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Degreeing Camshafts -- Information Required

  • Thread starter Thread starter Suzuki_Don
  • Start date Start date
srsupertrap said:
A dial indicator extension works on the GS1000 2V and lets one rotate the enginine over & over without the cam contacting the dial indicator and screwing up the measurements. Since the 2V valve shims are all 29.5 mm it should work just fine on the GS650 etc. I mount the magnetic base on top of the cam cap with the V edge of the base wedged in front of the cap bolts.

No one responded to this thread but it appears others know the same info.

http://www.thegsresources.com/_forum/showthread.php?t=130291&highlight=cams
Click to expand...


SUPERTRAP that is a very good article/comment. I don't know how I missed it when searching for info on degreeing cams.

Thanks a lot.
 
srsupertrap said:
Suzuki GS 750, 850 & 1000 Cam Installation Instructions
Note: If you have Andrews Cams and you read this whole thing they recommed visually setting 1/16" below the
cylinder head surface to achieve 108 timing. :confused: Last time I was adjusting these cams in 2008 I tried this
visual method first and verified it was +/- 2 degrees. Pretty freakin close.

http://www.mediafire.com/download.php?11z99jjjtby

How to Degree Cams circa 1982

http://www.mediafire.com/download.php?aj0emhylwj9

Finding TDC (Positive Stop method)

http://www.mediafire.com/download.php?b9j9lzzlvnu

Note: If you never used mediafire, you have to "Click Here to download Files"
Click to expand...

I'll ask this question and see if anyone has an answer for me.

Apparently on the GS motor the norm for degreeing the camshafts is to have the exhaust cam number higher than the intake cam by about 2 degrees. An example would be Intake 106 degrees and exhaust 108 degrees.

On my motor the 650 specs from the manual have the exhaust lobe cente at 103 degrees and the intake at 106 degrees. Which is in reverse of the norm.

When I checked the lobe centre on the motor the reading I took tallied with what the manual stated.

Exhaust 103 degrees
Intake 108 degrees

Opinions are sought if there is a reason for these numbers being in reverse. My worry is that it is done this way to prevent the valves hitting the piston at TDC. The 650 has a very closed combustion chamber, with squish characteristics.

19CombustionChamberNo3Cyl.jpg


I dont want to reverse the numbers and have them at say exhaust 106 and intake at 104 and find I cause engine damage.

I have also read somewhere that the danger of valve and piston contact is likely to happen where lower numbers are employed. More risk at 104 than at 108 for instance. Anyone care to comment on this.

And I don't want to pull the head and do the clay thing to check the valve to piston clearance.

I need comments on why the numbers on the stock timing are in reverse from people more conversant than me.
 
Last edited:
Does Anyone Know the Answer to This

Does Anyone Know the Answer to This

Are there any knowledgeable people out there on cams and timing to answer the question above?
 
Well if this helps. I installed my cams by mistake 1 tooth out and didnt notice until i rotated the engine a couple times to check the exhaust center, which was less than 90 deg. There was no interference rotating by hand so no valves were hitting pistons. I cant say that if I ran it like that there wouldnt have been bent valves. So, you can be quite far out and not get interference. I just installed my new cams and set them at 105/107 just like I had set the old cams. no problems what soever.
Suzuki maybe set the cams on those centers for emmisions reasons or gas mileage or whatever, not so much maybe for best performance.
 
Don, you can check piston to valve clearance EASILY without removing the head. Call me at 714-356-7845. Ray.
 
Never mind, I just looked to see where you are. You need to put a dial indicator on top of the #1 intake bucket & then, with the piston at TDC, pry down on the bucket slowly till the valve touches the piston. Read the dial indicator & it will tell you the clearance on the piston to valve. Repeat on exhaust side. Ray.
 
rapidray said:
Never mind, I just looked to see where you are. You need to put a dial indicator on top of the #1 intake bucket & then, with the piston at TDC, pry down on the bucket slowly till the valve touches the piston. Read the dial indicator & it will tell you the clearance on the piston to valve. Repeat on exhaust side. Ray.
Click to expand...

Ray you are brilliant. Thanks for the tip.

Any suggestions on how to hold the cam sprocket while torquing the sprocket bolts to the correct torque.
 
gearhead13 said:
Well if this helps. I installed my cams by mistake 1 tooth out and didnt notice until i rotated the engine a couple times to check the exhaust center, which was less than 90 deg. There was no interference rotating by hand so no valves were hitting pistons. I cant say that if I ran it like that there wouldnt have been bent valves. So, you can be quite far out and not get interference. I just installed my new cams and set them at 105/107 just like I had set the old cams. no problems what soever.
Suzuki maybe set the cams on those centers for emmisions reasons or gas mileage or whatever, not so much maybe for best performance.
Click to expand...

