2001 ST1100 Timing Belt Challenge

[GGely]

Hi everyone, hope everyone is having a great day. Me? Could be better...

I’m doing a bunch of work on my new to me ST1100 and got to the point today of changing the timing belt. The challenge is that no matter how many times I rotate the crankshaft, the left cam sprocket never aligns with the other two marks, cam and crank.

As usual left and right are from the riders position.

I can align the right cam and the crankshaft marks but then the left hand cam mark is pointing straight up.



This is a two owner bike (I’m #3) and been serviced for the last 9 years a a good shop here in town. Total mileage is 130,000 or 210,000km. Note that this is a “new” engine with 7,500 miles on it when installed some time ago.

I’m assuming I’m doing something wrong here but I can’t think of what.

Any suggestions are welcome!

Thanks in advance,

G

 

[dwalby]

Wow, if you're really off by 5 teeth, I'm surprised nothing's making contact. I'm also assuming you're aware that the crankshaft has to rotate two revolutions to get back to where you started, right? Is it possible you're on the other phase of that rotation? Rotate the crank another 360° and see what it looks like there.

Did the timing look correct before you removed the old belt? And if so, when you put the new belt on did you feel anything moving?

 

[GGely]

My thinking too! I think I’ve rotated the crankshaft enough times, 12 to 13 times total, that they should have aligned but I’ll go out after dinner and give it a go again. I’ll plan on being a putz and I’ll rotate it into the correct alignment...

I haven’t installed the new belt yet, waiting to sort out the timing mark issue first.

 

[dwalby]

Its hard to tell in the one picture, but it looks like the little punch mark at 3 o'clock on the crankshaft is aligned with the mark on the case, can you confirm?

I'm also thinking that if you were on the other 360° crankshaft phase those cam marks would be approx. 180° off from where they should be, so I think you're on the right phase, but double check just to make sure.

We had a mystery like this a few months ago, the owner determined that somehow the crankshaft marking was wrong with respect to #1 cylinder TDC, IIRC. That may be your next step. Pull the #1 plug and determine when the piston is at TDC, then note where the crank mark and each cam mark is aligned at that timing.

 

[GGely]

Yup, the crank mark is aligned with the case mark in that picture.

Your suggestion of finding out where everything is at #1 TDC occurred to me too. I’ll give that a go after dinner.

Thanks, dwalby, I appreciate your thoughts.

G

 

[GGely]

Ok, took a minute while the oven was warming up and rotated the crankshaft 360* and no joy. Another 360* and still no joy. One more time around and nope.

I’ll have to wait till tomorrow to check for #1 TDC, having opened a bottle of wine and not wanting to take any chances!

 

[Jim Van]

OK, your post isn't clear : Have you replaced the timing belt yet, or is this the way you found it BEFORE you replaced the timing belt ?

Please take a close-up pic of the crankshaft gear. I think I can see the crank punch mark in your pic , but I'm not 100% certain.

But it sure looks like the R camshaft gear is off by 5 teeth. So if this is the way it is AFTER you replaced the belt, then just go ahead and re-position the R camshaft gear CW by 5 teeth. Sometimes it's a little tricky getting it spot on.

 

[GGely]

Hi Jim, I’ll take a close up or two of the crank gear tomorrow morning and post them. I’m not sure how that helps, though given my lack of experience...

Every second revolution, the right side cam and the crankshaft marks line up but the two camshaft marks never lineup.

That suggests to me that it’s a camshaft issue. Does that make any sense?

 

[Larry Fine]

That suggests to me that it’s a camshaft issue. Does that make any sense?

That depends upon your answer to Jim's question.

 

[GGely]

My bad,didn’t read Jim’s post correctly. Per post #3, I haven’t changed the belt yet, this is how I found it.

Per post #5, the crank punch is on the case mark, as is the right cam mark. The left is off by 5 teeth.

 

[TerryS]

You can also check the cam marks on the back end of the camshaft.

 

[dwalby]

I'm curious to see how everything lines up with the #1 piston verified at TDC.

I'm going to predict that at #1 TDC the cams are aligned properly according to the punch marks, and somehow the left cam sprocket has been installed in the wrong orientation.

1. I can't imagine the engine would run normally with the timing off by that much, even if it magically didn't destroy the engine with piston/valve contact as soon as it was started.

2. Since the engine turns freely with no interference, and was running normally, I think the cam orientation is probably correct, or only off by a small/negligible amount.

3. the cam sprocket only turns a gear, not the actual cams. The cams have gears at their ends that mate with the cam sprocket gear.

4. I think because of the gear driven cam arrangement, the sprockets can theoretically be in any orientation with the cams, as long as the cam lobes are in the proper orientation with everything else.

