Topic: Cb350f Valve Clearance Issues

[zcb350fb]

I am having issues adjusting and checking valve clearance on my 1973 honda cb350f. My clymer manual says to turn engine to T mark via the ignition plate. I have that down but then it says cylinder at TDC will have loose valves at that point so you know that that is the one to Check and adjust. None of my valves are loose on cylinder one and four or 2-3 when timing mark is turned to T.

Cb350f’s need a valve clearance of .002in. Thats a tight tolerance. Could this be why i cannot feel them move?

I pulled plugs to look at piston heads to see which was at tdc but its to close to tell from that.

Any tips or ideas here please?


Thank you in advance!

[flatlander]

use a screw driver to feel down the spark plug hole, to see when the piston is up (carefully!). then with that one at TDC, adjust its tappets... and move on like that.

[robvangulik]

use a screw driver to feel down the spark plug hole, to see when the piston is up (carefully!). then with that one at TDC, adjust its tappets... and move on like that.

Thats not the way to do it, when you really cannot feel difference between 1 and 4 there is a good chance the tappets are set too tight. Turn both the set bolts one turn loose on both cylinders, and you should be able to feel which cylinder is on compression stroke with both valves closed and ready to be set right.

[flatlander]

duh! rob you're right.
i got hung up on the trying to see piston heads thing. but that is irrelevant of course.

[TwoTired]

With the 1.4 T mark lined up, BOTH 1 and 4 are at TDC.  One between compression and fire stroke, and one between exhaust and intake stroke. (4 cycle engine)

It the stroke between Compression and fire where you adjust the tappets for that cylinder.
Put you finger over the spark plug hole to feel for compression while turning the crank over.

Taking out spark plugs make turning the motor easier.

Cheers,

Edit: fixed auto correct error

[calj737]

With the 1.4 T mark lined up, BOTH 1 and 4 are at TDC.  One between compression and fire stroke, and one between exams and intake stroke. (4 cycle engine)

Exactly.

If your valves are too tight to determine their current gap, release ALL of them and set them all properly now. It doesn’t take long and then you’ll know they’re correct.

[flatlander]

the method described in the manual can be a bit confusing for some. here's one that's more straight-forward (not my write-up):

First take out the sparkplugs so the engine will be safe to rotate using the 23mm nut under the points cover(-do not use this nut to rotate the engine with the plugs in as it is actually only as strong as the 10mm (M6) bolt holding it on!).
 In this case (adjusters have all been backed out) temporarily tighten the adjusters on the two #4 cylinders valves to eliminate all play.

Rotate the engine until you see the T / F 1.4 marking through the inspection hole in the points plate, now whilst closely watching #4's tappets (look into the two closest adjusting holes) rock the engine back and forth either side of the 1.4 timing mark (~10 o'clock to 2 o'clock) - If you are not seeing the tappets move rotate the engine one full turn back to where you see the 1.4 again and repeat - what you need to see is the exhaust tappet coming up just as the inlet tappet is going down for #4 - this indicates that #1 cylinder is on compression stroke so you can go ahead and adjust #1's tappets.

Rotate the engine half a turn only till the T 2.3 timing mark lines up and adjust #2's tappets

Rotate the engine half a turn only till the T 1.4 timing mark lines up and adjust  "4's tappets

Rotate the engine half a turn only till the T 2.3 timing mark lines up and adjust  "3's tappets

I would normally double check that cyl 3 tappets were rocking before adjusting cyl 2 and that cyl 1 tappets were rocking before adjusting cyl 4 and that cyl 2 tappets were rocking before checking cyl 3, but not really necessary (I got into the habbit of doing that because the Honda's firing order of 1-2-4-3 used to confuse the hell out of me when I was under the assumption it would be the more common 1-3-4-2!)
Hope I haven't made this too confusing! John

[dave500]

the #$%*ing easiest way is this!with the spark plugs out and tappet covers off rotate the engine and watch as ANY of the intake valves starts to close,keep turning and watch the marks for that particular cylinders "T" mark come around,set that cylinder,then repeat for the other three,too easy!