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Camshaft wear.

rustybronco

rustybronco

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After having measured the camshafts on my GS1000EC, finding two (??) lobes undersized and after having two sets measured trying to find a replacement- only finding one camshaft of the two still above the service limits. After sending two camshafts to Ivor (psyguy) to replace the worn below service limits on his GS850GT and now finding one of the exhaust lobes on Stans (flyboy) GS1100GKE camshaft under spec, I've come to the conclusion that the camshafts on our bikes are either not properly ground or improperly heat treated.

I've seen way to many undersized camshafts in just the small sample I've taken, for mine to be the only ones having this issue.

Stan's exhaust camshaft 1-2-3-4
1.3994 ~ 1.4075 ~ 1.3840 ~ 1.4080 (service limit 1.3965)


Intake camshaft 1-2-3-4
1.4265 ~ 1.4245 ~ 1.4285 ~ 1.4300 (service limit 1.4181)

I calibrated my 1~2" mic on 12-22-2012 with one our service tech's 1" standard and double checked the lobe reading with my Mitutoyo dial calipers. Both instruments read exactly 1.3840"

If you have your camshafts out for any reason may I suggest you measure yours for wear as well.
 
Last edited:
rustybronco said:
After having measured the camshafts on my GS1000EC, finding two (??) lobes undersized and after having two sets measured- only finding one camshaft still above the service limits. After sending two camshafts to Ivor (psyguy) to replace the worn below service limits on his GS850GT and now finding one of the exhaust lobes on Stans (flyboy) GS1100GKE camshaft, I've come to the conclusion that the camshafts on our bikes are either not properly ground or improperly heat treated.

I've seen way to many undersized camshafts in just the small sample I've taken for mine to be the only ones having this issue.

Stan's exhaust camshaft 1-2-3-4
1.3994 ~ 1.4075 ~ 1.3840 ~ 1.4080 (service limit 1.3965)


Intake camshaft 1-2-3-4
1.4265 ~ 1.4245 ~ 1.4285 ~ 1.4300 (service limit 1.4181)

I calibrated my 1~2" mic on 12-22-2012 with one our service tech's 1" standard and double checked the lobe reading with my Mitutoyo dial calipers. Both instruments read exactly 1.3840"

If you have your camshafts out for any reason may I suggest you measure yours for wear as well.
Click to expand...

Yep they wear and you are well advised to measure them when evaluating any cams. Don't just look for visual indications of wear.
 
posplayr said:
Yep they wear and you are well advised to measure them when evaluating any cams. Don't just look for visual indications of wear.
Click to expand...
No Jim, you can't tell by looking at them. But why am I seeing I seen so many bad ones?? that's what I can't understand. And it's not like the most wear is found on number four camshaft lobe either.
 
rustybronco said:
No Jim, you can't tell by looking at them. But why am I seeing I seen so many bad ones?? that's what I can't understand. And it's not like the most wear is found on number four camshaft lobe either.
Click to expand...

Yes as Ed says "To Measure is to Know", we are saying the same thing. :)
 
I've also seen worn cams before. Surprising considering how durable the shim and bucket engines are. The valve pockets hold a puddle of oil which assures the lobes get plenty of lube. My guess is the metal is a little soft. At any rate, good thing is the 750, 850 1000 and 1100G cams all interchange. Not sure about the cam drive sprockets but suspect they interchange too.
 
Ed, it's very surprising indeed and I never would have expected it either.
 
The 750 is a different cam, it fits but he lift and duration is different, for more high revving fun.
 
tkent02 said:
The 750 is a different cam, it fits but he lift and duration is different, for more high revving fun.
Click to expand...
So if the 750 cams are used in a 1000 will there be a noticable power difference ?I have many sets of 750 cams and a couple 1000"S:)
 
The timing difference between the 750 and 1000 is only a few degrees. Not enough to matter. Lift is slightly lower lift too, although again, it's not enough to matter.
 
hjfisk said:
So if the 750 cams are used in a 1000 will there be a noticable power difference ?I have many sets of 750 cams and a couple 1000"S:)
Click to expand...

Try it and see, it used to be one of the things people did to wake up a 1000.
If you have the cams sitting around, take an hour or two and throw a set in.
I have not done it myself so I can't say for sure, but the two engines are definitely different in their power delivery, the 750 has less low end grunt and comes on harder at a higher RPM.

The 750 and 850 feel much different as well, the two engines are identical except cylinder bore and cams. Same head and everything, but the 850 shares the more sedate 1000 cam.
 
tkent02 said:
Try it and see, it used to be one of the things people did to wake up a 1000.
If you have the cams sitting around, take an hour or two and throw a set in.
I have not done it myself so I can't say for sure, but the two engines are definitely different in their power delivery, the 750 has less low end grunt and comes on harder at a higher RPM.

The 750 and 850 feel much different as well, the two engines are identical except cylinder bore and cams. Same head and everything, but the 850 shares the more sedate 1000 cam.
Click to expand...
So the 850 uses the same head as the 750? this is good info. I may try that cam switch on 1 of the 1000's this winter , as I have to tear it down to do the head gasket anyway.
 
hjfisk said:
So the 850 uses the same head as the 750? this is good info. I may try that cam switch on 1 of the 1000's this winter , as I have to tear it down to do the head gasket anyway.
Click to expand...

The 1979 850 used the same head as the 1977 - 1979 750, identical part number and everything.

In 1980 on the 850 they went to the CV carbs, so the intake ports are bigger to fit them. In every other way the head is identical to the 1979 head.

In 1980 they went with the 16 valve head for the 750, it is an an entirely different engine.
 
tkent02 said:
The 1979 850 used the same head as the 1977 - 1979 750, identical part number and everything.

In 1980 on the 850 they went to the CV carbs, so the intake ports are bigger to fit them. In every other way the head is identical to the 1979 head.

In 1980 they went with the 16 valve head for the 750, it is an an entirely different engine.
Click to expand...
Yes I knew about the 80 750 being a 16 valve but I did not know that the earlier 750/850's shared the same head just different cams.
 
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