valve question

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valve question

Post  jayjay on Sat Aug 17, 2013 3:15 am

Hello. I just bought a 2006 xr650r that has very low hours on it and today I pulled the carb off just to see what main jet and pilot jet was in the carb. After I pulled the carb off I took a flashlight and looked inside of the intake and everything looked like it was new.one thing that I noticed was that the left intake valve had what looked like oil residue on it down where the seat area would be and the right one did not. I managed to reach my finger down inside the intake and smear off some and it was more like sticky varnish then oil. When I got the bike I adjusted the valves and the exhaust were in spec but the intake were quite tight so the original owner would have rode it like that. Question is could the intake valves being to tight cause this or is this normal ? Is this something to be concerned about? I have not noticed any oil use or blue smoke. Any help would be appreciated,thanks!
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Re: valve question

Post  BuRP on Sat Aug 17, 2013 12:23 pm

Welcome. Any valve 'leaks' some oil past the guide (they must do this!), and obviously all are a bit different. A bike which has been standing for long can do with a fill of full synthetic and a few good rides, then drop it and refill - as it cleans best internally.
So, put fuel in and go ride bru, have fun!
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Re: valve question

Post  jayjay on Sat Aug 17, 2013 2:31 pm

BuRP wrote:Welcome. Any valve 'leaks' some oil past the guide (they must do this!), and obviously all are a bit different. A bike which has been standing for long can do with a fill of full synthetic and a few good rides, then drop it and refill - as it cleans best internally.
So, put fuel in and go ride bru, have fun!
Thanks for the reply. My concern was that it was leaking past the valve at the seat, so I stand corrected as I am no more then a backyard mechanic. One more thing. I have been reading that engine damage could result from riding the bike with the stock jetting installed or corked up due to running lean. I checked mine and it is still corked other then the tail pipe was drilled out. Is this a fact? I ride at 2000 to 6000 feet in elevation and for me this thing has plenty of power as is so could I leave it corked without damage?
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Re: valve question

Post  BuRP on Sun Aug 18, 2013 7:16 am

Honda made a racing bike which performed well. To be able to sell it in countries with strict emission laws they had to 'cork' it, meaning cripple the output, choke its breathing and ruin the riding performance hence satisfaction.
It follows it has to be 'uncorked' the second you get it. Lotsa info present on the net, so do this first and then come back here telling anyone raving reviews of how it scared you shitless, and then we can talk about any other stuff you want to put on BRP smile 
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Re: valve question

Post  DirtyErnie on Fri Jan 17, 2014 3:17 am

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Last edited by DirtyErnie on Sat Jan 18, 2014 5:56 am; edited 1 time in total (Reason for editing : ..)
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valve guide leak

Post  temporary kiwi on Sat Jan 18, 2014 12:13 am

yes oil will be drawn down the guide every time you shut the throttle, this causes high vacuum to draw the oil thru the guide, while the parts involved are in good condition the oil usage is minimal, it can get serious as the clearance increases thru wear, im having issues with this type off oil consumption due to the high velocity of my much modded cyl head ports and larger displacement, in conjunction with bronze guides and high lift cam which requires race springs

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Re: valve question

Post  BuRP on Mon Jan 20, 2014 11:09 am

Big ports and high-lift cams need shorter valveguides normally, hence a large bending moment on a shorter support (the guide) results in accelerated wear >>>> they'll use more oil, simple really.
But even if they're the same length this is the case, as higher lift results in a bigger moment on the valves.
Nothing's free in the high performance world  BRP smile 
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