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Falco
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PostPosted: 18:57 - 16 Apr 2017    Post subject: Valves Wearing? Reply with quote

Just calculated new shim sizes to adjust clearances, every valve was very tight and a couple of the new shims will be as low as 130.

There won't be much adjustment left when these are replaced, is this a sign the valves themselves are wearing?
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Nobby the Bastard
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PostPosted: 19:29 - 16 Apr 2017    Post subject: Re: Valves Wearing? Reply with quote

Falco wrote:
Just calculated new shim sizes to adjust clearances, every valve was very tight and a couple of the new shims will be as low as 130.

There won't be much adjustment left when these are replaced, is this a sign the valves themselves are wearing?


No. it's more the case that the valve seat gets crushed and the valve stem stretches.
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Falco
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PostPosted: 23:13 - 16 Apr 2017    Post subject: Re: Valves Wearing? Reply with quote

Nobby the Bastard wrote:
Falco wrote:
Just calculated new shim sizes to adjust clearances, every valve was very tight and a couple of the new shims will be as low as 130.

There won't be much adjustment left when these are replaced, is this a sign the valves themselves are wearing?


No. it's more the case that the valve seat gets crushed and the valve stem stretches.


Interesting, does this amount to the same thing (valves needing replaced in the near-ish future)?

I've only had rocker type valves before, but is that a lot of crushing/stretching for 23K? Shims only go down to 120, so there isn't much further down I can go?
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Kickstart
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PostPosted: 23:29 - 16 Apr 2017    Post subject: Reply with quote

Hi

Other thing that happens is the valve seats wear, so the valve is closer to the cam. Fix for that is head off and new valve seats.

Or bodge it and grind the shims down a touch

All the best

Katy
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Pete.
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PostPosted: 00:10 - 17 Apr 2017    Post subject: Reply with quote

Never heard of valve stems stretching. Clearances close because the valve sinks into the seat.
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Falco
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PostPosted: 00:27 - 17 Apr 2017    Post subject: Reply with quote

Kickstart wrote:
Hi

Other thing that happens is the valve seats wear, so the valve is closer to the cam. Fix for that is head off and new valve seats.

Or bodge it and grind the shims down a touch

All the best

Katy


Pete. wrote:
Never heard of valve stems stretching. Clearances close because the valve sinks into the seat.


Laughing These replies are not quite what I was hoping to hear.

I guess I have 3 questions based on this:

1) Is this kind of wear normal for 23K? I can't imagine the engine lasting to 100K if it keeps chewing up valves/seats at this rate

2) How hard is it to change valve seats? Job for a mechanic and many monies or a home job?

3) How thing can a shim be before it becomes a problem - how thin can they be ground before the valve seat has to be replaced to avoid damage?...asking for a friend Shifty
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jaffa90
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PostPosted: 01:15 - 17 Apr 2017    Post subject: Reply with quote

""""""""""""1) Is this kind of wear normal for 23K? I can't imagine the engine lasting to 100K if it keeps chewing up valves/seats at this rate."""""""""""""""""""""""""""
Have you a picture of the spark plugs and the mileage they have done?
Also have you heard the cooling fan kick in and when?
When was the last coolant change done?
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Pete.
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PostPosted: 08:32 - 17 Apr 2017    Post subject: Reply with quote

No idea what bike it is but in general shim under bucket valves usually do impressive mileages without adjustment. At 23k miles I would have expected no more than one minor adjustment and only a size or two at that. If he's getting down to minimum shim size at that mileage I would say it's going to get very expensive sometime soon.
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Kickstart
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PostPosted: 09:48 - 17 Apr 2017    Post subject: Reply with quote

Hi

Not sure on the bike. On some (eg, Yamaha FZ750) at 23K they are not even due to have been checked for the first time (and being terminally lazy I left mine until 60k). In general they rarely need changing. But if a very old bike (from before unleaded fuel being used in the USA for example) then they might not have hardened valve seats.

