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Discussion Starter #1 (Edited)
So, I've been looking at zero turn mowers for a couple years. I have between 3 and 6 acres to mow, depending on what I let grow up as field grass, a billion trees and lots of slopes/hills. I have been using a very old RX75 (36" deck riding mower) we unaffectionately call the "John Fawn". It's old and slow, but it gets the job done as the time spent mowing approaches infinity. My youngest son loves mowing and has adopted the mowing job. The time spent mowing is golden time to him (he's autistic and riding a mower is one of his "things").

OK, the time spent mowing is valuable to him but mowing every night of the week is taxing regardless who is mowing and the RX75 isn't getting any newer. We had been looking for a 72" deck machine since we cleared the land with the need to mow it with the brush hog, most trees remaining are spaced for that (lots of room). Anyway, an offer I couldn't refuse was made to me for a 960M during a chance trip to my dealer for a missing bolt/washer/nut in my ballast box extension kit last week.
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Somehow I walked out with a Ztrak too. The pic is from taking delivery the next day.

Yes it has Tweels, or what ever they're called... I'm the kid with the funny handle bars on his bike. The deal was for a floor model that wasn't moving it came with the tweels and run-flat fronts ('might as well be steel casters). It did come with the high end suspension seat which is very nice and my 72" deck (+ a 31HP kawi engine). I have mowed with it but have no contrast to draw from for comparison as I haven't mowed with pneumatics on a zero turn before. Its better than a RX75 I'll tell ya that... Its fast and nimble, boat loads of power and holds to my hills w/out issue.

My buddy who runs a lawn care business was here last night and took it for a ride. He really liked it. He said the tweels did nothing for the ride that his machine didn't already do ("I can't tell the difference", was his response on the tweels). But over all he was very positive on the machine. He runs Scags, only Scags.

First mowing was over 3x faster than the little john fawn - and we had no idea what we were doing. It will be even more significant as the learning curve is flattened. The new green machine sits next to the big tractor in the barn, which is currently curing its ballast box cement. Man, they get hot! 160F on the oven Tstat was the peak (medium-one according to the Tstat). I hosed the case down until it was cold again after the pick. It's currently about 140F. Sugar slowed the start of the cure, but after it got going...wow.
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Matt
 

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Congratulations - that should be a mowing monster!

I am sitting here staring at the pic - first time I saw one with tweels in "real life". I like it - I think....almost looks like it could be a space ship or something from the future.

I'd love to try one with the tweels some day - but will never happen as my only dealer is long gone.
 

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Nice machine. Now turn it over to your son!
 

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Incredible machine, surprised no suspension other than seat, and I guess tweel deflection.
 

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Discussion Starter #7
Not that I'm down on the tweels - they are very nice and by all accounts are great tires, just too expensive to make much market penetration. If they were cost neutral to pneumatics, I think they'd be on many, if not most, machines sold. I'm just in the group who wouldn't pay for them if I had the choice. I'm really thrilled to finally get a zero turn and my dealer more than eliminated the cost of the tweels in our arrangement so I'm at peace. :yahoo:

My ideal machine was carbureted, had pneumatic tires I could adjust (but also have to maintain) had the best seat I could buy, a high 20's/low 30' s HP gas engine and had the 72" deck. That started with a 950M in JD land. Note I didn't want to pay for EFI either. Due to my relatively low usage rate compared to a commercial user, it'd be a looooong time before I made the $$ difference back in fuel consumption.

The tweels don't bounce much, they just deform, which is the suspension benefit - I think in many cases tire pressure could be sufficiently lowered to emulate the ride. This may not be true if hills are part of the mowing job and traversing causes you to break the bead (heavier machines would have this issue I think). My seat, which is the highest seat option, is very nice and does a lot of the suspension work. The run flat fronts don't deform or bounce :thumbsdown:... but they do go around which makes the rest of the ZTrak awesome.

I have two details to work out with my dealer - one more important that the other.


