Setting valves on YM2000

California · Jun 10, 2015

clemsonfor said:
I dont set valves on anything else but figured this was simple so I would do it.
So you cant get your hand in there from the top and see the valves move? seems like you could, maybe remove the side panel?:confused3:

You can see the TDC (and injection timing) marks on the front pulley looking in from the top but you may need a light and mirror. And you can rotate the crank a little to get absolute TDC by turning the fan belt by turning the generator, all working from the top. You might need to remove the side cover to do this. My YM240 doesn't have side covers so I don't know about a YM2000. With the valve cover off you can see the rockers and valve stems move.

I think it is a good idea to torque the head and rocker shaft pedestals, and adjust the valves on these after many years use. Especially if this was one of the VN imports from back when all the Ebay Yanmars advertised 'new head gasket on every tractor'. To me I see this as part of the thorough maintenance that keeps equipment in service for years without problems.

I did this service on my YM240 and found a couple of head bolts way below spec, maybe a full revolution to bring up to spec. Cinching down the head bolts altered the valve clearance which was already tighter than they should have been.

Note to anybody - the valve cover gasket on these is rubber and re-usable so be gentle with it. And the valve cover gasket on later Yanmars is fiber half-embedded in a groove in the cover, also intended to be re-used. Be gentle with that one too, don't hammer something wedge-shaped in there trying to lift the valve cover.

And a safety caution: turning the crank by any means has a slight possibility of starting the engine, or at least making it fire one stroke, so be careful turning the crank.

Markey · Jun 10, 2015

California, your belt must be super-tight and you must be super strong to be able to turn over the engine by manually rotating the generator pulley. With such high compression, I struggled with a large ratchet on the crank-nut while laying on my back!

California · Jun 11, 2015

I should add that I began by bumping the starter with the valve cover off so I could see where it was in the valve cycle.

Then when it looked about right I looked down at the timing mark to verify, and turned the alternator while pressing on the belt to get traction. And this done very slowly, waiting for the compression to bleed off.

If the piston is near TDC then you aren't fighting much compression to move the crank a few degrees. You don't need precise TDC, just near it to assure you aren't on a cam lobe.

A couple of related notes:

1) Yanmar numbers the cylinders starting from the flywheel end of the engine. (A carryover from their marine history).

2) These twins aren't even-firing. One cylinder fires 180 degrees of crankshaft rotation after the other, then nothing happens for another 540 degrees of rotation. So consider that while looking for the point to adjust the other cylinder.

This 'odd' firing sequence lets the crankcase have approximately equal volume at all times. This contrasts with the old British motorcycle twins that were even-firing (360 degrees apart) with both pistons rising at the same time. I think it was their continual drastic change in crankcase volume that made them drip so much oil.

careyo63 · Jun 11, 2015

Of course I checked my Valves not long after I got my 2000 home and was going through everything. Checking them was real simple for me. I have a Remote switch I connect to the starter.

I removed my side cover so I could turn the motor a few degrees if needed. Only took a couple Min. and the settings were perfect. I was sure Steve@Spalding must have checked and set them.
HF. does have the switch that is almost worth picking one up if HF. is close by.

Search results for: 'starter switch'

normde2001 · Jun 11, 2015

No need to worry about TDC or pos. of piston, just put finger on rocker arm and turn engine until it has max movement, check/adjust, move on to next one then recheck all.

careyo63 · Jun 11, 2015

Hoye's shows exactly how to set them. When I removed my valve cover what was really odd, No Gasket. I've never put one on it. 450+ Hrs. that I put on it and still not Drip. If I remember correct I did use a small bead of High Tach form a Gasket on the Valve cover and let it dry. Worked Great. I hate Leaks

clemsonfor · Jun 11, 2015

Markey said:
You can remove the top valve cover, and you will see the rocker arms, adjusting screws, springs, top of the rods, and top of the valves. However, you can not see the actual valves, as they are working at opening and closing inside the cylinder head. DO NOT REMOVE CYLINDER HEAD!!! Also, do not start-up tractor with valve cover removed unless you want to get squirted all over with oil.

Ok yep i am not that dumb or ignorant on engine. I know you cant see the actual valve open and close but you will see the end of the valve stem where the rocker pushes it down. Even if i did not know any of the abouve the Hoye article describes what i am looking for.

Thanks for the tip incase there was someone who actually thought you needed to remove the head to adjust them.

Djames55 · Jun 15, 2015

The way the old timers did the valve adjustments... Was rotate the engine with the starter "Bump the starter" until the intake valve just starts to open on that cyclinder then you can adjust the exhaust valve on that cylinder... Then bump the starter until that exhaust valve opens then is almost closed then you can adjust the intake valve on that cylinder... This always gets the cam on the flat side for each valve... Very Easy...

California · Jun 15, 2015

Djames55 said:
The way the old timers did the valve adjustments... Was rotate the engine with the starter "Bump the starter" until the intake valve just starts to open on that cyclinder then you can adjust the exhaust valve on that cylinder... Then bump the starter until that exhaust valve opens then is almost closed then you can adjust the intake valve on that cylinder... This always gets the cam on the flat side for each valve... Very Easy...

Uh - I think its the opposite. When the exhaust valve gets nearly closed is just before the intake valve starts to open, or the intake is already beginning to open on a hi performance gasoline engine (so that inertia out the tailpipe will suck in fresh air/fuel). There's a chance that both lifters will be on the ramp portion of their cams. The way I learned it was adjust the intake as the exhaust valve starts to open, and the exhaust just after intake closes.

Or on an engine where two cylinders fire 360 degrees apart, bump the starter until an exhaust valve finishes closing just as an intake opens. Then adjust the other cylinder that fires at that moment. (Can't use this technique on the two and three cylinder Yanmars since they don't have any cylinders that fire 360 degrees apart).