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xs650 > > Motorcycle Systems > > Engine > > '75 low lead gas user |
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nokitov Full Member


Joined: May 05, 2008 Posts: 100 Location: Pittsburgh, PA
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Posted: December 24, 2008, 11:07 pm Post subject: '75 low lead gas user |
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Merry Christmas guys and thanks to Romer on the Shine Your Side Covers Ideas. Got the Right cover looking good and I'm on 320 grit right now. Anyway, I just remembered that my '75 was a low lead user and with low lead gas out of the picture for a long long time I was wondering is there something I need to do to the valves to make it more compatable to todays 87 octane no lead gas? Seems to me that I read somewhere that I need to change them out but I'm starting to forget more than I remember anymore. Was that the only question I had? Can't remember.
_________________ "If you get confused just listen to the music play"... J. Garcia |
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gordo 650Rider Supporter


Joined: Oct 09, 2008 Posts: 559 Location: CT.U.S.A.
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Posted: December 25, 2008, 12:43 am Post subject: Re: '75 low lead gas user |
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93 octane,I've seen valve seats cut right into a cast iron head,no seat's.And no problem's with the valve's.You should be ok with the stock set up,just keep it tuned & valve's adjusted properly.
_________________ '80 G, |
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Retiredgentleman 650Rider Supporter


Joined: Mar 03, 2007 Posts: 2258 Location: Calgary, Alberta 1978 XS650 SE
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Posted: December 25, 2008, 1:57 pm Post subject: Re: '75 low lead gas user |
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I have found that regular low test gas works fine in my 78SE. My engine is apart right now, and valves/valve seats were in good condition...................just needed lapping.
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nokitov Full Member


Joined: May 05, 2008 Posts: 100 Location: Pittsburgh, PA
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Posted: December 25, 2008, 4:47 pm Post subject: Re: '75 low lead gas user |
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yeah but werent 78's designed for no lead?
_________________ "If you get confused just listen to the music play"... J. Garcia |
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xsjohn Full Member


Joined: Jul 30, 2006 Posts: 5857 Location: North Carolina USSA
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Posted: December 25, 2008, 4:52 pm Post subject: Re: '75 low lead gas user |
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Dang.....tune it for premimum (92-93).........it's still junk compared to the 94 octane regular of the 60's.......
xsjohn
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BigGeorge Full Member


Joined: Apr 13, 2008 Posts: 267
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Posted: December 25, 2008, 6:16 pm Post subject: Re: '75 low lead gas user |
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nokitov... What I think you are asking is do you need hardened seats installed to compensate for the lead being removed from the fuel. For many years lead was used in fuel to cushion the valve against the seat and when they went to no lead, some older vehicles had problems with the valves pounding the non hardened seats right out of the head. Manufacturers then started installing hardened seats right at the factory. I do not know what year Yamaha started doing this. Maybe someone else can chime in here and enlighten us both..............BG
_________________ Those who dance are considered insane by those who cannot hear the music.... |
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nokitov Full Member


Joined: May 05, 2008 Posts: 100 Location: Pittsburgh, PA
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Posted: December 25, 2008, 7:05 pm Post subject: Re: '75 low lead gas user |
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Big/George, that sounds like the concerns I've read about in the past. I guess I have to weigh possibly using an additive for the lead no longer in the fuel, replacing the head with one with hardened seats, hardening my seats, or nothing.
_________________ "If you get confused just listen to the music play"... J. Garcia |
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jayel 650Rider Supporter


Joined: Apr 16, 2006 Posts: 3417 Location: SE Iowa 1974 TX650A
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Posted: December 25, 2008, 7:56 pm Post subject: Re: '75 low lead gas user |
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notikov your motor is new enough it doesn't need the lead the manufactures were swithing over in the 60's to the harder seats valves and guides
_________________ all it takes is time and money -- Where are we going and why are we in this hand basket? |
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nokitov Full Member


Joined: May 05, 2008 Posts: 100 Location: Pittsburgh, PA
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Posted: December 26, 2008, 1:07 am Post subject: Re: '75 low lead gas user |
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So it's further resolved, if it ain't broke, don't fix it and use 93 octane for cheap insurance. Thank you.
_________________ "If you get confused just listen to the music play"... J. Garcia
Last edited by nokitov on December 26, 2008, 8:02 pm; edited 1 time in total |
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Tomterrific Full Member


Joined: Jul 30, 2005 Posts: 149 Location: Columbus, Ohio
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Posted: December 26, 2008, 3:28 pm Post subject: Re: '75 low lead gas user |
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High test, high octane premium gas is still no lead. The stock seats are fine with no lead. You should use high test, high octane fuel because of the very real risk of detonation. If you are worried about 20 cents, just think how much a holed piston from detonation will cost. And as far as not needing premium fuel, 95% of the time s*** gas is fine, it's the 5% when conditions are ripe for detonation that your engine needs premium.
Not everyone holes a piston every year but several people do. Everyone of these folks whether they ride an old Brit bike or a Yam650 had cheap 87 octane in the tank. This is one place "penny wise and pound foolish" is a great saying.
Tom Graham
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