Our TT 1 Ducati 750 cc Engine Loves 36 mm SmartCarbs Flat Slides

Posted by Scot Wilson on

At Italianiron, we have fun with our builds and this TT 1 with Ducati 750 cc engine has been proven to be a highly successfull build based upon the reception and praise that we recieved at the World Superbike weekend at Laguna Seca this year. I have written blog posts about the build itself on my website for your review. Yet looks are one thing but engine performance is something else. We remain extemely exicited about our collaboration with the engineers at Technology Elevated, manufacturers of SmartCarb flat-slides that are transforming the performance of our Ducati twin cylinder TT & F1 Racers for Track and Road. Shown below is the first start-up of our 750 cc engine.

Our build started with a 750 cc Elephant engine that I picked up from my friends in Oisterwijk, The Netherlands. After we completed our engine work, we bolted this 750 cc engine into one of our TWC chrome-moly race frames . This engine originally produced 61 hp and after the engine modifications and the addition of our 36 mm SmartCarbs, we are just over 70 bhp at the rear wheel. I do think that these numbers are understated as not all dynos are created equal. However, that is a different discussion for a different day. It is interesting that due to the linear power delivery and performance of our SmartCarbs, that we started by using the same set-up of 36 mm SC with #13 metering rods, 80 clicks of adjustment for our TT 1 engine that we used on our TT 1000 engine. 

Our 750 cc heads have been professionally flowed, cut for using dual plugs per cylinder and we are using 13:1 high compression pistons. Yet, I remain amazed at how the SmartCarbs "wake-up" these vintage Belt & Bevel Ducati engines! As mentioned in earlier blog posts, the benefit of the SmartCarbs is a 30% saving in fuel consumption, 6 to 14% improvement in HPadaptability to altitude and other atmospheric changes, ease of adjustment and 80% less hydrocarbon emissions. However, ease of adjustment and tuning remains a very significant benefit of using our SmartCarb flat-slide carbs over other brands. Initial power improvement upon start-up was 66 bhp instead of 61 bhp. Finding bhp or almost a 10% improvement over the baseline is something to applaud. 


Based upon the data that we were getting from the dyno, however, we saw that this healthy 750 cc engine could benefit from setting our SmartCarbs even a little leaner. We adjusted our SC flat-slides 3 clicks Left, for Leaner, and found almost 5 bhp more power through the entire rev range. Finding almost additional bhp for a total improvement of approximately 16% over the initial baseline is something to celebrate! This is achieved due to the patented “keyhole” venturi shape of the SmartCarbs that provides crisp bottom end "snap" of a smaller bore carb with linear transition through the mid range to the full bore at the top of the rev range. Our Domino race throttles are also a perfect match with the instant throttle response of our 36 mm SmartCarbs. Simply simpatico!!

When I was racing Ducati bevels, the common wisdom was that "bigger is better". One of my last races of the season at Mid-Ohio tested that theory. I had replaced 40 mm DelOrto's for 42 mm DelOrto's on my 750 ss DomiRacer bevel drive. I could tell that my friend and Pro Racer, Malcolme Tunstall was not convinced of the success of my theory or application. However, being the fine English Gentleman that he is, Malcolme did not comment. As a result of my flawed theory, I had a horrible race as I was literaly "drowning" my engine with too much liquid fuel and literally suffocating performance!! That was late 1990's. As a result of carbs being too large they were also more difficult to tune and using oversized carbs was also the reason for the historical troubles that I had when using the "finnicky" 41 mm Keihins on other racebikes. (see my blog post, SmartCarbs versus Keihins). Discussing the problems of turbulence that is created when inlet port and carb size is mismatched versus achieving linear velocity of the fuel mixture will be the subject of another blog post. 


Fast forward to today and after 50 years of "revolutionary" evolution, modern, smaller 36 mm SmartCarbs flow more fuel mixture more efficiently than their larger round venturi counterparts. This is due to the fact that they are a single circuit and they appreciate the increased velocity that a slightly smaller throat size affords. Our SmartCarbs still make more peak power than the stock carbs, but the bottom to mid is where the real improvements are. When the new batch of smaller billet SmartCarbs are available, we will do some more R&D as to how small we can go in size and still maintain superior performance. 

With our new affiiation with Molnar Manx-UK, the new owners of Two Wheel Classics, we will also build some Norton racers that will use these SmartCarbs. Time to wake up some British Iron!! Come and experience the "pinnacle of carburetor technology" at Italianiron.com and Technology Elevated.


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