2003 st1300 valve clearance a bit tight

[97rr]

Hi all,

i just did a valve check on my 2003 st1300 with 15000 miles. The Exhaust valves of cylinder 1 are tight by 001 at 0.008, as is one of the exhaust valves of cylinder 2.

the rest are pretty well within spec. Thoughts? Should I get those in spec soon, or wait until 32k check?

 

[Kevcules]

My thoughts are I would take care of the tight valves fairly soon. Not an emergency though. I also wouldn't wait another 15,000 miles. IMHO
These valves don't seem to wear much, so you "may" be ok for another 15,000 miles, but why chance it.
I have two intakes on the min spec as of roughly 5000 kms ago. I check every two years and I'm due again this winter. If they have fallen out of the range, I'll adjust them......good luck.

 

[Larry Fine]

Why not adjust the two while you have it open?

 

[dduelin]

I think if you are like me you'll just worry about it until you take care of it. I was in a similar spot at I think 65,000 miles. I found one exhaust at .008 and had been watching it and four other exhaust valves on the tightening side of .009 since the first check. ( I checked the valves every 16 to 20,000 miles to that point ). I put it all back together and tried not to think about it but I only lasted about 1,000 miles before I read all I could about it and tackled the job. It wasn't that hard in the end to reshim all 5 back to middle of spec. I never had to touch them again to the last check at 174,000 miles before I sold it. Lackoworry is a good thing.

 

[Bmacleod]

If I have a valve right at the edge, (.009 in this case) it would be in my head all the time, but I admit that may be a bit OCD. .008 is an absolute no go and I couldnt hit the starter button until it is a perfect .010. The spec. is there for a reason. Why push it?

 

[OhioDeere]

Just some thoughts. If you was to go back and remeasure all those gaps. what would it be the second time around? I've re-adjusted quit a few motors because someone adjusted the valve gap incorrectly to dimension.
Although that motor is made precision. the valve gap is not that critical by .001". the gap is to allow for growth of the parts when engine is at temperature. Would I adjust the gap? NO. Also, how accurate do you think you measured the gap? Is there error there? .001" is pretty hard to gauge on this setup. What was the temperature of the engine when you measured it? If using feeler gauges, your trying to feel for "just rubbing" for the measurement. Not a "tight feel". All measurements should be taken around 70°F give or take a little. Realize oil temp is critical for this. a film of oil on the bucket will influence the gap dimension by an easy .001 - .002". I like to blow the oil off with an air line to make sure they are clean.
I work in an environment of precision machining. Teaching metrology is always the hardest skill to teach to apprentices for the tightest spec with basic metrology tools. What one feels in the gauges may be different to another between .001"

 

[John_Diego]

There are those who will disagree with me.
But, .001 is very small, the valves are set when the engine is cold. The valves operate at a much higher temp that you cannot measure, so what ever you set the clearance at it is just a guess. Take another look @ 100K mi.

 

[drrod]

If you had 10 people measure the valve clearances on the same bike, how many do you think would be exactly the same? And what would the variation be (if any)?

 

[jfheath]

There is no danger of the valves colliding with the piston head when the clearance has become too tight. What has happened is that the seat between the valve and the valve opening has worn down a touch, so the spring is pulling the shaft of the valve closer to the cam. ie less clearance when the valve is cold.

The valves keep themselves cool by remaining in contact with the water cooled casing for as long as possible. Because the gap is smaller, they are pushed away from the seat and into the hot gasses a tiny fraction earlier in the cycle (But they cannot be pushed further towards the piston than when the bike was new). This means that they get hotter - which can be a problem, depending on how the bike is ridden.

So yes - they need to be within spec. Is it a disaster if you ride with it for a little while longer ? Personally, I wouldn't have thought so, but it would niggle at me until I had done them. Will you be able to tell the difference when you adjust them ? Yes.

 

[STraymond]

I have always heard that the ST1100 engine is an "interference" engine - and assumed that the valves could colide with the pistons. Is that only due to timing errors e.g., timing belt broken or too loose causing valves to open at the wrong time and colide with pistons?

 

[diferg]

strongly suggest you rotate engine, realign timing marks,and take measurements 3 or four times in the span of about an hour, ( DO NOT START THE BIKE!) record all your measurements. compare all measurements ( if they are all the same with each measurement then YOU ARE THE MAN! dont forget to fully rotate engine and realign timing marks for each set of readings. I really hesitate to disturb a bearing because of one "ALMOST" measurement!

 

[Larry Fine]

I have always heard that the ST1100 engine is an "interference" engine - and assumed that the valves could colide with the pistons. Is that only due to timing errors e.g., timing belt broken or too loose causing valves to open at the wrong time and colide with pistons?

That is correct.

 

[STraymond]

That is correct.

Thank you, Brownie Man! That does seem to remove any urgency caused by overly tight valve clearances.

 

[SMSW]

I have always heard that the ST1100 engine is an "interference" engine - and assumed that the valves could colide with the pistons. Is that only due to timing errors e.g., timing belt broken or too loose causing valves to open at the wrong time and colide with pistons?

Lets split a few hairs here, Ray. If your timing belt breaks or jumps a tooth because of a broken tensioner, the valves will open or remain open while the piston is rising in the cylinder. The piston does the colliding, and usually the result is a bent valve that will no longer close. Occasionally, the piston will get damaged, a valve will break off the stem, or you could even see a broken connecting rod. Any of these would tend to ruin your day. A non interference engine might have the valves off to the side - think tractors and inline engines. The valves are outside the combustion chamber (usually in the block next to the cylinder, not the cyl. head) and there is no way for the piston to reach out and touch the valves. You can also find lower performance (compression) engines with overhead valves and sufficient room atop the piston at TDC for the valves to open fully without contact.

 

[Bmacleod]

I have always heard that the ST1100 engine is an "interference" engine - and assumed that the valves could colide with the pistons. Is that only due to timing errors e.g., timing belt broken or too loose causing valves to open at the wrong time and colide with pistons?

yes, that is correct

 

[OkieRider]

Once one is out, I normally take the opportunity to adjust all the intakes towards the tight side as close to each other as possible and all the exhaust on the loose side as close to each other as possible. It's not that much more work to do all compared to just one. The main hassle is putting a micrometer to each shim. See if your local Honda dealer will trade shims with you.

 

[Larry Fine]

The main hassle is putting a micrometer to each shim.

Aren't they marked?

 

[OkieRider]

Aren't they marked?

Yes.

The shims coming out, if Honda originals, are probably labeled correctly. The aftermarket shims likely to be going in are not.

How many times do you want to remove and reinstall your cams?

 

[Larry Fine]

The aftermarket shims likely to be going in are not.

That's nuts! I would never install unmarked shims.

How many times do you want to remove and reinstall your cams?

Well, zero. I did my '82 Nighthawk 750 decades ago.

 

[STraymond]

Once one is out, I normally take the opportunity to adjust all the intakes towards the tight side as close to each other as possible and all the exhaust on the loose side as close to each other as possible. It's not that much more work to do all compared to just one. The main hassle is putting a micrometer to each shim. See if your local Honda dealer will trade shims with you.

So, are you saying that intake valve clearances tend to loosen (increase) over time?