How do you all feel about this valve adjustment method?

[estcstm3]

Hi All,

I found this xs650 valve adjustment video online. Seems very straightforward and easy but two things I have read contradictory statements here.

1) The gentleman said you can rotate the crank(?) either direction, I thought we could only rotate counterclockwise, however I am not sure the reasoning behind this
2) Does it make sense to not look at the timing marks?

 

[TwoManyXS1Bs]

It's a good video to watch for those who are still learning about valve a adjustments, adds to the knowledge base.

However, note that the points cover is off. The quicker way would be to rotate the engine until just after the left points open, then adjust the left side valves, no need to reference the rotor mark.

Sure, you can turn the engine backwards. But don't do that while adjusting the camchain tensioner...

 

[estcstm3]

So adjusting from the biggest gap is a common practice? I would be one of those that needs to expand their knowledge base. I didn't grow up working on bikes and am slowly learning....

I know littlebill has a valve adjustment video but he is adamant about adjusting on the compression stroke.....

 

[Brian902]

On a BMW 4 cylinder I did last year, the easiest method was to use the back wheel with the gearbox in 2nd to bump the engine over to TDC, with plugs out of course and then check for clearance. The factory then tells you what other valves can be checked when #1 is a TDC. To adjust you remove the cams and replace buckets. Big job requiring lots of care and attention.

Other companies want you on TDC for each cylinder because the base circle of the cam may not be exactly the same in all areas.

My preference has always been to be at TDC on the compression stroke because that is when the big bang happens.

That being said and you have a hard time reading timing marks;
-rotate engine counter clockwise (for a XS650, others may be different) until intake valve opens (goes down) and then closes (comes up) you have just completed the intake stroke and the piston is sitting at the bottom.
-rotate engine until the piston comes to the top, using a straw to check piston travel as you rotate the crank, you have just completed the compression stroke.
-with the piston as close to the top as possible, a little either side of TDC is not important, adjust both valves.
- repeat steps for other cylinders
- job done

This method has never failed me and on the BMW and others where it is impossible to see timing marks and or turn over the crank, this was the easiest and sometimes the only way.

 

[TwoManyXS1Bs]

That video has its roots in the procedure used by an old Yamaha mechanic. I suspect that procedure may be an evolved shop procedure that has its origins in detecting misground cams of the very early '70s, per this service bulletin:

 

[XS650D]

I used the method u saw on u tube and it worked great,my valves were set by a bike mechanic 50 miles before i bought bike but decided to cheak them anyway just to see what he set them at and compared his reading and method with this method and got exactly same reading so it works perfect,i like it better myself,i then changed the 3/6 setting to 2/4 as per this old mechanics advise,much quieter plus a little more torque of the line.not sure why that would be.

 

[TwoManyXS1Bs]

...i then changed the 3/6 setting to 2/4 as per this old mechanics advise,much quieter plus a little more torque of the line.not sure why that would be.

That's pretty much in keeping with this service bulletin:

View attachment 43089

 

[estcstm3]

I used the method u saw on u tube and it worked great,my valves were set by a bike mechanic 50 miles before i bought bike but decided to cheak them anyway just to see what he set them at and compared his reading and method with this method and got exactly same reading so it works perfect,i like it better myself,i then changed the 3/6 setting to 2/4 as per this old mechanics advise,much quieter plus a little more torque of the line.not sure why that would be.

awesome im going to give it a try!

 

[itsatoy]

I think I will give that method a try since it seems pretty fool proof for a newb but I just wanted to check. Does that bulletin apply to an '81? I don't know when it was issued. My Clymer manual shows .002/.004 for the TX650A, XS650B but .0024/.006 for '79 and later.

 

[TwoManyXS1Bs]

I spent a lot of time collecting the early service/parts bulletins, to augment my manuals and tooling for my XS1Bs. Most of them cover 70-73, with some later issues that would be of interest for upgrades.

That particular bulletin, posted above, number M4-047, is probably from 1974 (the '4' in M4), covering the TX650A.

The very early bikes went through a lot of teething changes, and documentation (manuals) were understandably lacking, typical of the early 70s. As time went on, the machine was refined and matured, and documentation got better.

With that in mind, you can probably trust the later models documentation for better and more exhaustive specifications and details. So, I'd recommend following the specs in those later/newer manuals...

 

[itsatoy]

Thanks TwoMany, I figured it was probably issued before my model was released or at least before the 70-82 Clymer was printed.