FS730V

[Covah2423]

I have a Toro zero turn 60” mower with a Kawasaki FS730V engine. My son and I both use it, we both have 1.5 acres to cut. While he was using it he said it stopped engaging the blades, practically killing the engine. It has 317 hours on it. I changed the PTO or clutch, all pulleys and belt. Belt was shot. It got better but was still struggling when the blades were engaged. I then put a new carb, plugs, air & fuel filters on it. Did a compression test and I had 130 & 165lbs. Ran better but when I engaged the blades it would pop, miss for about 15 seconds and then clear up and I was able to cut the grass. Every time I engaged the blades it popped, misfired and then cleared up. So the next day I pulled the valve cover off the side with 130lbs and found the nut for the rocker had fallen off. Figured I found the problem. I put it back on adjusted the valves and ran it. Pushrod was good. When I engaged the blades it was normal. Tried it 3 or 4 times and it was fine. Later that day I changed the oil& filter and put on new blades. Went to cut some grass and it was back to popping and missing but never cleared up. Next day I pulled the same valve cover and nothing was wrong. I adjusted the valves again to check them and then I checked compression on both. My side with 130 was now 145 and the other side was 155. I rechecked the first side and it was now only 90lbs. Did it several times and still only 90. Put it back together and ran it and it was back to popping & missing when engaged the blades but cleared up after 15 seconds. Today my nephew who has a outboard business came over and checked the compression and was still only 90 & the other side 165. So then we pulled the head off expecting a bad valve but there was none. Did a leak test on it and it is fine. Head gasket is good. The only thing he noticed was the cylinder was dry and smooth. Any ideas?

 

[MParr]

That's high hours and your compression is not in the desired range. Also, the oil pump could have failed. You should probably start weighing your options. That engine is tired.

 

[StarTech]

Okay first if the oil had failed the engine would trying seize. Now the Georotor pump does wear out causing first low oil pressure at idle.

Now a valve could be seizing in the valve guide causing the sudden pressure drop. The only way to know is to disassemble the head and eyeball things. I had a very to fouled due to bad stem seals.

Also you can't re-use the head gasket. Even if it look good the naked eye.

 

[Covah2423]

Okay first if the oil had failed the engine would trying seize. Now the Georotor pump does wear out causing first low oil pressure at idle.

Now a valve could be seizing in the valve guide causing the sudden pressure drop. The only way to know is to disassemble the head and eyeball things. I had a very to fouled due to bad stem seals.

Also you can't re-use the head gasket. Even if it look good the naked eye.

Thanks for your input. Never intended to use old head gasket, just meant it was not blown.

 

[Covah2423]

Okay first if the oil had failed the engine would trying seize. Now the Georotor pump does wear out causing first low oil pressure at idle.

Now a valve could be seizing in the valve guide causing the sudden pressure drop. The only way to know is to disassemble the head and eyeball things. I had a very to fouled due to bad stem seals.

Also you can't re-use the head gasket. Even if it look good the naked eye.

Thanks for your input. Never intended to use old head gasket, just meant it was not blown

That's high hours and your compression is not in the desired range. Also, the oil pump could have failed. You should probably start weighing your options. That engine is tired.

 

[Covah2423]

Sorry it’s 317 hours not 3170 hours. I must have hit the zero by mistake. Thanks

 

[txmowman]

Engaging the PTO putting that much load on the engine would indicate it is not firing both cylinders efficiently. If spark has been confirmed, this would indicate either a valve sticking when the engine gets hot, or possibly a loose valve seat. The nut on the rocker arm coming loose is the mystery unless someone has adjusted the valves previously and did not tighten to the proper spec. (Most “mechanics” do not)

Which rocker arm nut was loose, intake or exhaust? A loose valve seat is rare but possible. It would be very difficult to see when the cylinder head is cold. Unless of course it came out, shifted and wedged between the valve.

 

[Covah2423]

Engaging the PTO putting that much load on the engine would indicate it is not firing both cylinders efficiently. If spark has been confirmed, this would indicate either a valve sticking when the engine gets hot, or possibly a loose valve seat. The nut on the rocker arm coming loose is the mystery unless someone has adjusted the valves previously and did not tighten to the proper spec. (Most “mechanics” do not)

Which rocker arm nut was loose, intake or exhaust? A loose valve seat is rare but possible. It would be very difficult to see when the cylinder head is cold. Unless of course it came out, shifted and wedged between the valve.

