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How do I time the cams?

  • Thread starter Thread starter GSNewbie
  • Start date Start date
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GSNewbie

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I have looked through the manual and done searches here and really can't see how to check my timing! (And yes, my chain may have stretched but that's not the question here. My cam chain may have jumped a tooth and I want to make sure they are correct).

Having done car engines, it's usually TDC on #1 piston (far left on the bike) and then both cam marks are level with the head.

How do you check timing on a '80 650G?


Thanks for your help!
 
GSNewbie said:
I have looked through the manual and done searches here and really can't see how to check my timing! (And yes, my chain may have stretched but that's not the question here. My cam chain may have jumped a tooth and I want to make sure they are correct).

Having done car engines, it's usually TDC on #1 piston (far left on the bike) and then both cam marks are level with the head.
Click to expand...


It's pretty much the same for a GS.

With #1 (and #4) at TDC, the rectangular notches on the right end of the cams should be level with the head and pointing either directly at each other or away from each other.

Sort of like this:
(>)_______(<)

Or this:
(<)_______(>)


Here's how to find TDC: http://bwringer.com/gs/tdc.html

If you've skipped a tooth, there's a precise procedure for setting time that varies by model, so a manual would be a good idea at that point. But verifying is easy enough.
 
Thanks!
Oh, will I need new gaskets to check it?
They were not so fun to make...
 
1..Number 1 piston at TDC
2..Take off point cover and look thru the hole in the timing plate. You should see a "T" mark lined up with the mark on the housing.
3..Look at the EXHAUST CAM. There should be a number 1 on the sprocket. This arrow points to the FRONT of the engine and is level with the top rim of the head.
4..On the Exhaust cam youll also see a number 2..this will be pointing straight up, while the number 1 arrow is level with the head surface.
5..On the INTAKE cam sprocket there is a number 3 arrow which points straight up as well.
6..Count the number of pins ( link pins in the chain ) between the one the number 2 arrow is pointing at and the one the number 3 arrow is pointing at. The pin that the number 2 and 3 arrows are pointing at counts as number 1 and 20.. (1------------------20)
7..If there are 20 pins between the 2 arrows, then look down at the ends of the cams. Youll see two squared out notches on the ends which should be pointing directly at each other. If all this checks out then youve just confirmed cam timing. Never rotate the engine backwards or with the cam chain tensioner removed.
8..if theres more or less pins between the 2 and 3 arrows, then you index the intake cam it the way it needs to go in order to establish the 20 pins between arrows 2 and 3.

Always turn the engine forward ( clockwise from the ignition bolt ) and NEVER turn the engine without the cam chain tensioner in place.
 
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You may need a new valve cover gasket.

The gasket, if you find one, in the timing cover doesn't actually do anything, so you can leave it out if you don't have another.

Most of us can use the same valve cover gasket for several years -- just coat it with a thin film of grease before installing the first time.

If your valve cover gasket is 30 years old or so, you'll need a new one. Buy an OEM Suzuki gasket -- the aftermarket ones are crap.
 
chuck hahn said:
1..Number 1 piston at TDC
2..Take off point cover and look thru the hole in the timing plate. You should see a "T" mark lined up with the mark on the housing.
3..Look at the EXHAUST CAM. There should be a number 1 on the sprocket. This arrow points to the FRONT of the engine and is level with the top rim of the head.
4..On the Exhaust cam youll also see a number 2..this will be pointing straight up, while the number 1 arrow is level with the head surface.
5..On the INTAKE cam sprocket there is a number 3 arrow which points straight up as well.
6..Count the number of pins ( link pins in the chain ) between the one the number 1 arrow is pointing at and the one the number 2 arrow is pointing at.
7..If there are 20 pins between the 2 arrows, then look down at the ends of the cams. Youll see two squared out notches on the ends which should be pointing directly at each other. If all this checks out then youve just confirmed cam timing. Never rotate the engine backwards or with the cam chain tensioner removed.
8..if theres more or less pins between the 2 and 3 arrows, then you index the intake cam it the way it needs to go in order to establish the 20 pins between arrows 2 and 3.
Click to expand...

Chuck, are you sure it's twenty pins on a 650G?
 
tkent02 said:
Chuck, are you sure it's twenty pins on a 650G?
Click to expand...

