While the inlet valves have remained .06mm the whole time, the exhaust clearance has gone from both .05mm at 27k/kms to both .06mm at 35k/kms to .08mm and .09mm at 45k/kms
Is this normal? should I expect them to continue this trend. Or are there other variable that could reverse the trend?
That is weird. When they wear they get too tight. They are wearing in completely the incorrect direction - at the rate you are going you'll have to find some thicker shims next time!
I've got nothing constructive for you sorry other than something seems up.
@1018, OK that's something, I'd only ever heard of people discovering their clearance was too tight but I never knew for sure which way they are supposed to wear. All I can add is that the clearance was checked after the head was retorqued, not sure if that is relevant or not, previous times it's possible that they were checked before a retorque.
Have you done a compression test? I'm wondering if maybe you have carbon build up around the valve seats.
Has to be carbon build up. Better do something about it because it cam potentially lead to burnt or bent valves.
are the camshaft cap bolts tensioned down properly?
Bugger, I was happy that they've moved into a better spec, now I'm sad again :¬(
Will a cheap $20 tester like this be OK...
https://www.ebay.com.au/itm/AU-SHIP-Petrol-Engine-Compression-Tester-Kit-Tool-Set-For-Automotives-Motorcycle/262525463116
@Joolstacho, have not checked yet.
@anyone, if this is just a bit of carbon build up can this be attended to without removing the valves by running some sort of product through the engine? Also how big a job would it be to clean the valves. How much disassembly would it involve.
Also let's say hypothetically I get a good compression, what would that mean with regard to the next step to take. I will note that the bike runs well and does not feel that it's losing power anywhere.
Quote from: Joolstacho on November 19, 2017, 04:03:55 PM
are the camshaft cap bolts tensioned down properly?
Good idea Jools- I didn't even think of that. User, if you check the cam cap bolts, do NOT over tighten them! Don't want to add another problem......
I've heard of so many different ways to clean carbon build up, but have never tried any of them (if you Google them, they seem like sketchy procedures......but people claim each one works). If you want to do it properly, it might be a good idea to take the head to a small engine repair shop. Removing and cleaning the valves isn't exactly a hard job, but it does take some special tools and it can be devastating if you do it wrong (especially reassembly).
OK I can't find 'camshaft cap bolts' listed in the service manual. Are these them?
(https://s7.postimg.org/qwvcqom9n/cap_2.jpg)
Yep.
OK, right well I've ordered a cheap compression tester and I'll get it checked at the garage as well to check the calibration. In the meantime while I'm waiting for my tank to empty so I can check the journal cap (which looks to only be 10Nm anyway) I have a question.
This has always had top quality 100% 91 octane which I believe is equivalent to (87 in the states) and it is rarely fanged, and only 45k/kms what would cause it to accumulate carbon build up on the valves, (assuming that a retorque of the cap doesn't alter anything)
Also if this is a carbon build up and there is some consequent leakage what would you expect the psi to read assuming that the piston rings and any other stuff where pressure can leak are not leaking? hope that makes sense. Alternatively assuming that there is not leakage anywhere what reading would indicate that? Over 160?
On my 50K bike everything used to get loose with wear. That's an indication cams, shims etc are wearing more than the valve and seat. IMHO - good thing. Easier parts to get at.
Cool.
Buddha.
Quote from: The Buddha on November 20, 2017, 04:53:28 AM
That's an indication cams, shims etc are wearing more than the valve and seat.
I would think that's pretty much impossible considering those are hardened steel and the valve seat is bronze.
I found that exhaust valves set at the minimum .001" of the Suzuki .001-.003" spec required constant shim changes and the one on my 97 GS (bought new) was down to a minimum 215 shim with no where to go at 70k miles. While I was pondering what to do next I was rear ended and the bike totaled and replaced with my 02 GS.
Early on with the 02 GS I began setting exhaust valves at a wider .003-.005" spec and they settled down and required little attention after that. Minimum shim at 100k miles was a 245 with plenty of adjustment left.
Both the 97 and 02 GSs had the same intake valve shims in them that they came from the factory with, no shim changes. My valve check log:
https://i.imgur.com/SksMPhb.jpg
Quote from: mr72 on November 20, 2017, 07:31:37 AM
Quote from: The Buddha on November 20, 2017, 04:53:28 AM
That's an indication cams, shims etc are wearing more than the valve and seat.
