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Measured valve clearances, now what?

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I have a 2009 KTM 250 SXF that I bought new that now has 44 hours on it. I will be replacing the top end this weekend and went ahead and measured the valves prior to beginning.

The first time I measured the valves was at 15 hrs and was the following:

LI: .178mm (.007")

RI: .152mm (.006")

RE: .178mm (.007")

LE: .178mm (.007")

As of today at 44 hours, the valves have not moved and I suspect have not moved one bit since it came off the showroom floor. I am a fast C rider.

Per my owner's manual, spec is:

Intake: 0.10 - 0.15mm (.0039 - .0059")

Exhaust: 0.12 - 0.17mm (.0047 - .0067")

So according to the manual, I am slightly out of spec. I've never really understood this, but does this mean I am tight or loose? Does this mean I need to shim or have the valves cut? Is it too close to not even worry about? The bike is hard to start but I imagine that's because of the top end that I am about to replace.

Further, I have read on here and ktmtalk that spec is closer to Intake: .004 - .008" and Exhaust: .005 - .008"; which would mean I am fine and in spec.

I wanted to try and clear all this up since I will have the head removed and it would be easier to shim valves if necessary.

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I think you're good.

Only the left intake is slighty loose; the others are in spec (on the loose side but in spec).

I would'nt touch anything.

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one intake is a smidge loose. tight intake valve is often a sign consistent with hard starting, not loose valve.

when valve job is first done, they say the vales might tighten a wee bit, so they set on the looser end of the spec, but still in spec.

since you already have it out, wouldn't be hard to re-shim the one that is loose, or leave it. Yes, they are shims that you use. you need a shim that is slightly thicker, to put you back in spec. It would need to be .001" thicker, or better yet, they have a chart to show you what size shim you need.

did you check your compression? low compression also = hard start.

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This really annoys me that KTM insists on selling separate repair manuals. I obtained one and surprisingly, spec per KTM repair manual varies from the Owner's manual. Repair manual says:

Intake: 0.10 - 0.20mm Exhaust: 0.12 - 0.22mm

Which means I'm in spec according to that. Leakdown test showed 50% leakage past the rings which is why I am doing the top end.

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Wanted to bump this. I've got the head apart and do not know if I should shim it since the shims are already removed. If so, I'm not really sure what I should shim it to.

What are the effects of loose valves anyways?

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where did your shims go? do you know which shim size was on each valve?

this is what I just cut & pasted from a quick google search. Although it is for a car, the exact same principles apply for bike:

Valve Adjustment Discussion

In General...

Incorrectly adjusted valves can cause the engine to stall. Too tight, and they don't seal/seat down properly, so that cylinder isn't working hard enough and will eventually burn that valve. Too loose and the valve timing changes, so the engine sounds rattly and runs rough.

If the valves are tight, they just lift off the valve seat slightly, so they don't fully close. This just makes for leaking gases. The exhaust gas is the problem here. If it leaks past the valve continuously on each stroke, it heats up the valve (which needs to sit down on the cooler seat to shed some of it's built up heat) and so the valve stretches, which causes it to be opened more, which creates a worse leak.....

Driving the car around with tight valves for a short time in cooler weather (and on reasonably short trips) would not cause any real problems, since the valves would not have been at peak temps anyway.

Tight valves for too long would probably eventually cause excess wear on the cam follower too, since it would be rubbing all way round the cam, rather than just on the hump.

Remember that valves must be set COLD, as the valves stretch when hot to take up the slack.

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