Checked my valves for the first time and my intake valves are tighter than .15 - more like  .102 for all 4 (1985 k100)

Guessing I need to replace all those shims? Or is tight on the intake side ok?

Exhaust are all.25

(Bike runs til hot then stalls out but tight intake valves wouldn't be related right? I think that prob is bad coil)

timz1000 wrote:
Guessing I need to replace all those shims? Or is tight on the intake side ok?

Your intake valve clearances are not ok.

The valve clearances should be within their specified ranges. The only way to bring them within their specified ranges is to remove the existing shims then substitute shims that put the clearances within the range.

It is helpful for readers if you include your bike's year and model in your profile so it shows up in every post.

Wot Laitch sez. You really, really have to fix those valve clearances to make the bike run right.

Dai wrote:Wot Laitch sez. You really, really have to fix those valve clearances to make the bike run right.

Thanks - will do.

timz10000 wrote:

Dai wrote:Wot Laitch sez. You really, really have to fix those valve clearances to make the bike run right.

Thanks - will do.

This looks like something I can do myself if I buy the special tools (still available I see from the guy on this list for $29) and buy the shims, right? 

It seems funny that all 4 are off by the same amount. Not sure how that would happen.

This brings to mind a surprising and disappointing experience I had when I first bought my used K100RS.  I checked the valves personally. They all seemed to be in spec.  I later took the bike to a professional mechanic - of which I knew the history- for some electrical work that I deemed beyond my abilities. He did the electrical work, and also looked at the valves.  He reported that a number were too tight.  I was puzzled but didn't feel I should challenge the mechanic, as he was trained and all.  Well, I later found they were needlessly adjusted.  What's all this have to do with anything?  Well, I've concluded that a K100 engine runs well enough with loose valves.  I wouldn't want to run one with tight valves, though. Set them to proper specs and you can look forward to many miles without revisiting the work. They seem to be very stable in service. 

timz10000 wrote:
This looks like something I can do myself if I buy the special tools (still available I see from the guy on this list for $29) and buy the shims, right?

It does look that way. If you know the right people, they might even give you the shims you need. Much depends on your personality, their shim supply and your shim requirements. You can even swap shims, like Pókemon cards. There are a couple of thorough explanations on YouTube about the extraction, replacement size calculation and installation procedure.

timz1000 wrote:
It seems funny that all 4 are off by the same amount. Not sure how that would happen.

The cam lobes do that to them.

All will be reveled in the fullness of time.

Laitch wrote:

timz10000 wrote:
This looks like something I can do myself if I buy the special tools (still available I see from the guy on this list for $29) and buy the shims, right?

It does look that way. If you know the right people, they might even give you the shims you need. Much depends on your personality, their shim supply and your shim requirements. You can even swap shims, like Pókemon cards. There are a couple of thorough explanations on YouTube about the extraction, replacement size calculation and installation procedure.

timz1000 wrote:
It seems funny that all 4 are off by the same amount. Not sure how that would happen.

The cam lobes do that to them.

All will be reveled in the fullness of time.

Thanks much for the advice. Every time I'm about to get frustrated that the bike isn't fixed, I learn about a new system - it's like k100 school. Let's just hope I graduate someday 

timz10000 wrote:
Every time I'm about to get frustrated that the bike isn't fixed, I learn about a new system - . . .

There is no need to wait until your bike spanks you to learn about its system. Clicking on the Portal tab will reveal two resources—among others—that might put you ahead of its naughty behavior. The EFI Troublshooting guide will explain most of the bike's engine fuel prep and delivery systems among its pages. The You just bought a used K100 article will also guide your expectations.

Laitch wrote:

timz10000 wrote:
This looks like something I can do myself if I buy the special tools (still available I see from the guy on this list for $29) and buy the shims, right?

It does look that way. If you know the right people, they might even give you the shims you need. Much depends on your personality, their shim supply and your shim requirements. You can even swap shims, like Pókemon cards. There are a couple of thorough explanations on YouTube about the extraction, replacement size calculation and installation procedure.

Be careful using secondhand shims. They can be 'dished' due to wear from the cam lobe. You need a micrometer to measure them properly, not vernier calipers, so that you can take a measurement in the centre. If they're dished, they are Kaput! They're cheap enough so just buy new ones imo.

timz10000 wrote:

Thanks much for the advice. Every time I'm about to get frustrated that the bike isn't fixed, I learn about a new system - it's like k100 school. Let's just hope I graduate someday 

What you need to remember about BMW maintenance is:  there is a right way, a wrong way, and a German way.  You must learn the German way...

Good morning timz (still evening for you of course!). I think it's true to say your tight clearances must be due to the slight deformation of the valve seats which results in the valves being deeper in the head in the closed position (viewed from the head gasket face side).
This does reduce your safety margin which is sometimes insufficient even when the tappet clearances are set in range (ask RickG about his burned valves after some wide open throttle riding on his 1100!)

IMO it is doubtful whether you will notice the effect of slightly tight clearances on the way the bike runs under normal conditions as the extent to which gas flow and valve timing are altered is minimal. I wouldn't be happy riding with tappet clearances on the tight side because of all the other factors which can consume safety margin through abnormal heat load conditions. Things like inaccurate ignition timing, mixture control, effect of substandard fuel, etc - all of which I don't feel I have the experience to have an accurate handle on....

rawdonball wrote:Good morning timz (still evening for you of course!). I think it's true to say your tight clearances must be due to the slight deformation of the valve seats which results in the valves being deeper in the head in the closed position (viewed from the head gasket face side).
This does reduce your safety margin which is sometimes insufficient even when the tappet clearances are set in range (ask RickG about his burned valves after some wide open throttle riding on his 1100!)

IMO it is doubtful whether you will notice the effect of slightly tight clearances on the way the bike runs under normal conditions as the extent to which gas flow and valve timing are altered is minimal. I wouldn't be happy riding with tappet clearances on the tight side because of all the other factors which can consume safety margin through abnormal heat load conditions. Things like inaccurate ignition timing, mixture control, effect of substandard fuel, etc - all of which I don't feel I have the experience to have an accurate handle on....

Thanks much! 

I plan to make the valve clearances correct. I still have my main problem which I think is a bad coil (bike stalls and won't start after it gets hot - already replaced Hall Effect Sensors) - guessing intake valves wouldn't cause that issue.

I still have my main problem which I think is a bad coil (bike stalls and won't start after it gets hot - already replaced Hall Effect Sensors

Did you swap out just the sensors or the wiring from them as well. The wiring insulation breaks down and can cause issues for the voltage signals from the sensor as they are very small amplitude.

Mike

mike d wrote:I still have my main problem which I think is a bad coil (bike stalls and won't start after it gets hot - already replaced Hall Effect Sensors

Did you swap out just the sensors or the wiring from them as well. The wiring insulation breaks down and can cause issues for the voltage signals from the sensor as they are very small amplitude.

Mike

I just swapped out the sensors themselves, which came with small wire leads that i soldered to the harness. Hm... Do you think I should replace the wires (and if so, can one buy just that wiring?)

I would double check where the external wiring enters the HES chamber. The wire is meant to have a heat resistant covering. It is this that can break down and cause problems.

Mike