2003 st1300 valve clearance a bit tight

[jfheath]

My clearances, if they have changed, have only ever got tighter - ie the gap reduces.
I choose shims that put the clearances just on the slack side of the centre of the tolerance range.

I posted an Excel spreadsheet on the forum years ago that does all of the working out for you, and lets you play with the clearance , redistributes your existing shims and shows you which shim numbers need to be obtained. I wonder if is still on here somewhere.

 

[SMSW]

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

As the valves open and close, they are hammering against the valve seat, and wearing both the edge of the valve and the seat. Over time and miles the valves will seat farther into the head, pushing the top of the valve stem closer to the rocker arm or cam. In our case, on the ST's, the valve stem is covered by the shim and bucket, so any wear (usually negligible) takes place on either the cam or bucket's bearing surface. In all cases the clearance will decrease as the seats and valve surface wears. If you use the wrong oil (heck, I have to squeeze in an oil thread here) you might wear down the cam or burn the bucket but I think this has been eliminated in modern engines with virtually any oil you buy. (Whale, shark liver oil, and snake oil are not included in "virtually any oil you can buy").

In the old days, before Stellite and other hardened valve seats, a valve job required the mechanic to insert a mandrel into the valve guide, slide a cutter over the mandrel (looks like a cone shaped cutter, but the point has been cut off (truncated cone) and cut the metal to the correct angle. Sometimes a second cutter was used to narrow the contact area of the new valve. Then valve lapping compound was dabbed on the head or the valve, it was dropped into the guide, and a suction cup on the end of a hand cranked drill rotated the valve back and forth while rotating it completely. The valve was pulled out, the compound wiped off, and you looked for an even 'frosting' band on the midline of the valve and the mating seat. Sometimes the valve guides had to be pressed out and replaced, then reamed.

Anyone please correct me if I made any mistakes in my description above - I only did that once back in prehistoric times (BC - before computers).

 

[ReSTored]

Can't speak to the 1300 specifically but on the 1100 clearances get tighter for both intake and exhaust. When checking clearances record everything and also record the thickness of all shims whether you replace them or not. Good info for next time. I try to leave things in the 50% - 75% of the range, i.e. if an intake measured .005 I'd try to leave it between .006 and .0065 if you have or can order the appropriate shim. If you have a record of the shims in place you can do your measuring and then ordering in advance of actually pulling the cams.

 

[Bmacleod]

When checking clearances record everything and also record the thickness of all shims whether you replace them or not. If you have a record of the shims in place you can do your measuring and then ordering in advance of actually pulling the cams.

This is very good advise. Also, if you know all your shims, you are SOMETIMES able to move some shims around to obtain some proper clearances and cut down on the number of shims needed

 

[Kevcules]

In all cases the clearance will decrease as the seats and valve surface wears.

If the valve or seat wears, the clearance will decrease. If the cam lobe wears, the clearance will increase.

 

[SMSW]

If the valve or seat wears, the clearance will decrease. If the cam lobe wears, the clearance will increase.

Right, but cam lobe wear is frowned upon and relatively rare, and is the stuff of legend when a modern engine experiences this. Example - did not some Harleys have cams wearing or was that cam bearings wearing?

 

[Kevcules]

Right, but cam lobe wear is frowned upon and relatively rare, and is the stuff of legend when a modern engine experiences this. Example - did not some Harleys have cams wearing or was that cam bearings wearing?

I agree, most times the valves will get tight. I do know that some motorcycle manufacturers cam lobes were like butter. Not Honda though afaik.
Similar to the cam on the 80's Chev 305 engine. I had the pleasure of changing one. Not too bad of a job.

 

[SMSW]

I agree, most times the valves will get tight. I do know that some motorcycle manufacturers cam lobes were like butter. Not Honda though afaik.
Similar to the cam on the 80's Chev 305 engine. I had the pleasure of changing one. Not too bad of a job.

I think this happened a bit to high performance engines because when you are sqeezing out more hp, you want faster valve openings, more aggressive valve timing and higher lifts. These can lead to steeper cam profiles, stronger springs, and higher loads on the cam face. This is in addition to heat treating errors in manufacturing. One way to reduce this would be with a roller cam follower, but these introduce their own set of problems. Everything in engine design is a compromise.

 

[OkieRider]

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


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

The aftermarket shims are marked, but their markings are inaccurate. It would actually be better if they were unmarked because that would be less deceptive.

