Article [13] ST1300 - Valve Clearance Check How-To [VIDEO]

[jfheath]

Is there any merit in my removing the cams one at a time - I was thinking of using a cable tie to lock the cam chain to the inlet cam wheel (so as to ensure the chain does not move in relation to the wheel) then removing the exhaust cam, doing the shim change and then repeating the process for the inlet cam?

Also, how critical is it to use the Honda sealant (or similar) on the cam covers when refitting them?

I'm so sorry to wake you up from whatever life stage you are now at - you asked this question 16 years ago and I have only just spotted it. But someone else awakened it, so I'll answer for the benefit of anyone else looking in.

Using cable ties (or something) is an excellent idea to keep the chain from dropping into the depths.

But it is not a good idea to rely on the cable tie to keep the timing position. This is because in order to get the camshaft off, the chain has to be slack which measn that the shaft being removed will create a lot more slack. The chain loops around both cams and also around a sprocket which is half the size down in the depths. Much depends on how you manage this slack, and how you mark the camshaft / chain position when you put it back. It is possible to have the chain looped round the bottom sprocket with teeth engaged on the down side and engaged with the teeth on the up side, not engaged around the bottom of the small sprocket - it has formed a loop.

You will not notice this while the chain guide is off, but you will when you try to tighten it all up. Possible after the marker cable ties have been removed.

Use the cable ties by all means - but you should still check the timing marks when the T marks are aligned through the spy hole.

Sealant - it not necessary at all around the flat part of the camshaft cover lid. Bu it must be placed where the half moon shape forms an angle of 90 degrees. I use sealant all aroun the curev of the half moon, on the 90 degree corner and part way along the flat near the moon. That junction has no pressure on it, and it WILL leak oil over the front of your crankcase.

 

[thelonious]

Thanks for all the tips above, it was helpful when I checked my clearances.

All the intake valves were in spec but annoyingly most of my exhaust valves were at 8 thou, which is just out of the quoted spec of 10 +/- 1 thou in the manual.

Looking at it metrically, 8 thou is 0.203mm, against a spec given in the manual of 0.25 +/- 0.03mm.

The bike has done 65k miles and runs beautifully, as far as I know the valves have never been adjusted.

My thinking is valves that are 0.002mm too tight are not going to cause a problem, in fact I am more likely to create a problem by trying to change them.

I plan to leave them as they are and check again in 8-10k miles to make sure they get no tighter.

Is this a terrible idea? Has anyone encountered any issues running with the valves slightly on the tight side?

Thanks.

 

[jfheath]

The valves get tighter because the valves wear into the valve seat. The valve springs pull them higher towards the cam - so there is less clearance between the top of the valve and the cam.

This means that when the cam rotates, the valve is pushed away from the seat slightly earlier than spec and they seat and seal slightly later. That doesn't meant that they risk collision with the rising piston, because the valve isn't being pushed any further into the bore that it was before the seat wore down.

But it does mean that the valve is in contact with the valve seat for slightly less time that it should be. It is the cylinder block that is kept cool by the coolant circulating through the system - so the valve head has marginally less time to get a dose of 'colder' metal to cool it down. Also the valve is opening slightly earlier in the cycle, and closing slightly later in the cycle than it should be. And that will affect performance slightly. If that continues as things expand, the valve may never actually close.

I suspect that the issues will arise if you are riding this thing in situations where the engine is running hot. Pro-longed high revs. High Altitude. Heavy acceleration. High outside temperatures. You might start to hear pre-ignition / pinking / rattle.

Check your maths - 8 thou inches is 0.2032 mm - that for a spec of 0.25 +/- 0.03 - So 0.28 to 0.22mm Yours are 0.2032mm so 0.017mm outside the permitted range. Call it 0.02mm So yours would be OK if the permitted range was 0.25 +/- 0.05mm

All of the above comes with a health warning: I do not know what I am talking about. I have done the valve adjustments a number of times, and I know that the clearances get smaller with wear. For that reason, I always shim them to be slightly on the slacker side of the spec rather than bang in the middle. I have wondered why the clearances get smaller as things wear down. The above is my explanation to myself. Once I had come to the conclusion that pistons were not going to collide with valves, I was happy - providing I didn't ride the engine into extreme tempertures. The risk is that the engine will be running hotter and exahust valves do not get the cooling spray of cold fuel. Having said that the exhaust valves have much bigger clearance than the inlet valves (0.25mm vs 0.16mm). Perhaps check that your plugs are the correct ones and not inclined to make the engine run hotter than normal.

