Toro only starts with gas drip directly into carb - NOT without. Hot or cold.

Rivets said:
“ Think most engine manuals say like every 5 years, pull head and clean valves.” This is something I’ve never seen or heard. Personally I wouldn’t do this on my own equipment or charge a customer for unless there is some other reason to pull the head.
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Not for nothing. I looked at 3 of my push mower engine manuals. One a Briggs, one a Kawasaki and the other the gutless Honda GXV160. They all say at X amount of time, clean the combustion chamber....

Briggs manual
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Kawasaki manual

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Honda GXV-160 engine manual

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Here's a Kohler engine manual I just grabbed off the internet. Every 100 hours have the combustion chamber decarbonized.

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Ok, I’ll concede that it’s being posted in owners manuals. That’s what they say in the manuals to CYA. I guess you’ll tell me that a majority of home owners would even think about doing this Or know what it means. I’ll still stick to my statement, “NO NEED TO DO THIS UNLESS YOU SUSPECT OTHER PROBLEMS “.
 
it is just my suspicion but almost all of my power equipment heads loosen up after many hours. It probably is less a liability for the manufacturer to say "clean combustion deposits" than say "retorque the heads", or "replace the head gasket." The two latter would sound like a design problem where cleaning carbon deposits would be a use issue. GM used to have their mechanics dribble water into the carb while the engine was hot and running so it blew quite a bit of the carbon off.
 
I have no idea about the need to decarbonise .
I have a feeling that it is added for historical reasons rather than actual necessity
With modern lean burn engines I never see appreciable carbon build up and on old side bangers there is no need unless the carbon is actually hitting the head .
The engine makers tell you to change plugs & oil filters at very short intervals where as in practice I would be lucky to change a plug at anything less than 500 hours, in fact some of the commercial customers with several thousand hours are still running the original plugs
The only time I decarbonize is when I do a head gasket or stake a valve guide.
For the past year I have been using my 1943 500cc side valve motorcycle
The makers recommended monthly decarbonizing when used daily, this bike has not been touched for 5 years
A piston builds up a carbon cover on the piston which is very beneficial to the piston
ON high performance engines, with squish bands of 0.020" then 0.005" of carbon can be a problem but in a vertical shaft mower engine it is akin to playing with yourself .
 
Chunks of carbon can break away, get into the bore, piston and ring area and gouge the crap out of these mostly aluminum bores. Yes some are cast iron lined. When that happens we get deep scratches which lead to oil burning. No secret where this leads.

Guess I'm the only one that buys/has old push mowers. Every one I've pulled the head on has plenty of carbon to make a sandwich out of. Huge chunks on the backside of the valves......
 
Rivets said:
Ok, I’ll concede that it’s being posted in owners manuals. That’s what they say in the manuals to CYA. I guess you’ll tell me that a majority of home owners would even think about doing this Or know what it means. I’ll still stick to my statement, “NO NEED TO DO THIS UNLESS YOU SUSPECT OTHER PROBLEMS “.
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I'm a home owner. I follow what's inside these engine manuals. Why? These people made these engines and know what and how to keep them alive.

Shop mechanics would never do this, I agree. Why? People want the cheapest repair possible and will not pay for something they've never heard about. Most people have been programmed with spark plug and air filter only in their brain. Anything past this and you guys get a ton of questions.

Some people run plugged up air filters and never change the oil. To each his own I guess.
 
In viewing a few videos on rebuilding carbs it is reported that the o rings and gaskets are susceptible to degradation from carb cleaner.
Wonder if the o rings on my main tube were affected by previous use of carb cleaners or starting fluids? That tube doesn't move/abrade so I can't see what else would cause failure.
Does ethanol containing gas cause the same issue?
 
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