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Valve Clearance Check Question

Started by kevink, June 09, 2010, 12:50:18 AM

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kevink

Hey guys,

I'm in the process of checking the valve clearance. I have a haynes manual to guide me through it, but I'm a little confused at what seems to be contradictory information.

From my understanding, we're supposed to rotate the signal generator rotor until 1) the R-T mark aligns with the center of the signal generator (the one on right as seen if we're staring directly at right side of engine) and 2) the notches on the camshaft sprockets point inward toward one another. At this point, we can measure both intake valve clearances and right exhaust valve clearance. However, the manual also states that "the camshaft lobes must point away from the tappet as shown at A or B, Figure 97 to check valve clearance." I have the R-T mark aligned and the notches pointing toward each other on the inside now but when I look at the lobes, they're not anything like what FIG 97 shows. The lobe on left intake actually points toward the tappet. Furthermore, the 3/arrow mark on the intake cam and 2/arrow mark on the exhaust cam seem to have different orientations than what is shown in FIG101 on page 90 of the Haynes manual. Granted this is a 1989-2002 repair manual and the GS is a 2003, but I imagine it shouldn't be different.

My question is if this is unusual or if I'm doing this incorrectly/missing some information. I don't know much of the bike's maintenance history, but I'm wondering if perhaps the cams had been tampered with previously and were not reinstalled correctly?

Not sure if this is related, but the bike also has a stalling issue when coming to a stop, no throttle applied, clutch in. I've cleaned the carbs, checked hosing, checked for leaks, checked float height, and now just am checking the valve clearance as per another thread I found.

I have photos but can't find my cord at the moment but will get pictures up soon.








current stable: gs500e(work in prgoress), xr600r
old ride: f650

romulux

If the lobes aren't aligned correctly the first time you align the signal generator with the RT mark, turn the bolt at the signal generator one complete turn and you should be where you want to be.

One complete turn is I think half (?) an engine rotation, so the cams will face a different direction.
GS500K1

I don't know anything about anything.  Follow suggestions found on the internet at your own risk.

marcusk

I have seen clips for this on you tube from start to finish.  if you are like me those fancy moving pictures help allot

kevink

Quote from: romulux on June 09, 2010, 03:38:00 AM
If the lobes aren't aligned correctly the first time you align the signal generator with the RT mark, turn the bolt at the signal generator one complete turn and you should be where you want to be.

One complete turn is I think half (?) an engine rotation, so the cams will face a different direction.

Hmm, so is the orientation of the notches actually not important then? If I do give it half a rotation, I can get the cam lobes to face away from tappets correctly, but the notches no longer faces each other. So, it's a bit conflicting in what the book instructs to what I'm seeing as faulty. Is it really important to measure clearance with the R-T mark?



current stable: gs500e(work in prgoress), xr600r
old ride: f650

gsJack

#4
I just did my 21st GS500 valve adjustment last Sunday and aligned the L-T mark on the rotor with the coil to the upper right.  I never saw a Haynes manual but do have the Clymers and seem to remember having some confusion the first time about 11 years ago.

Align the L-T mark with the upper right coil as viewed from the right side of the engine with the cam notches pointing inward towards each other and the right intake and exhaust and left intake valves are ready to check.  The cam lobes for those three will then be away from the valve axis and the left exhaust will be compressed.

Then turn the crank clockwise one full turn which will rotate the cams one half turn making the notches point out away from each other and align the same coil/marks.  The left exhaust valve will then be in position for measuring the gap.  It is important to align the notches and timing marks properly to get an accurate measurement. Measuring with the cam lobes pointed directly away from the valves will give an inacurate reading.  
407,400 miles in 30 years for 13,580 miles/year average.  Started riding 7/21/84 and hung up helmet 8/31/14.

utgunslinger13

GSjack,

If you were to measure with the cam lobes eyeballed to be pointed away from the shims, but not using any of the alignment marks as a reference, how could this affect your measurements?  When I measured mine, I aligned the R-T mark with the upper right coil then measured the 3 open valves.  But when it came time to measure the left exhaust I just dropped it in gear and turned the wheel till the cam was pointing away from the valve.  Will this cause an inacurate reading?
Check out my current project build:

http://gstwins.com/gsboard/index.php?topic=41982.0

gsJack

This thread is causing an old man a lot of brain strain trying to remember things from 11 years ago.   :icon_lol:   When I started checking valve clearances on the 97 GS the first time I just turned the cam lobes away from the valve as I had done with bike and car engines for decades and got readings that were too tight making it look like they needed shim changes already.  I then checked the Clymers Manual and did it with the cams on the alignment marks and found all valve clearances were OK.  I didn't actually change any shims on that 97 engine until about 40k miles.  The amount they were different was not great maybe about .001-.002" tighter at most with the cam lobe turned away from the valve.  If you got spec clearance on the left exhaust valve that way then you might actually have a bit more clearance if rechecked on the marks, I wouldn't worry about it now just check the right way the next time.  I like the exhaust valves a bit on the loose side anyway.
407,400 miles in 30 years for 13,580 miles/year average.  Started riding 7/21/84 and hung up helmet 8/31/14.

gsJack

#7
Quote from: kevink on June 09, 2010, 12:50:18 AM

..........from my understanding, we're supposed to rotate the signal generator rotor until 1) the R-T mark aligns with the center of the signal generator (the one on right as seen if we're staring directly at right side of engine) and ..................


I just took a look at the Suzuki 89-99 GS500 Shop Manual and it clearly says the R-T mark is lined up with the coil on the left and shows the left one in it's sketch.  So it's actually the L-T mark that aligns with the right coil.  This must be where my confusion originated from using the Clymer manual which is like the original shop manual.  I copied that original Shop Manual page and it also shows where the cam lobes point when the cams are in the checking position.  Not too clear but here it is:

http://img.photobucket.com/albums/v443/jcp8832/manual_valve_adjust.jpg

Edit:  Just took a pic of my 02 pickup coils with rotor in position to check valves and the position of the cam notches either turned inward or turned outward determines which ones are to be checked:



Interesting, my 02 Rotor is marked L-T only and not with a R-T like in the manuals.  My 97 was marked R-T on the back side and that mark is what lines up with the left coil when setting the valves.  Both the 97 and 02 are done exactly the same way as shown in the pic above.

407,400 miles in 30 years for 13,580 miles/year average.  Started riding 7/21/84 and hung up helmet 8/31/14.

kevink

Hey,

Yeah, thanks for the clarification. I followed procedures with respect to left signal generator, but the lobe orientations were still off. Whoever was working on the bike previously had installed the camshafts incorrectly (I'm assuming this was causing it to run funky and stall on deceleration as if the valves were not adjusted correctly, although I'll still check valve clearance once I have it torqued properly) . Anyways, I've corrected that and was in the process of putting her back together until I sheared one of the cap bolts...boy, I should have done it by feel instead of using the torque wrench. Anyways, I've never had this happen before. Does anyone have any experience with extracting it? I recall in the past that some people drill into the bolt, the remove reverse it out?

current stable: gs500e(work in prgoress), xr600r
old ride: f650

kevink

Actually, on the topic of bolt extractors, does anyone have a recommendation for a "good" quality screw extractor kit (complete)?
current stable: gs500e(work in prgoress), xr600r
old ride: f650

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