 

[OkieRider]

Although I did have a Kawasaki which had intakes that tended to get loose, I'm not making that general statement. It's a preference rooted in my history of riding Hondas that are torquey out of the box like the CB900C, VFR, VTX, and now the ST. By shimming intakes on the tight side, you are causing the valves to open sooner and longer. It doesn't hurt bottom end performance noticeably because that's what the tune already emphasizes, and it helps them some on the top. On sport bikes I'm not racing, I have done it the other way to make them more torquey for riding in traffic and with stop lights.

 

[Kevcules]

I've heard that before that some racing engines have their intake valves adjusted on the tighter side of the range to get more performance. I'm sure it works, but for the regular driver who doesn't necessarily enjoy having to go into the engine and shim the valves often, If I have to,I'll shim to the mid and high side of the range for longevity and peace off mind.

On my Kawasaki KLR650 back in the day, most of the riders on the forum adjusted both the intake and exhaust valves to the loose end of the ranges. Not sure any gains were given, (no power anyways ) but it let us not have to back in and check them for a good amount of time. It seems like the ST valves and valves of most newer modern bikes don't wear very much at all.

Since the valve gaps of our bikes don't seem to change hardly at all for many many miles, I'm wondering if the valve and seat and also the cam lobes are wearing ever so slightly together, to maintain the gap? There is minute wear in every engine component when running correct? Maybe it's just the newer metal technology, making bullet proof material?

 

[OkieRider]

KLR is a different matter. The difference between checking valves and adjusting valves isn't that great. If you're doing it in the winter, it doesn't cost you any ride time and then you know it's done right. It is less key whether you opt to adjust a little tight versus a little loose so much as whether all your intakes are similar and all your exhausts are similar.

 

[Al st1100]

As the valves open and close, they are hammering against the valve seat, and wearing both the edge of the valve and the seat. Over time and miles the valves will seat farther into the head, pushing the top of the valve stem closer to the rocker arm or cam. In our case, on the ST's, the valve stem is covered by the shim and bucket, so any wear (usually negligible) takes place on either the cam or bucket's bearing surface. In all cases the clearance will decrease as the seats and valve surface wears. If you use the wrong oil (heck, I have to squeeze in an oil thread here) you might wear down the cam or burn the bucket but I think this has been eliminated in modern engines with virtually any oil you buy. (Whale, shark liver oil, and snake oil are not included in "virtually any oil you can buy").

In the old days, before Stellite and other hardened valve seats, a valve job required the mechanic to insert a mandrel into the valve guide, slide a cutter over the mandrel (looks like a cone shaped cutter, but the point has been cut off (truncated cone) and cut the metal to the correct angle. Sometimes a second cutter was used to narrow the contact area of the new valve. Then valve lapping compound was dabbed on the head or the valve, it was dropped into the guide, and a suction cup on the end of a hand cranked drill rotated the valve back and forth while rotating it completely. The valve was pulled out, the compound wiped off, and you looked for an even 'frosting' band on the midline of the valve and the mating seat. Sometimes the valve guides had to be pressed out and replaced, then reamed.

Anyone please correct me if I made any mistakes in my description above - I only did that once back in prehistoric times (BC - before computers).

You are correct about the old ways.. you reminded me of doing a 3 angle cut , what a pain. I have seen in my days, bucket shims get tighter and push rods get looser. Most engine use hydraulic lifters but I do see honda engines with high miles (>100k) that have misfire codes due to tight valves. Hondas use solid lifters across all the platforms to the best of my knowledge.

 

[97rr]

I wanted to give an update. I ended up adjusting the valves that needed adjusting to get them within spec. I also had to fix the cooling plumbing on the top, thermostat area, which had my bike apart for close to a month waiting for parts. The leak at top was the catalyst for getting the bike apart in the first place and in turn checking the valves.

The o-rings on the inlet joints that attach to the heads were completely flattened and therefore leaking coolant. Thanks to all the good write ups here and the manual, I was able to get it all done.

I rode the bike today and it was a pleasure. Now I just need to change the oil and I'll be done for another 16K miles.

Thank you all.

 

[jfheath]

Good stuff, well done - and thanks for the feedback. Its always good to know when something has worked out ok.

Not everyone will agree with my next suggestion mostly due to the expense, but fit a new filter and give a quality fully synthetic oil a try. I'm not going to try to explain or describe it. I have reverted to semi-synth once, but went back to fully synth and use nothing else now.