Early and Late 900 engines / heads

[m600_888_900ss]

Hi all,

Does any one out there know the differences between the early (circa 1991/2) and late (circa 1998/9) 900 heads? I think I read somewhere that early heads have bigger valves but cannot be sure. Is this true and which are the better to go for? Which produce more power and have better power potential? Also are the monster and SS engines the same?

Andy

[Yorkie]

I am sure that the older engines have larger valves and produce more power, and are therefore better to tune!

Someone with vast amounts of knowledge will be along shortly!!

I have just had a 1994 ss engine shoved into my 1999 frame and its got the bigger valves etc!

Yorkie.

[squiffything]

I am sure that the older engines have larger valves and produce more power, and are therefore better to tune!

Someone with vast amounts of knowledge will be along shortly!!

I have just had a 1994 ss engine shoved into my 1999 frame and its got the bigger valves etc!

Yorkie.

Ere who are you calling Shortly It's big big big with you tall people ain't it.

[Nickj]

Big valves can flow more gas so yep they're the ones to go for. One of the limiting factors in tuning on the 600/620/750's was the small valves, it does limit what you can do to them.

[Pedro]

900cc Bikes from around 96/97ish onwards use the same heads as the 750 so have smaller valves sizes

[Yorkie]

Squiffy,

I dont know where you get this small man complex!

As for the SS/Monster engines they are the same less jetting on the carbs and where the oil cooler sits!

Yorkie.