Shim safe thickness will depend on on the design. Personally I am dubious about grinding them down (for a start it is going to be bloody annoying the next time you do the valves, and choose the shim sizes based on what is written on the current shims). If you do then it needs to be done very carefully and accurately. Some are under bucket, some on top of the bucket. Some bike spit them shims out occasionally at the best of times.

Changing valve seats is a fairly specialised job. I would expect most mechanics would remove the head and send it away, or if a fairly common engine just tell you to source a 2nd hand engine as being a cheaper and quicker solution.

All the best

Katy
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Falco
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PostPosted: 12:28 - 17 Apr 2017    Post subject: Reply with quote

jaffa90 wrote:
""""""""""""1) Is this kind of wear normal for 23K? I can't imagine the engine lasting to 100K if it keeps chewing up valves/seats at this rate."""""""""""""""""""""""""""
Have you a picture of the spark plugs and the mileage they have done?
Also have you heard the cooling fan kick in and when?
When was the last coolant change done?


No sorry, I put new spark plugs in about 700 miles or so ago, I doubt they will show anything. The old ones came with the bike and I have no idea what their millage was, they looked fine, perhaps a touch lean but it was marginal.

I have not heard the cooling fan at all, but the temperature gauge is always at the bottom by the time I stop at each end (there are longish runs to allow it to cool). The gauge does work and goes up and down as I'd expect on warm days and in heavy traffic.

Last Coolant change was about 500 miles ago, no idea before then (I did around 500-600 on the old coolant, but the temp gauge has never gone above the 1/3rd mark)


Pete. wrote:
No idea what bike it is but in general shim under bucket valves usually do impressive mileages without adjustment. At 23k miles I would have expected no more than one minor adjustment and only a size or two at that. If he's getting down to minimum shim size at that mileage I would say it's going to get very expensive sometime soon.


It's a CB500S (2001). It's very odd, the shims in there were all fairly big (210 down to 192) but considering the odd sizes I assume it has been done at some point, so I am uncertain why the clearances have closed so much in such a short time/millage.


Kickstart wrote:

Hi

Not sure on the bike. On some (eg, Yamaha FZ750) at 23K they are not even due to have been checked for the first time (and being terminally lazy I left mine until 60k). In general they rarely need changing. But if a very old bike (from before unleaded fuel being used in the USA for example) then they might not have hardened valve seats.

Shim safe thickness will depend on on the design. Personally I am dubious about grinding them down (for a start it is going to be bloody annoying the next time you do the valves, and choose the shim sizes based on what is written on the current shims). If you do then it needs to be done very carefully and accurately. Some are under bucket, some on top of the bucket. Some bike spit them shims out occasionally at the best of times.

Changing valve seats is a fairly specialised job. I would expect most mechanics would remove the head and send it away, or if a fairly common engine just tell you to source a 2nd hand engine as being a cheaper and quicker solution.

All the best

Katy


Bike is from 2001, so it's not that. Definitely seems like something is wrong with this amount of wear. After some consideration I went for a shim set, to cover me for future adjustments as well, without the hassle.

If changing the engine is the cheaper solution, that sounds like a pretty expensive (£180+ on ebay for the really scabrous ones and that doesn't even cover labour costs to get the old one out and the new one in).
I don't seem to have much luck getting bikes with healthy engines.
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Tdibs
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PostPosted: 16:20 - 17 Apr 2017    Post subject: Reply with quote

May sound obvious, but are you 100% the timing was correct when you measured the clearances? First time I did mine I was very slightly off and got similar results that had me WTFing. Re-measured to make sure and I had the timing just a little bit off.
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Falco
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PostPosted: 19:03 - 17 Apr 2017    Post subject: Reply with quote

Tdibs wrote:
May sound obvious, but are you 100% the timing was correct when you measured the clearances? First time I did mine I was very slightly off and got similar results that had me WTFing. Re-measured to make sure and I had the timing just a little bit off.


