Kohler diy rebuilt K241 ticking

[JeremyNzl 2]

Hi Guys, 

 

Looking for some advice, 

 

We rebuilt this k241 with a +.010 piston, Its had a rebore to +.010 but they did it off the manual specs and not the piston.

Not ideal with an aftermarket piston but I wont get caught on this next time. 

 

Its developed this oscillating ting noise, its not the metal cover its there with it on and off, 

its 100% from the cam side, does it under low load / slow idle, 

Have setoscoped the motor with a screwdriver to the ear, and I cannot locate it.

but its in the top.

 

Have rechecked valvel clearances x2 already , 1st before initial run, and again day after, very minimal adjustment made after 1st run. 

 

Ting noise clearly heard in the video , appreciate any advice. 

 

Jeremy Nz 

 

https://www.dropbox.com/s/txf8fciaqi5rozg/2021-06-10%2009.08.11.mp4?dl=0

[Maxwell-8 4,289]

2 hours ago, JeremyNzl said:

100% from the cam side,

 

2 hours ago, JeremyNzl said:

Have setoscoped the motor with a screwdriver to the ear, and I cannot locate it.

but its in the top.

These are flatheads and the cam is level with the cam. Is the sound coming from the area cam-crank or from the vave area? 

If it coms from the cranck-cam area. Did your properly torque the rod bolts?  

 

Strange to hear is klicks now an then, not all the time  

Maybe a broken bearing?

 

 

Edited June 10, 2021 by Maxwell-8

[JeremyNzl 2]

Yea its a cracker of a problem.

 

New crank bearing installed, with 1 gasket and 1 shim

Rod end was 2x torqued, 20%over then backed off and retorqued to spec.

 

I believe the noise to be around the exhaust valve. location.

I seem to get an unburnt fuel discharge with every ting, 

 

When I short the mageneto out to stop it I get the same noise often till it quits rotating. 

Edited June 10, 2021 by JeremyNzl

[squonk 41,287]

Exhaust Valve sticking. When it sticks and releases you will get a click like a tappet adjustment. Doesn't stick all the time so that will account for the oscillation. It would also account for the unburnt fuel. Were the guides and stems checked? 

Edited June 10, 2021 by squonk

[JeremyNzl 2]

27 minutes ago, squonk said:

Exhaust Valve sticking. When it sticks and releases you will get a click like a tappet adjustment. Doesn't stick all the time so that will account for the oscillation. It would also account for the unburnt fuel. Were the guides and stems checked? 

Thankyou for you diagnosis,

 

The rebuild kit came with valves, and i recut the seats to 46deg neway cutter and hand lapped them.

I do not have replacement guides. 

 

I did not measure the stems nor touch the guides, I have the head off it atm so I will remove exhaust valve and reinspect.

 

I very much appreciate the advice received. 

[ri702bill 8,472]

Jeremy:

Me thinks that Squonk has has accurately located your problem - and it IS a problem. If left as is, the exhaust valve will not always close and it will not be able to transfer its heat to the valve seat, resulting in a burnt valve.

Two items come to mind - chuck up the loose valve in a drill and spin it to check to see if it bent. Also, new valve stems are usually too long to allow grinding to fit to achieve your correct valve clearance to the tappet. Check your clearances for both valves.

 

My first instinct was a possible piston slap condition - most machine shops will NOT bore a block oversize without having the new piston on hand to verify its skirt size. Its not so much as the bore diameter but that the bore is round and provides the proper skirt clearance.

Bill

Edited June 10, 2021 by ri702bill
added piston info

[JoeM 7,874]

Could the ACR not be right?

Just thinking.

[Gregor 4,847]

Possible loose valve seat?

[tunahead72 2,424]

Any updates @JeremyNzl ?