Timing Chain adjustment - marks on cam reversed

[POINTinTACT]

Rebuilding a 1981 GS850. This it the 3rd GS i've worked on, but a problem I haven't seen before (or if I have, I don't remember). I know that it is supposed to be 20 pins from the #2 arrow to the #3 arrow. On the images in the manual, the arrow is on the left of the #2. On this set of cams (and a spare set that came in a parts box with this bike) the arrow is on the right of the #2. This will obviously make a one tooth difference. I'm not sure if it should still be 20 pins across, or if the count needs to be different so I'm not one tooth off?? Has anyone seen this before?

 

[Steve]

You see that notch in the sprocket just above the point of the arrow? THAT is where you start counting your timing chain links. I'll bet you anything you wish to wager there is a similar notch just above the point of the arrow that is near a #3 on the intake cam. Stop counting when you get there.

NOW, ... just so you don't do the mistake that I made (several times), ... the pin that will be above the #2 arrow mark is not ZERO, it is ONE. I don't know how many times it did it, but I would start with the pin over the arrow, then move to the next pin and count "one", "two", etc. WRONG. The pin above the #2 arrow is ONE, then continue with two, etc.

Yes, I repeated my self (over and over), but it really is that important. :encouragement:

.

 

[POINTinTACT]

Steve - thanks for the rapid reply. Unfortunately, it doesn't clear up my issue. I know that the chain pin lands in the notch between the teeth, but here's the problem: On the other cams I've seen, and in the pics in the manual, the arrow is on the left of the #2 (on this cam it is on the right). So, if the arrow is stamped in the same position as the cam shown in the manual, but the numeral 2 is switched to the other side - then the pin count/distance would be the same. However, if the numeral 2 is stamped in the same position as the cam shown in the manual, but the arrow is switched to the other side - then going 20 pins from arrow to arrow would leave me one tooth off. Without a cam that matches the one in the manual to reference, I can't figure out how to tell which position is switched. (especially because the #1 and it's corresponding arrow are also reversed from the pic in the manual, so I don't trust counting teeth from there). I'm sure there is some easy way to look at this and confirm, but i've been working on the bike all day and my brain is mush. (here's a pic from the manual to reference against my original pic)
-EDIT- based on looking at the bolt that attaches the sprocket and counting from there, and also trying to count from where the #1 arrow points, it looks like the arrow is in the same position, but if anyone knows for certain that would be great.

 

[fastbysuzuki]

On page 69 of the workshop manual there is a picture of the cam chain run on the camshaft ends there is a slot cut in each these should be aligned facing each other as shown. I guess you will have to try putting the chain on one side of the arrow and slowly turn over the engine making sure no piston to valve contact takes place and see how the two slots align and adjust chain position to suit.

 

[Steve]

This it the 3rd GS i've worked on,

On the other cams I've seen, and in the pics in the manual, the arrow is on the left of the #2 (on this cam it is on the right).

Were the other GSes 850s? Although Suzuki was quite the master of parts bin engineering, there is no guarantee that all the #2 marks are on the same side of the arrow. Even within the same year, it could be different. If you look at the specs in the manual, the intake valve timing on the '79 cams. I have no doubt that the pictures in the manual were taken when the bike was first produced, which was '79. Although they mention the timing change and include a diagram, there is no picture of the timing mark, but it's possible that the number on the other side of the arrow might be an undocumented service note so you can tell the cams apart.

Trust the arrow, put the engine together, go for a ride. :encouragement:

.

 

[POINTinTACT]

After looking at it with a clearer head today, I believe I have confirmed that the arrow is still in the "20 pins across" position and they just flipped the numeral to the other side. Thanks for your input!