No, in the sense that this is the 1st time checking valves buckets under shims. Lining up the T- mark on the rotor with the notch on the case meant that the IN- And EX-marks on the cam sprockets didn't quite line up with the casing (for cylinder 1). In the end I used the marks on the sprockets rather than the notch on the rotor. The cam lobes were pointing away from each other at 50-60 degrees angle.

As far as I can tell I followed the instructions correctly. I'll be turning it over by hand a couple of times with the new shims, any suggestions of places I might be going wrong to double check once that is done?
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yen_powell
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PostPosted: 19:59 - 17 Apr 2017    Post subject: Reply with quote

Did you have the points of the cam lobes facing away from the bucket when you read the gaps?

Are you using metric feeler gauges?
Did you measure the gaps with a cold engine?
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Falco
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PostPosted: 20:40 - 17 Apr 2017    Post subject: Reply with quote

yen_powell wrote:
Did you have the points of the cam lobes facing away from the bucket when you read the gaps?

Are you using metric feeler gauges?
Did you measure the gaps with a cold engine?


The cam lobes were pointing like this when I took the readings:

https://i63.tinypic.com/wwep9f.jpg

yes, metric feeler gauges (or rather the metric readings on the gauges)

Yes, engine was cold, off for 2 days except for a quick 1 min run to make sure oil wasn't leaking after refitting alternator cover, the day before checking.
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Robby
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PostPosted: 20:55 - 17 Apr 2017    Post subject: Reply with quote

Either the engine is terminal - in which case I wouldn't waste the money on shims and would just ride it til it dies and then change the engine - or you cocked up the measurement.

The majority of the problems inside the engine that I see are down to someone misdiagnosing a problem or cocking up a routine bit of maintenance and deciding to strip the engine.

This gives memorable things like "It's misfiring, must be rings, I'm going to change the rings" (spark plug was loose), or "It's burning oil, must be the valve stem seals, I'm going to rebuild the head" (oil filter was loose).
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Falco
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PostPosted: 21:15 - 17 Apr 2017    Post subject: Reply with quote

Robby wrote:
Either the engine is terminal - in which case I wouldn't waste the money on shims and would just ride it til it dies and then change the engine - or you cocked up the measurement.

The majority of the problems inside the engine that I see are down to someone misdiagnosing a problem or cocking up a routine bit of maintenance and deciding to strip the engine.

This gives memorable things like "It's misfiring, must be rings, I'm going to change the rings" (spark plug was loose), or "It's burning oil, must be the valve stem seals, I'm going to rebuild the head" (oil filter was loose).


Honestly, I'd be happy to say that its human error on this one, but as far as I can tell, I have done the checking correctly.

Only thing I can think of is that I have seen a couple of how-to-s that show the cam lobes as pointing away from each other horizontally, rather than at an angle. The problem is, if I do that, the the marks on the sprockets won't be level with the engine casing (which is specifically mentioned in the haynes).

I suppose I could put it back together tomorrow with the old shims and try adjusting and checking again...
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Kickstart
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PostPosted: 23:55 - 17 Apr 2017    Post subject: Reply with quote

Falco wrote:
If changing the engine is the cheaper solution, that sounds like a pretty expensive (£180+ on ebay for the really scabrous ones and that doesn't even cover labour costs to get the old one out and the new one in).
I don't seem to have much luck getting bikes with healthy engines.


If it does need major work then a cylinder head gasket is £36, inlet valve is £18 and exhaust valve is £30. So just replacing the valves will cost ~£230 +vat just in parts (Honda parts from Fowlers). The ebay engine sounds a bit cheaper now!

All the best

Katy
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jaffa90
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PostPosted: 00:32 - 18 Apr 2017    Post subject: Reply with quote

Just found this,
https://www.motorcyclenews.com/news/new-bikes/2013/july/jul0413-honda-cb500-valve-clearance-shock/
It sounds like a cover up for inferior valves or seats.
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trevor saxe-coburg-gotha
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PostPosted: 04:28 - 18 Apr 2017    Post subject: Reply with quote

Falco wrote:
It's a CB500S (2001).