Tom. it's 20 pins on the "G" and 19 pins on the "E". If you are doing the 650 top end conversion on a 550 bottom end then you go with the 19 pin arrangement.
 
Yeah...I went to Basscliffs Website and read the service manual...which also may be a good idea form this gentleman. Has the entire process in section 3.
 
chuck hahn said:
7..If there are 20 pins between the 2 arrows, ...
Click to expand...
Just something for the new guys to keep in mind, ...

Make sure you count the pin over the #2 mark on the exhaust cam as #1.
A common mistake is to start there and count the next pin as #1. Not good.
The pin directly over the #2 mark is the #1 pin.
Likewise, the pin that is over the #3 mark on the intake cam is the one that should be #20.

Technically, that makes 18 pins between the marks, just didn't want anyone to mis-understand.
The correct count is 20 pins, INCLUDING THE PINS OVER THE MARKS. :o

.
 
Steve said:
Just something for the new guys to keep in mind, ...

Make sure you count the pin over the #2 mark on the exhaust cam as #1.
A common mistake is to start there and count the next pin as #1. Not good.
The pin directly over the #2 mark is the #1 pin.
Likewise, the pin that is over the #3 mark on the intake cam is the one that should be #20.

Technically, that makes 18 pins between the marks, just didn't want anyone to mis-understand.
The correct count is 20 pins, INCLUDING THE PINS OVER THE MARKS. :o

.
Click to expand...
Thanks for clearing that up :rolleyes:
:D
 
I went back and edited it to more clearly reflect that the ones that the 1 and 3 arrows point at count as number 1 and 20..hope its more clear now.
 
That's OK, Chuck, it was probably quite clear before the editing, just trying to prevent someone else getting hung up on a simple procedure that had me stumped the first few times. :oops:

.
 
Ive only done it once on the skunk #2 project bike. And thus my reason for adding to NEVER turn the engine over without the cam chain tensioner in place.
 
Thanks for the help guys. I'm working in the garage today and it's next on the list after listing my 48 Ford F1 for sale on the classifieds... Too many projects and not enough money for 'em all! :)
 
Ok, so I got some time and motivation and went through the cam timing. They checked out just fine with the 20 pin count and all. Pretty simple check other than I didn't look up the torque specs on the valve cover bolts.

And then compression check... I guess I put off the compression check because I was afraid that may have been the issue. It is near 90lbs on 3 cylinders and 130 on #2. I'm not sure it's worth it at this point.

Parts I should replace or fix for this job:
Valve cover gasket.
Head gasket
Cylinder gasket
oil bypass gasket
cam chain
cam chain sliders (ouch $)
Rings
hone job
valve seals
regrind valves?
and who knows how much more...
Then it still pops out of 2nd under load and I need a speedo (to replace the one the needle broke off of).:eek:

On a 3rd world rebuild: cylinder gasket/head gasket
rings/hone
valve seals...:-&
Where's the cheapest place to get parts?
 
Did you check the compression with the engine hot and throttle held wide open?

Did you adjust the valves to assure they are seating fully?

How many miles are on the bike? GS's are super durable and most compression loss problems can be traced to big miles (100,000+) or abuse (no valve adjustments).

How long as the bike been sitting inactive? The compression will increase after some good solid miles if it's sat for a while.

Good luck
 
I'm going to just answer these in line...
Nessism said:
Did you check the compression with the engine hot and throttle held wide open? Um, no it was cold. I will start over with another gauge too.

Did you adjust the valves to assure they are seating fully? No. Not for about 1k miles.

How many miles are on the bike? GS's are super durable and most compression loss problems can be traced to big miles (100,000+) or abuse (no valve ad
​
justments).
About 34k according to the speedo, but I got it up and riding last year after 8 years of being in boxes. No abuse IMO but the second gear popping out into 3rd has to be from abuse. I assume the teeth are worn or there is slop somehow.

How long as the bike been sitting inactive? The compression will increase after some good solid miles if it's sat for a while.

It was ridden 1300 miles least year +/- (and never ran through the revs past 5800 except if not under load. Thats the thing, it starts good as long as it is primed. Never had much problem starting if I didn't flood it. Blubbers a bit on choke with some smoke; clears up decent off choke.

I have as much fun riding on these old ones than the '02 SV. I just know better than to bring a sword to pistol duel.:rolleyes:
Click to expand...
 
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