How to lock the tappet screw with its lock nut

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old man emu
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How to lock the tappet screw with its lock nut

#1

Post by old man emu »

While trying to solve a tappet adjustment problem on a friend's bike, I noticed that the nut being used to lock the tappet screw was not the same as Part# 223-38. I guessed the reason was that the engine was rebuilt some time ago in Eastern Europe and the correct part was not available.

When I looked at a picture of 223-38, I saw that, apart from the slit cut in it, one end of the nut was tapered. This seems to allow the nut to be screwed down into the tappet assembly.
Tappet lock nut.png
Tappet lock nut.png (179.76 KiB) Viewed 214 times



To lock in the tappet clearance, do you set the gap by screwing the tappet screw up or down until the gap is correct, then, holding the tappet screw in position, screw 223-38 down the screw and into the head of the tappet assembly (Part# 200-29) until it locks?



RUBONE
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Re: How to lock the tappet screw with its lock nut

#2

Post by RUBONE »

There is movement at the final tightening based on how much clearance there is in the thread pitch and you have to determine that change by doing it, there isn't any guideline. Adjust, repeat, get it right. Welcome to to the old world..

old man emu
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Re: How to lock the tappet screw with its lock nut

#3

Post by old man emu »

RUBONE wrote:
Mon Mar 30, 2020 2:12 am
There is movement at the final tightening based on how much clearance there is in the thread pitch and you have to determine that change by doing it, there isn't any guideline. Adjust, repeat, get it right. Welcome to to the old world..
I can see where you are coming from talking about thread wear over time, and I agree that the optimum solution would be to replace the old components with new ones. Maybe my friend will do that - the parts only cost about $US30 for all four nuts and screws.

But that's not what I would like to know. Does the chamfered end of 223-38 get screwed down into 200-29 to cause the locking of 221-40?

flatboy1950
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Re: How to lock the tappet screw with its lock nut

#4

Post by flatboy1950 »

Yes , the lock nut is split & as you tighten it down into the taper , it locks.

old man emu
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Re: How to lock the tappet screw with its lock nut

#5

Post by old man emu »

Better go out an do a tappet adjustment and lock the adjuster correctly!

Thanks everyone for your replies .

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