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Valve Adjustment Question, looking for thoughts...

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I just finished adjusting my valves, and I'm second guessing myself.

Opened up my 2009 YZ250F to check the valves after break in. The bike's got about 9 hours on it.

The valves were all in spec, but at the tight end of spec .10 on the intake .17 on the exhaust. The bike had been a bit hard to start, so I thought maybe that was related.

Well I dug in and 2 days later and $80 in parts and new tools later they are adjusted. Still in spec, but a bit looser. .13 on 2 intakes (.10 on the other cause I ran out of shims) and .20 on the exhausts.

She fired up on the 3rd kick, no throttle, after standing cold for a week, which is actually a first, and I was able to take the choke off almost immediately, also a first. I guess I'll ride it and see if it starts a little easier in the woods after a stall or other incident. Don't really even know if valve clearance affect starting that much. Oh well.

I could hear a little valve lash right after it started then I realized I had the cams apart and replaced the oil, so some of that was probably oil getting pumped up into the cylinder head. Then I continued to imagine I heard more that there probably was.

Still, Should I have left them at the tighter end of the range? How much does being at either end of the spectrum affect performance in that regard? I'm thinking about ordering a few more shims since I can get them all right around .11 and .18 which would make me feel a lot better overall. I hate being on the verge of spec since just a minor variation in measurement could mean you're out of spec.

Oh well, opinions?

Thanks!

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I think you're probably OK with how you did it. What I'd be concerned more about is injesting dirt. Clean the air filter and use the grease around the lip to seal it up. Another trick I've been doing for the last year is doubling up on the filter and actually using a Flo on top of a TwinAir. After a year, my valves haven't moved a bit.

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I try to shoot for right in the middle of the tolerance. If its right on the edge of being tight when you adjust them (cold) once its warmed up that tolerance gets tighter and can make it harder to start once its warmed up. I dont like going to loose either because I worry about the cam lobes smacking the buckets though I dont know that that is really an issue. It sounds like you got them right where they should be though. 👍

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Thanks Ron and Charlie. That makes me feel a lot better! I started up my '06 this morning side by side with my '09. The '06 just had the piston replaced and valves adjusted by a pro so I figured that would be a good test to see if it sounded funny. Sounds virtually the same except for the exhaust note. I do feel a lot better about it now.

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Thanks Ron and Charlie. That makes me feel a lot better! I started up my '06 this morning side by side with my '09. The '06 just had the piston replaced and valves adjusted by a pro so I figured that would be a good test to see if it sounded funny. Sounds virtually the same except for the exhaust note. I do feel a lot better about it now.

What were the differences on the exhaust note?

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The '06 has a more shrill exhaust that's a little emptier. The '09 is a little more bass and has more "volume" sound. It's almost like my cheap aftermarket TI header on the '06 has a slight leak.

Could just be the factory packing on the '09 vs the aftermarket packing I installed recently on the '06 too.

What were the differences on the exhaust note?

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