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lumpy790

My new project YZF450

42 posts in this topic

Picked up a 2008 YZ450F basket case off of craigslist in Charleston SC. :clap: The clutch basket had shattered and they already picked up a used clutch off of eBay and split the cases and cleaned it out. Closer inspection found cylinder needs to be replated :headshake and the ignition looks like a piece of metal got spinning and whacked one of the pickups cracking the coating. A little JB weld and we will see what happens. The head checks out good. Debating on getting a rod kit and putting it in since im already there......and I can press it in the crank my self.

Found a new OEM cylinder, piston, rings, pin, clips & gaskets on ebay for only $425.....and a complete aftermarket gasket set for $60 .......all should be delivered today. :bike:

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fun project.

what did you get it for if you dont mind sharing?

I paid a little more than I should have since I had to replace the cylinder.

Since the motor is basically all apart except for splitting the cases I decided to press a new rod into the crank.

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Fun project..

Interesting Odd man out bolt in the cam cap.

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Find anything funny with the head? helicoil for the one bolt? Cams binding in bores after cam caps tq down?

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I noticed the bolt and checked the head out closely before buying it. Threads were fine. Usually these bolts stretch and break before the threads get damaged. The cam cap bolts are already on my OEM parts list.

I will be swapping the Red wheels & rear sprocket off of my 2 stroke and already had a front cog.

My wife will be traveling for the next 2 weeks so my plans are to do a bunch of work on the Moto Hose Box Van and the YZF .........get to use the kitchen table...hehehehe

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its been a while since I updated anything about this build.......when I bought it I was told "all you need to do is put it back together" but after closer inspection I found wear on the cylinder from the piston being in to long. When I water checked the valves there was no leaking so the head seems ok. I picked up a cylinder & top end. Since it was already pretty much apart I decided to press in a new rod and main bearings and cam chain. Thank you Chuck at Privateer Connection for pressing the new rod in for me!

I have been procrastinating pulling the valves out to pop new valve seals in but tore it apart last night. This is my 1st time dealing with TI valves (400 & 426 had steel valves) and I am not sure if these are OK or not. I cleaned them up a little with a Brillo pad.

Intake

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Exhaust

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What do you guys think? Are they good?

If not what brand of aftermarket valves do you recommend?

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They look like they are currently serviceable, but the trouble is that there isn't a way to tell with any accuracy how much of the hard coating is left, since it starts out so fantastically thin. The exhaust valve actually looks better than the intake. The fact that there is a uniformly "clean" wear pattern on the intake face indicates that there is "some" wear. The coating on the valves is only about .0006" thick so measuring the wear is nearly impossible.

And again, if you reuse them, which you could right now, there's no way to know when they'll wear through and start sinking.

I would replace them with OEM Yamaha valves as opposed to any aftermarket product unless you're building a very high output, serious race only engine. In that case, I'd ask Ron Hamp at Ron Hamp Cycles what he uses on his 60+hp YZF's.

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I am obviously paranoid from the people who put down thumpers!

After bead blasting all of the valves there was no wear. It was all carbon!

Again..... a huge thanks to Chuck at www.PrivateerConnection.com for helping me out and giving an honest opinion! BTW.....if your at an East Coast SX this year you can say hi to Chuck as he is Jimmy Weinert Racings - #44 Les Smith's mechanic.

Motor is 99% ready........found the clutch nut was missing

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There is a fairly good chance that using glass media on the valve faces may have been detrimental to the hard coating. Not a good idea.

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Chuck is a professional motor builder here and I doubt he would have steered me to his cabinet if it was going to be a problem.....probably why he does not use the standard blast material sand.

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Chuck is a professional motor builder here and I doubt he would have steered me to his cabinet if it was going to be a problem.....probably why he does not use the standard blast material sand.

Does he deal with titanium valves much? Blasting them is fine for a steel valve, but I personally would never blast a titanium valve. Ti valves have a very thin ti-nitride coating that is what makes them tough. Once that coating is gone your valves will begin to tighten and will be toast in less than 10 hours. This is why people who don't maintain their air filters have problems, the dirt going into the engine damages the coating and their valves tighten up in a matter of hours. This is the same reason why you should never lap titanium valves either.

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Chuck builds MX motors every day and has for many years........ Builds Ti valved heads just about every day.

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