Falco wrote:
Bike is from 2001,

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Falco
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PostPosted: 14:01 - 18 Apr 2017    Post subject: Reply with quote

Kickstart wrote:
Falco wrote:
If changing the engine is the cheaper solution, that sounds like a pretty expensive (£180+ on ebay for the really scabrous ones and that doesn't even cover labour costs to get the old one out and the new one in).
I don't seem to have much luck getting bikes with healthy engines.


If it does need major work then a cylinder head gasket is £36, inlet valve is £18 and exhaust valve is £30. So just replacing the valves will cost ~£230 +vat just in parts (Honda parts from Fowlers). The ebay engine sounds a bit cheaper now!

All the best

Katy



They both sound expensive! ~200 before labour? That's a lot of money for a bike with less than 25K on it.

Put the cams back in and checked 2 of the clearances clearances, still the same Sad

Can someone confirm that the lobes are pointing in the correct direction to take the clearances? The IN- and EX- marks are both lined on the engine casing in this position, though the T mark on the rotor is a fraction off from the notch in the inspection hole

https://i65.tinypic.com/2h64yuq.jpg
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A100man
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PostPosted: 14:49 - 18 Apr 2017    Post subject: Re: Valves Wearing? Reply with quote

Falco wrote:
Just calculated new shim sizes to adjust clearances, every valve was very tight and a couple of the new shims will be as low as 130.

There won't be much adjustment left when these are replaced, is this a sign the valves themselves are wearing?


Hang on, if they are that bad (tight) you wouldn't be able to get a feeler in there at all. Not mixing metric and imperial measurements by any chance are you? What measurements are you actually getting with the old shims?
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Falco
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PostPosted: 15:45 - 18 Apr 2017    Post subject: Re: Valves Wearing? Reply with quote

A100man wrote:
Falco wrote:
Just calculated new shim sizes to adjust clearances, every valve was very tight and a couple of the new shims will be as low as 130.

There won't be much adjustment left when these are replaced, is this a sign the valves themselves are wearing?


Hang on, if they are that bad (tight) you wouldn't be able to get a feeler in there at all. Not mixing metric and imperial measurements by any chance are you? What measurements are you actually getting with the old shims?


Why wouldn't I be able to get a feeler in? For the 1st exhaust valve with a clearance of 0.178mm, a shim size of 0.210 and a specified clearance of 0.260, gives a replacement shim size of 0.130. I can easily get a 0.15 feeler into that gap.

The measurements:

https://i63.tinypic.com/2jfysyx.jpg

The left hand circle is for cylinder 1, the right for cylinder 2

Sadly I don't think it is as simple as a metric/imperial mix up. Tried it with my old set of feelers which are metric only (but don't have the same level of gradation) but still couldn't get the 0.15 feeler into the 1st inlet (C).
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iansoady
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PostPosted: 16:22 - 18 Apr 2017    Post subject: Reply with quote

I like to have the base circle definitely on the follower, ie opposite the peak. You are turning the engine over between measurements, niot trying to do them all in one position, aren't you?
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Falco
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PostPosted: 18:51 - 18 Apr 2017    Post subject: Reply with quote

iansoady wrote:
I like to have the base circle definitely on the follower, ie opposite the peak. You are turning the engine over between measurements, niot trying to do them all in one position, aren't you?


tried it with peak facing 180 degrees away from the follower, marginal difference. The engine has to be turned over to change from cylinder 1 to 2, but I took them again and turned the engine over between each measurement, no change.

At this rate I am tempted to take it to a garage to see if they get the same readings or if I am just being exceptionally dense.
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Fizzer Thou
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PostPosted: 21:53 - 18 Apr 2017    Post subject: Reply with quote

It may well be that the valves are like this and worn unevenly (new valve on the right)

https://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/Workshop/CIMG2957.jpg

The new valves were lapped in and gave a perfect seal.Sometimes the seats need to be recut,but in this instance it was not necessary Thumbs Up
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