I picked up a '98 ST1100 a couple years ago. Now working on valve adjustments. The clearances are pretty much 'reasonable', not too far off spec ranges. Except #3 Exhaust, right .06 inches and #2 right exhaust .09 inches. The book ranges .007 to .011 inches. Should I be concerned about those numbers? Or, just go ahead and re-shim to spec?
Huge valve clearance???
- Thread starter Kim.ST.MN
- Start date
Yikes, I've never heard of such measurements, are you sure you're measuring correctly?? Also, a typical feeler gauge set only goes up to 0.035" so you must be stacking feeler gauges to get those measurements, or is there something wrong with your math? Or are you reading the measurements in millimeters instead of inches??
bdalameda
PaleoCyclist
Have you been running the engine or has it been sitting a long time? If it has been sitting perhaps the valves are not seating all the way and giving you false readings. I would make sure you run the engine and gat it fully warmed up and then let it cool down and check the valve clearances.
Thanks for getting back to me. The bike has not been ridden much in the past few months. I've got the bike pretty much un-tuppered at the moment. Did the fork seals, brake pads and radiator switch. Going to check the timing belt next while I've got it this stripped. The 2 valves with huge clearances were 'springy'. Might that be a 'not seating' thing? When pushed gauge between cam and lifter, I was able to push lifter, and it would spring back.
that doesn't sound good, you shouldn't be able to push the lifter. Never been there, but one guess is a broken valve spring or some other issue with the springs that is reducing the spring force that closes the valve. It sounds like you have ridden the bike, was there anything unusual about the engine performance when you rode it last?
Also, what were you using for a feeler gauge when you measured the .090" and .060" clearances?
Yikes is what I said too. And yes, I had to stack up the gauges on those 2 valves. Reading in inches. A chill ran down my spine when I read 'is there something wrong with your math'. I actually have a degree in math. There was a time when I enjoyed interpolating logs, multiplying multiple digit numbers in my head, visualizing 4th degree environments, proving Fermat's last theorem (but I misplaced my work)...blah, blah blah.... Heck, now I can't add 2 numbers without a calculator. So.... I won't be surprise if there is some kind of user error.
The bike (engine wise) has run pretty good. No flags have popped up. My main ride is an ST1300, but I like the 1100 for around town stuff. Yes, I was using feeler gauges on those large numbers. Just had to stack em up. I didn't I hit bottom on the .09" one. I just figured the number was large enough to ask for help. Do you know if a broken valve spring is an 'easy' fix?
bdalameda
PaleoCyclist
I've never heard of an ST1100 breaking a valve spring. If the engine was running fine it is doubtful it is a broken valve spring. There have been odd occurrences of valve not fully seating due to buildup in the valve guides of a very gummy residue from incorrect fuel supplier fuel additives in ethanol blend fuels. This can be a real problem in ST1300's that is well documented a few years back, but I have not seen it in a ST1100 - not saying it could not occur though. When this happens and the engine cools down the valves will stick open slightly - if you can get the engine to start the heat will loosen up the valves and everything will operate normally again. Usually a good dose of Seafoam and new fuel will address the problem. Also you can physically push down on a valve cam follower and it will be springy but a very stiff spring requiring a good hard push and a solid feeling stop when closed. If it feels sticky it could be a problem with the fuel additives.
Thank you..... at this point it sounds like I need to run her a bit to heat it up, non-oxgenated fuel, Seafoam, et.al.. I'll do that after I check the timing belt and get the radiator back on. In the mean time, if you think of anything else. Let me know.
Kim
The 1100 is possibly the easiest 4 cylinder bike in the world to remove the cams on. I'd suggest taking the shims out for a look and seeing if the shim on your "dodgy" valve is significantly thinner than the rest (or even missing completely). From memory the shims are typically around 2mm thick; I only have a degree in Chemistry but I believe that is pretty close to the huge clearance that you are seeing.
