Warped intake valves

Thanks for the pics. I don't see any signs of overly lean combustion (grey, white, light tan colors) or excess heat (square edges on plugs). What do the combustion chamber and valves (face, seat, stem) look like?
 
If you still use the original advance mechanism, check it if it's all free and fully working.
That's how I fried unfortunately once the small ends of my old XS engine as the bushings (mine had bushings not needle bearings) within the cam didn't let the mechanism advance sufficiently.

Kind greetings from Italy

Christian
 
If you still use the original advance mechanism, check it if it's all free and fully working.
That's how I fried unfortunately once the small ends of my old XS engine as the bushings (mine had bushings not needle bearings) within the cam didn't let the mechanism advance sufficiently.

Kind greetings from Italy

Christian
I just found my Harley shirt from Varese, Italy. I made that trip late summer on my Buell. I stopped into Ace Cafe, in Switzerland on the way there.
The advance is free. I checked burst before taking the top end apart. Chin Chin
 
The Harley shirt from Varese is very nice (besides I'm more of a Wr, Kr kinda guy) but don't worry originally I'm from Vienna, so,

Servus und schönen Abend

Christian
 
The Harley shirt from Varese is very nice (although I'd be more of a Wr, Kr kinda guy) but don't worry originally I'm from Vienna, so,

Servus und schönen Abend

Christian

Ps: I can also be found on xs650.de (although for reasons of time budget rather rarely)
 
The Harley shirt from Varese is very nice (although I'd be more of a Wr, Kr kinda guy) but don't worry originally I'm from Vienna, so,

Servus und schönen Abend

Christian

Ps: I can also be found on xs650.de (although for reasons of time budget rather rarely)
I have a WL45 project stashed away...I really dig KR's and XR's...Just don't the the monetary resources...
 
Thanks for the pics. I don't see any signs of overly lean combustion (grey, white, light tan colors) or excess heat (square edges on plugs). What do the combustion chamber and valves (face, seat, stem) look like?
I have some pictures on phone of combustion chambers and intake ports to post later. Both valve guides are cracked! I need part numbers to order standard size guides. Do you know which part numbers I should use? I have a winter Rally coming up this week. So my energy has shifted to preparing for that event. I would like to get these on order, and unfortunately my manual for this bike is in a barn in NY.
 
Hey if you're located in Germany why don't you the guides from xs-laden, they have a great selection and are really nice!
Ask for Uwe and greet him from me ;)

I also dig in particular the Xr's but unfortunately outta my budget.
Would have loved to have a Wr but now that i have the Ajay (V2 1000cc flatty) I'm more than happy.

All the best

Christian
 
Both valve guides are cracked! I need part numbers to order standard size guides. Do you know which part numbers I should use?
That too is unusual, but explains your symptoms. Question is why they cracked??

Anyway, below OEM p/n's for valve guides, o-rings & seals
Valve seals x4 341-12119-02
Guide o-ring x4 93210-15151
In valve guide x2 341-11133-11
Ex valve guide x2 341-11134-11

If you have trouble locating locally, CMSNL.com does have them in Netherlands.
https://www.cmsnl.com/yamaha-xs650-1979-usa_model8641/partslist/A-05.html

You'll also need an 8mm driver to install new guides and an 8mm reamer to finish size it, once installed. IDK about EU suppliers, here's my US go to
Valve guide reamer, valve guide driver

https://goodson.com/collections/reamers/products/1-4-drive-high-speed-steel-reamers
https://goodson.com/products/manual-valve-guide-drivers-metric?_pos=4&_sid=3a5feab14&_ss=r

Now one additional point: when you replace guides, you must also re-cut new valve seats to get a seal as the valve location will change some
 
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