  1. Backfires... a lot of them. :nunu: Any shut down not preceded by an idle period will cause one. Poor starts (The dealer did this himself) can very bad ones. Even idled, the engine will sometimes backfire on shutdown, certainly a stall will generate one. I don't hear the carb. fuel solenoid switching at all... I'm not sure I can on the JD but I could hear my buddies Scag open and close. I'm going to talk with the dealer on this today.
  2. A minor issue, my seat back is not stiff. Regardless of the adjustment, it always has several degrees of play in the recline setting unless its in full upright against the stops. I'd like to get that addressed along the way.
Any thoughts on those items? I have lots of experience with engines and this one is very susceptible to creating a backfire event. More so than most/all gas engines I've worked with. I mean, idling briefly (e.g. 30sec to a few minutes) at shutdown is standard practice but still induces the event sometimes and not following the practice guarantees a report.

July is my area's highest deg. day value month. Slow grass growing currently. Not much seat time in the new machine right now. :cray:

Thanks!
Matt
 

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Not that I'm down on the tweels - they are very nice and by all accounts are great tires, just too expensive to make much market penetration. If they were cost neutral to pneumatics, I think they'd be on many, if not most, machines sold. I'm just in the group who wouldn't pay for them if I had the choice. I'm really thrilled to finally get a zero turn and my dealer more than eliminated the cost of the tweels in our arrangement so I'm at peace. :yahoo:

My ideal machine was carbureted, had pneumatic tires I could adjust (but also have to maintain) had the best seat I could buy, a high 20's/low 30' s HP gas engine and had the 72" deck. That started with a 950M in JD land. Note I didn't want to pay for EFI either. Due to my relatively low usage rate compared to a commercial user, it'd be a looooong time before I made the $$ difference back in fuel consumption.

The tweels don't bounce much, they just deform, which is the suspension benefit - I think in many cases tire pressure could be sufficiently lowered to emulate the ride. This may not be true if hills are part of the mowing job and traversing causes you to break the bead (heavier machines would have this issue I think). My seat, which is the highest seat option, is very nice and does a lot of the suspension work. The run flat fronts don't deform or bounce :thumbsdown:... but they do go around which makes the rest of the ZTrak awesome.

I have two details to work out with my dealer - one more important that the other.


  1. Backfires... a lot of them. :nunu: Any shut down not preceded by an idle period will cause one. Poor starts (The dealer did this himself) can very bad ones. Even idled, the engine will sometimes backfire on shutdown, certainly a stall will generate one. I don't hear the carb. fuel solenoid switching at all... I'm not sure I can on the JD but I could hear my buddies Scag open and close. I'm going to talk with the dealer on this today.
  2. A minor issue, my seat back is not stiff. Regardless of the adjustment, it always has several degrees of play in the recline setting unless its in full upright against the stops. I'd like to get that addressed along the way.
Any thoughts on those items? I have lots of experience with engines and this one is very susceptible to creating a backfire event. More so than most/all gas engines I've worked with. I mean, idling briefly (e.g. 30sec to a few minutes) at shutdown is standard practice but still induces the event sometimes and not following the practice guarantees a report.

July is my area's highest deg. day value month. Slow grass growing currently. Not much seat time in the new machine right now. :cray:

Thanks!
Matt
I don't know what is in your manual, but....

When I had a 757 with Kawasaki motor, the manual instructs to shut down the engine at 1/2 throttle. Well I couldn't stand to do that and shut it off at idle. Sure enough - backfire every time. The only other way I found I could shut it down at idle is to let it idle for at least 1 full minute. Being I was loading it on my trailer each time I would load it and let it idle while I tied it down - then shut it off.

What does your manual say?
 

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What does your manual say?
I just checked and oddly enough JD does not have any of the 960M operator's manuals available on line.
 
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I have a different engine but can't really think of it backfiring. Not saying it never does it but not enough that I notice. That said I have read of them doing this so I don't think this is a sign of a problem. I will say they sure seem loud compared to other Kawasaki engines like in my X585.
 
