Large Spine Frame XS650 / Egli / Rau / Cafe Racer

[rehar]

Jim, Thanks for the insight on the heating cycles. Extremely helpful in my understanding of these gaskets.
JP, Brilliant! I would have never thought about the spacer to allow the motor to roll over over. Thanks.
JP, regarding the spring measurement, I'm not sure I understand: If Valve is fully open, we would be measuring the compressed spring height, do I have that right?

 

[jpdevol]

Yes sir...measure from the head surface to the top of spring, then subtract the thickness of whatever's under the spring (cup & any shims). Spec on stock spring is 27.8mm for outer spring.

 

[jay760]

OK, there is a hole on one end of the Megacycle cam that can be used for visual reference.
(The marking is on the opposite side of the engine though...)
36 tooth sprocket - means alignment is either correct (assuming it was assembled correctly from the factory), or could be off by 10° increments.
Not 100% sure, but alignment looks about right.

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Next, I backed off the adjusters most of the way out, then spin the engine. No sound, no clicking. The cam does still move the valves a bit, but not fully open.

Your making the same mistake I did there, my timing was 10 degrees out, 36 teeth on the sprocket=10 degrees a tooth, but the cam moves at 1/2 the speed of the crank making it 20 degrees, cost me a fair bit that mistake

 

[rehar]

Thanks Jay. So, if I'm off 10degrees, one tooth at the cam would be 20 degrees off on the Crank (Crank would have 18teeth). If so, even better. Personally, I'm visually challenged to see 5 or 10 degree rotation difference from left side of engine, crank (slot) to right side of engine hole in cam. But 20 degrees would be much more noticeable. Do I have that right? Ha ha...

 

[Jim]

 

[Jim]

 

[rehar]

Hi JP, when you say the spec is 27.8. Is that the intake, exhaust? and is it MAX? As in, less than 27.8 (ie 27.0mm) is too much compression on the springs?

I've decided to make and use a degree, in the minimum, it will help me keep track of position (Verbiage was taken from a sample pic on the web... pls ignore). (There are many pics you can download from the web, print and past onto an appropriate material (I had an old piece of plexiglass laying around. Bigger the better, this one is 8" because I could fit it onto a single piece of printer paper.)

Once mounted, placed a wire screwed down to the case with an M6 bolt.

Using a dial indicator I can find max open / closed position of the valve. Just focusing on Number 1 piston, INTAKE.

It's difficult to measure a few things. 1) The Valve spring retainer shim thickness and 2) difficult to get the mitsutoyo caliper / depth gauge down on to the machined surface the spring is riding on. But I think I got it.

27.8 SPEC

mm Item
2.8 Valve Spring retainer shim (washer)
27.95 Valve fully opened/compressed (#1 Intake, including shim)
25.15 SPING HEIGHT COMPRESSED (less shim)
37.85 Fully closed (#1 Intake, including shim)
9.90 Compression/Valve Travel

 

[jpdevol]

So here's the pertinent page from the '74 Manual

 

[jpdevol]

As I read it, it's the actual spring itself. I reckon now what needs to be determined; is your measurement of 25.15mm at or near coil bind and causing the clicking noise - potentially causing damage while running?

The shadetree me (as Yamaha doesn't tell us) would fashion a method to compress the spring itself (out of head) and measure where coil bind occurs. I think some clearance between coils is needed too - maybe .020"+ (?)

 

[rehar]

Unfortunately, this is all starting to make sense and getting to the root cause. Time to order some aftermarket springs? Who to order from...

 

[jpdevol]

I see Megacycle recommends RD Springs 103-Y - they're SoCal too. Were there additional shims in-place above the bottom cup?

https://www.rdvalvespring.com/spring-kits

 

[rehar]

Without disassembly, it looks like just the one valve spring retainer shim.

I downloaded their full catalog pdf yesterday but could not find anything with XS650, XS-650, TX650... etc... (I should have searched for Yamaha 650/750 TWIN) Stupid me, really, I should have spotted it. Thanks for the Megacycle info. Hope I can get parts by next weekend.

