I understand how the pros see throwing parts at the problem is not a good approach. This is common behavior in many different aspects of life.
What I don’t understand is why they rag on the poster. People with problems they can’t solve tend to come here last not first so a helping hand goes much further than a tongue lashing. With your help they will learn and pass it on to others.
it cost nothing to throw dirt on someone. that's the number one problem with internet haters. do that in person...yeah, I don't think so. there WOULD BE A COST and CONSEQUENCE. behavior online has always been a strange experiment. I don't understand it but I know it's a real thing. And the weird part is that most of the negative people happen to be pretty good at a certain skill set. ego...I'm pretty sure that's the thing.
Having said that..I have rhino skin. Always have. It doesn't bother me. And lawnmower forum has been a very good overall
I had a problem with my Kubota ZT mower and did all the normal stuff mentioned here. None of it worked. Yes I threw some parts at it, fuel pump, filter, cleaned carb, checked valve lash still had no power and ran poorly. I said F it and bought a new OEM carb……in the process of installing it I noticed a warped intake. Replaced that and it runs like new. I’m no expert but have rebuilt many motorcycle engines, auto transmissions and raced cars and did all the tuning and engine swaps. Maybe not the sharpest tool in the shed but I know how to do most stuff. The problem is so many ideas are thrown out on this fine forum that you still end up throwing a bit of parts and time at it. sometimes the “experts” don’t have the answer either LOL.
yes, and sometimes, with the older mower, it's multiple issues. So you solve one and the problem does not go away until you solve the next..and the next..and the next. (this is common with older mowers that have not been well maintained).
I had a recent problem that highlighted this very situation: high revving and surging at all rpms'..from idle to wot...high revvs and surging.
the leak down test confirmed to be the valves were NOT the root case. the carb was cleaned and no issues and choke was not stuck closed. governor action was clean and proper. No fuel pump or fuel filter issues. wooddruff key was not slammed.
So I decided that the problem was likely head cylinder gasket...one or both. I got the after market copper gaskets because better squish and heat transfer and of course while it was open, cleaned the cylinder head, valve and seats and did a light lapping for good measure. Put in new plugs because it was over a year and they looked heat damaged. This did not solve the problem. The high revvs and surging continued. turns out the issue was the gaskets has blown on both intake manifolds, because the intake manifolds (made of aluminum) were slightly warped. Instead of replacing the intake manifolds, I installed my own slightly thicker gaskets and with some yamabond. Problems solved. root cause: blown head gasket failure due to high heat cycle because intake manifold was warped - air was getting sucked into cylinders after the carb and causing a serious lean condition, and because this was a kawa v twin (691), it also had the effect of surging. So it was two things. understanding the root cause is almost always a 20/20 perfect hindsight thing. But have a basic understanding of how the engine operates (normally) helps quite a bit when making good assumptions about where the problem (OR PROBLEMS ..plural, more than one) exist.
I am pretty sure what caused it: triple digits heat in south louisiana running the mower hard and getting caught in a surprise hard cold rain shower. Manifold intake distorted just enough to cause the gaskets to fail and open up.
In hindsight, I should have realized this as a lean condition and starting looking at the root cause of it, because the engine was running very hot...and the plugs are cooked.
It was that moment, when I modded all my mowers with a engine oil temp sensor...so I could monitor and shut down quickly. Probably the best thing I've done to engineer in a little preventative maintenance in my mower fleet. The air cooled engines operating in triple digit heat take a serious beating. All the maintenance schedules are of no use. Everything is done on a much shorter schedule because of it.
interestingly..the old vintage dixie chopper (silver eagle classic) with the generac motor and generac hydros has a really large oil cooler radiator, commercial duty oil pump, and oil radiator fan. It has not quit and has never had a problem with the heat. But it cuts like crap (old chain and sprocket suspended deck..that bounces way too much to make a clean cut) and so it's solely a mini bush hog, which it does very well for tall buffalo and even small bushes and undergrowth.
