Topic: cb550k timing marks

[robermcm]

First time I timed my CB550k was a pain because the manual was vague about where to time the 1&4 cylinders, i.e., what do you match up against the stationary reference mark.  Here's my story.  Maybe it will help someone else....

I was trying to time my cb550k with a timing light.  Per the manual, cylinders 1&4 are supposed to align against the reference mark on the 'F1.4' timing mark (looks like  || ), which is to the right (ADVANCED) of the Top dead center mark and (so I thought) also to the right of the 'F1.4' mark.  I could not get the timing to move that far to the right.  I twisted the main points plate all the way counter clockwise and got it to the 'F' on 'F1.4'.  I turned it the other way for fun and it lined up with top dead center (FULLY RETARDED).
 
Cylinders 2&3 were RETARDED a bit too, but not nearly as much as 1&4.
 
If it was TOO FAR ADVANCED, I'd think the spark advance was opening too soon, but it's the other way - NOT ADVANCED ENOUGH.  I looked at the spark advancer and all seemed fine.
 
The bike runs well otherwise and is very strong at higher RPM's and idles fine with clean acceleration off idle.



AND THEN I REALIZED....
 
The 1 & 4 cylinders get timed off the actual letter 'F' on the ignition plate and the 2 and 3 cylinders get timed off the vertical lines (e.g. || )that show.  How dumb is it that there are two types of marks and one is a letter with vague alignment characteristics!!  Even more confusing, I wonder what the vertical lines to the right of F 1.4 are for?  Maximum advance?  There's something in the manual that says at 2500 rpm the strobe should between the marks. (TDC and ||  ?)  Maybe that's why they're there?
 

Final picture - I think this is right

TIMING cylinders 1 and 4
         stationary reference mark                      |
         marks on the spinning ign plate     T        F1.4     ||

TIMING cylinders 2 and 3
         stationary reference mark                     |
         marks on the spinning ign plate       2.3  ||

[TwoTired]

The letters on the timing plate are labels for the marks around the periphery.  The letters are NOT alignment marks themselves.

Sorry,

[robermcm]

Well that's just embarassing. I do have bad eyesight. 

What's still ambiguous to me is WHICH marks should align to the stationary mark for 1-4 and 2-3.  The instructions in the owners manual are vague (to me at least) and the pictures are blurry.  I'm currently thinking it's the marks on the timing plate over the 'F' for both sets of cylinders.  That correct?

And if that is correct, are the || marks to the right the upper limit for the spark advance at 2500 rpm+?

Thanks.  And sorry for clogging up this forum with such a dumb question.  I'd defend myself, but I got a pretty bad start!

[TwoTired]

Perhaps this will explain it?

The rotating plate on the end of the crankshaft is a minimalist degree wheel, with only the most important marks placed on it.  The most important mark is the "T" for TDC or Top Dead Center.  This is when both the crank and the piston are on the crest or peak of the rise.  Pistons 1 and 4 travel in unison, as does 2 and 3 but the crankshaft throws are 180 degrees offset.  Therefore two "T" marks are on the wheel; one for 1:4 and one for 2:3.

The ignition point of spark, occurs just prior to the piston reaching TDC, as the main expansion point of the Air/Fuel burn occurs delayed from initial ignition.  Engines rotating faster need more advance in order to place the main expansion along most of the power stroke.

Back to the marks...
The labeling on that small timing wheel reads T F 1:4.  Above the T and F are two marks ( || )  The left mark is the T mark (TDC), the right mark is the F mark (Fire) where you want the spark to occur at idle RPM. 
To the far right of the degree wheel label are two more index marks.  These are full advance marks, between which the spark timing should occur at engine RPMs 2500 or above.  You'll need a strobe lamp to check this

The 2:3 timing is identical to the 1:4 timing except the marks are 180 degrees offset.

Hope this helps...

[robermcm]

I just wrote a big long reply, then reread your note and finally get it!  I didn't see the marks on the wheel (i.e. '||') as TWO marks, but one (for top dead center, for example).

Many thanks.  I can go time this old gem now.

[robermcm]

Twotired,

Okay, I'm so frustrated at this point!

If I time my bike per your instructions '(the timing mark on ignition plate for both cylinder banks is the rightmost mark of the || marks above the 'T' label), it runs like a severely retarded timing. 

To make matters worse, using the strobe, sometimes the timing mark shows as aligned per your specs and sometime it shows off the mark - typically closer to aligning over the 'F' label.  What would make it jump around like that? Leaky capacitor?  It makes it impossible to set the timing and know that it's where it should be.  Idle is steady at 1000 and advancer seem tight, although I did not check the springs with a scale.

If my low speed timing is somehow messed up, can I time the bike using the fully advanced marks at 2500 rpm?

I am really stumped!!

[TwoTired]

Hondaman posted his on timing jump.
http://forums.sohc4.net/index.php?topic=34455.msg355556#msg355556

I seem to remember some talk of cheap points moving around on the pivot post.

Hard to imagine a condenser causing this, issue.  If it were excessively leaky it could reduce the max coil charge or drain it faster I suppose.  You could disconnect it temporarily to see what effect it has on timing jitter.

Is your timing clamp on the ignition wire well away from other wires and the engine case?   Could your ignition wires be leaking intermittently?

Have you checked your plug cap resistance?  Are your spark plug new with clean insulator tips?

Cheers,

[Romhog]

BTW, this is old news and not a current post but wanted to share my perspective on being confused about these marks from when I was working on this last year.

(this is for manually setting the timing) and  in my example I will only speak of the 1:4 marks but the same is true for 2:3 ones as well.

This may have already been said in a different way, but I noticed the 2 marks both close to the TF and 1:4  (lets call these 2 marks the left set) and to other  2 marks "after" the text (lets call these the right set)
Originally I thought these marks were in pairs and you had to like up the mark on the block "between" those 2 marks.... don't know why I thought that.. Only to find out later that the T, F's are really just the 2 marks on the left side "set" another and the other pair of marks (on the right) should be ignored. The right par of marks to the right of the 1:4 markings are used in the strobe timing light version of setting the timing.

Anyhow, what I'm saying is sort of covered in various posts,  but wanted to share the way my mind "was working" when I was confused about all the marks. 



Paul.