Hi Guys,

Just wondering if anyone has a clue of what is going on with my bike. Since I serviced it and changed 1 inlet shim from a 262 to a 265, the bike seems to sound different (very burbley) and lacks power on takeoff, when it gets to around 5k it seems to be ok again. I only use Motul oil and NGK sparkplugs, could it be a bad batch of fuel?

Put the old shim back in see what happens 

I'll try that! but then it will be out of tollerance again. right now its at 0.06mm which is near enought to perfect

Running at .03mm clearance is still in spec and won't hurt anything if you are just running it long enough to find out if that is the source of your problem. My guess is the problem is something else they messed with.

Quote from: Bluesmudge on November 21, 2011, 04:28:03 PM
My guess is the problem is something else they messed with.

They??

The way I read it the O/P did the work 

yeah I did the work, didn't change anything else. just doesn't sound the same and seems to lack grunt on take off!

also with the original 262 shim the clearance was 0.13, 0.05 above tolerance. but when i put in the 265 cleaance was 0.06. i know the math doesn't work, but I tried a 270 first and had no clearance at all!

Seems unlikly that changing the shim would make such a dramatic difference.
How did you change the shim? Did you take the cams out? (No reason why you should).
What else did you do during the service? Clean or change the air filter? Thinking if it's a K&N drop in the restrictor may be dislodged.

yep cleaned the k&n air filter, I'll check the restrictor! that may explain it, too much air! thanks mitch

Quote from: Aussie GS500F 06 on November 21, 2011, 03:51:55 PM
Hi Guys,

Just wondering if anyone has a clue of what is going on with my bike. Since I serviced it and changed 1 inlet shim from a 262 to a 265, the bike seems to sound different (very burbley) and lacks power on takeoff, when it gets to around 5k it seems to be ok again. I only use Motul oil and NGK sparkplugs, could it be a bad batch of fuel?

Just to be clear.. You decreased clearance by .03mm? Clearance almost never widens on the GS500... The only reason you'd typically want to install a larger shim is if the gap was set wrong during a previous adjustment, or you have *very very very* unusual wear to the cams.

If your valves were tight with the 262 clearance, they are going to be excessively tight at 265, perhaps even partially open. it's not unusual to see bikes with .03mm of clearance at 4K miles... So, possible you now have zero clearance? 262 sounds like one of the original shims the bike came with. I've seen those oddball sizes on factory bikes; most of the aftermarket shims I've seen come in standard increments of .05mm.

Quote from: burning1 on November 21, 2011, 07:20:06 PM

Quote from: Aussie GS500F 06 on November 21, 2011, 03:51:55 PM
Hi Guys,

Just wondering if anyone has a clue of what is going on with my bike. Since I serviced it and changed 1 inlet shim from a 262 to a 265, the bike seems to sound different (very burbley) and lacks power on takeoff, when it gets to around 5k it seems to be ok again. I only use Motul oil and NGK sparkplugs, could it be a bad batch of fuel?

Just to be clear.. You decreased clearance by .03mm? Clearance almost never widens on the GS500... The only reason you'd typically want to install a larger shim is if the gap was set wrong during a previous adjustment, or you have *very very very* unusual wear to the cams.

If your valves were tight with the 262 clearance, they are going to be excessively tight at 265, perhaps even partially open. it's not unusual to see bikes with .03mm of clearance at 4K miles... So, possible you now have zero clearance? 262 sounds like one of the original shims the bike came with. I've seen those oddball sizes on factory bikes; most of the aftermarket shims I've seen come in standard increments of .05mm.

I was thinking the same thing.......I have never heard of a valve being loose....they always tighten up!  Somebody asked, and the OP never answered..."did you take the cams out of the bike?, or swap shims with the cams in place?"  It almost sounds to me like you might have not adjusted the valves right, or did not put the cam chain back on right if you removed the cams for shim-swapping...either one will mess up the timing and give you really bad running symptoms....

If neither of these are true, how old is the fuel in the tank?

Also, did you rotate the engine through a couple of revs after changing shims? Often oil gets under the shim, and produces a false clearance reading. Turning the engine over a couple of times using a breaker bar will get you a better reading on the running clearance. Agreed about the cam chain timing thing... Again, if you set the timing you must run the engine through a few revs by hand and re-check. Often, the timing won't be correct.

Rule of thumb: Double check every thing you touch under the valve cover after manually turning the engine through a few cycles. Saves a lot of time and headache.

Nope Cams wern't removed! bucket was pushed down and shim was removed. and yes decresed the clearance by 0.03....manual states that clearance should be between 0.03 and 0.08. my clearance was 0.13mm so adding 0.03mm should have given me a clearance of 0.10mm but I found after fitting the shim that the clearance was only 0.06mm...checked it several times. talked with a BMW master tech and he said that that is usual! and yes rotated the engine quite a few times, i had read about the oil building up underneath the shim and it giving a false reading

As for fuel I ride regulary and go through a tank every 2 weeks. but thinking about the last time I filled up, it was at a small chain service station.

Clearance almost never widens on the GS500... The only reason you'd typically want to install a larger shim is if the gap was set wrong during a previous adjustment, or you have *very very very* unusual wear to the cams.
why is this the case? you would expect it to wear and gaps increase. after all it is metal against metal with a thin smear of oil in between?

