How to: Set the Valve Lash on a 4 stroke engine

[@michaelchristopher2939]

I thank you for putting up this video. After watching a bunch of your videos, it has given me the confidence to rebuild my saito engine. Thanks again !

[@PeteSztencel]

Very nice: clear, practical, and helpful. Good lighting, too. My oldest Saito is over 25 years old, still runs like new. Fine engines. Re valve gaps: the little blue steel feeler supplied by Saito is 0.1mm, the maximum recommended gap (i.e. if it fits, the gaps need adjusting). It's just a warning gauge, really. They recommend (as you do) a gap of 0.03mm as a minimum (0.002"), which works very well. One other quick point: I like to use the short leg of the Allen key to adjust, and hold on to the long end whilst tightening the lock-nut. A bit more leverage makes it easier to stop the gap adjustment from changing as you tighten the lock-nut. Great videos - thanks for posting!

[@felippejonsson6078]

Thanks for putting this up, learned alot. I have two saitos to set the valve lash on.

[@rtoebak76]

Very good explanation. This helped me out a lot. Should it always have thight compression even with no carb on? I will check later but if throttle is wide open on my normal nitro engines it turnes over much easier.

[@dmrcflyr2]

A four stroke head is a sealed chamber unlike a 2 stroke engine. So yes it can and should have compression without a carb installed.

[@rtoebak76]

@@dmrcflyr2 Thank you David. I just bought a plane with saito 91 and it turns round to easy. I will check the valves and otherwise disassemble it totally. Owner says it runs fine. Turning over my thundertiger 15cc is way harder.

[@dmrcflyr2]

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[@tomepixel]

David, What advantage is there to setting valve lash to 0.04 vs 0.1 mm, curious .

[@miadulislam9469]

I want to use this engine for my rc ship. But problem is, this engine's rpm is very high. How i can reduce the rpm? Please give me a suggestion...

[@Gary1H]

Thanks for the informative vids. I had been using the supplied .1 gauge that came with my Saito 125 and setting it tightly to that but I ordered some feeler gauges and will set it with a .03mm so it’s just nipping at it as you describe. Don’t know why they supply a .1 as that would adjust a slightly large gap than ideal.

[@dmrcflyr2]

You can use it as a 'no-go' gauge by simply setting the lash so that it does not pass through, but will still enough gap that you can feel movement on the arm.

[@rtoebak76]

If the valve lash is to big, can you lose compression that way?

[@dmrcflyr2]

More likely to feel a loss of compression if the lash is set too tight. Too tight and the valves overlap open and thus a loss of compression is felt.

[@davesaldana7263]

Hi Dave I have a Saito 180 that constantly wants to run backwards do you have any suggestions

[@dmrcflyr2]

Can you provide a bit more information? I have never had an engine run backwards when using an electric starter. So you must be hand starting. Are you bump starting or rotating CCW? How are you priming the engine? I would need to knwo the exact sequence of events you are doing because the issue lies in your method for starting.

[@admargodoy]

Hi David!! This can be applied on Saitos FG's (gas engines)?

[@dmrcflyr2]

I have never had a Saito gas engine, but the design looks identical. I would say yes.

[@nealjag3917]

thank you buddy