I'm curious to see how this thread plays out, never heard anything like what you're describing before.
When you said the two loose valves feel "springy", I assumed that to mean you can compress the valve stem fairly easily, is that correct?? As bdalameda said, it is possible to compress the stem, but it takes a fair amount of force. You can force a feeler gauge that is slightly too thick into the measuring gap, and it will compress the valve slightly to accommodate the feeler gauge, but you'll feel a distinct 'snap' when you pull it back out. The fact that you said you didn't even hit bottom at .090" is extremely odd, and suggests you could easily stuff thicker and thicker gauges into the gap without much spring resistance. Can you be more specific regarding the amount of force required to push the valve stem down while taking the measurements.
Regarding your question about a broken valve spring being an easy fix, we don't know if that's even the problem for now, but how comfortable are you with removing the cylinder head? If you remove the head yourself and take it to a machine shop, its not generally an expensive proposition to do minor valve work.
And as Terry said, the typical shim thicknesses are in the range of say 1.80-2.20mm, so if someone forgot a shim entirely it might explain the clearance you're seeing in the .060-.090" range, but I recall the shims sit in a little pocket that takes up some (maybe as much as 1/4-1/2) of the shim thickness, so I can't imagine what's going on with your measurements to get that large a clearance.
When you said the two loose valves feel "springy", I assumed that to mean you can compress the valve stem fairly easily, is that correct?? As bdalameda said, it is possible to compress the stem, but it takes a fair amount of force. You can force a feeler gauge that is slightly too thick into the measuring gap, and it will compress the valve slightly to accommodate the feeler gauge, but you'll feel a distinct 'snap' when you pull it back out. The fact that you said you didn't even hit bottom at .090" is extremely odd, and suggests you could easily stuff thicker and thicker gauges into the gap without much spring resistance. Can you be more specific regarding the amount of force required to push the valve stem down while taking the measurements.
Regarding your question about a broken valve spring being an easy fix, we don't know if that's even the problem for now, but how comfortable are you with removing the cylinder head? If you remove the head yourself and take it to a machine shop, its not generally an expensive proposition to do minor valve work.
And as Terry said, the typical shim thicknesses are in the range of say 1.80-2.20mm, so if someone forgot a shim entirely it might explain the clearance you're seeing in the .060-.090" range, but I recall the shims sit in a little pocket that takes up some (maybe as much as 1/4-1/2) of the shim thickness, so I can't imagine what's going on with your measurements to get that large a clearance.
A broken valve spring can also be replaced, without head removal, using compressed air in the cylinder to hold the valve on its seat whilst you remove the spring.
I've heard of that before, how easy and reliable is that method?
Kevcules
Site Supporter
Very reliable and very easy. Worst case is you remove the head to replace the spring which is what you would have done anyways.
Since we are all guessing about a broken valve spring. Try this. Compare the pressure needed to move (open) the other valves under this and/or both valve covers. If these two valves are significantly different, something is indeed wrong w/ the springs. If all are the same, springs are probably ok.
Learned about that one in auto class, but haven't done it myself. No reason why it wouldn't be reliable, as long as you have the tools and compressed air. Certainly easier than taking a head off. There's another method if you don't have air. Slip a piece of plastic rope through the spark plug hole, with the piston at BDC and push some rope into the cylinder. Then move the piston up to compress the rope against the valves, holding them tightly on their seats.
Regarding required force to push the valve stems down: I used the same pressure on each valve. That is, if a gauge slipped through, I would bump it up to next size and try again. I used, I think, significant force to try to slip through, if no go, I'd use the measure of previous gauge. In the case of the 2 weirdo's, that same force caused the lifter to 'release' and the gauge slipped through. The same 'feeling' occurred with all of the larger gauge combinations. Tomorrow, I plan to remove the cams and lifters to see what I can see.
GGely
Site Supporter
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Man, Grade 10 was soooo long ago...