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 Post subject: CAM differenece
PostPosted: Wed Jun 17, 2009 4:13 pm 
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XT cam? is it the same as the SR?

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 Post subject: Re: CAM differenece
PostPosted: Thu Jun 18, 2009 2:13 am 
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Yes, exactly the same

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 Post subject: Re: CAM differenece
PostPosted: Thu Jun 18, 2009 3:16 am 
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up to 1984 they're the same. sr cam from 1984 onwards has a bit more lift apparently and, more importantly, is harder (nitrided) and must therefore only be used in conjunction with the matching post '84 rockers. these rockers, apart from also having a harder surface, have an improved oiling arrangement - hole in the rocker arm rather than in the face which sits against the cam lobe.

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 Post subject: Re: CAM differenece
PostPosted: Thu Jun 18, 2009 3:26 am 
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Hi,
In Germany there was a third sort of cams after 93...it has lower lift and in kolaboration with lower compression more narrow exhaust and reduced early egnition it had lower power due to noise laws. #
The 48T nitrated cam can be built together with the old 2J4 rockers if it is polished properly. The Nitrate needles eat the crome plated 2J4 rockers if not polished.
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Rei97


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 Post subject: Re: CAM differenece
PostPosted: Thu Jun 18, 2009 8:44 am 
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I knew the very late cams were crap, but didn't know there was a difference after 84.

Nitriding is also not vey good as it leaves the surface suspectable to corrosion. Doesn't matter if you use the bike all the time, just don't leave it unsed with out protecting the surface.

Sounds like a knee jerk reaction to the high cam wear rate, using the later type rocker arms seems to cure the wear problem without resorting to hardening the surface. This is the same as the XS650 set up, which never had cam wear problems and i believed used a normal chilled iron cam.

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 Post subject: Re: CAM differenece
PostPosted: Sun Jun 21, 2009 3:01 pm 
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hey rei

rei97 wrote:
The 48T nitrated cam can be built together with the old 2J4 rockers if it is polished properly.


i've just bought one of these of ebay. what does "polished properly" mean in this instance? is this something i could do myself and if not, what would i tell someone at a machine shop?

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john

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 Post subject: Re: CAM differenece
PostPosted: Mon Jun 22, 2009 2:30 am 
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Hi:
something like this :
http://www.louis.de/index.php?partner=h ... r=10003798
and a drill with 2000rpm....
And a lot of patience...
Then the surface changes from black-dull to metallic-brilliant.
If the 48T cam is a used one most of the job is already done.
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Rei97


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 Post subject: Re: CAM differenece
PostPosted: Mon Jun 22, 2009 12:20 pm 
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mmm...ever bought a new cam fom Yamaha? they come dull black.........and become shiny with use...are we chasing our tails here or what?

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 Post subject: Re: CAM differenece
PostPosted: Mon Jun 22, 2009 3:52 pm 
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Location: Germany Stuttgart, where car was born
Hi...
you describe the change from brandnew grey to shiny
That is the way of the 48T cam.
The gray is the nitrid needles which kill the chrome surface... that stuff expires to shiny... Then a 2J4 rocker will last for ever...if the lubikation is OK.
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Rei97


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