Topic: how do i properly torque the lock nut when adjusting valve clearance?

[Todd Richards]

All

I recently checked/adjusted the valve clearance on my 1982 CB650SC, that have the SOHC & locknut/adjusting screw system to maintain proper intake and exhaust valve clearance. I have the proper tool that allows me to hold the adjusting screw whilst tightening the locknut, by hand. The issue i have is how to properly torque the locknut? (the driver on the adjusting screw is inaccessible when attempting to applying torque with the torque wrench i have., therefore it just turns with the nut......)

Can someone please share your method to obtain the proper torque? hopefully, i am not in meed of additional special tools?

Thank you for your time and assistance, greatly appreciated

[tlbranth]

I'm gonna get a lot of #$%* for this, but I rarely use a torque wrench. After 50 years of messing with mechanical things I just decide when it feels right. Just cinch the locknut down 'good'.

[Todd Richards]

I have a set of tappet wrenches just like the ones you show.. and basically just used them to get the nut loose-adjusted-tight. seems to have worked OK.. i just worry that improperly torquing (too light) might let the nuts come loose.

so far-so good!

Thanks for your advice, greatly appreciated

[Fritz]

You can try to get a used tappet adjuster screw and nut or find a different nut of the same size and pitch.
Or you could take one screw and two lock nuts out of your engine.
Hold the screw in a workbench vice and use your torque wrench to tighten it to 10lb-ft /15Nm and use a box wrench trying to a) tighten it just a little bit more and b) unscrew it. This way, you should learn how to feel the torque you need to tighten the lock nut.

[MCRider]

You can try to get a used tappet adjuster screw and nut or find a different nut of the same size and pitch.
Or you could take one screw and two lock nuts out of you engine.
Hold the screw in a workbench vice and use your torque wrench to tighten it to 10lb-ft / 15Nm and use a ring wrench trying to a) tighten it just a little bit more and b) unscrew it. This way, you should learn how to feel the torque you need to tighten the lock nut.

Great idea!

I use a stubby fatbladed screwdriver and a good 10mm box end wrench, 12 point. After snugging in the clearance, hold the stubby real tight in the groove and give it one moore with the box end wrench, resisting the turning of the screw with the stubby. Then check the clearance again. If it budged, start over.

If the clearance is slightly big, put some English on the stubby as tightening the nut, and maybe it will move the adjuster just a skosh tighter.

Its an acquired skill.

[Todd Richards]

Fritz, Great Idea!!!

I am going to get some of the nut/adjusting screws and then practice a bit.


Thank you so much, Appreciated

[Raul CB750K1]

Not really related with the original post, but I would like to share with you how do I adjust the tappets.

I have always had a hard time using the feeler gauges, and I seldom felt that I had really adjusted them properly. No matter how strong you hold the screwdriver, it always seems you have been unable to keep the tappet from turning when tightening the locknut.

I don't use a feeler gauge anymore. What I do now is, in first place, measure the thread pitch. It represents the distance from threat to thread. Thus, with every turn of the tappet -360º- the tappet goes in and out the pitch distance.

So, if the clearance is -say- 0.10mm, what I do is to calculate how many degrees should I have to turn the tappet to make it go in and out that amount. I loosely tighten the tappet until it makes contact with the valve stem. Visualize the slot, and loosen the tappet by turning it counterclockwise the required number of degrees. If you manage to mark with a sharpie where the slot should point to -by using a piece of paper where you have previously cut a triangle with the required angle- it is pretty simple to adjust, and even if you can't be 100% accurate, the deviation is small enough to make me feel confortable with the adjustment.

[dave500]

just practise it,youll get a feel for it,if you have the manual disreguard any torque settings for 6mm bolts,just feel them down remembering they arent wheel nuts.

[flybox1]

I'm gonna get a lot of #$%* for this, but I rarely use a torque wrench........... I just decide when it feels right. Just cinch the locknut down 'good'.

+1
..and those tappet wrenches are nice to have around.

[Fritz]

just practise it,youll get a feel for it,if you have the manual disreguard any torque settings for 6mm bolts,just feel them down remembering they arent wheel nuts.

The manually is specific about the tappet adjustment nuts. But I agree: You should learn to feel the right torque with practice. These screws are very tough and it does not hurt if you tighten them a little more than stated in the manual.
With all other bolts and nuts on the bike, you should obey the numbers though until you have enough practice.
Especially alloy threads tend to be overtightend which sooner or later lets you search for repair coils... (oil drain plug, spark plug, oil filter bolt being the most "popular")

[lucky]

I'm gonna get a lot of #$%* for this, but I rarely use a torque wrench. After 50 years of messing with mechanical things I just decide when it feels right. Just cinch the locknut down 'good'.

I do not use them either I just use a 10mm box end wrench.
Use reason. Don't go crazy on it.
Even the dealers did not use a torque wrench on that part.

[CoachDoc]

I'm gonna get a lot of #$%* for this, but I rarely use a torque wrench. After 50 years of messing with mechanical things I just decide when it feels right. Just cinch the locknut down 'good'.

LOL.....and there I was thinking I was the only guy who did this. I guess this defines "old school" wrenching.

[Raul CB750K1]

I'm gonna get a lot of #$%* for this, but I rarely use a torque wrench. After 50 years of messing with mechanical things I just decide when it feels right. Just cinch the locknut down 'good'.

LOL.....and there I was thinking I was the only guy who did this. I guess this defines "old school" wrenching.

I always say that, once you have stripped a thread, you learn how it feels "tight enough"

[dave500]

try to be aware of what metal your threads are into aswell,an alloy case thread will strip damn easy even using a torque wrench set at the spec with 6mm bolts.

[scunny]

they tend to tighten, so I adjust just a bit loose, tighten down on the lock nut then check the clearance.

[lucky]

they tend to tighten, so I adjust just a bit loose, tighten down on the lock nut then check the clearance.

Also if the clearance is .003 then check to see if a .004 will go in. If it will then you know it is still loose.

[Todd Richards]

that is how i do it. use the correct shim to set the gap, then use another shim as the not-go gage.

[Teatimetim]

I third on the no go gauge

[tlbranth]

try to be aware of what metal your threads are into aswell,an alloy case thread will strip damn easy even using a torque wrench set at the spec with 6mm bolts.

Well said Dave.
One place I always use a torque wrench is on head bolts. When I did so on my 750, all my cases stripped. I put in helicoils and studs instead of bolts. Don't know why honda didn't use studs to begin with.