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Lapping does not increase compression. Will not remove pits, not used for removing carbon, and has zero effect on performance. There are tons of marketing ads pushing this crap and it's all a lie. The only value of lapping is to verify correct contact location of the seat on the valve and the...

Precisely the behavior of my engine. Thought at first it was fuel pump related but no....ignition. Pulling cylinder 1 plug cap resulted in a very rough running engine. Pulling the #2 however engine ran smoothly. When I say smoothly that means the ignition was consistent with #1 coil but still...

As it so happens I just had to replace both coils at 480 hours. Yes they do fail and it not ucommon for them to fail . The post below explains why. The transistor managed coils are not all that robust given the hostile environment they live in ,primarily heat related...

I would pay to watch him do that....🤔

You ought to watch some YouTube videos of Pakistanis rebuilding engines.

The fuse kits from Amazon and others are crap. There are tests of fuses rated at a specific amperage that continue to operate at 400% above stated rating. All are Chinee made.

Just replaced both of mine at 480 hours on the originals. The result was dramatic.

Yes...there are two transistors in each coil and they can and do fail. Every revolution of the engine creates a spark. At 3300RPM that's 55 sparks a second. The high heat environment doesn't bode well for long life.

This is not a plea for help as it has been fixed, just a heads up on cause and effect. The ignition coils on these engines are different from the #1 and #2 side with different part numbers and have a pair of transistors inside the units that control primary winding charging and field collapse...

Lapping just makes the seat and valve shiney.

Exactly.

Why does a compression release exist? For the weak human pulling the cord. No engine equipped with a starter should ever require a compression release. And no amount of adjustment of the valves will fix a worn compression release cam lobe. Drain your oil and look for sparklies. May be worse...

Kawasaki makes their small engines in MO and NE. One of the first to do so. Toyota, Subaru, Nissan and Honda followed suit. Not everything is made overseas. Tariffs can be avoided. Buy American. Just because it sounds foreign doesn't mean it's not built here by American labor and materials. Some...

Japan's Tanaka when they were still in business. The only manufacturer with a 7 year residential warranty, 3 year commercial. Light, simple, trivial to work on. Still believed the customer was smart enough to make their own carb adjustments.

I've never had to do a decarbon. Ever. Everything I own that is air cooled two stroke and under 8000 or under RPM runs close to 100:1 gas/oil. Including Ultralight acft engines. Rotax reccomemends decarbon every 50 hours. That's just insane. Ball bearings and needle bearings require scant...

What, exactly, are you "well known" for? 🤫🤔

Called pre-ignition. A hot bit of carbon, a sliver of metal that is hot enough to ignite fuel vapor. https://en.m.wikipedia.org/wiki/Pre-ignition This is what separates mechanics from on-lookers.

If the pump gaskets are stiff and inoperable the exact opposite of what you describe will be the condition.

If it's flooded, simply remove the spark plug and pull it over a few times...then wait. Fuel will evaporate. Install plug, reattempt starting. You don't need to pull it over 25 times in rapid succession.

Like trimmer line can't as well.

Trace the white back and run a separate new wire to the switch S terminal that supplies the 12v solenoid. If that works you're looking at two relays that must operate to send power on to the solenoid.

A replacement head that uses cable or wire rope. That'll keep you busy trimming and not changing line all the time.

Those cheap modules can be used to convert an old points and condenser saw to electronic trigger so don't see why they wouldn't work the same as a name brand. I've converted a few old McCollough and they start easier and run just as well.

Ground?

I think it's more "disturbing the Force"......electric mowers have that effect.

Full throttle?

You are now, officially, a parts cannon. 🤔

Pretty simple....cut out the back of the frame hole.

If this machine has any time at all on it, and a lot of starts, the starter commutator get glazed and the brushes don't make adequate contact. All you'll get is a sight click from the relay or the stronger one from solenoid. Easy fix. Remove and disassemble starter. 600 grit paper to clean the...

If it cranks when jumped, what made you think it was the solenoid? It has to work to actuate the Bendix.

How old is the mower? Lots of hours? If that's the case might want to drop the starter and check the commutator. Neighbors mower did just what you describe so pulled it for them and cleaned the heavily varnished commutator. It's an easy fix if you have the tools and skills. The one thing I would...

Mine on a 54" Lightning has lasted from 2008. They are units originally designed for gates and the big 10' sat dishes, ball and screw actuators. Be wary of the travel at the very end of the stroke as sometimes the unit will not retract because the ball has reached the end of the screw and...

Just for those reading this, the washer is a Belleville type that is cup shaped. The concave side goes toward the shaft the convex side toward the bolt head. If put on upside down the washer is just along for the ride and secures nothing.

Looked at a parts breakout.....is there perhaps an opportunity to safety wire the tube to the body of the pump? There is the nice lip on the tube but can't tell if there is an opening above to slip the wire thru. I'd avoid any kind of chemical restraint such as epoxy, unknown how long that would...

Mostly incorrect . Everything made after the early 80s has switched to materials that are ethanol agnostic as it doesn't do anything to them. Pre Buna-N orings were the common failure and after the switch to Buna-N no more problems. Same holds true with diaphragms.

Most likely the impulse port for the fuel pump diaphram in the carb body.

Hence the need to exactly specify which engine gets the same carb spec as the OEM carb. If you cannot adjust them they are pre jetted for a specific displacement engine.

Almost forgot....the old spark testers were just neon bulbs in a non conductive pen except for a cupped aluminum cap that fit over the plug wire. If the bulb lit up, spark. Also useful to check electric fences to see if they're on or not.

An inexpensive IR thermal gun is worth its weight when diagnosing some problems. Objective measurement beats subjective measurements every time. 😏 Well...that's just not true. As an aviator of injected engines, you may have the capability to run rich of peak EGT or lean of peak EGT......rich...

Seems to me you're out voted by "broad brush" real world experiences. What you may think is a Yamaha may not actually be a Yamaha but one in name only.

A Kawasaki is a better bet.

On my 731 the plug leads are carbon track type....meaning they have a carbon impregnated string carrying the electricity to the plug. I cut the rubber boot off and found that the cap had not been fully crimped to the lead and did not contact the carbon string. Replaced both caps with these...

How do you know it "overheats"?

Sounds like "what he can do" will resolve itself......

Obsessing over straightness and angle is unnecessary. Whatever the angle, irregardless of "straight", when the steel blade hits the grass blade the steel wins. Every time. A dull blade tears, a sharp one cuts.....for awhile. Be more concerned about balance.

Loosen is not removed....mud daubers love, for some reason, to build mud capsules in the muffler. Make sure that's not the case. Otherwise, remove carb, disassemble, inspect and blow all passages out with at least 30 psi or higher. What you describe can be either fuel starvation or blockage. I...

https://www.amazon.com/SIMPERAC-Carburetor-RY252CS-RY253SS-RY251PH/dp/B0BWF5CMX2

F4040 Tygon yellow fuel line is rated for gasoline.....not all yellow, or for that matter, any color, lines are gasoline rated.