I know a few times in Spain, hot summer days, long steep climbs, high engine revs, low oxygen/high altitudes, E10 fuel, ST1300A6 (tuned weaker than the A8 and later), it would start to rattle like made and feel and sound weird. (this had nothing to do with valve celarances - they were spot on before this holiday). I just stopped and admired the view and gave the engine a breather. It was fine when we set off again.

I suspect that it might do that sort of thing much sooner in similar circumstances.

But as for recommending that it is OK to ride the bike when the valve clearances have extended the tolerance range by 66% . ie +/- 0.05mm instead of +/- 0.03mm -- No, I couldn't do that.

 

[thelonious]

Thanks for the reply… yes I meant 0.02 not 0.002mm too tight! Both left and right sides affected unfortunately.

I agree, valve recession is pretty much the only way they can tighten up, I wasn’t worried about component clash.

Good point about possible valve overheating in high temp high load situations, I will keep an eye (or ear) out for anything unusual. Mine’s a 2002 so I guess it would run slightly richer than later models.

Still tempted to leave it alone… any other opinions?

 

[W0QNX]

I'll give my opinion then make comments. Opinion: Leave it and ride it another year at least.

Comments:

Bottom of IN TOLERANCE is 0.22mm or .00866 inches. How is it possible suddenly all 8 of your ex. valves changed to .0080000? All of them the same? Did you check them with the engine %100 cold like at 68f degrees? In my feeble mind no way all 8 are suddenly at .0080000". Some have to be good so a GOOD recheck is needed. Don't change any that are in by .0005".

Even valve gap can be subjective to "feel". Was it a completely free movement of the feeler gauge? Did the .009 drag but still go into the gap? If so than it's so darn close to IN SPEC that I wouldn't worry. If the .008" gauge passed easily then it was somewhere between .008 and .009" so maybe it was .008888. Well above .00866. (well above is relative to if you ever worked in tenths or millionths of an inch HAHA). your gap isn't at .008000" unless the .008" is tight on insertion. If it slips in easily your probably closer to .0086" than .008"

FYI my bike is at 432,000 miles. I checked the valves last at around 250,000 miles and they just don't change much after the first 75,000 miles or so very much. Therefore I haven't bothered checking since. This is common with lots of bikes nowadays with the good materials used.

As with anything YMMV (your mileage may vary).

More comments I shouldn't make concerning an above post:

"But it does mean that the valve is in contact with the valve seat for slightly less time that it should be. It is the cylinder block that is kept cool by the coolant circulating through the system - so the valve head has marginally less time to get a dose of 'colder' metal to cool it down. Also the valve is opening slightly earlier in the cycle, and closing slightly later in the cycle than it should be. And that will affect performance slightly. If that continues as things expand, the valve may never actually close."

The statement is correct but since the total valve lift is like .250" (my guess) .001" valve to cam gap will be a very very minuscule amount of time lost on the seat, so insignificant on our ST1300. I doubt you could tell the difference if it were .010" less lift.

And on the opens earlier and closes later, that would mean better exhausting not less (longer duration open, .252 lift vs. .250"!) so better performance not worse. Reality is .002" LESS gap difference probably can't be measured in performance gain or loss in an ST1300. If it can than the closer to bottom of the tolerance it would run better than at the top (more clearance, less lift).

Last comment, I respect jfheath 100% and I appreciate and use his contributions to the board over the years!!!

 

[thelonious]

I'll give my opinion then make comments. Opinion: Leave it and ride it another year at least.

Comments:

Bottom of IN TOLERANCE is 0.22mm or .00866 inches. How is it possible suddenly all 8 of your ex. valves changed to .0080000? All of them the same? Did you check them with the engine %100 cold like at 68f degrees? In my feeble mind no way all 8 are suddenly at .0080000". Some have to be good so a GOOD recheck is needed. Don't change any that are in by .0005".