Quote from: Aussie GS500F 06 on November 21, 2011, 08:25:01 PM
Nope Cams wern't removed! bucket was pushed down and shim was removed. and yes decresed the clearance by 0.03....manual states that clearance should be between 0.03 and 0.08. my clearance was 0.13mm so adding 0.03mm should have given me a clearance of 0.10mm but I found after fitting the shim that the clearance was only 0.06mm...checked it several times. talked with a BMW master tech and he said that that is usual! and yes rotated the engine quite a few times, i had read about the oil building up underneath the shim and it giving a false reading

As for fuel I ride regulary and go through a tank every 2 weeks. but thinking about the last time I filled up, it was at a small chain service station.

Clearance almost never widens on the GS500... The only reason you'd typically want to install a larger shim is if the gap was set wrong during a previous adjustment, or you have *very very very* unusual wear to the cams.
why is this the case? you would expect it to wear and gaps increase. after all it is metal against metal with a thin smear of oil in between?

I am suspect of the initial reading of the specs....if they spec'ed at .13, and you added .03mm, that would give you a spec of .10mm......If it did not, then the initial measurement was wrong.  I would pull the cover and re-check the valve clearance specs-document, then spin the crank around a few times-ensure the cams are at the proper position-and re-measure.

Post up with the findings.

Quote from: Aussie GS500F 06 on November 21, 2011, 08:25:01 PM
Clearance almost never widens on the GS500... The only reason you'd typically want to install a larger shim is if the gap was set wrong during a previous adjustment, or you have *very very very* unusual wear to the cams.
why is this the case? you would expect it to wear and gaps increase. after all it is metal against metal with a thin smear of oil in between?

.13 on the intake or on the exhaust? A few of us have experimented with wider exhaust valve clearances... Factory recommends .03-.08, but we found that .08-.12 works better. We found that with .12mm valve clearances, the exhaust valve wear is significantly reduced, and valve adjustment intervals go up dramatically. Less maintenance required, and a strong indication of a happy, healthy engine.

You're right that wear occurs during normal operation of the engine. However, the most significant wear is to the valve seat - the part of the head behind the valve. As the valve seat wears, the valve recedes into the head, causing the end of the valve to get closer to the cam lobe. If there is insufficient clearance between the end of the valve (technically the bucket) and the back of the valve lobe, the valve doesn't seat quite properly against the head. It heats up, wear accelerates, and eventually damage occurs.

If the valve clearances expand, it indicates that the buckets, cam lobes, cam bearings, or cam journals are wearing faster than the valve is receding into the head. That kind of wear would be incredibly abnormal, and to me would indicate damage, severe oil system failure, or bad materials.

Keep in mind that the maximum permitted wear on the camshaft journals is only .15mm, where the valves will typically recede into the head as much as 1mm over a 100,000 mile lifetime of the engine.

the clearance was on the intake RHS.

I can now see why they usually decrease in cleannce, as the head/ valve seat is made from alloy and cams/shims case hardened steel! maybe a recheck is needed, the bike has done 33k and I'll need to hang onto it for quite a while longer so I don't want any premature damage to occur because of something as simple as checking and maybe replacing a shim.

Thanks for the lesson!

looks like it will be a job for the weekend!

Ok dumb question, but since I plan on doing valves soon and I have yet to rebuild a head on a motor, I have a simple question.


At which point do you measure the clearance of the actual valve bore?  For example, I understand how adding shims brings you to the appropriate clearance, but how do you measure the gap originally?  Is every valve head have a standard clearance of .13mm? 


Thanks!

Quote from: NickyNumbers on November 22, 2011, 05:57:48 AM
Ok dumb question, but since I plan on doing valves soon and I have yet to rebuild a head on a motor, I have a simple question.


At which point do you measure the clearance of the actual valve bore?  For example, I understand how adding shims brings you to the appropriate clearance, but how do you measure the gap originally?  Is every valve head have a standard clearance of .13mm? 


Thanks!

You should check the valve clearance soon after getting a used bike to get a baseline for the clearance...that way, if they move in the future, you will know how much they are actually moving. As stated above, the valvetrain on these bikes should last for 100,000 miles.  No, the factory specs are .03-.08mm acceptable tolerance for all four valves set from the factory.  Some on here have experimented with widening that gap to .10mm on the exhaust valves with good results. 

A valve that is too tight will usually act up as it is warming up and at lower revs.
Of course if it is far too tight, yes it will act up all the time.

The GS valve wear pattern isn't all that definite. I'd not guess which way yours could be going, but mine with 48K miles was always going loose. I had to get thicker and thicker shims through out its life with me starting @ 15K or so @ the first valve adjustment.

Kawasaki's ninja series bikes usually wear tight ... they do have the valves sinking into the head.
Cool.
Buddha.

Sorry I've been flat out, checked the valve clearance again and everthing was fine! the air cleaner restictor was not in properly, but it still ran poorly, when I refilled the tank I made sure that I used premium fuel, problem fixed..must of had some old crappy fuel, from when I filled up previously