5. At the factory they align the cam sprocket with the marks as a matter of convenience, not necessity, and then align the cams with the punch marks. Since timing belt replacement is a rare occurrence, I'm going to speculate that this may have been caused at the factory, unless there's history on the bike to indicate that the engine was rebuilt.

 

[TerryS]

By Jove, I think he's got it! The cams and the belt sprocket are out of phase. The belt sprocket is pinned to the shaft by a Woodruffe key, but the gears themselves can be in any position relative to the drive gear. So option one would be just to pull the cam covers and check the marks at the cam ends are correct with respect to the crank and the other head, option 2 would be to set the belt sprocket to the correct marked position with respect to the crank and then move the cams so they are also correct.

 

[GGely]

Thanks everyone!

I’m with you dwalby re point #1. Although I have only a few minutes running the engine, it sounded like the other ST’s I had looked at, not sounding at all like a washing machine on the spin cycle filled with ball bearings, nuts, bolts and washers, in the moments before silence ensued...

Thanks for pointing out how the cams are driven, I wasn’t aware of that. Given that 1. the PO had put this motor in some 20,000km or 12,000 miles ago for a total of 30k km/19k miles and 2. The shop hadn’t changed or most likely even looked at the belt, I’m thinking that the sprocket out of phase with the gears is likely and it probably started at the factory.

So the plan this morning is coffee, bagel, coffee, walk the dogs, then out to Garage Mahal to pull the cam covers, set #1 at TDC and see the results.

I’ll post my findings and pictures as soon as I’m back in the house.

Thanks again!

 

[Larry Fine]

If you get it at the right TDC, and everything lines up, you shouldn't have to turn anything as long as you don't turn anything.

 

[GGely]

If I understand you correctly, Larry, you’re saying that assuming the camshaft and crankshaft marks all line up with #1 at TCD, I could leave the LH sprocket 5 teeth out. Is that correct?

Given that I wouldn’t need to look at it again for 100,000 miles and it’s not likely I’ll be the one doing it then, I could just document the issue and let the next owner know about it.

Or...

All of this assumes that the synchronization between the camshaft and its sprocket is the issue. Following that trail for a bit, I’m thinking that to re-synch them is a matter of setting #1 at TDC, confirm all but one mark lines up, removing the timing belt, remove the LH camshaft, rotate the sprocket to line it up and replace the timing belt.

Is that about the size of it? Or, since I don’t know as much about these bikes as you folks do, am I blowing smoke out an orifice?

 

[GGely]

I do have a copy of the FSM, which will be well used before this is all over.

It’s a mainstay in my library!

 

[Larry Fine]

What I mean is: if the actual (not indicated) timing is correct now, and if you replace the belt and everything is set exactly as they are now, the actual timing will be the same, and thus, correct.

I haven't needed to do my 1100 yet, so I'm only speaking from logic and mechanical experience. You don''t have to set the engine anywhere; you just have to duplicate what you have now.

The least you could set the timing incorrectly by would be one belt tooth. The marks are more important when assembling or re-assembling an engine than when replacing the timing belt.

Don't move anything while the belt is off; just put it exactly as it is now.

 

[GGely]

Ok, that’s the page I’m on, Larry, thanks.

Should know what’s what by about 10:30am EST.

 

[Jim Van]

By Jove, I think he's got it! The cams and the belt sprocket are out of phase. The belt sprocket is pinned to the shaft by a Woodruffe key, but the gears themselves can be in any position relative to the drive gear. So option one would be just to pull the cam covers and check the marks at the cam ends are correct with respect to the crank and the other head, option 2 would be to set the belt sprocket to the correct marked position with respect to the crank and then move the cams so they are also correct.

I think Terry & Dwalby has it diagnosed !!! Yup, it's hard to believe the bike would be running OK with the one camshaft being 5 teeth out of phase.

Now that they have enlightened me, I would say someone previously when changing a belt was off 5 teeth, but just compensated by installing the cams with THEIR index lines properly positioned ( in the above diagram). That's the "bottom line" , not the index's on the camshaft pulleys. Hard to believe tho, since that would be a lot more work than just re-positioning a camshaft pulley.

At this point, if it was my bike, I would pull the valve covers to see if the camshaft index lines / punch marks ( 1 & 6 above ) are all lined up when cylinder #1 is at TDC ( on compression, not exhaust ) when the crank punch mark and projection ( 9 & 10 above ) are lined up. They should be, regardless of the position of 2 & 3 and 4 & 5 .

Being me, I would rotate the R camshaft 5 teeth CW, and then pull the camshafts on the one side that are off and re-position them so THEIR index's are properly aligned ( again).

But getting deeper into the swamp here, If the pitch of the camshaft pulleys and cam gears is different, there presently could be a slight out-of-phase condition. So that may be a good reason to get everything back to what is shown in the above diagram.

Maybe the bike will run even better after getting everything back to the OEM condition in the above diagram.

I'm jealous at all the fun you will be having with this ........