Author Topic: Did my first valve adjustment today.............gulp........ (Read 4071 times)

dylboss · « **on:** April 28, 2011, 06:53:14 pm »

So first ever valve adjustment today on my '78 CB550. 26K on it. Not sure if it has ever been done. Just picked the bike up 2 weeks ago with no history on it. Runs, but definitely needs a tune up. So, started with the valves.

Followed the service manual to a "T". I guess some of the concerns or lack of confidence was when the manual said to start by making sure the "T" 1-4 was lined up on the points along with cylinder 1 at top dead center of the compression stoke. Was a little uncertain how to make sure that cylinder 1 was at top dead center other than removing the spark plug and physically looking at the piston as I rotated the engine with the kick starter. So, that's where I started.

I followed the service manual with the correct sequence 1 by 1. Put the feeler gauge under each of the tappets and adjusted accordingly. Some of the tappets I couldn't even get the feeler gauge under (even with the screw completely removed), which was concerning.

Then I moved to the second stage of rotating the points one rotation to make cylinder 4 go to top dead center. What was strange was that both cylinder 1 and cylinder 4 were then both at top dead center, so I'm not sure why the manual even says to do that to complete the other tappets. Nevertheless I got all tappets (that I could get the feeler gauge under) tightened down to the right tolerance, and I just tightened down the screws on the ones that I couldn't get the feeler gauge under to the point that it barely touched down.

Did I totally screw this up, or am I on the right track?

Thanks.

Dusthawk · « **Reply #1 on:** April 28, 2011, 07:39:33 pm »

Cyls 1 and 4 are at top dead center at the same time, but only one is on compression each time due to Cam position. When 1 & 4 are at top dead center(TDC) cyls 2 & 3 are at the bottom of the stroke. The easiest way I determine if each cyl is on TDC of the compression stroke is placing a finger over the spark plug hole(remove all 4 spark plugs to make it easier to turn the crank) and when air is forced past your finger it is on compression stroke. Then, look at the timing marks and line up the "T" mark. You should see a 1-4 near the first "T" mark and when you turn the crank one half turn you should see a 2-3 near that "T" mark. You need to turn the crank after each adjustment to bring the next cyl to TDC compression to adjust the valves of that cyl. That's probably why you couldn't get the feeler gauge under some of the tappets. I personally prefer to adjust each cyl from 1 through 4 in order, 1, 2, 3, 4 but some prefer to follow firing order. If you make sure each cyl is on compression with your finger then line up that cyls "T" mark, you will always be at TDC compression of that cyl and you can adjust those valves.

DarcyCB400F · « **Reply #2 on:** April 28, 2011, 07:58:43 pm »

Did you remove the timing cover to see the timing marks?
Remiving a tappet screw to get the guage under it seems entirely wrong... the valve had to be in open position which means you can't adjust it... something seriously wrong.
Perhpas you shouldn't start the bike until you have this figured out...

dylboss · « **Reply #3 on:** April 28, 2011, 08:03:16 pm »

I think I'm missing the TDC compression stroke aspect of this. I'm going to try the finger test on this for cylinders 1 and 4 and redo.

Thanks.

dylboss · « **Reply #4 on:** April 28, 2011, 08:09:57 pm »

Quote from: Dusthawk on April 28, 2011, 07:39:33 pm

Cyls 1 and 4 are at top dead center at the same time, but only one is on compression each time due to Cam position. When 1 & 4 are at top dead center(TDC) cyls 2 & 3 are at the bottom of the stroke. The easiest way I determine if each cyl is on TDC of the compression stroke is placing a finger over the spark plug hole(remove all 4 spark plugs to make it easier to turn the crank) and when air is forced past your finger it is on compression stroke. Then, look at the timing marks and line up the "T" mark. You should see a 1-4 near the first "T" mark and when you turn the crank one half turn you should see a 2-3 near that "T" mark. You need to turn the crank after each adjustment to bring the next cyl to TDC compression to adjust the valves of that cyl. That's probably why you couldn't get the feeler gauge under some of the tappets. I personally prefer to adjust each cyl from 1 through 4 in order, 1, 2, 3, 4 but some prefer to follow firing order. If you make sure each cyl is on compression with your finger then line up that cyls "T" mark, you will always be at TDC compression of that cyl and you can adjust those valves.

This is great help. Thanks.

Spanner 1 · « **Reply #5 on:** April 28, 2011, 08:14:14 pm »

Wait now... when the 'T' mark shows in the points plate 'window' , either #1 or 4 cyl. is at Top Dead Center or #2 or 3 is at TDC, no exceptions..

No reason to look down a plughole !!
If your at the 'T' mark for , say 1+4 and the rockers vs. valve stems are 'tight' then rotate the crank until 1+4 mark shows again and yer at TDC on the compression stroke , verified by feeling for 'play' in the rocker arms... that's how ya do it

DarcyCB400F · « **Reply #6 on:** April 28, 2011, 08:40:02 pm »

Quote from: Spanner 1 on April 28, 2011, 08:14:14 pm

Wait now... when the 'T' mark shows in the points plate 'window' , either #1 or 4 cyl. is at Top Dead Center or #2 or 3 is at TDC, no exceptions.. No reason to look down a plughole !!
If your at the 'T' mark for , say 1+4 and the rockers vs. valve stems are 'tight' then rotate the crank until 1+4 mark shows again and yer at TDC on the compression stroke , verified by feeling for 'play' in the rocker arms... that's how ya do it

+100%!! Great advice!!

