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| cafebob |
 Posted: Sat May 19, 2007 10:48 pm |
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Rookie
Joined: 16 May 2007
Posts: 7
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so i just recived a set of cb900 pistons, and am thinking of using them to big bore my 77 cb750 super sport. Anyone tried this yet and know what kind of valve clearance ill be looking at? Also, I can get the cylinder houseing from the same bike, no chance of them bolting on to my bottom end?
thanks
bob |
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| Satanic Mechanic |
| Posted: Fri May 25, 2007 7:48 pm |
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Moderator
Joined: 04 Sep 2005
Posts: 309
Location: Munich, Germany
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Hi Bob,
and welcome! I have no personal experience with using the cb900 pistons, but from what I have heard they should work quite well with little or no machining. When installing them, I would check the valve clearance in any case. Of course it laso depends on the cam you are using.
I have just received pictures from a friend who is using CBX pistons - they required little machining to make room for a Megacycle 125-65.
As for using the cylinder block from the CB 750 - the cylinder spacing fits, but I am not sure about the studs. If they fit, you'd need to check what the cb 900 uses for oil passages.
Hope that helps, |
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| Satanic Mechanic |
| Posted: Sat May 26, 2007 7:49 am |
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Moderator
Joined: 04 Sep 2005
Posts: 309
Location: Munich, Germany
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| I just had a look at a CB 900 cylinder block. It won't fit easily - for starters, the CB 900 only has 12 cylinder studs. |
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| RC30 |
| Posted: Sat May 26, 2007 10:14 am |
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Rookie
Joined: 22 May 2006
Posts: 6
Location: Hessen, Germany
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You can use 900 DOHC pistons in combination with 750 DOHC conrods.
With 750 SOHC conrods you must machine the top of the piston, but there is not enough material. You must check these carefull.
You can not us these pistons with hot cams because there is not enough material for deeper valve pockets. |
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| cafebob |
| Posted: Sat May 26, 2007 3:58 pm |
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Rookie
Joined: 16 May 2007
Posts: 7
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thank you for the imput. a couple more questions. So i take it can not valve pockets be machined to fit performance cam? Will using the shorter rods help here? Anyone one have an estiment of compression ratio? Any idea on finding a cylinder gasket? Also, cycle-x just droped the price of their 850cc big bore kit to 200$...makeing it very close cost wise to going the cb900 piston route. What are your feeling about the advantages of going wither way. Thanks again, you guys are great.
C.B. |
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| RxmanGriff |
| Posted: Mon May 28, 2007 4:28 pm |
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Junior member
Joined: 28 Jul 2006
Posts: 26
Location: Colorado Springs, CO, USA
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| It might not matter to you but I've heard that CycleX uses 1 piece oil rings with their kit. |
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| Satanic Mechanic |
| Posted: Mon Jun 04, 2007 2:15 pm |
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Moderator
Joined: 04 Sep 2005
Posts: 309
Location: Munich, Germany
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I just looked at Cycle-X's web site. Their 850cc kit comes complete with head gasket, and at $199 it really sounds tempting. I would always prefer a kit specifically made for the 750 over the CB 900 pistons, just for the reason they are designed for that engine, they have deep pockets for hot cams, they have the right c/r, and if they even have the same weight that the stockers, I would definitely go that way.
Oh, and I am not afiliated with them  |
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