the GREAT advice and help you gave me here that gave me the confidence to think for myself and pull the flywheel without damaging it.

I want to especially thank charlie_stevens25, lawnmower dan, snuffyinATL, and lewc3548. Y'all are great folks.
This is a GREAT forum and a great group of people.

What a great Christmas present! Thanks all!!!!!!!!

mrcoffee, wish more people were as resourceful and determined as you to keep their 2-stroke mowers going. Maybe a lot of them wouldn't get needlessly tossed out. Anyway, great job. And you're right about this forum and those who offer advice. They've been very helpful to me as well.

If the engine has compression, there is no need for replacement. Even if it doesn't, you could put a new piston and rings in it. The guy just didn't want to mess with it.

"However, don't use a hammer and screwdrivers to pop the flywheel, as the crankshaft and con rod are one piece,"

Really. This scared me. Can you imagine a crank and rod cast out of one piece of steel? Am I missing something here?

Thanks for replies.

[quote]If the engine has compression, there is no need for replacement. Even if it doesn't, you could put a new piston and rings in it. The guy just didn't want to mess with it. [/quote]

It seemed repairable to me too.

About the "crankshaft and con rod are one piece" business - lew3548 sounds like he knows what he's doing to me, so I guess what he's referring to is that toro only sells the two (actually 3 including the bearing?) pieces as a single assembly, which is true, and that that is what he meant by "one piece". Don't mean to speak for him, but I expect they're aren't too many folks hanging out here this time of year.

It would be a unique engine design if the crank and rod were cast out of one piece of steel though, wouldn't it? lol

Anyone care to share their take as to why the tech at the Toro dealer gave me a $470 estimate on repair with a short-block engine replacement and tried to steer me to a new lawnmower?

Or am I just getting paranoid in my old age to suspect impure motivations here?

Sounds like the mechanic wanted your mower to me.

I don't think I'd go back to that shop. I also don't see how removing the flywheel would have any adverse effect on the crankshaft or connecting rod. The most likely damage from a forceful attempt would be a broken flywheel. Of course, you don't want to beat on the flywheel or crankshaft, because the bearings could be damaged. Lawn-Boy says to pull up on one side of the flywheel and hit the opposite side with a rubber mallet. This works every time for me.

heh heh. Got the same mower waiting in the shed. I just had to clean out the carb to get it running. Runs real well too. I like my 10441 push mower better, as I just use it for trimming. 30k hrs. Gives me the warm fuzzies. I figure that I use a mower about 8 hrs a yr trimming. Nice to know I have a good backup mower though. .

IMHO, mrcoffee's experience is more proof that you can't keep a good 2-cycle down.

the 20684 'Zuki 2 cycle was my 1st 2 stroke mower. After going through several 4cycle mower engines that were dead or dying with less than 1000 hrs on them, I am converted. Curse you EPA. I was checking out 2stroke powered snow blowers the other day. Intrigued by the engines, disappointed by the poor quality machines they were mounted on.

I've had my Toro Model 20684 GTS (Suzuki 2-stroke) Mower new since 1988 and I never even changed the spark plug until yesterday. I am loosing power when it needs it and I can't understand why. It still starts in 2 or 3 pulls, the compression seems ok by the way it feels when I pull the starter rope, no scoring observed thru the intake port, (I have not checked the exhaust port yet), I rebuilt the carb yesterday because the inside diameter of the fuel line was grossly deteriorated, causing particles of rubber to clog the inlet to the carb. Interestingly the manual states no ethanol should be used because damage to the fuel system can result, I wonder if this was the cause for the grossly deteriorated fuel line? (All the gas around here states up to 10% ethanol!). The only issue with the rebuild is the governor setting, I need to figure out how to set that so the idle is back to low rpm as normal, not it seems to be left to cut speed if you know what I mean. My mistake was not to mark the relative position between the governor shaft and the governor arm, (any help anyone?). Well it looses power when it needs it, higher grass, and it is so frustrating, It runs great under no load. I believe the lower crank bearing is going because I can hear a knock of late that is not normal, like the knock you may hear when the bag gets full and the blade is hammering away at a grass clog, but it knocks when it is clear. I wonder if there can be an air leak by the lower bearing that cause its lose of power, but I also believe an air leak will likely cause it to seize up, so I am stumped. Is there anyone out there who can help me out? It's been a great unit but I refuse to believe it has reached the end of its service life! Help!!!!!!!!!!

I think by the connecting rod and crank being "one piece," I think lew meant that the con rod doesn't have a removable bearing cap like most automotive rods. Instead, it's a one-piece rod and the crank is probably pressed together with the rod already on it. This would be as opposed to a one-piece cast or forged crank, where the rod(s) have a cap and two-piece bearings on the big end to fit onto the crankshaft journal. The upshot is that if you fubar the crankshaft by prying the flywheel off, you have to by a whole new crank/rod/piston assembly, instead of just a crank (which would be bad enough on its own!).

hi dom,

I'm no expert on the toro 20684, but I have torn in down and repaired it a couple of times. I'd be suprised if the bearing was the problem unless you are using the mower in a commercial situation from what I have seen.

I suggest a couple other things to check that might do the trick.
1) replace that deteriorated line with some that tolerates ethanol if you haven't already.
2) replace the air filter sponge iyha, or clean it if it hasn't been cleaned this year by washing it out with soap and water and re-oiling it
3)check the muffler exhaust gasket and replace if needed. My mower was making a low pitched ticking sound and if you air-fuel mixture is out of whack, that could sound like a chug sound. If I understand this correctly, the tuning of the muffler cavity is part of the process that draws fuel in from the carb.
4) Check the flywheel impeller and see if it is clogged up or the plastic intake to the air filter.

FWIW, my mower is running great now with the help of all the fine folks here. After I tore it down, replaced the sheared flywheel key, cleaned the carb, and replaced the air filter and exhaust gasket, it ran (and still runs) like new. I'm sold on this two-cycle. Best mower I've ever had. Easy to understand and fix.

BTW, you did find the repair manual on the toro website, right? It should be pretty helpful to you in reseting the governor.

mrcoffee