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Discussion Starter #12 (Edited)
I don't know what is in your manual, but....

When I had a 757 with Kawasaki motor, the manual instructs to shut down the engine at 1/2 throttle. Well I couldn't stand to do that and shut it off at idle. Sure enough - backfire every time. The only other way I found I could shut it down at idle is to let it idle for at least 1 full minute. Being I was loading it on my trailer each time I would load it and let it idle while I tied it down - then shut it off.

What does your manual say?
It says to do exactly that! Well, it says "at least" 1/2 throttle and to do this for "at least 30 seconds"... so I'm doing it very wrong by idling the engine before shutdown for a prolonged period. :hide: This is stated in bold to help prevent back firing/damage to the harware.

Now the obvious question, for me at least, is why 1/2 throttle or more? Is this because the higher charge air flow rate cools the system better than a low flow idle or or what?

I will try it out! :bigthumb: When the grass grows again....

Thanks!
Matt
 

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Discussion Starter #13

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I would suspect the instructions to shut off at greater than 1/2 throttle may be to properly scavenge the fuel remaining in the carb passages after the solenoid shut off.
They may have the engine tuned at idle with the throttle butterfly cracked open a bit and allowing enough air to mix with the residual fuel to get the backfire.
In ye old days on some cars I owned auto makers didn't use a solenoid to shut off the fuel and when you shut off the engine you could get some "dieseling" or motor running on after key off. They solved that problem by adding a solenoid to the throttle plates. Solenoid activated gave proper butterfly position to maintain a clean idle, solenoid off fully closed off the butterfly to starve the engine of air.

I know I always idled down to shut off every small engine I ever owned, and never had backfires, and cringe when I see someone kill the switch from full throttle. I guess there is nothing to do but follow the instructions the engineers created for you.

By the way, could you please share more pics of the gorgeous machine?
 
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Discussion Starter #15 (Edited)
Some Pics!

Last minute edit: The half throttle or above "idle" before shut down eliminated the backfire issue on shutdown!

By the way, could you please share more pics of the gorgeous machine?
OK... some pictures. Sorry about the contrast, pics are from my cheapie phone and it was very sunny today.

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And a nod to the machine that basically made the yard and house in the background possible (showing off new ballast box)...

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And a family portrait since I've got everyone out of the barn...

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Anything specific you want to see? Perhaps glamour-shot closeups of the RX75 chick-magnet? :bigthumb: A sad note on the RX75. The deck drive pulley fatigued off this afternoon while doing some mowing (there are places not ready for the new mower). So a-parts-hunting I will go....

Matt
 

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Matt, those Deere are bad to the bone. You have a dream set up going there, congratulations, and the lawn looks real nice too.:thumbup1gif:
 
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Nice looking machine. :bigthumb:
 

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Awesome looking JD ! These machines are an abolete animal of a mower....good luck with it and I hope your son enjoys the heck out of it...
 

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Nice looking stable of the Green I have been looking at Z tracks and I like the Tweels. think they are supposed to be Helpful on hills. Im thinking on going with the R series not the M :good2:
 
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Discussion Starter #20 (Edited)
Nice looking stable of the Green I have been looking at Z tracks and I like the Tweels. think they are supposed to be Helpful on hills. Im thinking on going with the R series not the M :good2:
First, Thanks!!

I'm liking the Tweels more and more. They do hold well on my hills and they ride great. I have spun the Tweels on grade behind my house (which you can kind of see in the background of the photos I posted) but only in the very steepest area with very thick healthy grass. Watch pivoting on 3pt turns....:banghead: Very unforgiving on thick lawn grass. Good traversing hold.

I had considered a R series as well, the transmissions look like they would hold up better on my hills. Plus the deck lift and other niceties. It was mostly a cost function for me - these machines are awesome and regardless of who makes them, awesome $$$ as well. If I had been made a similar offer on a 970R as on my 960M...I would have jumped on it even though it would have been $1k or so more. It's a better machine where hills are in the picture.

Matt
 
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