OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions on Other Engines SOS VALVE CLEARANCES

Hi guys,
I have in my possession a Baumr-AG 21" 248cc Self-Propelled Push Button Electric Start 4in 1 Lawnmower - 890SXe. Item Number: MOWSFPBMRA214.
I purchased it just over a year ago, brand new, and I must admit it's not a bad unit. Wide cutting area. Self propelled and plenty of grunt for around the home.
I thought it time to do a major service. When it came to valve adjustment I was surprised to see that with piston at TDC on the compression stroke, I was unable to squeeze a 0.08mm (.003)
filler gauge between either inlet or exhaust valve.I was able to squeeze a 0.06mm (.0025) but only just on both valves.
I'm pretty sure that with clearances this small, the valves need adjusting. 0.06mm seems way to close.
My issue is trying to find the correct specifications is just about impossible. There's nothing in the user manual. Baumr-AG website is no good. Edisons website where I purchased the mower from are completely useless. And at least 3 hours on the internet got me no where.
Does anyone know what the inlet valve and the exhaust valve clearance should be set at?
Or can anyone point me in the right direction please?[b][/b]
I have included a couple of pics that may help with identification.
Thanks for your time and help
Dave

Hi Dave,

If you can't find the original specs ,I would just set the clearance the same as a Honda motor .006 thou intake and .008 thou exhaust..

I'd turn the motor over until one valve is fully open ( intake open) then check and adjust the other valve ( exhaust clearance check adjust)
then turn motor so exhaust valve is fully open and adjust intake valve.

You adjust the valves as above, otherwise you can mess up the adjustment when the compression release works on a valve at top dead centre.

Cheers
Max.

Cheers for the response, Max.

I had an inkling the Honda road was the way to go, but your conformation seals the deal. Really appreciate it.

I'm intrigued by the technique you mentioned for valve adjustment - turning the engine until one valve is open while the other is closed. It's a new one for me,
as I'm accustomed to the TDC compression stroke method. Could you shed some light on the advantages of your approach?
I'm all ears for a good technique.

Thanks again for your insight!
Dave

Hi Dave,

With a lot of small engines they have an Automatic Compression Release when on Top Dead Centre so you
can't adjust the valve clearance at TDC because the valve should be slightly open,

Different motors use different techniques to reduce compression when starting ,if you were to adjust clearances at TDC
your compression release would not work and the motor would be difficult to turn over also you will have too much
clearance if adjusted at TDC.

There are a few Youtube clips showing how to adjust clearances in different types of small engines.

See below valve is open at TDC at starting RPM. Also a patent PDF below for Tecumseh.

Cheers
Max.

Hello again Max

Well, let me begin by saying that the only reason I felt the need to adjust the valves was because I bought it brand new and 12 months had passed. I thought it was running OK.

But now that the adjustment has been done using the method you described Max, it definitely has improved power output. Better throttle response. Not quite so loud on the exhaust too.

Full disclosure, I did put a new plug, fresh oil, new air filter and new set of cutting blades so I can't give you all the credit. Ha ha ha ha. Just kidding.

Thanks again