I would think that's pretty much impossible considering those are hardened steel and the valve seat is bronze.
I've measured valve shims with tens of thousands of miles on them at both centers and edges with a quality micrometer and never detected any wear in them.
Quote from: mr72 on November 20, 2017, 07:31:37 AM
Quote from: The Buddha on November 20, 2017, 04:53:28 AM
That's an indication cams, shims etc are wearing more than the valve and seat.
I would think that's pretty much impossible considering those are hardened steel and the valve seat is bronze.
Cams are not hardened. They're treated with something - not exactly making them hard. Something that makes them retain oil maybe ?
You understand that there is no back and forth movement on the seat/valve contact face right. The cam drags across the shim, with the oil film protecting them. Valve/seat doesn;t have oil, it has a thin layer of carbon but there is no sliding friction.
BTW mine had a crows foot type scratch on one that I watched for 50k miles and it did get slowly fainter over time, but never went away.
I have measured shims and have found them thinner than the marked number, but not had them wear in the time I have used them.
I've seen weird wear patterns on them to start with, no wear occurring in my use.
I dunno, I had that bike with pretty rough commute type use for much of its life, it used oil prolifically and never skipped in spite of any of these problems.
Cool.
Buddha.
Quote from: user11235813 on November 19, 2017, 07:16:42 PM
OK I can't find 'camshaft cap bolts' listed in the service manual. Are these them?
(https://s7.postimg.org/qwvcqom9n/cap_2.jpg)
BUT! (I should have mentioned), -take care not to overtighten these bolts as they can easily strip the threads in the head if they're over-torqued.
I will report back on friday, when my $20 compression tester will be delivered, I'll also be getting a $10 check at the local bike shop to check the calibration on the cheap tester.
Talking to the bike shop the offered the suggestion that the difference could be accounted for by the weather. Earlier tests were done in winter. However there was no change to inlet valves and winter in Brisbane would be close to summer in some places.
@Joolstacho, yeah I've already double checked it to be 10Nm and I have a decent inch/lbs torque wrench. However seeing as the torque is so low, if these bolts were loose wouldn't that cause some very dramatic problems? Also Suzuki never mention even checking them during a head retorque. But I will check anyway.
BB Friday with the compression result.
BUT if there was enough carbon build up to give me another .002 - .003mm of clearance, would you expect to see that reflected in the compression numbers?
If carbon is building up around the valve seats, your exhaust valves would be slightly open all the time. So yes, your compression would be lower than it should be.
@Big Rich
Cool, can't wait till Friday. Will report back.
Quote from: Big Rich on November 20, 2017, 08:47:57 PM
If carbon is building up around the valve seats, your exhaust valves would be slightly open all the time. So yes, your compression would be lower than it should be.
Exactly, and also it's likely there's more carbon build-up on one side of the valve than the other which can lead to bending the valves enough that they won't seal against the valve seat even if you clean the carbon off.
Likewise, the carbon on the valve is not only an uneven surface compared with the valve seat, but it's abrasive. So it'll cause uneven wear in the valve seat along with peening so the valve seat will wear to the degree that it won't seal even if you cleaned the carbon.
Suffice to say carbon on the valves is a not so great thing.
Quote from: Big Rich on November 20, 2017, 08:47:57 PM
If carbon is building up around the valve seats, your exhaust valves would be slightly open all the time. So yes, your compression would be lower than it should be.
But think about it. In a normal motor so much carbon flies through everything, you dont get a coating more than a few atoms thick @ any given time on anything. More interestingly exhaust valves have less carbon than intake due to the faster flow speeds and higher temps. So a building carbon situation is a problem by itself, the lower compression and looser valves are just another symptom.
Cool.
buddha.
I have seen a lot of exhaust valves that "lost their seat," a term that means they no longer seal. Almost always it is an exhaust valve, and when it is taken out, there is no metal color left--only carbon. If left untreated, the valve will "burn," that is lose metal and will be totally ruined. I It is not supposed to be done, but I have lapped in valves and had them work for a long time--the purists will disagree, but lapping does work although I recommend new exhaust valves especially. The Buddha is right about the intake valves--I've seen carbon really thick on them. A couple of suggestions--run valve clearances a little loose, especially on the exhausts, and run the mixture a little rich.
