Is this valve adjustment legit?

[Ccanady]

So I plan on doing some adjusting and came across this video. Is it ok to use this method? I know its usually used in sync with turning the crankshaft and timing to get everything on the correct TDC and compression stroke. But he doesnt seem to care about either one..as long as its got the most space..

 

[XSNate]

I don't really see all that much time saving? I'm sure a bit maybe. But I don't want to burn a valve trying it on my motor!

 

[retiredgentleman]

There's really nothing wrong with the method he is using. I think its easier to just use the timing marks to position the crank.

His suggestion of using 0.002" for intake and 0.004" for the exhaust, is too tight in my opinion.

I use 0.003" and 0.005".

 

[jd750ace]

There's really nothing wrong with the method he is using. I think its easier to just use the timing marks to position the crank.

His suggestion of using 0.002" for intake and 0.004" for the exhaust, is too tight in my opinion.

I use 0.003" and 0.005".

I agree. .002 and .004 work OK on a water cooled motor, but that's too tight for air cooled IMO. I use .003 and .005 as well.

 

[Ccanady]

I ask because I have never done valve adjustments and I just felt that eliminating the "timing" factor would eliminate some of the confusion.

 

[xjwmx]

I have never done valve adjustments

He calls the normal way the hard way, but I think his is the hard way! His way takes several steps to find the place to make the adjustment, but the regular way you just turn the crank to tdc and make the adjustment. His way would be good if the bike was missing the timing marks for some reason.

Incidentally use a wrench to turn the crank instead of a ratchet because with a ratchet it will flip past tdc and you'll have to rotate it another turn. Try and you'll see. fwiw I use .003 and .006

 

[Brian902]

Try this:
- remove both plugs
- turn engine counter clockwise as viewed from the left side, as per the normal rotation of the engine, be careful if you use a wrench because you can hit the brush assembly when the engine snaps over
- watch for left intake valve rocker to move down, opening the valve and keep turning until the rocker rises again, closing the valve
- now put your straw down the left plug hole, same side as the PMA, of course, and turn the crank until you feel the piston rising and is at it's highest point. you can go back and forth a bit to make sure, but at this point both the intake valve and exhaust valve rockers should be loose, in other words both valves closed.
- you are at top dead center on the compression stroke for the left cylinder
- adjust the valves on that side.

now do the right side watching this time for the right intake valve to open and close and then feel for the piston to come to the top. A little harder to do but you will get it and then adjust the intake and exhaust for the right side.

- then remove the cap on the cam chain chain adjuster at the rear of the engine below the carbs and adjust it in while rotating the engine a few times until the plunger is just flush with the end of the adjuster. Tiny bit of movement is fine but the inner plunger should not extend past the adjuster.

Your done.

Good Luck.


Attached document might help. Sorry about the poor quality. PM me and I can send you a better copy that is too large to upload here.

 

[Maurice]

Brian, wouldn't you adjust the cam chain tension before doing the valves? Adjusting it after could throw off the adjustments a bit...

 

[Brian902]

You can do it before or after, it's more important not to forget to do it.

The small amount of rotation of the cam a loose cam chain would make would have no effect on adjusting the valves when using the above method.

Valves are closed on compression and power stroke for many degrees of rotation and at TDC on compression stroke you are in the middle of that range on the cam's base circle.

Experts could give you the exact number of degrees, I'm just a mechanic to lazy to do that calculation.

Just more food for thought; I like this method for any 4-stroke engine because it eliminates the chance of an error. Because some engines employ a type of automatic decompression mechanism holding an exhaust valve open temporarily to ease starting. Using this method and being that close to true TDC on the compression stroke, you are assured that all valves must be closed. Honda and BMW bikes with 4 and more cylinders often allow you to put one cylinder on TDC and adjust other valves because they are on the base circle which make the whole of adjustment quicker. Being from the old school I always ignored this method and do one cylinder at a time.

 

[Maurice]

Thanks makes sense. The valve adjustment procedure for the Hawk GT is similar to above: simply adjust anywhere the cam lobes are away from the rockers.

 

[Tomterrific]

Did not watch video but with my 360° twins, I've owned several, I observe when the opposite valve is at it's full opening. The adjusted valve is then on the base circle of the cam and is at the proper position for adjustment.

When I worked at a Mack Truck dealership as a mechanic (1971-72) we adjusted valves with the engine idling. It's easy to feel the drag on the feeler gauge as it is pulled through the adjuster. This is by far the quickest and easiest way to adjust valves but not doable on most engines.

Tom

 

[richardthemotorcycle1]

I just recently bought my first XS650, doing this valve adjustment to your bike, is this a yearly maintenance thing? or as needed? I have a 250cc scooter and I've done valve adjustments, (usually there are symptoms to know when its time to adjust) Just wondering.

 

[Brian902]

We're getting off track but this is funny.

Must have been hard on the feeler gauges.

All that pounding would ruin a feeler gauge in no time.

Did a 750 Honda the other day at .002th and my old gauge is almost ready for the garbage.

What clearance did you set the diesel engine valves at.

Valve adjustments once a year, but depends on mileage as well. Service manual says 5,000 miles (8,000 km).

 

[5twins]

As far as engine rotation direction by hand goes, just remember to turn the motor in the same direction that the wheels spin as you're going down the road.

 

[Brian902]

Right on 5Twins, the BMW I last worked on had so much tupperware that their user forum suggested 3 gear and using the rear tire to rotate the engine, in the proper direction of course. And a dowel to locate TDC as timing marks were too much work to get at.

 

[Tomterrific]

Those big slow turning diesels used a fairly thick feeler gauge, lots of surface too. All my super thin feeler gauges get all wrinkled pretty bad with use.

I remember buying strips of feeler gauge in the proper size instead of an entire set. Does anyone know of a source for buying a specific size?

Tom

 

[5twins]

http://www.msdiscount.com/columnar.aspx?cat_id=9126&category_site=STARTOOL