Reed Valvè Adjustment 1977 Johnson 70

[Lrdrlker]

When open up my throttle to WOT my reed valve are anywhere from (if you think of a clock) 1 o'clock 7 o'clock to 2 o'clock 8 o'clock. Since the roll pins are supposed to be at 12 and 6 at WOT ...where is the adjustment on these? Every video I have seen shows diagnosis and replacement but not adjustments. I must be able to loosen/adjust/tighten something somewhere! Any advice would be most appreciated. Cheers

 

[racerone]

Throttle plates is what you speak of.-----The reed valves are not part of / installed in the carburetor.----Look into the carburetor and see if the throttle plates are horizontal at full throttle on your control.

 

[Lrdrlker]

I watched a couple of videos on reed valves and WOW!!! Do I ever know nothing about how these engines work!!! The throttle plates are at the back of the carburetor and are controlled by the amount that the linkage opens them up which in turn is controlled by the WOT setting!
I watched a video on reed valves and conducted a simple test...take a piece of paper and with the engine running place it against the front of the carb. It should get sucked onto the carb and stay in place and the engine should bog. Low and behold, top carb , middle carb, bottom carb . Middle valve needs replacement! Well I'm in luck! I have a 1973 Johnson 65 horse parts motor that uses the same reed valves. I'm going to scavenge them off that!
Question: if a reed valve isn't working then is that whole cylinder not working? So, I'm only running on 2 cylinders? That explains why it bogged so badly and died whenever I put it in drive if that's true...cheers

 

[racerone]

You motor has 3 separate crankcases.-----Broken reed valves would mean that one cylinder is not working properly.---- That cylinder would lose crankcase compression.

 

[Lrdrlker]

So, it's running...but VERY poorly?

 

[Lrdrlker]

I think the bottom valve is just limping along as well. Didn't have the suction of the top carb. It sucked...just not as hard. I'll change that one as well to be safe!

 

[Lrdrlker]

Going to pick up a compression gauge I think...

 

[racerone]

A compression tester in the sparkplug hole can NOT FIND reed valve problems.----Reed valves have nothing to do with compression in the cylinder !!

 

[Lrdrlker]

I just want to know the compression of the cylinders. That is the condition of the pistons/rings. I realize that this is not related to reed valves.

 

[oldboat1]

Now that you've got your mind sraight on reed valves and throttle valves you can pull off the carbs and access reed plates easily enough. There's not much to do there, though. Look for stray bolts (!) that have wandered into the reeds (remove the bolts and make sure the reed is not damaged and lies flat.) That's really about all you can do anyway. Make sure the thin stainless reed is undamaged -- no cracks or parts missing. And do not reinstall it upside down go get it to lay flat. You can still find NOS replacement reeds buried in back room bins, but it is harder to find the old shops with back room bins.

Best to concentrate on compression readings and spark testing (ignition testing) -- need an open air spark tester from the corner NAPA or other auto parts store (not the inline type).

 

[Lrdrlker]

I'm hoping that the reed valves on my 65 horse are in good condition and will pop right in. Very fortunate to have that motor to scavenge from! Mot everything is interchangeable but enough to make it worthwhile to keep!

 

[Lrdrlker]

I pulled the entire reed valve assembly off my '73 65 horse...absolutely pristine! I held them up to a light and there is NO light coming through and all the reeds are perfect! Waiting on new gaskets for the face plate and manifold.