Even valve gap can be subjective to "feel". Was it a completely free movement of the feeler gauge? Did the .009 drag but still go into the gap? If so than it's so darn close to IN SPEC that I wouldn't worry. If the .008" gauge passed easily then it was somewhere between .008 and .009" so maybe it was .008888. Well above .00866. (well above is relative to if you ever worked in tenths or millionths of an inch HAHA). your gap isn't at .008000" unless the .008" is tight on insertion. If it slips in easily your probably closer to .0086" than .008"

FYI my bike is at 432,000 miles. I checked the valves last at around 250,000 miles and they just don't change much after the first 75,000 miles or so very much. Therefore I haven't bothered checking since. This is common with lots of bikes nowadays with the good materials used.

As with anything YMMV (your mileage may vary).

More comments I shouldn't make concerning an above post:

"But it does mean that the valve is in contact with the valve seat for slightly less time that it should be. It is the cylinder block that is kept cool by the coolant circulating through the system - so the valve head has marginally less time to get a dose of 'colder' metal to cool it down. Also the valve is opening slightly earlier in the cycle, and closing slightly later in the cycle than it should be. And that will affect performance slightly. If that continues as things expand, the valve may never actually close."

The statement is correct but since the total valve lift is like .250" (my guess) .001" valve to cam gap will be a very very minuscule amount of time lost on the seat, so insignificant on our ST1300. I doubt you could tell the difference if it were .010" less lift.

And on the opens earlier and closes later, that would mean better exhausting not less (longer duration open, .252 lift vs. .250"!) so better performance not worse. Reality is .002" LESS gap difference probably can't be measured in performance gain or loss in an ST1300. If it can than the closer to bottom of the tolerance it would run better than at the top (more clearance, less lift).

Last comment, I respect jfheath 100% and I appreciate and use his contributions to the board over the years!!!

I appreciate the reply!

It’s not all of them - #3 cylinder had one at 9 thou and one at 10 but all the others were 8.

By 8 thou I mean the 8 thou gauge would slide in but the 9 would not. I didn’t note if it was a stiff or sliding fit. So as you say somewhere between 8 and 9.

And yes engine totally cold, not been started for weeks as I am doing a light restoration.

432,000 miles? Amazing!

 

[TerryS]

The valves need clearance so that at the expected extremes of high temperature, they dont run out of clearance. Exhaust valves need more cold clearance because they run much hotter than the intake valves, so they will expand more and take up more of the cold cam clearance. If the cold clearance is inusfficient, the valve won't be able to close fully when it is hot, then you will lose valve seal and more importantly, potentially burn a valve. I've never checked valve clearances hot but intuitively, there should be very little clearance.

Too much clearance is much less harmful, valve lift (and thus airflow/peak power) is marginally reduced, and valve noise may be more obvious. John's suggestion of reshimming to the upper end of tolerance when you have to make a change is sound advice (in my uneducated opinion).

 

[W0QNX]

I appreciate the reply!

It’s not all of them - #3 cylinder had one at 9 thou and one at 10 but all the others were 8.

By 8 thou I mean the 8 thou gauge would slide in but the 9 would not. I didn’t note if it was a stiff or sliding fit. So as you say somewhere between 8 and 9.

And yes engine totally cold, not been started for weeks as I am doing a light restoration.

432,000 miles? Amazing!

No problem on the reply.

One of the best things you can do on the ST is have a record of the valve gap measurements so you can look for changes. And be mindful of how tight of an .008" it is. I'd save my info as .008, .0085, .009...

There are several valve threads here in the ST1300 articles that have an Excel spreadsheet for valve calculations and your history of measurements.

 

[vstrom.zrxdude]

65,000 mi is around when I first had to change 2 shims for thinner, last spring at 170,000 mi had to change 4 for thinner, that made it run smoother with no random misfires,

 

[bkra13]

On the topic of the right side cam chain tensioner access , I found that a small screwdriver handle that fits into a socket works quite nicely. Use a long ratchet extension and wedge the ratchet handle against the frame. No extra set of hands needed. Works with relatively short screwdrivers too.