It was the intake valve. To give you some history last September that same side stopped firing and when I pulled the valve cover off the rocker and bracket that holds it were off in the cover. Pushrod was bent. The bolt for the bracket backed out. I replaced the pushrod and put some lock tight on the bolt and everything was fine and ran great. I not 100% sure it was the intake but I think it was.

 

[txmowman]

It was the intake valve. To give you some history last September that same side stopped firing and when I pulled the valve cover off the rocker and bracket that holds it were off in the cover. Pushrod was bent. The bolt for the bracket backed out. I replaced the pushrod and put some lock tight on the bolt and everything was fine and ran great. I not 100% sure it was the intake but I think it was.

The rocker bracket bolt coming loose on the 726cc block is a known issue. The proper torque spec of the rocker bolt is 15 ft-lb but Loctite works too.

 

[Covah2423]

I have a Toro zero turn 60” mower with a Kawasaki FS730V engine. My son and I both use it, we both have 1.5 acres to cut. While he was using it he said it stopped engaging the blades, practically killing the engine. It has 317 hours on it. I changed the PTO or clutch, all pulleys and belt. Belt was shot. It got better but was still struggling when the blades were engaged. I then put a new carb, plugs, air & fuel filters on it. Did a compression test and I had 130 & 165lbs. Ran better but when I engaged the blades it would pop, miss for about 15 seconds and then clear up and I was able to cut the grass. Every time I engaged the blades it popped, misfired and then cleared up. So the next day I pulled the valve cover off the side with 130lbs and found the nut for the rocker had fallen off. Figured I found the problem. I put it back on adjusted the valves and ran it. Pushrod was good. When I engaged the blades it was normal. Tried it 3 or 4 times and it was fine. Later that day I changed the oil& filter and put on new blades. Went to cut some grass and it was back to popping and missing but never cleared up. Next day I pulled the same valve cover and nothing was wrong. I adjusted the valves again to check them and then I checked compression on both. My side with 130 was now 145 and the other side was 155. I rechecked the first side and it was now only 90lbs. Did it several times and still only 90. Put it back together and ran it and it was back to popping & missing when engaged the blades but cleared up after 15 seconds. Today my nephew who has a outboard business came over and checked the compression and was still only 90 & the other side 165. So then we pulled the head off expecting a bad valve but there was none. Did a leak test on it and it is fine. Head gasket is good. The only thing he noticed was the cylinder was dry and smooth. Any ideas?

The rocker bracket bolt coming loose on the 726cc block is a known issue. The proper torque spec of the rocker bolt is 15 ft-lb but Loctite works too.

I have a Toro zero turn 60” mower with a Kawasaki FS730V engine. My son and I both use it, we both have 1.5 acres to cut. While he was using it he said it stopped engaging the blades, practically killing the engine. It has 317 hours on it. I changed the PTO or clutch, all pulleys and belt. Belt was shot. It got better but was still struggling when the blades were engaged. I then put a new carb, plugs, air & fuel filters on it. Did a compression test and I had 130 & 165lbs. Ran better but when I engaged the blades it would pop, miss for about 15 seconds and then clear up and I was able to cut the grass. Every time I engaged the blades it popped, misfired and then cleared up. So the next day I pulled the valve cover off the side with 130lbs and found the nut for the rocker had fallen off. Figured I found the problem. I put it back on adjusted the valves and ran it. Pushrod was good. When I engaged the blades it was normal. Tried it 3 or 4 times and it was fine. Later that day I changed the oil& filter and put on new blades. Went to cut some grass and it was back to popping and missing but never cleared up. Next day I pulled the same valve cover and nothing was wrong. I adjusted the valves again to check them and then I checked compression on both. My side with 130 was now 145 and the other side was 155. I rechecked the first side and it was now only 90lbs. Did it several times and still only 90. Put it back together and ran it and it was back to popping & missing when engaged the blades but cleared up after 15 seconds. Today my nephew who has a outboard business came over and checked the compression and was still only 90 & the other side 165. So then we pulled the head off expecting a bad valve but there was none. Did a leak test on it and it is fine. Head gasket is good. The only thing he noticed was the cylinder was dry and smooth. Any ideas?

Update: pulled valves out of head and lapped them back in. They were fine, cleaned them, not much carbon build up.