how do i get carbon off of my oem valves to reuse them, and off the head? help!


18 replies to this topic
  • mwmx54

Posted March 03, 2013 - 03:37 PM

#1

I am rebuilding my bike, 110 hours on it 2010 yz450, I got the valves out, i am replacing the valve springs, and seals. the valves havent moved since new, so I am going to reuse them, but they have quite a bit of carbon build up, especially the exhaust vavles. do I just leave it? or is there a way to clean them? also, what is the best way for replacing the valve seals? thanks guys, and I did my cylinder with a scotch brite ball on my drill, how do I know when it is honed enough?
again, thank you guys.

  • grayracer513

Posted March 03, 2013 - 04:12 PM

#2

You can use a wire wheel on a bench grinder as long as you stay off of the face of the valve where it contacts the seat.

  • awag865

Posted March 03, 2013 - 06:22 PM

#3

As far as the honing goes jus make sure you hav some nice clean cross hatches in it but not completely covered in scratches.

  • Gunner354

Posted March 03, 2013 - 07:39 PM

#4

Put them in a small container and fill it with WD-40 and leave it for a day. The carbon should just wipe right off!

  • mwmx54

Posted March 03, 2013 - 08:52 PM

#5

Here's another question, my new wrist pin looks like it missed the polishing or chrome phase, it's Oem, dark gray color not very smooth, my old one, also Oem looks chrome. Is this normal?

  • grayracer513

Posted March 04, 2013 - 07:05 AM

#6

Here's another question, my new wrist pin looks like it missed the polishing or chrome phase, it's Oem, dark gray color not very smooth, my old one, also Oem looks chrome. Is this normal?


That is normal. It's a change in the way they're treated.

  • chouca222

Posted March 04, 2013 - 10:06 PM

#7

Put them in a small container and fill it with WD-40 and leave it for a day. The carbon should just wipe right off!


Could it damaged the surface treatment?

  • mwmx54

Posted March 04, 2013 - 10:56 PM

#8

i ended up using a little sea foam and scrubbing with an old tooth brush. it got most all of it off. good enough for my bike.

  • FinchFan194

Posted March 05, 2013 - 03:13 PM

#9

Put them in a small container and fill it with WD-40 and leave it for a day. The carbon should just wipe right off!

This did NOT work on my bike, left it for 48 hours and nothing. Took the head and valves to a machine shop and he vatted them for $20. Looked like new.

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  • Gunner354

Posted March 05, 2013 - 05:37 PM

#10

This did NOT work on my bike, left it for 48 hours and nothing. Took the head and valves to a machine shop and he vatted them for $20. Looked like new.

That's odd! Learned this from a very well known top fuel engine builder years ago. It worked on my wr a couple of years ago. Filled the combustion chamber with wd-40 when I removed it.The carbon wiped off the valves and head the next day like butter.

  • grayracer513

Posted March 05, 2013 - 06:09 PM

#11

Combustion chamber carbon can be broken down by any number of solvents, particularly when the engine is run as hard as a typical dirt bike. The carbon on the backs of the valves, especially the exhaust valves, is another matter.

  • Yzflier977

Posted March 06, 2013 - 08:38 AM

#12

I used carb cleaner on mine and wiped it off with a shop towel. But then I didn't have much buildup either.

  • FinchFan194

Posted March 06, 2013 - 10:09 AM

#13

That's odd! Learned this from a very well known top fuel engine builder years ago. It worked on my wr a couple of years ago. Filled the combustion chamber with wd-40 when I removed it.The carbon wiped off the valves and head the next day like butter.

Ya I went and bought a gallon of WD and was all stoked to get of done, didn't hardly touch it, it barely changed the color of the WD. Then I tried Seafoam, much more effective, but still like 80% of the carbon remained. Then after three days I called a local machine shop and I drive off to go get my parts at the dealer 10 minutes away, he had the parts clean and ready for me to pick up before I got there.

  • beercan

Posted March 06, 2013 - 05:09 PM

#14

just did a top end rebuild a couple of weeks ago i replaced my piston and rings but i was on a budget and did not get new valves i got my valves clean by scrubing and rescrubing it was a pain in the butt. i just wanted to add while you have the head off its pretty easy to do a leak down test and if any valves leak a cheap way to fix this is by laping them the lap and a lapping tool is about 20 bucks and it does take some time but worth it. i did this on a 99 yz400 and shes back to her to her old self.

  • grayracer513

Posted March 07, 2013 - 07:48 AM

#15

A leak down test is impossible with the head off, as it requires pressurizing the cylinder with air.

Regarding lapping valves, that's something should absolutely NEVER be done with titanium valves, only steel or stainless.

  • Gunner354

Posted March 07, 2013 - 03:41 PM

#16

Ya I went and bought a gallon of WD and was all stoked to get of done, didn't hardly touch it, it barely changed the color of the WD. Then I tried Seafoam, much more effective, but still like 80% of the carbon remained. Then after three days I called a local machine shop and I drive off to go get my parts at the dealer 10 minutes away, he had the parts clean and ready for me to pick up before I got there.

The only thing I can think of is that the gas formulation has changed. I do know that today's gas will cause lots of problems in the carb and jets if left for just a short time.

  • grayracer513

Posted March 07, 2013 - 04:54 PM

#17

Pump gas formulation changes twice a year in California and several other states.

  • asnyder2

Posted March 07, 2013 - 05:05 PM

#18

Google home made soda blaster. Works great for removing carbon with no pitting. Not sure how it will do on exh valve as I have never tried it on a valve but have cleaned many cylinder heads and pistons and makes them look new.

  • FinchFan194

Posted March 07, 2013 - 09:01 PM

#19

The only thing I can think of is that the gas formulation has changed. I do know that today's gas will cause lots of problems in the carb and jets if left for just a short time.

You think it is the ethanol? I just found a ethanol free 92 octane station 20 minutes from my house! Big time score!!!





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