Topic: CB750K clearance of the tappets

[Garryk]

1975 CB750K5
I set my valve/tappets on my bike a few months back by following instructions in the manual, EX- 0.08 , IN-0.05,ive noticed a lot of members on the forum and few websites saying they should be set as follows,EX-003 , IN-002, im confused and don't know what to set them at next time,could someone please explain why the difference in the different settings above.
Cheers
Garryk

[KC_Northstar]

Your seeing 2 different measurement standards.  In 0.05 and Ex 0.08 Is MM          in 0.002 and ex.003 is inches
Make sure you use the correct feeler gauge set with the matching settings    MM vs Inches.

[70CB750]

I have in my notes exhaust 0.004" and intake 0.003"; from what I remember it is Hondaman recommendation for longevity.

[Garryk]

KC,
Many thanks for your help and reply.
Next time I take valve caps off to set tappets i'll just stick to the, in-0.05mm and ex-0.08 knowing alls fine.
Respects
Garryk

I notice Honda in the manual have the following, in-0.0019in, ex-0.0031,,,if that's inches im more confused.so im sticking to the mm above.

[Garryk]

70CB750
Thanks for your help,will keep note of what you said,do you know what your inches would be in mm ?.
Respects

[KC_Northstar]

I notice Honda in the manual have the following, in-0.0019in, ex-0.0031,,,if that's inches im more confused.so im sticking to the mm above.

The conversion between inches and MM does not come out exact, so the .0019 inches gets rounded up to .002 and the .0031
inches rounds down to .003

Sounds like you have a metric feeler gauge, so just keep using the MM setting and you will be fine.

KC

[PeWe]

25.4 mm=1 inch
0.05mm/25.4= 0.001968503..... inch
0.08mm/25.4= 0.003149606..... inch

Better with a little bit too much valve lash than opposite ending up in bad valves
The inch system makes everyting sooooooo complicated

[ekpent]

Just a note for anybody who thinks they have an aftermarket performance cam maybe lurking in their engine its best to verify then see what they should be set at. Some call for .004 on both the intake and exhaust,little larger than stock

[70CB750]

70CB750
Thanks for your help,will keep note of what you said,do you know what your inches would be in mm ?.
Respects

That would be 0.1mm and 0.07mm, as PeWe said, better to err on the plus side -i.e. loser tappet is better that too tight tappet.

Also setting clearance with engine in the frame and tank right above is not the most precise method.

[Bootlegger56]

I aint gonna pull my engine to set valve clearances.  The tank yes....but not the engine.  I found the first couple of adjustments on both my K5 and K1 to be slightly difficult in the fact that you have to learn the best angle and position for the feeler gauge based on which valve you are adjusting.  Patience and a willingness to check and re-check with the next size up go a long way.  A little roll around shop stool with a tool tray under it is also the best Honda tool bucks I ever spent.  I run the .002" and .003" but then I like to tinker and don't mind checking mine every month or so.  If I was lazy I would opt for the larger clearances.

[Garryk]

Cant thank everyone enough for their replies and help.
Respects to you all.
Garryk

[lucky]

KC,
Many thanks for your help and reply.
Next time I take valve caps off to set tappets i'll just stick to the, in-0.05mm and ex-0.08 knowing alls fine.
Respects
Garryk

I notice Honda in the manual have the following, in-0.0019in, ex-0.0031,,,if that's inches im more confused.so im sticking to the mm above.

The first number (intake) .0019 is so close to 2 thousandths we will call it two thousandths. Thickness gauges are in even numbers like .002,.003,.004 and so on.

If a valve is too tight is when damage will occur.
What happens is that the valve if too tight does not touch the seat then the valve cannot dissipate its heat into the cylinder head and out to the atmosphere through the cooling fins.

When you are checking your valve clearances and your are checking .002 intake.
That is 2 thousandths.
Then try a .003, if it will slip in then you know that the valve clearance is still too large.

[Garryk]

Lucky,thanks for your reply and help.
Respects
Garryk

[Xnavylfr]

K2 manual says =  INTAKE side .05mm(.002")
                              Exhaust side .08mm(.003)

As others have said , better to be a little on the loose side than too tight... They also have a certain order they should be adjusted!!


Xnavylfr(CHUCK)