Trevor from Warragul · « **Reply #7 on:** April 29, 2011, 03:50:23 am »

An easier way to find TDC is to watch the inlet valve. When it goes in, then comes out, watch for the "T" mark. When it is lined up, you are on TDC of that cylinder's compression stroke...

ak58lp · « **Reply #8 on:** April 29, 2011, 04:51:46 am »

The easy way I found was to look at the cam lobes. If both of them are pointing down into the engine, that means that cylinder is ready to fire or at TDC. The other cylinder should have one valve just starting to open or close noted by the cam lobe starting to come up.

Toxic · « **Reply #9 on:** April 29, 2011, 06:24:57 am »

When the pointer is at T 1-4 and the number one cyl is on compression then you should be able to feel some free play on the adjusters... If they are tight then number 4 should be loose.
You want to start with number 1 on compression and follow the sequence in the manual

bender01 · « **Reply #10 on:** April 29, 2011, 06:52:11 am »

Listen to Spanners post!

dylboss · « **Reply #11 on:** April 29, 2011, 06:54:01 am »

Quote from: Spanner 1 on April 28, 2011, 08:14:14 pm

Wait now... when the 'T' mark shows in the points plate 'window' , either #1 or 4 cyl. is at Top Dead Center or #2 or 3 is at TDC, no exceptions.. No reason to look down a plughole !!
If your at the 'T' mark for , say 1+4 and the rockers vs. valve stems are 'tight' then rotate the crank until 1+4 mark shows again and yer at TDC on the compression stroke , verified by feeling for 'play' in the rocker arms... that's how ya do it

aha! Lightbulb just went off. Thanks for this. I will try this tonight. The tightness vs. play in the rocker arms was tripping me up for sure! Now I think I get it.

flybox1 · « **Reply #12 on:** April 29, 2011, 07:01:04 am »

Quote from: dylboss on April 29, 2011, 06:54:01 am

Quote from: Spanner 1 on April 28, 2011, 08:14:14 pm
Wait now... when the 'T' mark shows in the points plate 'window' , either #1 or 4 cyl. is at Top Dead Center or #2 or 3 is at TDC, no exceptions.. No reason to look down a plughole !!
If your at the 'T' mark for , say 1+4 and the rockers vs. valve stems are 'tight' then rotate the crank until 1+4 mark shows again and yer at TDC on the compression stroke , verified by feeling for 'play' in the rocker arms... that's how ya do it

aha! Lightbulb just went off. Thanks for this. I will try this tonight. The tightness vs. play in the rocker arms was tripping me up for sure! Now I think I get it.

yep. if your at T1-4 and there is no play in #1 exhaust rocker (and some in #4) then rotate around again(there now shouldbe play in 1, none in 4) and you're off and running with your adjustments.

camelman · « **Reply #13 on:** April 29, 2011, 01:40:45 pm »

I don't bother with the timing marks any more. I just push the kick start with one hand while holding a finger on the valve I'm working on. After it cycles down and up, I adjust it. I'm not sure how the 750s are set up, but this has worked on all of my bikes.

Camelman

HondanutRider · « **Reply #14 on:** April 29, 2011, 02:17:15 pm »

I've also done the same as Camelman. In fact, I've also set tappets with the engine running (still not hot). This method has the added benefit of verifying the oil supply. You slide a feeler under the tappet and move it while adjusting on the jumping rocker. If its too tight, it won't move; just right and it slides with some jerky resistance as the valve closes. Not recommended on a hot motor, and not for the timid or those afraid of a few oil squirts.

dylboss · « **Reply #15 on:** April 29, 2011, 07:15:26 pm »

Well, just adjusted the tappets based on all the recommendations. Everything seemed to go according to what most people were saying about the play vs. tight tappets. I think I got it!

Thanks to all for the help. Now on to the timing of the points, then the carb sync.

camelman · « **Reply #16 on:** April 29, 2011, 11:06:52 pm »

Check those mixture screws while you are at it.

dylboss · « **Reply #17 on:** April 30, 2011, 09:06:51 am »

I think I spoke too soon when I said "i think i got it". Fired her up and now all I hear is awful clicking sounds coming from the valves/tappets, and it seems to be running worse now than before. Won't stay idling at all and very choppy when trying to rev it up.

dylboss · « **Reply #18 on:** April 30, 2011, 09:31:48 am »

Well figured out the clicking. Inlet tappet 4 was way off. Fixed it, now clicking is gone, but it she is still running awful. Choppy as heck and won't hold idle.

juntjoo · « **Reply #19 on:** February 06, 2018, 10:59:35 pm »

Quote from: dylboss on April 30, 2011, 09:31:48 am

Well figured out the clicking. Inlet tappet 4 was way off. Fixed it, now clicking is gone, but it she is still running awful. Choppy as heck and won't hold idle.

I know this is old but I'm dying to know if your valve job messed things up as I did the same but don't know if it caused any damage. Don't think so as my symptoms preceded my first valve clearance adjustment, but still I'm concerned about how this might have messee things up. Tho when you set a clearance when there is none available, I think in effect you make more clearance which if I understand valve operarion good enough shouldn't harm anything, just not open the valve all the way. whereas if you'd set clearance at a point wherenthere was too much, you'd create even less clearance causing the parts to smoosh at the lobe's highest point, ouch.

News:

Author Topic: Did my first valve adjustment today.............gulp........ (Read 4071 times)