2006 yz450f: What are the chances my valves and crank are still good?

[Justin89]

Hey guys, I will be doing my first top end on my 2006 yz450f next week. I have a lot of hours (prolly about 80-100!!!)? on it but this thing still runs like a champ. I have had no REAL problems with it, it's just about that time. It starts and runs fine but lately it has taken a little more than one kick to start it cold:smirk: I am taking it to a friend of mind that has his own engine company and he said that he will give me a good deal on the rebuild. However, he said he has to check the valves and crank and all that to make sure that they are still in usable or good condition. Now, what are my chance sof these things being good to go? Slim? I dont know a whole lot about these engines especially the bottom end stuff. Any advice on what I should do/check or anything will be greatly appreciated.??

[Markopolo400]

When was the last time you checked your valve clearance?

I bet that everything is still well in spec, and unless you race the A class, there probably is no need to replace anything.

[Justin89]

Uhh..never. I never really thought that I needed too. My bike starts every time pretty much hot or cold. I ride in the 450 beinner class so Im no where ven close to A class type riding. I'm comming from Red so Im not used to my bike NOT puking valves every ride...

[kev8131]

All you need is your valves checked. More than likely they just need to be adjusted, probably why its getting harder to start, my opinion check em out.

Kev.

[kev8131]

Yea what he said, sorry I'm a friken slow typer!!!

[grayracer513]

I'm certain the valves are still good on my son's '06, which is the older of the two. I know because they have never needed an adjustment. No change in clearance = no wear, means they're fine. What I have no way of knowing is exactly how much longer they are going to stay that way.

The crank is fine right now, too. Unlike rings, which get gradually weaker over a long period of time, Ti valves and crank bearings show little or no wear until they reach a certain point, after which they are suddenly bad, and have to be immediately dealt with. This can be handled preemptively, but if you replace the valves or crank before they show any signs of needing it, you waste an unknown amount of the available service life. OTOH, by doing that, you avoid having a sudden failure at an inconvenient time, or a possibly catastrophic failure.

So when he goes to boot camp this fall, I'll stick a set of rings in it, and see how the rest of it looks.

[Justin89]

Yeah thats kinda what the guy said. Like I said before, the bike runs fine now I just dont want to take any chances. I'm just afraid because valves and cranks get pretty pricey with just parts alone...not including labor.?

[Family Man]

Gray, that statement scares me, "Unlike rings, which get gradually weaker over a long period of time, Ti valves and crank bearings show little or no wear until they reach a certain point, after which they are suddenly bad, and have to be immediately dealt with."

Does a valve adjustment mean that valve replacement is just around the courner. I was told this by a honda 450 rider, and am not sure if its true. My bike is harder to start these days, which I have been told is a sighn of the valves needing adjustment, Ive never adjusted them. I should start checking them. I have been realy good about freequent oil and oil/air filter cleaning/changes.

[grayracer513]

A valve adjustment means you need to check them frequently for a little while. If the clearance stays where you put it for 5-10 hours, the seat was where the wear was, and the valve is OK. If the clearance closes up right away, then the valves have worn through their coating, and need repalcement.

Bear in mind, my '03 450 went through two owners over 5 years and more than 350 hours without ever requiring one valve adjustment.

[Justin89]

Bear in mind, my '03 450 went through two owners over 5 years and more than 350 hours without ever requiring one valve adjustment.

That's what I want to here...? My Honda 450 needed a valve adjustment after every second ride. Now I have the yz450, I havent even thought about a valve adjustment...until now.?

[kain522]

I am the third owner of my '04 450 and my valves needed no adjustment when I checked them this spring. The first owner was a racer, so I assume (hope) he did proper maint on it. The second owner was a casual trail rider who had the bike one year and traded down to a 250 trail bike. This is my second year with the bike, and so far, all I've done is basic maint to it. Maybe this winter I'll at least do the piston and rings to be safe.

[SBRacing]

almost 70 hours on my 06.. still on the tight side of spec...

[Family Man]

Yeah, well I changed my air filter today and it started up second kick both times once cold and then hot after on a ride for a while. Hopefully that was it.

[Justin89]

Well that's happened too...too much oil on the air filter for me though.

[Justin89]

Thanks to all that replied!???

[FreshDonutsCAN]

listen to grey! ??

[Justin89]

listen to grey! ??

ALWAYS!!!??

[bigred455]

I will say one thing ,the the YZ valves straight from the factory should be checked even before starting it. They are so close to the bottom of the spec,I had to shim 2 07's (my personal bikes) BRAND NEW which were a hair too tight.

[Justin89]

O wow...never heard of that:crazy:

[rexbond007]

i just checked my valves this morning 90 hrs on the bike and have not moved from when i checked them at 20 hrs. this is a rock solid motor.