[sidemouse]

On my ztr today...
I adjusted the valves about 1-2 years ago...
It ran good for quite a while, but today while going up an incline it suddenly lost power.
It will run "all right" without load but it does pop and sputter a little.
Engage the blades and it pops and misses just a little more, eventually settles down but engage the hydraulic drive and it barely gets out of its own way, push it and it dies.
It has fuel flowing out at the pump side, the air filter is dirty but removing it completely did nothing.

Both spark plugs have carbon deposits, one was pretty cruddy in that regard.
Gaps were correct, I replaced them but little improvement, gapped .030

I'm leaning towards some kind of valve / pushrod issue...
Any thoughts?

The first plug came out of the left side (looking at mower from behind).
The second dirtier one came out of the right side.

 

[MacLawn$]

On my ztr today...
I adjusted the valves about 1-2 years ago...
It ran good for quite a while, but today while going up an incline it suddenly lost power.
It will run "all right" without load but it does pop and sputter a little.
Engage the blades and it pops and misses just a little more, eventually settles down but engage the hydraulic drive and it barely gets out of its own way, push it and it dies.
It has fuel flowing out at the pump side, the air filter is dirty but removing it completely did nothing.

Both spark plugs have carbon deposits, one was pretty cruddy in that regard.
Gaps were correct, I replaced them but little improvement, gapped .030

I'm leaning towards some kind of valve / pushrod issue...
Any thoughts?

The first plug came out of the left side (looking at mower from behind).
The second dirtier one came out of the right side.

View attachment 517530 View attachment 517529

Hows the fuel quality? Carb adjustment / Idle and run RPM? The. Again you did touch the valves so might want to double check what you touched

 

[hal]

Check yer coils.........

 

[Scott87]

Well, well.
I thought you were the super mechanic? You’re always trying to be one on here.... Why, this section of the forum is just filled with your advice on how to fix engines. 🤣

Better get the service manual and check the troubleshooting chart for “no power” and go through the list.

Lets stop with the personal attacks here on Lawnsite! Its not a good look for somethiing I used to be proud to be a member of and I don't think I can use my real company name here much longer. I'm not calling Baker out here but asking all members to look at the content they are posting and keep it positive or don't post.

 

[rippinryno]

When it starts to lose power like that, see if you can pull the choke and get the engine to stay running or respond to the choke better.

I'm also going to recommend checking the valves again, especially since you said you adjusted them. I've checked valves on all 6 of my mowers in the past couple years and they have plenty of hours on them. I've only had to adjust a couple and it was very minor.

Did you have the running issue prior to adjusting valves?

There's a carb vent tube on some of those, check that make sure it's not plugged up.

Pull your fuel cap off and see if it runs fine after you release that to be sure your cap is venting properly

Hows the fuel filter, change it out.

This sure sounds like a fuel delivery issue to me so i'd be going that route.

Lets stop with the personal attacks here on Lawnsite! Its not a good look for somethiing I used to be proud to be a member of and I don't think I can use my real company name here much longer. I'm not calling Baker out here but asking all members to look at the content they are posting and keep it positive or don't post.

I couldn't agree more. I will call out Baker because I've seen this now in numerous threads and from a guy who's fairly new to this forum. Time to be more kind around here so folks can get the help they need.

Me, well shoot i'm still running wheel bearing that have play in them, shoulda been burnt up a long time ago.

 

[Scott87]

Is it possible there's some water in your fuel? I always keep a can of iso-heet in the trailer for these occasions.

 

[sidemouse]

When it starts to lose power like that, see if you can pull the choke and get the engine to stay running or respond to the choke better.

I'm also going to recommend checking the valves again, especially since you said you adjusted them. I've checked valves on all 6 of my mowers in the past couple years and they have plenty of hours on them. I've only had to adjust a couple and it was very minor.

Did you have the running issue prior to adjusting valves?

There's a carb vent tube on some of those, check that make sure it's not plugged up.

Pull your fuel cap off and see if it runs fine after you release that to be sure your cap is venting properly

Hows the fuel filter, change it out.

This sure sounds like a fuel delivery issue to me so i'd be going that route.



I couldn't agree more. I will call out Baker because I've seen this now in numerous threads and from a guy who's fairly new to this forum. Time to be more kind around here so folks can get the help they need.

Me, well shoot i'm still running wheel bearing that have play in them, shoulda been burnt up a long time ago.

Few updates I forgot to post:
I did loosen a fuel cap, no difference.
Choking makes no positive difference, it will throw black smoke when choked and like it wants to die then (which is normal on a hot engine).

The mower was running pretty rough prior to adjusting valves, yes.
Hard to start, would lose power at times then it would come back but it got progressively worse over time.

