generator valve adjustment

[BillHoughton]

My rig has an Onan generator (model KY-FA26120, if that helps with my question). I cannot, for the life of me, figure out how to turn the motor over to top dead center so I can check/adjust the valves. There's no visible place to crank it around. My experience, from motorcycling days, is that a one-cylinder motor, randomly turned over with the starter, will rarely settle on top dead center. Help!

[BillHoughton]

Well, duh. When I looked at the fan end, I could reach in and put a socket on the nut that retains the fan. I guesstimated top dead center, and then checked after by rotating the engine until I was confident the valves were each off the cam to check again.

Glad I checked. The link that Wolfe included in his reply says that valve adjustment is critical on that series of Onan generators - the valve keepers will apparently fall off if the valves aren't right. And, on mine, the intake valve was way too loose (0.005", when the optimal setting is 0.002" and the max 0.003"), and the exhaust valve so tight I couldn't get a 0.002" feeler gauge even to start in.

Onan calls for valve adjustment every 500 hours; for the amount we use it, my driver's license will have expired for the last time before I have to do that again, which is fine with me: I'd have been grateful if Onan's engineers had used a finer pitch on the rocker studs, because I found myself getting it just right, then tightening the locknut and finding it too tight on checking; and repeating that a LOT.

But done now; another project off the list.

[BillHoughton]

Thanks, Wolfe. So it does matter. We bought this used, and I have no idea when the valves were last adjusted, if ever. So I guess I do need to figure this out. I'll post about my success, he says confidently...

[wolfe10]

A discussion of valve adjustment on the KY Onan:

https://lasmotorhomes.com/case-studies/500-hour-service-interval-on-ky-kv-onan-generators/

[maillemaker]

The SmokStak forum is *the* place for serious Onan technical questions:

https://www.smokstak.com/forum/forumdisplay.php?f=1

My Onan 4BGE has a 3/8" Hex socket on the shaft on the generator end of the genset. A 3/8" Hex Driver with a ratchet works great to turn the motor.

Be sure to remove the spark plugs to make it easier for the engine to rotate.

Steve

[ron_dittmer]

I never heard of adjusting the valve clearances on an Onan generator before. Motorcycles yes, my 1981 Toyota Corolla and 1983 Toyota motor home yes..... but Onan generators? What is the recommended hours of usage before requiring it?

[77rollalong]

some have and allen key hole in the generator end or a hex shaft also on the gen end that you can use as well

[Chum_lee]

If you take off the genny cover there should be a rocker type remote starter switch on the panel underneath. Just click/bump the switch with the spark plug removed and your finger in the hole.

Chum lee

[DrewE]

A socket on the fan/flywheel nut should also do the trick. Just plain grabbing and turning the fan by hand with the spark plug removed should not be all that difficult of a task.

[wolfe10]

Have not worked on that model, but on many Onan air cooled generators, the cooling fan can be accessed with a long screwdriver and the engine turned using the fan to rotate the crank.

[azrving]

This

Connected from small solenoid terminal to battery positive hold it upside down and tap it against a hard surface don't hold the button just tap it quickly slightly and it will keep bumping the solenoid and starter and very slowly roll the engine over as you watch the tappet movement