XJ 900 cam specs

This might be a bit obscure, and it seems that a lot of members here don't care much about getting more power from their XJ's, but wondering if anyone has the cam specs for the XJ900 cams handy? My Hayne's manual lists the 650/750 cams as follows:

Intake - 8.80mm (.347")
Exhaust - 7.80mm (.307")

Base circle diameter - 28.00mm (1.102")

Bearing surface diameter - 24.967-24.980mm (.983-.9835")

Except for XJ650RJ, which has a 8.50mm intake lift. No word on duration though, but I'd have to assume that if the XJ900 cam have more lift, they'd also have more duration. Reason I'm asking is that I have a shot at a cheap set of XJ900 cams, thought it might be a decent upgrade.

And before you tell me not to do it, I realize that everything else will have to change along with different cams. I have a lot of experience with high-performance motors (in fact, that's what I do for a living), but this is my first major foray into the motorcycle world. Thanks for the help guys...

 

Had a few minutes to search around, and found this on http://www.megacyclecams.com, who BTW, happens to regrind XJ cams for about $390 a set. Thought this might be good for future reference.

XJ 650/750:
Intake: .335" lift / 236* duration
Exhaust: .305" lift / 232* duration

XJ 900:
Intake: .343" lift / 240* duration 108* lobe center
Exhaust: .326" lift / 236* duration 108* lobe center
Intake opening/closing: 12btc / 48 abc
Exhaust openng/closing: 46bbc / 10 atc

So, an extra .019" of lift and 4* duration across the board. Not sure if it's worth it or not, but they're cheap, and it is an upgrade, so I might just go for it. 8)

Also, this makes me wonder who is wrong, the Haynes or Megacycle Cams. Because according to the Hayne's manual, only the RJ has a .335" lift, while the others have a .347" lift, which would actually make that larger than the 900 cams. I'm going to have to side with Megacycle Cams because they have to check the stock cams in order to be able to regrind them. I've seen too many other instances in which the Haynes are wrong. Guess I'll check mine when I get my motor torn down though.

 

From my Factory Yamaha 900 Seca Manual:

Cam Cap Inside Diameter :25mm (+ 0.021mm, -0.000mm)

= 0.984" (+0.0008",-0.000")

Camshaft Outside Diameter: 25mm (-0.020mm, -0.033mm)

= 0.984" (-0.0008",-0.0013")

Shaft to Cap Clearance: 0.020mm~0.054mm

= (0.0008"~0.0021")


Intake Cam:

From Base Circle to Tip Of Lobe : 36.75mm~36.85mm (1.447"~1.451")
Diameter of Base Circle: 28.05mm~28.15mm (1.104"~1.108")
Lift: 8.75mm~8.85mm (0.344"~0.348")




Exhaust Cam:

From Base Circle to Tip of Lobe: 36.25mm~36.35mm (1.427"~1.431")
Diameter of Base Circle: 28.55mm~28.65mm (1.124"~1.128")
Lift: 8.25mm~8.35mm (0.325"~0.329")

Valve Timing:

Intake Open 38 deg BTDC
Intake Closed: 58 deg ABDC

Exhaust Open: 66 deg BBDC
Exhaust Closed: 26 deg ATDC

Overlap: 64 deg

Camshaft runout limit: 0.06mm (0.0024")


Requires a 120 link camchain.

 

Thanks Mac! Exactly what I was looking for! :wink: