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Discussion Starter #1
Ok, after reading the link below about what years of M900 had small valves and weird cams, I decided to check my engine number and it turns out that I, according to the link, have a small valve engine. My questions are: a)Has anyone swapped a mid 90's Monster or 900SS head onto a later model Monster? b) Has anyone had their small valve head machined to the earlier(larger valve) spec? c) How difficult of a job is it to swap cams? I am thinking of obtaining a set of used heads, have them rebuilt with better cams/larger valves and swapping mine out. What can I expect to pay for a good set of 900SS or Monster heads? Dave

http://www.moto-one.com.au/performance/900equal.html
 
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Discussion Starter #2
I bought a used set for ~300 off ebay. I've seen some go for more ~600 and some a little less. I've been told that new valves and porting/polishing range from ~800 to ~3000 depending on who does it and what you want done. You get what you pay for but there are diminishing returns per dollar spent.
 
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Discussion Starter #3
I would farm out any machine work, but would do the rest myself if I could get a nice used set to start with. Not sure I would want the porting/polishing just new guides and maybe a bead blast. Dave
 
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Discussion Starter #4
Not sure I would want the porting/polishing just new guides and maybe a bead blast
What will a bead blast do for you? If it were me, (and it was, my 900SS has a BCM 944 kit and ported heads) and I was opening the engine I would go for a 944 kit and have the heads checked by someone who knows what they are doing (BCM, MBP/CA-Cycleworks). The places I mentioned are honest guys who will tell you whether you have a good head casting and whether its worth it to work on the ports or just give the heads a good once-over with an angle job on the heads (assuming you find some big valve heads). If you are going to do it, do it.
 

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Hi Mirror, if your heads say V2 on both of them near the valve covers on left side, they have the proper large valves. 750 heads have W1/W2 instead. I think someone on the big list tried to say this wasn't the case, but I can't imagine anything otherwise... I've heard this lots of times as well as seeing Pongo's heads (W1/W2) for myself.

Chris

PS - hmmm, W1/W2? or W1/W3? Anyway, sure as heck isn't V2/V2, which means happiness!!!
 

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Hi Mirror, if your heads say V2 on both of them near the valve covers on left side, they have the proper large valves. 750 heads have W1/W2 instead. I think someone on the big list tried to say this wasn't the case, but I can't imagine anything otherwise... I've heard this lots of times as well as seeing Pongo's heads (W1/W2) for myself.

Chris

PS - hmmm, W1/W2? or W1/W3? Anyway, sure as heck isn't V2/V2, which means happiness!!!
Hey Chris,

I didn't try to "say this wasn't the case." I did, however, question it. All I know is that when I was trying to figure out what I had (because my '99 has some S features and lacks others), Bruce at BCM told me I had to look at the cams. If it were as easy as looking at the marking on the head, I'd think Bruce would have told me that. I've never followed up with him on it (other than to verify that I had the 900 cams that go with the big valves) so I would not make a definitive statement about whether the "V vs. W" is conclusive. You could very well be right and for some reason Bruce never made that connection. I dunno. Just seems odd to me.
 

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Every carbed 900SS I've seen has 'V2' stamped on its heads. Zina's 00 m900ie has V3/V2 and the 01 mh900e has 1J/V2. Every small valve bike I've seen has W1/W2 (just checked the two small valve m900 engines in the garage, too).

The oral history of this "technology" goes back to when the m900 first got the small valves. It was a Big Deal back in 1996/1997 and the realization that V2 was original proper carby 900ss heads is not of my origination.

There are a lot of shops and industry icons that have ... gaps of knowledge (I am example... there is a lot that I really don't know... and I'll admit it when that happens). An example is that not many people know that small valve M900s come with 750 cams. I didn't know this (or care) until I got Pongo, my `97 m900. Even though some will say the ultimate rule could be based on the cams (I agree with this concept, really), we cannot make absolute rules about anything when it comes to Ducati.

BUT... I would always say that if there was W1/W2 on the heads, that they are 750 heads with hemispherical combustion chamber (bad), small valves (bad), and 750 cams (not just bad, but crap too). Proper 900 heads have "bathtub" style combustion chamber, 900 cams, and larger ports and valves.

Now, we go through all this... but we also have to know origin of the engine... There's every chance that someone put larger valves in 750 heads to attempt a "fix". (BTW, this will only leverage some extra money out of your wallet... Guy Martin's machining is only "fix" of crap W1/W2 heads)

;D

PS - And Bruce probably isn't a loser sitting on computer all the damn time absorbing other people's hints, tricks, and wisdom, then carefully considering said info and checking it out before adding to his own "knowledge base". Like many who lend advice, a lot of what I know is partly based on shared knowledge compared against the litmus of my experience and then passed on again...
 
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Discussion Starter #10
Hey Chris, thanks! I just checked my heads and the front reads W2 and the rear W1, crap! I guess I will proceed with my search for the V1/V2 heads! Dave
 

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will big valve 900 heads work on a 90's 750?
From what I've been told, yes. But this is one of those things where I worry a bit about true compatibility. I would lean more to saying "maybe". There are lots of little issues that can crop up... like does it have the round teeth in the belts versus square teeth? Will the top of the cylinders make good seal in the bottom of the 900 heads? If you run high compression pistons, will the valve reliefs work with the 900 combustion chamber and valves? Or will the pistons need more machining. I'm sure the list goes on...

Chris
 
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