GS850G Has anyone done the valve clearances on one of these as i am not sure what position the cam should be?

Question

THE HAYNES MANUAL SAYS THAT THE CAMSHAFT CAN BE IN 2 POSITIONS,BUT DOES NOT THEN SAY WHAT THOSE POSITIONS ARE ?

Answer 1

That's confusing.

The Cylinders are numbered Left to Right sitting on the bike,,,1-2-3-4.

#1 and #4 are Up at Top Dead Center simultaneously,,
"The 2 Outer Cylinders"

While # 2 & #3 are both at Bottom Dead Center,,
"the 2 inner cylinders"

---1-----------4----Top Dead Center
----------------------Centerline
------2----3--------Bottome Dead Center

Or like:
Cap P =Piston UP,,
Small p =Piston Down.

P--p--p--P
then when it rotates,
p--P--P--p

...................................
Anyway,,,when a piston pair are at Top,,
One's on Exhaust Stroke and the other is on Compression Stroke.

From There,,,
Rotating the Crank 1/2 Turn,,,brings the Other Pair of Pistons to the Top.

Valve Clearances are set only on Compression Stroke,,,when Both Valves are Fully Closed..

You can't set the Other Cylinder which is simulataneously at Top Dead Center,because it's on Exhaust Stroke.
At that point,,,the Intake Valve is just Beginning to open while Exhaust Valve is just Finishing closing.

.............................................
As You turn the Crank and set it on TDC mark,,,
You can see the Camshaft Lobes.

The Cylinder which is ON COMPRESSION will have it's :
*INTAKE VALVE camshaft lobe pointing APPROXIMATELY "Rearward" .

*Exhaust Valve Lobe pointing Approximately "Forward"

Keep in mind the CAM runs at 1/2 Speed of the CRANK.
So 1/2 Turn of CRANK,,,moves CAM 1/4 Turn

After TDC on Compression Stroke>
Cylinder Fires for Power Stroke DOWNWARDS.

So Next Event is EXHAUST,,,which Begins Before Piston reaches Bottom.

Therefore when you view the Cam Lobes while at TDC/Compression Stroke,,,,,,
The EXHAUST VALVE is NEXT to Open.
It's Lobe will appear to be pointing basically "Forward".


..................................
They're NOT telling you that you CAN SET the VALVES in 2 Cam Positions.

They're telling you that even though the CRANKSHAFT/PISTON is at Top Dead Center,,,,
The Cam can be Either on Compression Stroke OR Exhaust Stroke.
One of 2 Cam Positions.

Always use ONLY the Compression Stroke/Valves -fully-closed Position.
Then Rotate the Crank 360*/ 1 Full Turn to set the Other Cyl on IT's Compression Stroke.

By the Time You're finished,,,
You will have rotated Crank 4 Full Turns and stopped at EACH Individual Cylinder's TOP Dead Center Position ,,On IT's Individual Compression Stroke.
That's where the Valve Adjustment is measured/made.

ONLY On Compression Stroke.

So,,Haynes is saying,,,
"You may be at TDC ,,,,but CAM can be in Right or WRONG position at TDC.
Use Only COMPRESSION STROKE TDC,,,,,,
And not Exhaust Stroke TDC"

Hope I haven't confused the matter worse,,lol.

Good Luck with it!
*Great ol' bikes btw

Answer 2

This is how you do it. Set the #1 cylinder to TDC check both intake and exhaust valves...#2 exhaust valve...and #3 intake.
Rotate crank one turn so that #4 cylinder is now on TDC check both intake and exhaust valves...3#exhaust...and #2 intake, thats it.
Spec is .001 to .003 inch, most feeler gauges don't have .001 strips, but, most have .0015 so use that it will work perfectly (IE if you cannot get the .0015 in its too tight, if you can get a .004 in its too loose). Make all your measurements first keeping notes make adjustments as needed later. If you change a shim rotate the engine through at least once to squeeze the oil out from under the new shim before you recheck the clearence. Any other questions just ask.

Answer 3

Look harder. It's got to be in the manual. There's usually a timing mark on the crankshaft that lines up with another mark. Look on the side cover for to see if you have a large bolt or 2. The marks will be visible after removing. There also should be marks on the camshaft sprockets that will line up to the head when you are at TDC. 1 set of adjustments will be done at #1 cyl. TDC and the other at #4 cyl. TDC.

Answer 4

Simple answer, turn the engine over until the lobe of one cam is pointing directly away from the shim.
You'll find one of the other lobes is also in the same position, do the clearances on them and take a note of which ones you've done, turn the engine over again until the next pair are in position and do them and so on.

Answer 5

low point on the lobe after engine is warmed up

Answer 6

Bottom dead center so the valve is completely free ~~

Answer 7

All have been explained had one way back and enjoyed it
Nice bike