Cosentino Engineering is proud to announce the release of its Billet FCR Velocity Stacks kit for Keihin 39 and 41mm FCR carburetors. The billet aluminum velocity stacks replace the standard aluminum Sudco filter mounts or the plastic or spun bellmouth of various lengths they also sell. The kit includes 2 anodized velocity stacks, matching K&N air filters and the recommended jetting sizes.
These velocity stacks are a bolt on accessory dyno tested to provide significant mid-range torque and increased top end power when compared to the standard filter mounts. The following dyno charts are for a KTM 950 tested on a Dynojet 250 dyno.
Rarely do bolt-on engine modifications result in such a clear-cut improvement over the entire operating range! These velocity stacks were designed to provide the proper intake port length to maximize cylinder filling and to incorporate the largest K&N filter possible, thus minimize pumping losses by providing more than double the filter area for the engine to breathe through. The result is 3.5Hp more peak power, nearly 4ft-lbf more torque across the entire rpm range, and 7% better economy! Increased throttle response and decreased front tire wear are important side benefits. The first test ride by Flanny was stopped before completion due to a serious case of acute torque intoxication. He may never recover.
This modification makes any carbureted 950 comparable with the latest 990 injected bikes. This dyno chart shows Flanny's carbureted bike compared to Gino's new fuel injected 990R with an aftermarket exhaust and modded ECU map. The 950 loses a small amount of top end power to the new FI model but still has significant mid-range gains: the place where most riding is done. Another benefit is the super smooth torque curve when compared to the lumpy FI version. If you want the top end power, a set of 41mm FCRs instead of 39s would bump up the maximum power with only a small reduction in midrange torque.
For those who already have a 990R with fuel injection there are large midrange gains to be made by stripping off the FI setup and retrofitting FCRs fitted with this kit. We tested sakurama's bike, which is a 990 FI engine that has 39mm FCR carbs. It compared very nicely to Gino's FI bike, only losing a bit of power on the top end. A set of 41mm FCRs would add a bit of top end making it a tough choice to keep the FI or go with a simpler and more reliable carburetor.
There are some pictures and videos of the testing process on the last few pages of sakurama's '950 Refresh' thread. Velocity stack length and jetting were varied until we got the best combination of wide power spread, good peak power, and stable air/fuel ratio.
The complete kit, including 2 velocity stacks, matching K&N filters, jetting, and an instruction manual, costs $469 + shipping. The kit fits under the stock KTM seat and requires no mods to the bike. The velocity stacks are available in an anodized black or KTM orange finish. Because the ADV list is one of the best online destination for motorcyclists we're giving a 10% discount to any ADV member. Just PM me and we'll send you a paypal payment request for the discounted amount.
We are currently developing kits for other motorcycles that use the FCR carb as an upgrade. Likely candidates are air cooled Ducati twins and the SV series from Suzuki. If you have a bike with FCRs that you think is not performing optimally, give a call and maybe we can develop a suitable kit to release its potential.
We will also be expanding our product offering to include complete carburetor kits prejetted to the specific application and fitted with our custom velocity stacks, low tension throttle return springs and TPS sensor brackets.
Check in for updates.