Valve adjustment

[gregjo1948]

Just came across a Kawasaki twin with a different type of valve adjustment than I've worked on before. I had a customer bring a Ferris walk behind with a two cylinder Kawasaki engine. He was in a rush to get it repaired so, I gave it a quick look. He said an employee was mowing and it stopped firing on one cylinder. I determined which cylinder was faulty and it had good spark and seem to have compression.(did check with tester) Figured it had a valve problem so pulled the cover off. The "standtion" nut had worked loose letting the push rod to become out of the rocker arm socket on the exhaust valve. It appeared there was no adjustment on the valve but realized the bolt holding rocker to the standsion rotated the bushing which was cammed to adjust the valve lash. Adjusting older valves the lash was .004 to .006 but I couldn't get this one near that close. I adjusted as close as I could and it ran fine but I would like to know what the lash should be and why I couldn't adjust it to .004 to .006. Any help would be appreciated. gregjo1948 (never even took the mower off his trailer)

 

[Rivets]

If you could post the engine numbers we might find you a service manual.

 

[Boit4866]

As Rivets suggested, provide the engine model. Engine valve lash gaps vary across engine makes and models. My FH580V has lash specs of .004-.006 as you mentioned. From your description I would look at damage to the rocker cups where the push rod rests. I suspect the valve lash maintenance has been neglected and the push rod was banging inside the cup. Probably why you can’t get it within spec now. I would take a look at the other cylinder head valves to see if the lash is too wide.

 

[Boit4866]

BTW, I am finding that the valve lash adjustment/maintenance is the most neglected of these small push-rod engines. If these engines begin to experience valve related issues, damage has already begun.

 

[bertsmobile1]

The valve lash on your mower is via an eccentric bush within the rocker
The rocker bolt should have a square section on the shaft that engages with the bush.
This set up was invented around 80 years ago to reduce the weight of moving parts thus lessen vibrations & allow faster rocker movement.
If the bolt is in the bush correctly andthe rocker is not damaged you should be able to get around 1/4" of adjustment at the vlave stem.
If this is not enough then either the rocker is faulty or the valve stem has shifted or it has the wrong valve fitted.

 

[7394]

Bert- That is the adjustment set-up my 2014 Kaw FRX 651V has. Easy to adjust. Just have to take ones time.

 

[gregjo1948]

Thanks to all for the replies. I can't give you the engine numbers because as soon as I got it running, the landscaper took it back to mowing. This time of year in upstate NY, the lawn mowing contractors can't have downtime as the grass grows almost fast enough to see it happening.

 

[slomo]

BTW, I am finding that the valve lash adjustment/maintenance is the most neglected of these small push-rod engines. If these engines begin to experience valve related issues, damage has already begun.

Not necessarily.

YES on the neglected maintenance items.

slomo

 

[slomo]

The valve lash on your mower is via an eccentric bush within the rocker
The rocker bolt should have a square section on the shaft that engages with the bush.
This set up was invented around 80 years ago to reduce the weight of moving parts thus lessen vibrations & allow faster rocker movement.
If the bolt is in the bush correctly andthe rocker is not damaged you should be able to get around 1/4" of adjustment at the vlave stem.
If this is not enough then either the rocker is faulty or the valve stem has shifted or it has the wrong valve fitted.

Curious how you knew this without the engine numbers? Guess you are just "that" good.

slomo

 

[Rivets]

Slomo, a little detective work, without model numbers is probably what Bert did to make his evaluation. The OP stated it was a walk behind Ferris mower with a Kawasaki twin engine. Plus he said it had a different valve adjustment setup. I asked for numbers, because is it easier to offer help and I didn’t want to take a stab in the dark. I’m willing to bet he has an FS- series engine, which is a twin using an eccentric adjuster through the rocker arm bolt. Both Bert and I may be wrong, but I’m willing to bet not, due to each of us having a couple of years working on Kawasaki engines. We call it working with what you’re given, experienced guesses.