Billet FCR Velocity Stacks

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.

Looks Great Chris.

I rode Flanny's bike. Very nice, but the Throttle pull was crazy. Interested to see what you come up with for a fix for that.

That along with the TPS sensor mount are some of the things holding me back from putting the set on the 950 SE.

Keep us posted,
Craig

You have a PM

Good stuff Chris...

It will be a better world with everyone riding around all high on torque!

B.

Watching the development and the results of your work was very enjoyable. Will they fit under my 950SM fuel tank?
Can't wait to place an order!

>>Watching the development and the results of your work was very enjoyable.

Thanks, lots of fun, especially when it all works better.

>>Will they fit under my 950SM fuel tank?

Probabaly. Where is the stock airbox relative to the upper frame rails? If you post a pic of the bike without the tank on and the underside of the tank I can tell you for sure.

>I rode Flanny's bike. Very nice, but the Throttle pull was crazy. Interested to see what you come up with for a fix for that. That along with the TPS sensor mount are some of the things holding me back from putting the set on the 950 SE.

Hopefully you won't be held back for long. Will test springs and hopefully finalize the TPS mount this week.

I'll see if I can come up with a pic of that. I have the FCR's installed and the box is off.

>>I'll see if I can come up with a pic of that. I have the FCR's installed and the box is off.

That may be easier. The filters protrude about 6 3/8" from the munting flange of the carb body and need clearance for about a 3 1/2" diameter filter top that tapers as it approaches the carb to 4 1/4"

I'm in!

The kit does include the jets, yes?
.

Yup. Recommended jet sizes are 155 for the 950 and 168 for the 990 and are provided.


Just finishing up the TPS adaptor and will machine the first samples over the next couple of days.

Sounds great..also waiting to hear about the throttle spring....any word on a choke system?? I hear they are a bear to start when cold/

Ooh! I'd like a choke too please!

Throttle springs are in progress. I tried to wind some samples on my simple spring winder but couldn't get an acceptable result so I ordered a few samples in different wire sizes from the vendor that makes the springs for my vintage fork upgrade kit.

The choke is also in progrsss, the aim is to make something that uses the stock KTM clutch master cylinder choke lever and maybe the stock KTM choke cable too. It may need some carb machining so would require the carbs to be sent to me. I'll try to avoid that but it may be unavoidable.

Hey Justin, I am 98.2% sure they will from my recollection of your bike at the Bend rally. Our prototypes just fouled Flanny's seat (back carb) and we cut a sliver out of the plastic but Chris redesigned them to set the filter lower down over the bell mouth so they should be within the stock airbox dimensions.

I really want to hear what you think when you get them installed. You may end up a bit fatter with your 41's so getting the chance to jet on a dyno would be helpful especially with your own exhaust. If you do be sure to get some before and after graphs. I know you rip on that bike so I'm looking forward to your impressions.

Gregor

Making good progress on the first batch of velocity stacks.....



Will be shipping the first orders soon.

Yay - way to be on top of this Chris.

I tool my bike out for a short ride again today, and was gob-smacked at the difference that these stacks made in the mid-range all over again!




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I'm going to send you a set of the final ones ASAP and if you could send the test ones back it would be great. Black or Orange? I have a couple of other bike configs to do testing on and need the adjustable versions back.

What the heck...Orange!


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Beautiful craftsmanship. Email sent