OEM Valve Guides

[dps650rider]

Been trying to put together a set of 1st oversize valve guides for a winter project but there appears to be some confusion on part numbers and dimensions.

Anybody know where I can find this information?

 

[Wingedwheel]

https://www.summitracing.com/search/part-type/powersports-valve-guides/make/yamaha/model/xs650
See if this is what you’re looking for.

 

[jpdevol]

Been trying to put together a set of 1st oversize valve guides for a winter project but there appears to be some confusion on part numbers and dimensions.

Anybody know where I can find this information?

If you want the p/n's for OEM cast iron guides:

 

[dps650rider]

Thanks for that and I guess I'm a dummy for overlooking that information in the shop manual that I have.

So what are the pros and cons between stock iron guides and the bronze ones made by Kibblewhite? Wouldn't the bronze ones wear more quickly?

 

[Jim]

Bronze needs a slightly bigger clearance than cast iron. Allows for a looser valve fit.
The big difference is in heat transfer. Bronze does a much better job than cast. Since we're an air cooled engine, that helps.
With todays bronze alloys, wear difference 'tween the two is pretty close to a wash.

 

[jpdevol]

If you're using OEM valves, then cast iron is fine and probably preferable. If you're using stainless steel valves, it's generally considered a requirement to use bronze guides. The bronze guides - additionally - require a (pricey) carbide reamer to size them as a HSS reamer won't cut it (wears-out the reamer).

 

[dps650rider]

Going to be using OEM valves. One thing I need to do is if I use stock guides is to shorten them. Interestingly I was comparing dimensions of the Kibblewhites found here https://www.mikesxs.net/valve-guide-exhaust-bronze-xs650-0-001-oversize.html with an OEM guide I have on hand and I can duplicate the groove that holds the seal if I shorten the OEM guide by 0.200". This makes it the same as dimension A in the drawing on Mike's web site.

So I have been searching ebay looking for OEM guides that are 0.001 oversize. I have found some that are supposed to fit but the part number prefix is different (341-11134-11 for example) but so far have not been able to figure out what the difference is.

 

[dps650rider]

What is the difference between part numbers 256-11134-11 and 341-11134-11?

 

[Wingedwheel]

What is the difference between part numbers 256-11134-11 and 341-11134-11?

The way I understand it is the first set denotes the model engine/bike it was used on, second set denotes actual part # and third gives what change the part design is at.
https://yamaha-enduros.com/index.php/workshop/decoding-yamaha-part-numbers

 

[jpdevol]

It appears that Yamaha superseded the part number somewhere along the line: my guess is they are the same part

https://www.cmsnl.com/products/bushing-valve-guide-ex_2561113411/

 

[dps650rider]

I've been looking at pictures of these on the web and have noticed a couple differences. Some of them have a shoulder for the inner valve spring to keep them centered and others do not. The ones from Mikes have a groove for an O ring where it fits into the head and others do not.