Briggs VTWIN 23HP. 445577-0499-E1

[Tbone0106]

Sounds like a valve lash problem. 120 psi is too high for that engine, and 0 is obviously too low. It sounds for all the world as if the valve lash was set on both cylinders at the same time, with neither piston at TDC. That would cause one cylinder's valves to be open most of the time and the other's to be closed.

Sounds crazy, but I've seen it.

 

[srwa]

Appreciate the info.

I thought 120 # psi was way to high,checked several times, always the same.When I first got the mower it was running, not very well. Checked compression, either 60 or 80 on #1 cylinder and 40 psi on number 2. Disassembled engine.

Forgot, set valve lash initially before tear down, same compression. Also, the book says set #1 cylinder @ .005(13mm) 1/4 inch after TDC and # 2 cylinder either @ TDC or the same as #1. Have to look it up.

Have an exhaust valve coming on or before the 14th. Will be in touch.

 

[VRR.DYNDNS>BIZ]

Sounds sorta like a dropped or broken valve seat. Although it is not unheard of someone using a piston stop and punching a hole in the piston. Leak down test should point you in the right direction.

Valve seat is a definite possibility but more common is valve guide migration. Once they move from overheating, if in or out, either way complete valve travel will not occur, thus setting the lash will do no good. This happens far more often than seat in head coming loose. The best fix is buying a new head but occasionally simply driving the guide back flush inside the cylinder will last if the nesting which is the usual cause, is prevented.

 

[srwa]

Mean while, back at the ranch............ finally received the exhaust valve...first one lost in transit. Correction on the original post, the original valve head is warped, not bent. When in the seat there is approx. a 1/16 "opening" between the valve and the seat on one side, and if the valve is turned the opening follows around........if that makes any since.

Going to reset and double check the valve lash. Will be back with the compression #s soon as I can borrow a compression gauge tester from Autozone

 

[srwa]

Compression on # 2 cyl., which the exhaust valve was replaced, 165 lb.s, compression on #1 cyl. 120 lb. s.

Thats a 27 to 30 percent difference.

Will recheck valve lash on # 2 cyl......it's a little high, wouldn't U think?

 

[srwa]

Finally got this engine back together with several new parts, one being a new carb. Cranked engine, runs like a new one. Shut engine down. Fuel starts leaking big time out of the #2 cyl. intake.

Removed carb. with intake. Took carb. apart, float seems to be working as it should. Reassembled everything, started engine, runs good. Shut engine off. Fuel starts leaking out of #2 cyl. at the intake.

Have packed several sticks of dynamite under tractor, have not lit fuse....yet.

Thoughts, comments, criticisms,??

Have watched several Utube video's saying its a sticking float.

 

[bertsmobile1]

Sit down with a soothing peppermint tea and think this through.
Where does the petrol flow?
It can only go through the carb unless your particular mower has a fuel tank vent into the manifold and AFAIK only Kawakasi do that .
So the fuel has to be going through the carb and for that to happen it has to be going through the float valve because that is the only path.
Because of EPA regulations the carb can not be connected to the atmosphere so the air vent to the float bowl and the overflow ( usually the same passage ) is into the engine.
So this is what is happening
The fuel is going through the float valve and overfilling the float chamber then flowing through the overflow / air vent that comes out of a hole which is on the same side as the No 2 cylinder.
Now there can only be one cause for this
Float valve is not closing off the fuel supply .
Now this can be caused by a few things
1) dirty needle or seat
2) seat that has moved
3) obstruction holding the float down
4) excessive supply pressure.
To check 1 & 2 you remove the float bowl and get some one to crank the engine while you work the float with your finger . The fuel flow should stop before the float touches the top of the carb ( note fire risk here )
No 3 will be found by close inspection of the float & float bowl and any gasket or seal that can foul on the float .
No 4 is checked by removing the fuel cap after you stop the engine
If you hear a pressure release the fuel tank vent ing system is faulty.

A carb float is only good for around 10 psi as the fuel pumps 5 to 7 psi .
When people swap a gravity feed carb onto a pump supply engine this occasionally happens .

 

[srwa]

Makes sense, but whoed thought on a new carb. But, on a massed produced item made in China.

And thats the reason for the new carb. The first time it happened (the old carb.) it emptied the gas tank into the crankcase.

 

[srwa]

Took the new carb. off,cleaned,hosed jets out with carb. cleaner, checked float etc. put back together and cranked it up. No fuel leakage, cranked & ran a few minutes 1/2 dozen times. No leakage.

Cranked it again, turned a few revolutions then got a "free" wheeling flywheel. Then I hollered OH BLANK, now I got real problems. Then I said, self, check the flywheel key. Low and behold key was sheered.

Am curious,has anyone every sheered a flywheel key??

 

[bertsmobile1]

I replace about 1/2 dozen or so a year