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Exhaust cam wear on a TSCC (16 valve)

  • Thread starter Thread starter oblique
  • Start date Start date
O

oblique

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Just opened up the valve cover to take a peek...the lobes have lines worn into the centre that I can feel with my fingernail similar to this:



How much longer can I use this camshaft and is this typical of these motors? Bike is a 1980 750L.
 
All too common for that model engine. The one and only unreliable GS engine. Not sure about longevity. Shimming the oil pressure relief spring is reputed to help force more oil to the various parts in need.
 
80-82 1100e cams work as well. You have to swap gears but the exhaust is identical and intake gives a boost, needs a small main jet bump to match
 
This spring - where is it found?

Thanks for the swap suggestion but I'm on the tail end of a rebuild and cant wait to finish.

I just check the clearances - most of the valves were tight but only by .001 from minimum (0.004) - I suppose this is an oiling issue but what about their proximity to the extra heat from the exhaust directly below?
 
oblique said:
This spring - where is it found?

Thanks for the swap suggestion but I'm on the tail end of a rebuild and cant wait to finish.

I just check the clearances - most of the valves were tight but only by .001 from minimum (0.004) - I suppose this is an oiling issue but what about their proximity to the extra heat from the exhaust directly below?
Click to expand...

Oiling is easier to deal with that rerouting the exhaust
 
oblique said:
Just opened up the valve cover to take a peek...the lobes have lines worn into the centre that I can feel with my fingernail similar to this:



How much longer can I use this camshaft and is this typical of these motors? Bike is a 1980 750L.
Click to expand...

Not sure what you are calling wear. My cam looks just like that, though there is no pitting or signs of any thing bad. The line is from the pad that runs on the cam. there is a space between the pad so it leaves that line. Take a closer look at your cam. And as far as it being "The one and only unreliable GS engine" naw I don't buy it. Mine has 56,000+ miles and haven't touched the engine internals at all. Good oil, new filters and good maintenance is the key.
 
I will let the photos speak for themselves. The lobe pictured is one that happened to be facing up - the rest are all cut deeper on either side of the groove left by the space on the valve 'tappet'. Motor has 55,000 kilometers.


 
Last edited:
My Valve Adjustment

My Valve Adjustment

^^Wow!

When I did the valve adjustment on my "T", the lobes did not have the wear as seen on this cam. The pics in this thread aren't that great but you can see they aren't as bad as the ones above: http://www.thegsresources.com/_forum/showthread.php?t=215260

I'm with MrBill on the reliability thing mentioned by nessism. If you take care of the maintenance it will provide years of happiness.



Ed
 
That may be true but it wouldnt explain why my intake cam has no wear or even any discoloration. If poor maintenance is the culprit then it wouldve affected both cams.
 
I experienced a similar situation on a Yamaha, when Chevron changed their recipe on Delo oil. It cost me a cam and rockers
 
Valve Adjustment

Valve Adjustment

oblique said:
That may be true but it wouldnt explain why my intake cam has no wear or even any discoloration. If poor maintenance is the culprit then it wouldve affected both cams.
Click to expand...

The only thing I can think of is...

If the VALVES are not set at exactly the same clearances (On both CAMS), then I'm thinking this would explain why one side is messed up.

Oil flow to the Cam may also be a problem. Getting technical now...



Ed
 
Last edited:
oblique said:
I will let the photos speak for themselves. The lobe pictured is one that happened to be facing up - the rest are all cut deeper on either side of the groove left by the space on the valve 'tappet'. Motor has 55,000 kilometers.


Click to expand...

Okay, now that is a different story now that we can see your cams. Mine do not look like that at all save for the line in between.
 
oblique said:
That may be true but it wouldnt explain why my intake cam has no wear or even any discoloration. If poor maintenance is the culprit then it wouldve affected both cams.
Click to expand...

Just curious how you ride it? Gentle, not winding it out much or do you race the crap out of it at every opportunity? Maybe a lot of highway cruising?
 
The bike was ridden from Toronto to Vancouver, up to Alaska and back by the previous owner. The rest of its life was spent locally I believe. Cant speak of riding style except that the stock exhaust was ditched for a 4-1 system at some point if that may be a clue.
 
OK, I was thinking if someone babied it maybe it never got the oil punp going fast enough, but that's probably not it.

You want that camshaft?
 
That is an oiling issue. Period.
Your head may be toast. Take out the cams and see what the cam journals look like.
 
oblique said:
That may be true but it wouldnt explain why my intake cam has no wear or even any discoloration. If poor maintenance is the culprit then it wouldve affected both cams.
Click to expand...
PO might have been running it on ditch oil or stupidly extended change intervals - there's no telling. Even if he'd paid some attention to it, the oil of choice might have simply ran out of protection in the more hostile environment of the exhaust cam lobes.
 
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