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Checking valve timing

G

Gasket

Just got it firing!
Joined
Jul 3, 2009
Messages
5
Location
Norway
Hi.

I roughly checked the valve timing on my Cali II, it seemed to be outside spec., but I would like to get more accurate readings.
The specs in the manual apply for a rocker cleareance of 0.15mm. Mine are set to 0.20mm.

So here's my plan - with a degree wheel on, of course:

Start at TDC. Slide a 0.05mm feeler blade between the stem and rocker, slowly rotate the engine until the blade binds, and note the angle. Then continue engine rotation until the point where the blade is released, and note that angle. Same for other valve. Repeat process for other cylinder.

I have never done this before, so I thought I'd check if this method sounds OK, if there's a better method, if I am missing something etc...

How accurate should the valve timing be?
 
NEVER! :)

Seriously... there aren't many shops to go to really...

So I have missed something then...? I thought this was a relatively simple mechanism to figure out...
 
Gas, you are making it too complicated. Just measure with the feeler gauge that gives a little drag, that's the correct size.
0.15 vs 0.20 isn't such a bad deviation, but I know how you want to get it down right.

Joe
 
:blush:

Ah... seems I've been too hasty... I only read the specs, and ASSumed - since it says rocker clearance should be 1.5mm (.0059" ) - that I had understood it all and that the millimetre value was wrong (to my slim defence... typo in manual: .0059" = 0.15mm).

Sorry about that... I'll go through chapter 13.6 and see what wisdom it'll bring...
 
sign216 wrote:
Gas, you are making it too complicated....

Joe
Click to expand...
Joe, I take it you're talking about rocker / valve clearances...

I was trying to check the opening / closing angles for the valves... :)
 
Gas, you're right. I was talking about rocker / valve clearances. Glad you caught my error. I empathize with you on the book's error. I find so many errors in the manual's metric to English conversions, that I've stopped using English units (oh, the horror of it). So much for God's units.

Joe
 
Ok,
If you are trying to accurately check the timing forget the feeler gauges.

Here is how to do it properly (in my view).

Mount your degree wheel with indicator and find TDC. The best, fastest and most accurate way to do this is by using a piston stop (an old sparkplug with a bit of metal welded onto the end). Rotate the engine one way until it hits the stop and then the other. Adjust the degree wheel until TDC is symmetrical so if you rotate the engine either way TDC is the same number of degrees either side.

Remove piston stop.

Buy a cheap dial gauge and arrange it so that the tip rests on the top of the valve collet. Zero the gauge with the valve closed. Spin the engine and note the lift - enter the lift vs degrees into excel. The centreline (point of highest lift) is really what you are trying to determine. Plot the numbers.

You don't say why you think your timing is off - Guzzi has been known to very occasionally put their timing marks in the wrong spot but why did you come to this conclusion?

Ta ChrisR
 
Pete: You crack me up!

Chris: Hoooraay! Valve timing and Valve clearance are no longer confused.

Gasket: And yeah ... why do you think the valve timing is off?

FBC
 
Timing specs are usually given with a 1mm valve lash 'Clearance' so if you are trying to work out if the timing is the same as the book says by working out when the guage is grabbed or released it will be wrong anyway.

Use Chris's method or set the gap to 1mm and then check when lift begins with your dial guage on the spring cap. Make sure you have accurately determined TDC by a dead stop or bubblometer.

Pete
 
Hey Pete,
Bubblometer??? Educate me please?
I thought I was doing it the trick way with a bend piece of wire put on top of the piston through the spark plug hole connected to the tip of my dial gauge .....
Jurjen
 
Hollow out a spark plug and connect a length of thin hose to it.

Run hose into a beaker of water or oil starting with the piston at BDC end of induction. Wind motor over and watch bubbles, when near TDC watch carefully and observe the meniscus at the end of the tube. At TDC you can judge it to within a fraction of a degree by looking at the curvature of the meniscus.

Pete
 
coor Pete
that's a novel take on determining TDC for me !! Looks like I'll give that a try next time.
Cheers for the tip
 
Chris: Thanks for the proper procedure.

Why did I think it was off?
I rebuild the engine over the winter. Among other things the old worn cam shaft was replaced by a used low milage one.
The bike's not running quite right, so I'm checking the complete setup.
With the degree wheel on I spun the engine and observed valve movement, mainly to confirm that

a) it's the right cam shaft (opening intervals roughly as long as specified)
b) the cam/crank is lined up correctly (intervals not offset). Yes, I could remove the timing cover but I didn't have a new gasket... :side:

Since the rocker clearance - lash - was unchanged at 0.2mm, the valves clearly opened/closed way before/after spec. I consulted the manual, and got the decimals wrong - I now believed the lash should be even smaller (0.15mm), which would push the values off even more.

Then, slightly confused, I posted here.

THEN I read the manual further and discovered my mistake - the specs were for a lash of 1.5mm.

So - before I saw Chris' post - I went back and set the lash to 2.0mm and performed the "pinch check" with a 0.5mm blade, after the method described in the original post. Just to clarify: The idea is that
total lash 2.0mm
- blade 0.5mm
= control lash 1.5mm.

So the moment the blade is pinched/released, lash is zero.

The open/close points I found were pretty close to spec... valves open a bit early (3-6 degrees) and close more or less correctly.

I will get a dial gauge and check properly... but from my rough "pinch check", can I assume that it's the right cam shaft and it's lined up correctly?

Pete, the manual says timing specs are for a lash of 1.5mm (0.059" )... where does the 1.0mm lash come into the equation...?

And yes, thanks for the bubblometer... I also learned a new word... "meniscus"... B)
 
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