FCR Carb - Planning While Saving My Pennies

[MSW]

Hey Carb experts, I have a couple of questions about Keihin flatslides.

So I know exactly what kind of dough I'm having to save up, I want to figure out roughly what it's going to cost me to get a set of Keihin FCR carbs for the Baggy. And, seeing as suitable FCRs never seem to pop up on eBay, etc., I'm looking at purchasing new. Problem is, over here in the States, the main dealer in Keihin carbs (Sudco) offers a very limited selection.

Question 1: Given the very few models they offer a Keihin FCR for (see offerings below), is there one here that is a direct match for the Yamaha 660 motor? I'm thinking the SRX600, but I really don't know anything about that motor.

Question 2: What kind of venturi diameter should I be looking at? 33? 35?

Question 2b: What's the upside/downside of going with the larger diameter? I understand from searching past posts and the internet that anything larger than 35 is probably not going to be workable for a bike that's intended for the street, but would the 33 or 35 be streetable?

For background, I currently run the tunebike carb kit (not happy with that part) with the tunebike powerheaders and a Holeshot can. I haven't done any mods to the internals, and I'd rather save that step until after I try new carbs (trying to do this incrementally until I find my sweet-spot of performance/economy/rideability). If I did go the next step, I'd probably start with getting the head ported, then explore boring/crank options.

BTW, I'm not trying to build a race bike here. Although I am trying to improve the performance as much as possible, I want to find a level where the bike is still practical for everyday use, and I've stopped short of breaking the bank.

Any and all thoughts welcome. Thanks!

EDIT: Oops!!! I forgot to include the available models from Sudco:

http://home.pacbell.net/adw_msw/fcr_carb_p1.jpg

http://home.pacbell.net/adw_msw/fcr_carb_p2.jpg

[droy]

MSW

Timely post. I just installed a set of 35 FCR's on my Skorpion Sport. I was very very luck to get them second hand from DEMARK ( former poster on this list who's on a 6 month peddle bike adventure) who had them on his Baggy so they were jetted spot on.

I installed them over the winter and just did a quick shake down run yesterday and was VERY impressed with the responsiveness and seat of the pants power increase. For the first time i was able to do a rolling wheely from 10 mph (could never do that with rejetted stock carbs). As for the 35 size it appeared to work for me in my short run - Bill may disagree. I'm also running a Barker large ID header.

BTW - DeMARK rebuilt these carbs after having exhaust heat issues from the stock baggy header. You may want to look into some heat protection.

[MSW]

Thanks for the info droy.

I had a different header heat issue on my bike (larger header making contact w/radiator hose), so I went and bought some header wrap. Gives the bike a very "Road Warrior" look. If I don't end up swapping out the carbs for FCRs, though, a rebuild and some tweaking to the jetting will definitely be on next winter's refurb list.

Have you noticed any significant changes in gas mileage since swapping carbs?

Thanks again.

[jcstam]

I was reading the posts about the carbs and I wondered it anyone had adapted a yamaha raptor carb to this 660 cc. engine. I've got a 1996 Scorpian Sport and I'm running the Hole Shot exhaust with the carb jetting and changes that came with the exhaust. I can get my hands on a used Yamaha Raptor 660 carb set and wondered if it would work.

[Bill Jurgenson]

if it will fit under the tank, it will certianly work. Hose size for the airbox may also be an issue if you are still using the airbox. When installing the Mikuni 34mm flatslides, one needs to use the larger right hand hose for the left side as well, enlargening the hole in the box to fit.
For testing just run the carb without the hoses if they cause problems and then get the K&N dual filter to replace the box entirely.
Also the Raptor carb has only a single wire since it has butterfly valves.

[basser23]

Yes, the Raptor carbs will work,most have used them on Baggie's and Mastiff.
You'll have to use 2" tubing on the right side carb to mount that carb..I guess you
could use Raptor manifolds, but...they tilt at the wrong angle(Raptor is canted forward,ours
is more vertical,,dont know if this makes a difference) I would also use a K&N without the airbox
Chip

[Bagiraboy68]

Help ,


I have a 2002 MZ Baghira Street Moto. I need a carb body or just the brass intakes they are gone and will not run at all at idle. All it does is pock and crack.

Please help if you can!

Mike