OK. Thanks for the quick reply. Good comments on MR SUZUKI's possible focus in '82.

I have now slotted my sprockets and set the timing to 104? and 106? for the intake and exhaust respectively as suggested by Ray. Made one mistake though, I forgot to torque the camshaft cap bolts. I nipped them down when I installed the cams and in my eagerness to degree the cams forgot to torque them down. So I will have to do that tonight and recheck the timing. Don't think it will change much if any.

Then I will see how it operates when I eventually get it all back together and start the motor.
 
Last edited:
Rapidray,
Great tip to measure the clearance between the piston and valve. BTW what's the minimum clearance for street engines based on your experience?

Suzuki_Don,
What was the clearance you measured? I wouldn't think (assumption) 650 stock cams could not kiss the pistons no matter how they were timed. But that's why I didn't comment.
 
Last edited:
srsupertrap said:
Rapidray,
Great tip to measure the clearance between the piston and valve. BTW what's the minimum clearance for street engines based on your experience?

Suzuki_Don,
What was the clearance you measured? I wouldn't think (assumption) 650 stock cams could not kiss the pistons no matter how they were timed. But that's why I didn't comment.
Click to expand...

I haven't checked the valve to piston clearance yet. I am waiting on a dial gauge.

How do I hold the sprockets while I tighten the bolts to 12 lb ft.

BTW I torqued the cam cap bolts down to 1.2 ?? (whatever in metric). I then rechecked the timing and the results were Intake 104.5 and Exhaust 105.75 degrees. Not sure at this stage whether to leave it at that or try and get the 2 degrees separation that Ray advised at 104 & 106.
 
Button it up and ride it. That's closer than Mr. Suzuki himself cared to be. You should of seen my numbers with the stock sprockets. Not even close to the specs.
 
chef1366 said:
Button it up and ride it. That's closer than Mr. Suzuki himself cared to be. You should of seen my numbers with the stock sprockets. Not even close to the specs.
Click to expand...

That's rich from someone who is a pedestrian just like me. Ha ha.

I went to a Ford swap meet today (Sunday) and came across a dial gauge. It was just what I was after to do a final check on my cams. It even came with a pointer bent to a similar shape that I will need to place it on my buckets. It's good because it is just a piece of wire with a thread on it to go onto the dial gauge and if I bend it about a bit I won't feel so bad if I bugger it up. Best thing is it came with a magnetic stand with all the attachments and the dial gauge for $25. A BARGAIN.

S3010099.jpg


DIAL GAUGE AS DESCRIBED
 
Hey Don,

Did you do any port clean up work on that head? The short side radius on these GS heads typically has a very sharp edge on the exhaust side which you can easily dress smooth with a few strokes of a rat tail file. Definetly worth doing if you haven't already done so.
 
Nessism said:
Hey Don,

Did you do any port clean up work on that head? The short side radius on these GS heads typically has a very sharp edge on the exhaust side which you can easily dress smooth with a few strokes of a rat tail file. Definetly worth doing if you haven't already done so.
Click to expand...

No Ed I didn't touch the head as far as any porting is concerned.

I had the head chemically cleaned so there is not a sign of any carbon whatsoever on the head. I will have to have a look in the exhaust port and check. Is it something that can be done with the head installed?
 
Suzuki_Don said:
No Ed I didn't touch the head as far as any porting is concerned.

I had the head chemically cleaned so there is not a sign of any carbon whatsoever on the head. I will have to have a look in the exhaust port and check. Is it something that can be done with the head installed?
Click to expand...

Don,
The valves need to be out of the head to do the clean up work. Like I said, a rat tail file works great. I'm not a mod-it sort of guy but that edge was so sharp on the GS1000 heads I've had that even I couldn't resist.:D
 
Nessism said:
Don,
The valves need to be out of the head to do the clean up work. Like I said, a rat tail file works great. I'm not a mod-it sort of guy but that edge was so sharp on the GS1000 heads I've had that even I couldn't resist.:D
Click to expand...

Thanks Ed, I forgot to have a look last night. Hopefully the 650 head does not have that issue. Too late now anyway the head is on, cams degreeing has been done. Thanks.
 
Suzuki_Don said:
Thanks Ed, I forgot to have a look last night. Hopefully the 650 head does not have that issue. Too late now anyway the head is on, cams degreeing has been done. Thanks.
Click to expand...

Ed I had a look in the exhaust port last night and could not see any sharp edge. I could see where it might be on the 1000 engine, but mine was quite smooth there with just a casting line visible.
Thanks
 
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