Advice on 39 or 41 mm Kehin FCR's w/ small valve 900 heads (750 heads)

[silas]

IMO, the stock carbs are more restrictive than the W heads. All the pre-DS heads are choked up anyway, the W heads are just a little worse than the average V2 stamped SS head.

The jetting is the same on all FCRs: 41s or 39s; Monster or SS; 750 or 900. I've got a FCR FAQ here too. 900s get 41s and the 750s get 39s. It's about displacement and air volume, not what valves are in the heads. If you're thinking do both but want the FCRs either way, get them first and see if they are enough to make you happy.

Again IMO, no one should spend money on the insides of pre-DS engines in the name of power. Instead, they need to get a 696/1000/1100 engine and start there. We're starting to get people putting FCR41 singles on 1000DS engines. The first guy got 99hp and other than a nemesis ecu, the rest of his bike was all stock + slipons. 2nd guy is a racer and is essentially over-engineering his bike, so it's not quite done yet.

Chris

thanks for all the replies and help, esp. Chris.  i'm saving for the carbs and heads. interesting that some are putting fcr carbs on FI bikes.
I've ridden a monster s2r1000 & the 1000 cc motors seem a lot smoother on my 1st short ride. 

[krista]

Just talked to a customer today who raved about the Ignitech sparker driving his 1000DS engine using FCR41 split singles. He loved how the sparker helped the bike make power with only 32 degrees of advance. He said on a Factory Pro dyno, it got 98hp, which is like 115 dynojet hp -- same as a new R6. He's absolutely ecstatic. Keep in mind he also has head porting. The typical 1000ds engine with FCRs should be closer to 100hp.

I spent like $7000 to get 104hp out of a 900 engine...

Chris

[junior varsity]

What's the recommended airbox for this (on Monsters)? Stock Airbox without lid on it and K&N style filter? Pod-style individual cones?

I've seen people using those pod filters and I don't really know if that's for more power or really just streamlining stuff in the motor - getting rid of a lot of plastic, etc (but also having to figure out how to mount battery, coils, etc.)

[brad black]

After all *that* work, it's hardly a fair comparison with a stock pair of 'W' heads...

BTW, the 'W' heads went to the Cagiva's after 1998.  All 900's (AFAIK) in '99 and up got the 'V' heads.

the W heads came from the elephants - i think all the cagiva 900's had w heads, the gran canyon did.