Valve pics inside...Opinions?

07 KX250F, New to me, bike allegedly has around 50-70 hours, I decided to do a Piston (pro-x) & timing chain.(Preventive maintenance) Top of old piston is black and seems to have alot of carbon, valves are pictured below, should I lightly sand and clean them and be done ? The bike runs great, starts ridiculously easy hot or cold, or should I look at sending this off to mxtime for new valves.. The valves are in spec, but other than that I don't know much about determining their life expectancy.

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Edited by jsmith811

cant see the pics. I just did mine. spray a little oven cleaner on it and let it sit 5 min or so. Then hit it with some scotch bright pads. I took my valves out one at a time. Stuck em in a cordless drill then sprayed WD-40 on a scotch bright pad and ran it in the drill to clean up the valves. Put a little moly-lube on the stem and install em. Saw this on a procircuit video on you tube i think it was. The head looked almost like new

Edited by spin05

The pics are showing up on my screen.. not sure.. As for removing the original valves just to clean, I assume that takes a special tool ? If no one sees a valid reason to do a complete valve job, then I will clean and re-assemble.

no just press down with a 14mm socket on a T-handle.it will pop the keepers out .Just make sure to put a waded up sock or something under the valve so it wont move. To put back in just press back down the same way. Just do one at a time so not to mix anything up. I looked everywhere toight on the web and can not find that video about putting them in a cordless drill.

YOu wont know until you take them out of the head. If you pull them out, and the surface thats cut at an angle to meat the valve seats is starting to get cupped out (you'll notice a ledge almost) or if you see a light metal material in a ring around the valve and its darker on both sides of the line you know the coating is coming off and the valves will soon be junk (hard to explain tried my best without having one in hand showing you)

Thanks dmm698. Thats exactly the part im tring to learn & understand. I assummed i would need a valve compressor or special tool to remove them, so the coating everyone refers to is on the inside of the valve assembly not where it meets the piston in the photo. I need a video. I dont completly understand how they come out but apparently its not too complicated. I will mark locations for my shims and buckets and see what i can do. Video would be nice.

Found this video. I assume the kx has the same setup

Edited by jsmith811

The tusk valve spring compressor is $35 and makes servicing valves easy. If you put Simple Green in a plastic container and soak the head and your valves for a couple hours the carbon will come right off with a toothbrush.

And don't use sandpaper or any tough abrasive on your valves. The coating you may have heard about is a very thin layer on the Ti valves to make them hard. When if wears off, valves die quickly. My two cents on this seeing your pics is to not remove the valves. Just clean the head, rinse well, pop in that new piston, shim the valves and ride.

Edited by Dragon67

Dragon67.... That's the conclusion I've come to, I have cleaned everything up, removed the flywheel and dropped in a new OEM Timing Chain, new piston should be here Thursday, should be able to put it back together then.

If it means anything the shims in the exhaust side have 308 written on them.. I wonder if any engine builders would know if that means they have been shimmed by previous owner based on their size..

Nothing appears to have been apart before based on bolt heads and appearance of bike..

and this bike runs great, starts great hot or cold, often times 1/2 kick... I just wanted to keep it that way, it did seem slightly down on power compared to newer kx250f's I've ridden recently.

Here is that video on cleaning your valves . Im pretty sure PC know what there doing.

That looks like a terrible idea. They also probably throw away valves after one race anyway. Not much different than lapping a valve which effectively destroys it.

They also probably throw away valves after one race anyway.

HA ha ha good point. Will find out,cause i just did it 2 weeks ago......LOL

Dragon67.... That's the conclusion I've come to, I have cleaned everything up, removed the flywheel and dropped in a new OEM Timing Chain, new piston should be here Thursday, should be able to put it back together then.

If it means anything the shims in the exhaust side have 308 written on them.. I wonder if any engine builders would know if that means they have been shimmed by previous owner based on their size..

Nothing appears to have been apart before based on bolt heads and appearance of bike..

and this bike runs great, starts great hot or cold, often times 1/2 kick... I just wanted to keep it that way, it did seem slightly down on power compared to newer kx250f's I've ridden recently.

308 could be available, but 3.075 is more common. Curious about what shims you need to get into spec? It's definitely a must to shim them up right. There are cool shim size calculators on line www.maultechatv.com/techguides/Valve%20Clearance%20Calculator/ is pretty cool. As for the cleaning video, I've done this too, but with "no scratch" scotch brite. The fine scotch brite may be fine, but I worry about the abrasive being too aggressive for coated Ti valves (which you have) . . . cost-based paranoia :) while you are at this carbon cleaning, have you serviced the silencer lately? Cleaning the core and repacking will make a difference in power if it hasn't been done.

Here is that video on cleaning your valves . Im pretty sure PC know what there doing.

followed the video and vales are int now have 10hrs on brand new top end

100.8 hours never had to shimm my valves top end at 50.2 again at 96.8 (cleaned valves) runs like new

followed the video and vales are int now have 10hrs on brand new top end

100.8 hours never had to shimm my valves top end at 50.2 again at 96.8 (cleaned valves) runs like new

thank you for that piece of mind........appreciated

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