In our long search for new carburetors, we finally came across Sudco, a company that had the exact kit we were looking for. They offered 39mm Keihin FCR carburetors for our 720cc Raptor, and the friendly customer service answered any and all questions we threw at them. After deciding on the kit, the order process was quick and simple. Before we could get too excited, it seemed the package was already in our hands. Sudco's shipping department is outstanding. The kit came double-boxed and protected from even the most disgruntled postal worker's handling.
Scouring through the box proved to be satisfying, as we combed over all parts the kit provided. After a quick count of all parts, we decided which adapters we were going to need and were pleased by the extra options included in the kit. The engine side adapters are a machined part that is perfectly matched to fit the stock Raptor intake boots. Two options were included for the air filter side of the carburetors; a set of flanges that allow the use of the stock air filter configuration, or "velocity stacks" for the asphalt guys. Also included was a push-pull style twist throttle kit with Motion Pro cables.
It is necessary to remove the front plastic and fuel tank for the install. The Sudco invoice included a notation that some aftermarket exhaust pipes will interfere with the accelerator pump chamber. With this in mind we made an initial test fit and found that our FMF head pipe was not immune to this. The design of the FMF head pipe, having two primary tubes that pass by the carburetors, is the culprit. After emailing a few different exhaust companies we found that the models that would fit were those where the two small primary tubes merged immediately as they come out of the exhaust ports. We were prepared for this issue and had another exhaust system ready to be installed. We were somewhat nervous about the final fit of the carburetors between the frame rails and the clearance issues that we heard about. But after removing the head pipe, the carburetors slipped right into place. The flanges provided in the kit aligned the FCR carburetors very nicely in between the frame and the OEM boots. We installed one of the exhausts that was said to have no problems clearing the new carburetors and were pleased to find no issues. Jetting these carburetors is a much quicker process than with the stock setup. The bowls don't have to come off to make a main jet change, and they have a large access that exposes them for a faster change.
The main reason we chose the 39mm Keihin FCR carburetor set is obvious; we wanted to get the most out of the modifications we have already made. The OEM carburetors were designed to flow for the stock configuration and were an obvious bottle neck for the 720cc build. The accelerator pump on the FCR carburetors are also an added benefit for larger displacement engines, as they help eliminate the off-idle stumble caused by momentary lack of fuel. Upon the initial startup with the new carburetors, there was very little tweaking to make them feed the 720cc motor perfectly. When grabbing the throttle quickly, the motor gains RPMs without a stumble. The off-idle response is simply amazing, and the overall responsiveness of the Raptor is drastically improved. The first ride proved the worthiness of this upgrade, as the engine responds much faster, pulls harder, and runs smoother than ever. The design of the carburetors seem to eliminate the stutter through rougher terrain that we experienced before, and they feed the engine without problems for even the longest of "wheelies". The seat-of-the-pants dyno tells us that this is possibly one of the best upgrades we have made to the stroked 660R powerplant. We hope to get some horsepower numbers on paper soon, but regardless, these carburetors are the perfect complement to any modified Raptor, as they let the large bore breathe as it should.
Sudco did their homework and put together an awesome kit at an affordable price, with a straight forward install. At just over $1000 we found their kit to be competitively priced, and found value in the time taken to make sure the package would cover every aspect of the install. The kit included everything needed to accommodate our Raptor. The entire evolution took less than 2 hours at a very leisurely pace, and dealt us no surprises or problems. The only recommendation we have is the addition of an instruction sheet that includes a description of the contents, along with a guide for steps and checks during installation. The seasoned builder will have no problems, but the new guy may be left wondering what the exact parts and steps were, or what checks should be made.
Take a minute and thumb through the online catalog at Sudco. These guys carry a huge line of replacement parts for nearly every major ATV manufacturer. The catalog shows exploded views of the carburetors with a breakdown of all parts and part numbers. They sell high-performance carburetor kits for just about every Yamaha ATV, and many others. We are positive you will find the same great customer service as we did. Give their tech support a call at 323-728-5407, or email them at Sudco@Sudco.com
Quality: 5/5
Performance: 5/5
Installation: 4/5
Value: 4/5
Overall: 4.5/5
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Right out of the box, the 39mm Keihin FCR carburetors are begging to be installed!
The bottom of the bowls contain large bolts that are easily removed for quick re-jetting.
The kit includes adapters to fit the OEM intake, and 2 flange options for the air filter side.
Also included in the Sudco kit is a push-pull twist throttle with Motion Pro cables.
Top view of the carburetors; with the right exhaust they fit without clearance problems.
Sudco created a great kit, making it easy to upgrade the fuel delivery of your Raptor!
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