5th Gen valve clearance inspection: something looks wrong. Is my cam timing off?

So I finally took my bike apart to do the valve clearance inspection. Going by the manual, the front cams align the way they're supposed to, such that when the 2T| and 4T| marks are in the TDC notch, the cam marks are parallel or perpendicular to the top of the cylinder head. However, on the rear cylinder, the cam marks are parallel or perpendicular to the top of the cylinder head when the :|F marks are in the TDC notch; when the 1T| and 3T| marks are in the TDC notch, the cam marks are slightly askew. The pictures below illustrate.

(1T|):|F

Cam position



1T| (TDC)

Cam position



(3T|):|F

Cam Position



3T| (TDC)

Cam Position


So I'm not entirely sure what's happening here, or what the consequences would be (The bike has always smelled like she's running rich, and there's been carbon buildup in the tailpipe... could this be why?), but one theory is that maybe the previous owner did a valve adjustment and put the cams back in wrong, so they were off a tooth. Can anyone tell me for sure what may have happened here, or what I should do about it? Should I ignore this and just check the clearances, or do I have to take the cams out and re-do this first (and probably end up needing to replace the shims to make them clear in the new, correct positions?)

 

Those timing marks are critical for cam timing, but not for valve clearance checks !! Worrying about the marks just confuses and wastes time.

All you need to do is rotate the engine so that each cam lobe is generally pointing away from the valve to be checked, In fact, anyplace the lobe is not contacting the valve is suitable for a clearance measurement.

 

Well I guess the question is I came here to do a valve clearance check, but found these timing marks off, so does this mean I need to fix the cam timing too? I really don't want to adjust the valves and then put the whole thing back together if I have another problem I need to fix still.

 

You didn't remove the cams dija ??

 

Not yet, but I'm going to have to in order to replace the shims, since there are valves out of tolerance on both sides. I'm not sure how to go about that process since I don't know what's up with the timing.

 

Not an easy job if you haven't done it once or twice. Only proceed with greatest caution as things can fuckup quickly if anything goes wrong. What were the clearances you found ?

 

I found 4 intakes at 0.05mm-0.11mm, and the rest except one at 0.13mm. Exhaust all within tolerances, though one was close at 27mm.

The inner intake valves on the front were really hard to measure, and incidentally were the furthest off at 0.05mm and 0.1mm

 

EvilStig, it DOES look like your cams are off a tooth. You are probably correct, previous owner was adjusting clearance (replacing shims) and did not time the cams properly.

Fortunately, one off tooth is not a huge issue, mostly running rough and burning bad, since bike does not have a knock sensor to detect mis-timed valvetrain.

I would disagree that valve adjustment and shim replacement is a complicated job, although it certainly is tedious.

Lastly, I use a straight edge or a think ruler to check for lines on the cams, I find that it is thin and sits nicely across heads. Eyeballing it is probably how you end up with one-off situations

 

what is your milage at ---- just curious

 

Your timing is definitely off by one tooth.
It is easy to do, the first time I did the shims, it took me three times to get one cam right.
Every time I would tighten the caps, the cam would rotate out by one tooth.
Once you get practice it is easy but tedious.
Pain in the arse job, but worth doing right and it saves you a lot of money.
Don't panic, have a go. It's not that hard.
Good luck.

 

MG & CH: Thanks for the tips! I'll have a stab at it tonight.

60,270. I bought the bike earlier this year at 38K. I'm starting to think I might wear it out eventually. It will be a sad day.

 

So after waiting weeks on gaskets I needed to put the cam covers back on, I finally have it all back together again, and it is idling and running much more smoothly than before, and not putting out as much unburnt fuel in the exhaust, so I do think that the timing being off was the problem.

Sadly, I did not park where the cogs fit together, since when I put it back together, the front intake cam timing mark was off by -half a tooth-, and since I don't know which way it was when I took it out, I couldn't put it back in exactly, so it may or may not be off a tooth from where it was before.

airbox was a PITA. I never want to do that again.