Both INTAKE valves are stuck opened - Page 2 - Yamaha R6 Forum: YZF-R6 Forums
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post #11 of 18 (permalink) Old 11-28-2012, 06:41 AM
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Re: Both INTAKE valves are stuck opened

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Originally Posted by paan009 View Post
Buckets looked good, but I'll pull valves out and check
so not cracked, are they froze in the bore or will they slide out nice and easy with no sign of scuffing or scraping on the sides or in the bore? use a magnet to pull out those individual buckets. remember there are shims underneath.

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post #12 of 18 (permalink) Old 11-28-2012, 03:59 PM Thread Starter
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Re: Both INTAKE valves are stuck opened

CONFIRMED- both valves are bent!

1989 GSXR750 w/91 Bodywork
1993 ZX7(950)
1996 YZF750R
2001 R6 Champions Ed.(in pieces)
2003 Zuma 49cc
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post #13 of 18 (permalink) Old 11-28-2012, 04:09 PM
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Re: Both INTAKE valves are stuck opened

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CONFIRMED- both valves are bent!
there ya go.

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post #14 of 18 (permalink) Old 11-28-2012, 04:20 PM Thread Starter
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Re: Both INTAKE valves are stuck opened

Thanks for the replies. I was finally able to shine a light down the intake runner and saw both valve stems obviously bent in the forward position. Surprised I didn't see nicks or damage to the piston.

1989 GSXR750 w/91 Bodywork
1993 ZX7(950)
1996 YZF750R
2001 R6 Champions Ed.(in pieces)
2003 Zuma 49cc
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post #15 of 18 (permalink) Old 11-28-2012, 04:55 PM
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Re: Both INTAKE valves are stuck opened

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Originally Posted by paan009 View Post
Thanks for the replies. I was finally able to shine a light down the intake runner and saw both valve stems obviously bent in the forward position. Surprised I didn't see nicks or damage to the piston.
as the guys early on in this thread speculated, it is highly likely they DID make contact.. they are out of the way enough that it didn't break the heads off the stems. You are very lucky the valves were in the down position. I had a engine failure recently. Con rod bolt broke. with the rod shoved through the front of the block by the crank, and the piston at TDC. the valves had nowhere to go, and the camshaft lobes cracked the buckets. When the buckets split, it tore up the bore the buckets ride in, and nobody services those, so my ported head was/is junk.

Do you know if you floated the valves with an overrev?? On a high mileage motor, it's possible the springs were not able to close the valve fast enough, the piston made just enough contact to bend the stem, and bingo. Stuck valves. was everything else in tact? cam chain tight, pistons didn't crack, etc.

MICHELIN, EBC, Proflow Technologies
Silkolene, JenningsGP, Engine Ice, Sharkskinz, Pit-Bull


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Last edited by MELK-MAN; 11-28-2012 at 04:57 PM.
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post #16 of 18 (permalink) Old 11-28-2012, 07:07 PM Thread Starter
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Re: Both INTAKE valves are stuck opened

I bought the bike from a kid this summer that forgot to mention he over-revved the motor and bent valves! Luckily I got it for cheap when I saw that he didn't have a complete bike and parts were missing. No worries on my end. If anyone is interested in a great parts cylinder head, this is it! I have all parts/hardware to boot. PS- I also over-revved a $1000 Mototune epoxied/ported cylinder head on a built motor and snapped the valve and ruined the piston. They're both sitting on top of my toolbox as a reminder NOT to miss a ship or Ka-boom!

1989 GSXR750 w/91 Bodywork
1993 ZX7(950)
1996 YZF750R
2001 R6 Champions Ed.(in pieces)
2003 Zuma 49cc

Last edited by paan009; 11-28-2012 at 07:09 PM.
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post #17 of 18 (permalink) Old 11-28-2012, 07:19 PM
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Re: Both INTAKE valves are stuck opened

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I bought the bike from a kid this summer that forgot to mention he over-revved the motor and bent valves! Luckily I got it for cheap when I saw that he didn't have a complete bike and parts were missing. No worries on my end. If anyone is interested in a great parts cylinder head, this is it! I have all parts/hardware to boot. PS- I also over-revved a $1000 Mototune epoxied/ported cylinder head on a built motor and snapped the valve and ruined the piston. They're both sitting on top of my toolbox as a reminder NOT to miss a ship or Ka-boom!
not difficult to believe that is exactly what happened. I wouldn't be surprised if it was a recent GP shift convert, and he went down a gear thinking he was going up. There is no rev limiter for the rear tire turning the motor.. and ba-ZING. Valve float, and the heads of the valves can touch the pistons. This was a best case in actuality. they didn't break off. Are you sure the camshaft lobes and buckets look good for those two valves? not that I need it, just curious.

MICHELIN, EBC, Proflow Technologies
Silkolene, JenningsGP, Engine Ice, Sharkskinz, Pit-Bull


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post #18 of 18 (permalink) Old 11-28-2012, 07:28 PM Thread Starter
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Re: Both INTAKE valves are stuck opened

Buckets are fine. removed them with just a magnet, so no stick.
I have NOT inspected the cams/lobes, but I'll have time this weekend.

1989 GSXR750 w/91 Bodywork
1993 ZX7(950)
1996 YZF750R
2001 R6 Champions Ed.(in pieces)
2003 Zuma 49cc
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