Bent exhaust valve

[BCoop]

I was loosing my mind with my carbs thinking they were the problem for my weird lean and rich symptoms but then noticed my exhaust valve wasnt closing all the way. So I took the opportunity to clean and paint the whole bike plus do a rebuild on the engine. When I opened it up I found a bent exhaust valve on the left cylinder.

Why would my valve be bent?
Should I change just the one valve or all the valves and guides?

 

[gggGary]

One likely setup is that someone did a start after the bike had sat a LONG time, the valve guide was sticky and the piston hit it.

I'm real big on lots of oil and lots of kicking over any engine thats been sitting for a while before a start is attempted.

 

[BCoop]

That makes sense. The bike has been dropped while running and while being moved and has been run all out without a tachometer so a good chance it was over revving. Think any of these things could do it as well?

Also, is it as simple as replacing the valve and guide to solve the problem or are there other things to address with a bent valve?

 

[gggGary]

Yes I would guess it could have been over revving also. Dropping it should not bend a valve unless the drop somehow caused a no load rev up.

No motor builder am I but yeah replacing valve and guide and then grinding/lapping them to fit should do it.

 

[XSLeo]

You might inspect the valve guide for damage and wear. It may be ok. Replacing the valve is a given.
Leo

 

[BCoop]

Thanks for the responses. I think I will replace all guides and seals as well as the valves. Could I do this myself or is it something I should get done at a shop?

 

[TwoManyXS1Bs]

Will your valve spring compressor fit around the head and match the spring caps?
Does your spare oven go to at least 350°F?
Is the main shaft of your valve guide punch about 7.9mm in diameter?
Can your calipers and micrometers measure down to 0.0001", about 2 microns?
Do your small bore gauges reach at least 1.5" and measure down to 2 microns?
Is your 8mm bore reamer a straight flute and still sharp?
Is your valve seat grinding equipment sized for 35-48mm 3-angle seats?
Are your valve grinding cups of the right size?

 

[BCoop]

Lol, sounds like I'm going to outsource this to a local shop. Any good web sights that sell quality parts for these bikes?

 

[TwoManyXS1Bs]

Here's a few:

http://www.mikesxs.net
http://www.650central.com
http://www.boats.net/parts/search/Yamaha/Motorcycle/parts.html
http://www.hoosracing.com
http://www.bikebandit.com/aftermarket-parts?m=147213
http://www.motosport.com/motorcycle/rides/yamaha/xs650-parts
http://www.jcwhitney.com/yamaha-xs650/d57862j1s5.jcwx
http://www.ebay.com/sch/i.html?_kw=xs650+parts