Got the cheapie tester in today and it's not looking good, will take it to the bike shop for a confirmation.
Pressure was 110 and 120 :¬(
This is very annoying because the bike runs well and it doesn't feel like it's losing power. This could just be bad readings so I guess I'll have to wait for Friday for a confirmation.
Assuming that this is a carbon build up and bearing in mind the bike is running well what would be the best solution here.
If it's running fine then just ride it. Eventually it will stop running fine and you will need a top end rebuild. Then you can evaluate the valves, but replacing them is cheap insurance compared with the cost of the rebuild. Rings, valves, valve seats, gaskets.
+1. Keep running it for now - at least til the end of your riding season.
Plan on (and budget for) a top end rebuild. The service manual gives really good details about what needs done, and what needs replaced.
You could (and I don't necessarily recommend it) try and clean the carbon out yourself. Just like how people run Seafoam in their gas because their carbs need cleaned....there are tricks to cleaning carbon build up. I haven't done it, but I know there's plenty of tricks for it around the internet.
+2 on the ride it - my 50K miler was using so much oil for the last 15K of its life with me, I sold the bugger for 675 - after paying 800 for it 10yrs and 42k miles ago. Anyway, worn out these bikes are worth about as much as they are nice and fresh.
Cool.
Buddha.
Quote from: The Buddha on November 22, 2017, 06:46:44 AM
Anyway, worn out these bikes are worth about as much as they are nice and fresh.
BTW, this is a good point but also a two-edged sword. And the reason why this is true is because the typical GS500 buyer is a beginner and can't tell the difference between worn out and nice and fresh. Or putting it differently, there's a floor on running-motorcycle value, around here it's the $1500-2K range for a bike you can put on the road and use right now. Everything from ratted out UJMs with rust and dents and missing parts to Buell Blasts with faded plastics to my well-sorted GS500 are in the same range.
If you find a GS500 for $2K it might be worn out, it might be nice and fresh. It's hard to know. Unless you do that compression test before buying, it's going to be hard to know this stuff about a bike you buy used. I have seen GS500s that are only 10 years old with under 3K miles on them that won't run, while my 25+ year old bike with 21,xxx miles on it runs like new.
However, a bike you know inside and out and you know you just finished a top end rebuild is probably worth more
to you than a used bike with unknown heritage.
Just putting that out there lest you are tempted to sell this bike and start over. You've done a lot of work to find the issues with this one. You'd have to do similar work to find issues with any used motorcycle of this age. They all likely require similar amounts of investment to get them to "nice and fresh". This one rings and valves, another one a starter and clutch, another one has an undiagnosed bad rod bearing, another one generally needs new everything like tires, brake pads, caliper rebuilds, fork rebuild, etc. which all adds up to the same price as a top end rebuild, another one needs you to undo a lot of the previous owner's attempts at making it a cafe racer, etc. The rare gem out there doesn't need anything but you might spend years trying to find it.
mr72 is right about a bunch of things. First, unless you really know what you are doing, a used bike is a pig in a poke (does anyone use that expression anymore?). However, if you sort out your own bike, you know what is going on with it. Second, many of us find great satisfaction in fixing problems and making things better; the GS500 is a good engine to work on. Also, do ride it until it starts running badly before you worry about a top-end job. Remember, if you are not going to ride it for a while, you'll need to do something about making sure the carbs stay clean. Others can talk to you about winterizing. I ride at least a little every week or so, so I don't have the winterizing problem.
@ajensen, ok thanks for those thoughts. It only had 15k/kms on it when I got it seemed not hard ridden, been very reliable, had a leaky stator which I fixed and and I can't fault it.
Took it to the bike shop for a compression test but they'd lent it out, but they also reckoned these bikes are bulletproof and that if it's riding well which it is, that I should just keep riding it. They suggested I run a couple of tanks of 98 octane through it and go for a bit of a burn up the highway.
