ST1100 valve gaps - getting bigger or smaller?

[jusupov2002]

Has anybody hints how ST1100 valve gaps develop during the lifetime? Getting wider or narrower?

I measured valve gaps of my 1995 non-ABS ST1100 originally UK model 63733 miles ridden.

Intake: manuals tell 0.13-0.19 mm
1 front intake 0.13
1 rear intake 0.14
2 front intake 0.12
2 rear intake 0.17
3 front intake 0.16
3 rear intake 0.11
4 front intake 0.18
4 rear intake 0.16

exhaust: manuals tell 0.22 -0.28 mm
1 front exhaust 0.20
1 rear exhaust 0.21
2 front exhaust 0.25
2 rear exhaust 0.24
3 front exhaust 0.21
3 rear exhaust 0.21
4 front exhaust 0.24
4 rear exhaust 0.24

For me it looks that gaps are mostly at the narrow end. If gaps are getting wider during the life time I have no hurry to start playing with valve gap shims.
If the gaps are typically becoming smaller and smaller during the life time I most likely ride this season with gaps as they are now and will start messing with shims next winter.

 

[dwalby]

yes, they typically tighten over time, and the gap gets smaller, as your data shows.

 

[afrymoyer]

Right now you have 7 that need adjusting. You already have the valve covers off, why not just do it now? It really doesn’t take that much longer, plus you can put on new cover gaskets and be done with it for another 30,000 miles. Go get an aftermarket shim kit, such as Hot Cams, etc.

In my experience, they almost always get tighter as the valve seats wear. I may have heard of a couple guys that the clearance got greater. They were either carboned up, or using crap engine oil…

It’s best to set all the clearances right in the middle of specification. That’s were they run the best. Don’t forget to check the carb synchronization after a valve adjustment. Sometimes it’ll change.

 

[motornut]

As valves and the seats wear the the clearance diminishes. My preference when setting them up and checking for during its checkup is to set them at the largest gap. With the hard seats and the tough valves you will probably never have to adjust them again.
With 120,000 miles I haven't touched them since.
On the engines I worked on as a mechanic one of the benefits was a bit more torque, I couldn't tell but the engineers swore it was true.

 

[motornut]

Since 1st inspection I mean.

 

[dwalby]

technically they're not, but the worst offender is only about 0.001" too tight so its not an emergency to adjust them right now.

I agree with Adam, if it were my bike I'd adjust them now just to be done with it, adjusting valves on the 1100 is very simple.

There are several out of adjustment, you may be able to move some shims around to avoid having to buy new ones for every valve out of spec.

 

[Kevcules]

You have 6 valves at "out of spec" range. Since you checked them, you might as well adjust the ones that need it and also the ones close to the min spec since you're there. I would adjust all of them near the higher max spec, since they do seem to tighten with use.

When I checked my 08 1300 with only about 45,000 kms for the first time, I had 6 valves below min spec and 7 right at, or near min spec. I replaced 13 shims, some of which I re-used to different positions. Once you get to see what all the valve shim numbers are for each cylinder, further valve clearance checks will tell you what size shims you may need before you remove them.

Now I'm thinking I won't need to adjust my valves for a very, very long time, if ever again.
Good luck

 

[jusupov2002]

Thanks for the answers. As gaps are not that small I will start the riding season with them. And I will fix the gaps next winter.
I'm currently lacking garage time and to find out the correct shim sizes and getting new ones (most likely needed) is taking tooo long time for this part of the year.

 

[jfheath]

Mine have always got smaller - if they change at all. Often after the first change, I've not had to change them again. I go for a shim that will take them larger than the mid-point of the range.