i called carb parts wharehouse to see if they had a slide for my stock carb(witch they didnot and there does not seem to be one in exsistance)anyway they said they have a twin 35mm keihin fcr set up for the raptor,its a rack style set up like the stock carbs and they also said it has better throttel response and make about 5hp more.the kit comes with everything you need including adapters for the stock air box,they did say the throttel cabel is on the right side and touches the frame when it exits the carb,he said you have to clearance the frame abit but no notching or hacking away at it.he also said they have been trying to get keihin to redo the carbs so the cabel is on the left but keinin wants $125,000 to retool to do it,they dont think they will sell enough carbs to make it worth it.the 35mm fcr's are basicly yamaha 700 srx snowmobile carbs.they want 685.00 for the kit.since i cant find a slide for mine(on back order until 4/3/01) im really considering buying this set up.i also am trying to contact psi performance to see if they have a set up using their big air carbs.if they can set me up ill probabley go that route. caution when changing needle position be very CAREFULL putting the needle retainer back in the slide!

 

Did your slide break when you inserted the retainer???

 

yeah i broke it putting the retainer back in.it was kinda cold out and after i reinstalled it two of the tabs broke off,i tried epoxying them back on but it seems hopeless,there isnt enough area for the epoxy to hold.one other thing about the fcr carbs,he said they where for a srx,i think he ment 600 srx motorcycle.but i ckd out the carbs on there website they use them on alot of super bikes.still no word from psi though.

 

I now own this kit for the Raptor and actually rode it for the first time today.

I am trying to leave work now but I will post more information and details about modification later tonight.

So far I am really happy with the setup. But I am still jetting the carbs

 

Let us know all the details, SOON!!

 

OK Here it is.

Modifications Required

ACCELERATOR PUMP LINKAGE CLEARANCE
I did not notch my frame as it was describe above in the first post. Instead I used a turnbuckle to spread my frame where the gas tank sits between and then I inserted some fender washers into the top engine mount to keep it spread apart.
No permanent damage to the frame this way.

ACCELERATOR PUMP DIAPHRAM CLEARANCE
I had to dent my exhaust pipe a little bit to clear the accelerator pump diaphram. In addition I added some 1" spacers to where the exhaust muffler mounts to the sub frame. This moves the exhaust pipe further away from the carburetor. I also added some exhaust pipe wrap around the pipe to reduce the amount of heat near the carb.

THROTTLE CABLE BRACKET
I needed to add a 3/16" spacer to the rear of the gas tank to give clearance to the top of the carburetors and the throttle cable mounting bracket. Some additional modification will be needed for the bracket because it is still too close to the gas tank for my liking but it will be pretty simple.

I had to go to Sudco to get the ORING gaskets that go between the back of the carb and the airbox flange adapters that Carb parts warehouse provided (CPW).

CPW provided some mains for tuning but I still needed some richer mains for my intake system. THe jetting was close but not perfect.

Originally they provided me with 140 mains in both carbs. My air fuel ratio at Wide Open was around 14.5:1. I put 145 mains in and I got it down to 13.5:1. My goal is about 11.5 to 12:1 so I am having them send me some 150 and 155 mains. They are sending them to me for free, all I have to do is send them the smaller mains back.

The performance increase from changing from the 140's to the 145's was really noticeable and when I get it a little richer I think it will be fantastic.

Right now I think I really need a new beefier clutch because it seems like its slipping a little now.

Sorry for such a long post but if you hae anymore questions just post them.

 

please let me know how it works when you get it dialed in.i dohave a couple questions though.do you think the accelarator pump diaphram will clear whe using a big gun exhaust system,because of the larger head pipe diam. and it sounded like you are running the same size main jet in both carbs,wouldnt you want to run a size or two bigger in the right carb like the stock carbs?

 

Yesterday I had a chance to take my Raptor out with the FCR carbs and ride. It still isn't jetted to what I exactly want but it more than fine for riding. It certainly doesn't have any hesitations or anything and in fact is very responsive. I am just a perfectionist about the jetting, besides I have the tools to get it perfect so I might as well.

BOTTOM LINE
The bike is is twice the bike it was before. This would be the first modification I would do to your bike even before an exhaust pipe.

I have a heavily modified Air filter system that completely messed with the original CV carbs. I could not get the jetting correct on them. Basically I think it came down to needle jet taper that was giving me the problems with the CV's.

The carbs came with the same jets in both carbs so I have kept it that way. When I was working with the CV carbs I noticed that the left carb had a starter jet that the right carb didn't have. So, I think that could have been the reason for the main jet differences on those carbs, but that is just a theory.

I had to dent my stock pipe so I imagine you will need to do some modification to your big gun system. What I would reccomend is trying to squish the pipe so that it becomes oval instead of denting it.

This kit will solve any of the jetting complaints that anyone has with the Raptor.

 

I,m sorry I have more of a question than answer - I broke one of the tabs when moving needle too. What affect did that have on carb operation? I don't know if that caused it but mine will not hardly run from stop to start without revving it high to get going and then it runs fine above half throttle. I would like to go to single carb setup if available. Did you check with dealer to see if they could get the slide.
NakedRaygun would you be interested in selling a slide to derbyking and myself since you are not using and/or maybe we can replace them when located.

Let me know.

Regards,

 

Sure I would do that for you guys. I don't have my stock carbs with me right now because a friend of mine is using them to design a throttle cable adjuster for my new carbs but I can get them in about a week.

Is that too late?