 

[rehar]

Moving at a glacial speed - finally getting some time for this project. Engine is now together. Recommended springs from Megacycle installed. What is this Pinging, ticking, knocking sound? I think it is the same sound from before. I was able to quell it by either loosening up the valve adjusters, or loosening up the cam chain adjuster. If the adjuster is too Tight - should it click like this? Or is there something else wrong?

Valves are reasonably adjusted. Cam Pin is adjust to flush. However, it seems like, after Left intake valve closes - or very close to that point, the Rod "sometimes" snaps out further than flush. If I turn it by hand, slowly, I can get it to NOT snap out and make the click sound. I don't understand what is happening there - and maybe the sound is not that cam adjuster rod at all...???

Here is a video of the sound, while running. (Carbs need adjusting - high idle...)

 

[Jan_P]

With the screwdriver between the ear and a point at the motor one perhaps can localize it
I notice that the covers at the cam ends is not stock Hitting There on the inside ?

 

[rehar]

With the screwdriver between the ear and a point at the motor one perhaps can localize it
I notice that the covers at the cam ends is not stock Hitting There on the inside ?

Thanks, the Cam Cover(s) have clearance. I'll try and grab another video tomorrow, capture the adjuster pin movement and sound while hand cranking it.

 

[rehar]

Continued observations while I observe three different cases/tests (the last one may be the most interesting, if you want to jump ahead):
(277° crank)
FIRST Case: The tensioner at about 12mm from lock nut surface to end of the adjuster, threaded section (NOT INCLUDING the pin).


This was the same adjustment while motor running, horrible clicking sound, yesterday's video).

Turning the motor by hand this morning, I realize the clicking occurs as each of the four valves is on it's closing stroke.
Video Just an example - focusing on #1 cyl INTAKE valve movement and the click as it is on it's closing stroke. You can hear 2 of the four clicks occurring as I turn the crank (before this valve opens.

It seems the sound is made when the cam chain adjuster pin hits its' "hard stop" as it is being forced outward (toward the rear wheel).

When the pin clicks and I am able to measure the distance of movement beyond the adjuster's threaded section, the amount of exposed pin is about 3mm. The only time the pin extends out this far is when it makes the click. Putting my finger on it, the click is simultaneous with the motion of the pin "stopping". It rapidly pulls itself back inward as I turn the crank.

Following the pin INWARD, I get about 10mm of motion from the end of the threaded adjuster section. Total travel then - is loosely 13mm.


SECOND Case: Adjusting the tensioner OUTWARD, backing of tension, to about 20mm. The clicking still exists, but seems to be reduced in volume (or is it?). #1 cylinder INTAKE - is still loudest. Total pin movement and the amount that it sticks out and all, etc - is about the same as the first case.

Third Case: Next I removed the Tensioner pin completely.


Now, there is a sound (more of a clunk than a click) - and equally present as each of the four valves as they start to close (at least - at that "position" during the full cycle / hand cranking).

What the heck is this? Sounds like something hitting softer material...

 

[Jan_P]

To me it looks as the Pin is moving to much
There are setting / adjusting instructions in service manuals and so on line
I I recall right the adjuster plate with plunger can come out so one can look in -- if the sound is not going away after setting per Service Manual

 

[Jim]

Shouldn't be possible for a pin to stick out that far. You're missing some parts on the tensioner... the copper or steel/rubber washer for starters. Have a look in Tech, there should be a thread on tensioners. I'll have a look too.

 

[Jim]

You'll need to figure out what version tensioner you have, but this link should help figure it out. Shoutout to @5twins

https://www.xs650.com/threads/cam-chain-tensioners.1056/post-465622

 

[rehar]

Awsome Jim! As always thank you (and 5TWINS!). I will check out what I have and if there are any "spare parts" on the bench.
The missing Rubber washer/Damper part might very well solve the "clicking".

In the meantime, did you happen to listen to the last video? Do you think once properly assembled the "clunking" might disappear? I was shocked to hear anything at all with the tensioner removed.