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Discussion Starter #1 (Edited)
I have never seen a picture of the mythical suzuki mechanical governor system so since I had my motor apart I thought I would post a picture just to document it so that it may prove helpful to someone in the future.

Two 'wings' (there is another wing 180 degrees from the one pictured) open up due to centripetal acceleration and force the collar they are holding down towards the connecting rod and it pushes the metal rod that is also in the picture turning it a little. The metal rod goes directly to the exterior and hooks up to a large arm and then the governor spring......looks like zero wear on the parts on this machine:
 

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the metal rod wears out but not much else does on this marvel of desighn and build quality.i had to tear one open to replace the gov rod but this engine had 20,000 hrs on it. ran fine after the fix. but i retired it to back up status. engine was in service from 1990-2011. this was constant commercial use. never any other repairs except carbs
 

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Great photo Mantas, thanks for posting! I think GTP had some questions lately regarding this exact setup. He mind find this helpful.
 

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Discussion Starter #5
I will post another picture or two next time I work on it. Perhaps not so close-up so its easier to see.
 

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the rod that goes tru the block and connects to the external linkage. it pushes the inner parts via a fork -like a trans shift fork. the rod wore down and could not engage the fork right . i tore my hair out trying to find the cause of the gov issues on this motor. finally i decided to tear it apart and found the worn down end on the gov linkage rod.
 

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This is MOST helpful I was ordering parts for 2 rebuilds and knowing the actual internal parts are unworn ... Leads me to believe my governor rod too is worn. Thanks Mantas. Also Lawnboy Dan, I know the gov rod that goes through the block has a seal can the seal and rod be replaced with out opening up the case?
 

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Mantas have you figured out the surge issue yet if the internals are unworn?
 

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no the seal and rod can only be replaced after spliting open the case. it wasnt a hard job at all. before you condem the gov rod make shure you check the carb throttle shaft for wear. this is common on these and causes the engine to race mimicking a gov issue. on the inside of these engines everything is so robust you then know why these engines have such a long life. the crankcase seals are huge! i doubt they could ever fail to seal.
 

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no the seal and rod can only be replaced after spliting open the case. it wasnt a hard job at all. before you condem the gov rod make shure you check the carb throttle shaft for wear. this is common on these and causes the engine to race mimicking a gov issue. on the inside of these engines everything is so robust you then know why these engines have such a long life. the crankcase seals are huge! i doubt they could ever fail to seal.
Carb throttle shaft replaceable or has to be whole carb?
 

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Discussion Starter #11
As promised, I grabbed my camera to get a better picture of the gov system. Instead I just made a short video:
http://youtu.be/CdpkRC00tHM


the crankcase seals are huge! i doubt they could ever fail to seal.
I don't know about that. My upper seal is compromised upon visual inspection and I believe it caused the rusted bearing in my other thread. I don't know if the bearing was giving off heat and roasted the seal or if the seal let humidity/moisture in and rusted the bearing.....either way I'm changing both the seal and the bearing. For an extra $8 I'm changing the bottom seal as well.


Mantas have you figured out the surge issue yet if the internals are unworn?
The engine was only used at the guys house BUT had some issues. Gov spring had a bend that seemed like an accident or someone didn't take it off properly, carb was gross, gas tank/fuel line were gross and a bad seal must have been letting air into the block. The key was partially sheered and that had to mess up the timing:


It was a mild surge and I don't think there is much wear in the engine or carb so I would assume she will run strong. My other 2cycle Toro surged much worse before I cleaned the jets.

I'm really happy I decided to split the block because without that notion I wouldn't have discovered the key, bearing, and seal issues.
 

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it takes a really hard strike to damage the keys on these. suzuki uses a hard steel key unlike most. good luck finding another key. they are hard to come by. i had to special order the last one i needed from toro. gtp-there used to be a kit to replace the worn throttle shaft on the mikuni carb. if its no longer sold -then sadly you must replace the whole carb! the mikuni carb is the bane of existance of many and its too bad more didnt use the far more reliable walbro carb. yes the gov spring on the mikuni is fragile and care must be used when removing and installing it. a pair of tweezers is the way to go.
 

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Discussion Starter #13
it takes a really hard strike to damage the keys on these. suzuki uses a hard steel key unlike most. good luck finding another key. they are hard to come by. i had to special order the last one i needed from toro.
There seems to be many keys on eBay for part #81-2370. I picked one up from a guy in-state for $2.75 shipped.
 

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it takes a really hard strike to damage the keys on these. suzuki uses a hard steel key unlike most. good luck finding another key. they are hard to come by. i had to special order the last one i needed from toro. gtp-there used to be a kit to replace the worn throttle shaft on the mikuni carb. if its no longer sold -then sadly you must replace the whole carb! the mikuni carb is the bane of existance of many and its too bad more didnt use the far more reliable walbro carb. yes the gov spring on the mikuni is fragile and care must be used when removing and installing it. a pair of tweezers is the way to go.
To re-open an old thread, whats in the kit? A new throttle shaft? Does just the shaft wear and not the carb body?

Both my Suzukis leak around the shaft--my ex-commercial will overspeed big time when sprayed with carb cleaner so you know it's leaking good!
 

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yes the throttle shaft can be replaced but the carb body can and will wear to the point it will stick and suck air. this is one of the weak points of the mikuni carb. the trottle shaft is brass and the carb body alum. both wear fairly fast
 

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yes the throttle shaft can be replaced but the carb body can and will wear to the point it will stick and suck air. this is one of the weak points of the mikuni carb. the trottle shaft is brass and the carb body alum. both wear fairly fast
I was afraid a new carb body was going to be the cure. Even the $40 throttle shaft (maybe this could be found more cheaply than partstree) is an expensive fix, especially for Mowers I didn't pay more than $50 for. But of course, if I want them to last, they can't be sucking in dirt and running lean. Will think about this and any other possible fix.
 

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The alum. body wears much sooner. That bore can be bushed and reamed with a bronze or steel sleeve for a long lasting mikuni. Hardest part is removing the butterfly without causing damage.
 

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I am very tempted by this guy's suggestion.
http://www.perr.com/phpBB3/viewtopic.php?f=14&t=7952#p59550
Anyone here have experience subbing in a Honda carb for the Mikuni? I'd probably buy 5 honda carbs for spares given the 2 mowers and 'new' CCR3000 snowblower I just bought last weekend.
Nope, but it sure does sound like an alternative solution to a long standing problem -Toro's price$ on obsolete parts. For $15-$20 for an entire carb, its worth reaming a jet and ovaling out a couple holes. Hafta look into this.
 

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Well, I got itchy a few nights ago and spent ~$30 and ordered all the parts. Sure hope this works!

Should have everything here by sometime next week, then I can stop filling up this thread and will start another with my results.
 
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