DROPPERD VALVE Hi, I recently purchased a 2006 model XTX with 500ks on the clock. At 2000ks and taking bike up to the rev. limiter,(no rev counter) a valve dropped and did the piston in. Is this common on the yamaha 660cc XTX? Yamaha said they wouldn't cover the repairs even though the bike is only one year from purchase, and in the warranty period, if this was due to over reving. Isn't a rev limiter supposed to stop over reving, with it's electronic cut out?
Mitch

Dont think this is a common problem from what i know of the XT's engine. Very supprised your yamaha dealer will not repair it under warrenty, i think i would have a very harsh word with them about it. But they will probably just refer you to some small print somewhere.

As for the rev counter, they are only there to tell you how hard you are reving the engine, a rev limiter is a different thing all together. My old deauville had a rev counter but no rev limiter but have been told that if you rev it past 10k rpm the crank will break under the pressure and engine will go bang (some london courier did this for the crack supposidley).

Its was maybe something to do with the engine still not being fully run in and possibliby this is the cause of the breakage.

Feel for you about this. as said before i would have a read through the contract of the warrenty and have a harsh word with them about it. My yamaha dealer sounds very much like yours and would not even give you a few tank of petrol let allow fix something under warrenty.

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Plough on

Is the bike standard? I wonder if it is modded will they not honour a warranty based on that? I would of thoughts a dropped valve would be covered within the warranty period as its a mechanical failure.

Maybe a more enlighted person will clear this up. I bet that will cost a pretty penny.

Yours would be the first XT660 that I know of to drop a valve.

I would need to see the parts of the valve train to determine what caused the valve damage.

Did the spring break, did the spring seat break, did the valve guide come loose, did the valve snap in half, did the cottors come off or break, what is the condition of the valve end at the cottors.

If the cottors came off & caused the valve damage what is the spring tention as per workshop manual of the valve springs. Weak spings can cause this.

Only knowing all these facts could a dealer say it was warranty or not. Did they strip the motor? Is you bike standard?

If you are after parts PM CaptMoto he has a good second hand head complete, off his first motor.

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Mods that I have done to my XTX's

My 04 XTX
Stage 1 & 2 DNA filters / Kev fuel mod / snorkel mod / Drilled air box mod / Engine breather mod / Fork Spacer mod / 15w fork oil /
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My 07 XTX
Raptor 700 cylinder 102mm / Modified Crank Case to take a 105mm Raptor Cylinder / 11:1 102mm JE Raptor piston / Stage 1 Raptor Hot Cam / Ported head / Colder Spark Plug / +2mm Throttle body / DNA stage 1 & 2 filters / Modified Air Box / Snorkel removed / Worry Brothers stage 2 filter cover / 6mm & 8mm Bolts Replaced with Titanium Bolts / Recovered seat in Black / O2 Eliminator /

My 09 XTX
59HP at the rear wheel / Stage 2 Raptor Hot Cam / DNA stage 3 Air Box / Carbon Can Exhausts / Modified Exhaust Link Pipes / PCIII With Custom Fuel Map / Wideband Commander O2 Data logger / LCD100 Dyno Jet display & fuel adjuster / 2500 OHM HT lead instead of a 10K OHM XT lead / Extra Coolant Cooler / Protaper Fat Bars / Tail Tidy With LED Tail Light / OKE Protection Knobs / LED indicators / AIS blocked / Modified rear sprocket rubbers / Rear Foot Pegs removed / 09 ECU With 02 Sensor Changed To A 06 ECU / Complete wiring harnes Changed from 09 to 04 / Home made LED resistor flasher / Hole drilled in the fuel tank filler neck to allow quicker filling / Modified Bar End Weights / Progressive front fork springs, 15W fork oil, forks lowered 25mm, used XTR rear links lowering the rear 20mm, rear spring one click stiffer / Changed front & rear guards from blue to black / 47T rear sprocket / Speedo Healer V4.0 / Kev throttle cam mod / Throttle grip mod / The new 2010 O2 sensor mod is out, works a treat, The new 2012 O2 Controller is out, PM me for details

Now ride a 2018 MT09SP ABS + TCS

My KTM 990 SMR Mod book. http://www.ktmsmt.com/viewtopic.php?f=13&t=4946

Yes my friend, as Kev said I have 2 spare engines to sell for parts, anything you need let me know, head / piston / valves / cam, the lot!