Got some of this stuff to run though the tank http://www.supercheapauto.com.au/Product/Liqui-Moly-Carburetor-Valve-Cleaner-300mL/156710
I've bought an endoscope for 30 bucks and I'll still that down the cylinder and have a looks, not sure if I'll be able to see the valves but I'll get an idea of how much carbon is in there though. I've thought about maybe giving it a bit of a misting of water into the carbs but after viewing a few you tube videos on that I don't think it's very effective. Seems to be running fine so I'll put the valve cleaner through and a few tanks of 98 octane and give it a few more higher load highway runs and see what it looks like with the endoscope. But it's prolly not as serious at the moment as I might have imagined.
An Italian tune up might be in order https://en.wikipedia.org/wiki/Italian_tuneup
Quote from: user11235813 on November 24, 2017, 03:05:44 AM
if it's riding well which it is, that I should just keep riding it.
Yes to this.
QuoteThey suggested I run a couple of tanks of 98 octane through it and go for a bit of a burn up the highway.
This, however, makes no sense at all.
Quote
Got some of this stuff to run though the tank http://www.supercheapauto.com.au/Product/Liqui-Moly-Carburetor-Valve-Cleaner-300mL/156710
With any luck it won't hurt anything. Most likely won't help either, but who knows. I have run B12 mixed with the gas a couple of times in my bike, not that it needed it, just as a method to clean up whatever nooks and crannies I couldn't get to manually. IDK about this specific stuff, but the chances it will clean anything off the valves is slim if not zero.
Thing is, the carbon that flakes off easily will flake off when you run the bike at normal temperature. That's not the problem. But there is a carbon buildup that gets on the valves (and other parts of the cc including the top of the piston) that won't come off with any solvent. The normal course of action is wire wheel on a bench grinder to get it off, or chuck the valve in a drill press and use emery cloth to remove it. Or replace the valve along with the seat.
Thinking about it another way, if there is some kind of carbon that a solvent could loosen enough to chip off, would you want to chip it off? If it were along the edge of a valve then it would worsen whatever valve-sealing problem you have. And if a chip of it falls off it may find itself between the ring and the cylinder wall and score the cylinders or worse.
The head is not that hard to remove. So if you REALLY think you have carbon buildup you can tell by pulling the head and taking a look. Only cost is a head gasket and your time. Then if you find there's carbon you can decide to clean it, but you'll need some other tools. And it's going to be hard to talk yourself into putting the head back without doing the valve seats and stem seals. Then looking at the pistons staring you in the face it'll be hard to not pull the jug and do rings and clean up the pistons, then you've finished a top end rebuild.
Assume there is carbon buildup or some other cause of low compression. Worst case is you leave it alone, ride it, an it gets worse. Very worst case of getting worse is it winds up bending the valves. Eventually this will cause the bike to not run when hot, you will know something is bad wrong, and you will then have no choice but to remedy it. So by waiting for full-on failure to commence, you may add the full cost of replacement valves to the when there is a slight chance you might save some of that cost by machining the old valves if you do it now, but you probably wouldn't do that anyway. So really the choice is down to this: while the bike is running OK, do you preemptively do a top end rebuild now, or wait until it absolutely needs it? If it was me, I'd wait until it needed it, as long as you are not relying on this as your daily transportation. If it's your daily transportation, then I'd just find a time when it's convenient to be without the bike for 1-4 weeks and then do the rebuild then, knowing it will eventually need it. One way or the other, plan and budget for a top end rebuild (or whatever, get rid of the bike etc.) and beware that the bike may go from "running fine" to "won't run when hot" any day now until you do the top end rebuild. Could be a week, could be a year. But when that day comes, you will be forced to pay the piper.
@ mr72,
OK thanks for that comprehensive summation, plus some free gallows humour as well. Imagine if I took this in to have the bike serviced instead of checking the valves myself, they'd have simply measured the clearance and seen it in tolerance and given the bike back. Then I'd be riding it unaware that anything was amiss. I do take it for a lot of short rides so that could be an explanation. Yeah I was wondering about the higher octane thing, maybe he was thinking that a premium petrol might have better additives, but I do use fresh and good quality 91 though anyway.
I will take some pictures with the endoscope when it arrives and then run a couple of tanks of valve cleaner though and see what it looks like then.