The fact this time it started suddenly and has not changed in behavior between cold / hot leads me in the direction of valves, perhaps a bent rod... It could be a clogged jet, I might order a cheap aftermarket carburetor just to see but in terms of labor it's all about the same, might order up those valve cover gaskets since I'd be removing those to check the valve lash...

One thing I did forget to look into is carburetor linkage(s), an object such as a little stick could've lodged itself in there some kind of way, so I'll be doing that today...

 

[Breezmeister]

One thing I would do is change the plugs to a higher heat range, this will help burn off some of the carbon.

Looking at the linkage is a good idea, but what you want to check is the choke and throttle valve, are both opening completely at WOT ? I've seen screws come loose and even disappear and the throttle valve hang up.

The only other thing that I know of that could cause this, is the coils are on their way out. I would put an inline spark tester on it, make sure you are getting a nice blue spark at WOT, let it run for a while to heat up the coils......
.

 

[Crazy 4 grass]

Lets stop with the personal attacks here on Lawnsite! Its not a good look for somethiing I used to be proud to be a member of and I don't think I can use my real company name here much longer. I'm not calling Baker out here but asking all members to look at the content they are posting and keep it positive or don't post.

Ever since new management took over lawnsite, the moderating has pretty much been non existent. It's too bad too, I very much appreciated how it used to be.

 

[JC's_Lawn_Care]

I'm having what sounds like the same issue with a 21 hp briggs vanguard. Figure I'll start with the carb cleaning first. From the research I've done it could be the carb, coils, kill wire... Hope to figure it out soon since mine's been acting up off and on for a while now. I found some grass lodged in the governor spings last weekend, cleaned that out and it ran like a top. The very next day it wouldn't stay running at all.

 

[TXSteve]

I've found over the years that those who come across with belligerent tones, sarcasm, and bluntness are just flexing their muscles online because their wife won't put up with their crap at home.

 

[Crazy 4 grass]

I've found over the years that those who come across with belligerent tones, sarcasm, and bluntness are just flexing their muscles online because their wife won't put up with their crap at home.

That, or they just aren't a very nice ot tactful person.

 

[TXSteve]

That, or they just aren't a very nice ot tactful person.

Or have a huge chip on their shoulder for other reasons.

 

[Valk]

When I had a coil issue on a Kaw FH, it would cold start and run fine until it was warmed up, then run crappy w/ a faint smell of raw fuel. Diagnosis was to carefully pull off an individual spark plug lead while engine was running POORLY to see if it affects the performance. The cylinder w/ the bad coil will show little to no change in the poor performance when the lead is disconnected from the spark plug.
I'd also think an IR thermometer would show a colder cylinder head temp.

 

[ricky86]

......and check that a welch plug didn't come out of carb. There are/were two on top, engine side.

 

[NBrown]

I had a FH721D that had started losing power gradually over the years. It got to the point that it struggled on less then 10° inclines. My issue was a loss of compression though. It eventually got to the point where the crankcase pressure was beginning to push oil past the crank seals. I ended up rebuilding the engine with all OEM Kawi rings and gaskets. I honed the cylinders with a medium grit ball hone. I also replaced the plugs and coils while I was at it. The gap between the coils and the pickups on the flywheel are very crucial as well. After the initial break in run and oil/filter change, I put it in some of the tallest grass I could find and let her eat. I forgot how much power that engine started with. It had just lost it little by little over the years.

 

[sidemouse]

Yup, so update...
I did spray compressed air into the linkages, there was a bit of crud but not like insane amounts...
I also did a one-side at a time inline spark plug test, afaik we're good there.
So I did a video:

Going to order those valve cover gaskets next...
Check the valve clearances, might actually order pushrods too...
Because it ran good for some time, but if a pushrod is just slightly bent...

The reason I'm not leaning towards fuel supply, is because spraying ether into the intake doesn't make much difference, neither does choking it.

 

[milo]

just watched your video, that sounds like a coil cutting in and out on 1 cylinder. they are cheap for kawasaki and simple to switch out

 

[sidemouse]

just watched your video, that sounds like a coil cutting in and out on 1 cylinder. they are cheap for kawasaki and simple to switch out

Fair enough, it certainly could be that.
I'll order two up, since I don't know which, the mower's 15 years old so I'll just replace both...

I did want to add, there's about 1000 hours on the meter.

 

[milo]

Fair enough, it certainly could be that.
I'll order two up, since I don't know which, the mower's 15 years old so I'll just replace both...

I did want to add, there's about 1000 hours on the meter.

o

Fair enough, it certainly could be that.
I'll order two up, since I don't know which, the mower's 15 years old so I'll just replace both...

I did want to add, there's about 1000 hours on the meter.

you always want to replace both at the same time. easiest way to gap the coil is a business card between coil and magnet. I would also throw new plugs in at the same time