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See Jack's post way above. I've read from a few people cut down they have a better shape than any other option for us xs650 owners. I would love oem yamaha xs650 valves, but discontinued.

I was under the impression from Jack's post, people are cutting the XV valves to stock Xs650 valve size since they are 2mm larger on both intake and exhaust. Length would be unchanged due to being nearly identical.

The valves need cut down (2mm too large). Is that basic knowledge? I have a good machinist but he said he won't grind? Cut? motorcycle valves, he said they're unserviceable (I wanted my oem valves cut, I will later pull the head for a professionally ported head). He wanted me to buy new...

It's a 78' cover I think. 2F0 - 78. That matches the year with that engine code (78 or 79)

Is there a possibility someone who has done the xv valves correctly, could get a batch done with their preferred machinist. @gggGary @Jack @hooser (I believe this is Hoos racing?) After I get my house built (just breaking ground) I would be willing to help fund this operation.

I am doing a 700 je kit so bored oem cylinders but here's my 2 cents 1. No help 2. Buy a new guide, I bought mine from Hoos racing, unless yours is newer, in my opinion 3. I would clean them good with brake cleaner and oil the cylinder walls, then oil the rings before putting them in the...

Pamco e advance, Hugh pma and a tiny 4 cell battery and my revs super quick and clean. Super clean throttle pull (1 cable from carb to tube, not 2 into 1, aftermarket throttle tube) ex500 carbs, pretty well jetted Homemade 2 into 1 with a cone engineering quiet core (iirc) It revs super...

It should be caramel and dry. If it's black or wet, you have issues Edit https://ngksparkplugs.com/en/resources/read-spark-plug

My research so far : No resistors = fine for points, not for electronic ignition 5k resistor cap or plug (one or the other) = required to eliminate radio frequency interference 5k resistor caps AND 5k resistor plugs = spark duration is too short, runs inefficient and might cause issues. Not a...

The ngk brp7es is 5k ohms. Edit : quick Google search the boyer has 5k caps (as did my hhb / pamco kit). I didn't see it on Boyers website but you could contact them and check. I don't recall if the cap has any markings.

Either resistor caps or resistor plugs. I believe I have ngk resistor caps and ngk non resistor plugs now. Might have to switch around now

Just run non resistor plug caps and you're good to go I believe?

I'm actually in the USA, looks like you're UK. I just randomly came across those valves since they seem like the only aftermarket option that would be quality. Shipping can't be too bad on valves. Do you have a build thread on the engine?

That would be great. Are you going with different valve guides or valve guide liners? Local machine shop cutting the valve seats? Thanks Spenser

Haha I figured so. I wish I was working on my engine right now. It'll have to wait til Saturday though. I did a bunch of research and I found one place with aftermarket valves I might consider when I do a fully built upper end. http://www.smedspeed.co.uk/valve.html

Edited my post. I meant stainless*. Too many 14 hour work shifts.

Magnet test will tell you if they're stainless. I think I'd run oem for realibility. Im doing oem in my 700cc JE build. I will end up taking the head back off later when I have a ported /polished head/cam etc but until then all OEM engine wise. I'm also trying out the Hoos racing cam chain...

One more before I dropped compression in one cylinder. I'll have to get more pics when it's back together. It always bugged me the engine was the only untouched part. Now it'll be all shiny.

Lost compression (due to a sticking valve I believe), figured I should install 700cc JE pistons, new cam guide, and freshen up the top end. Bike only had 15k on it but sat for awhile. More carbon buildup than engine wear

See if this works.