How to build a “Duzucati”

It’s been a few years, but I really wanted to do a write up how I came to build my race bike: a Suzuki SV650 powered Ducati 1098S- or as I like to call it, a “Duzucati”. A big reason why I wanted to write this up is because building custom/one off race bikes used to be a lot more popular, but with the advent of the modern “street bike” (really a race bike with mirrors and blinkers) custom bikes have gotten a lot rarer. People no longer need to do radical custom modifications to get a bike to make good horsepower and handle properly- you just need to walk into the local dealer and give him some money.

I had originally planned on glossing over some of the problems in order to focus on the positive parts of the story, but after a lot of consideration I decided to tell the whole story because I wanted to be honest about the experience. Building the bike and making it competitive wasn’t easy and it seemed dishonest to pretend that everything went smoothly.

With that said, here’s my story…

After racing my rather uncompetitive 2001 SV650 in 650Prod, Formula 650Twins and Formula IV in the AFM for a number of years, I decided I wanted to build a proper superbike. I had bought my production SV used and had a bunch of problems right off the bat- like a fairing stay which snapped at the weld my first track day and a then dropped valve a few weeks later at Jason Pridmore’s Star School. I’d like to say things got a lot better, but racing is challenging and as I cover in this post– a lot of things can and did go wrong. After that bad experience, I decided I wanted to build the bike myself so I knew what I was getting and it would be reliable.

While I was pricing out building a SV superbike (turns out they’re not cheap either!), I came across this ad on the Bay Area Riders Forum. Wow. Now that is interesting. A ~300 pound SV650? That sounds amazing! I mentioned this to KC
at BRG Racing whom I had been working with and he was just as excited as I was to build our own Ducati/SV hybrid.

I was able to borrow a Ducati 848 rolling chassis from Ed Lloyd. KC and I visited Gerry at GP Frame & Wheel with the frame and a set of SV650 cases to see what would be required to drop a SV650 motor in the frame. Surprisingly, Tyson’s posts on BARF were pretty much straight on- you needed a rear motor mount bracket, but it didn’t seem that difficult- the main forward motor mounts and countershaft alignment was pretty much spot on. Of course we both knew the devil is in the details!

I ended up buying a slightly abused Ducati 1098S off of Copart in late 2012 and after a stressful snafu over shipping it from Montana, we started stripping the bike, selling of parts and KC started designing, mocking up and finally
fabricating the rear motor mount bracket. KC was adamant that he wanted to also fabricate the front fairing stay, rear subframe and rear sets so I could run a traditional foot operated rear brake since the Ducati mounts the rear brake on the motor. KC also took my M4 SV650 exhaust and modified it to fit on the bike.

While KC was busy with fabricating parts for the motor & frame, I was working on the electronics and wiring harness. We decided to go with a 2nd Gen EFI setup with DL1000 throttle bodies but I wasn’t really interested in running the OEM dash. Instead, I wanted to run an XT Racing GPX Pro dash. Still though, the OEM dash is useful for debugging EFI error codes and since I was planning a major overhaul of the wiring harness we wanted some kind of way to debug the system. After a ton of research, I was able to figure out how to reverse engineer the ECU to dash protocol and created my own ECU Decoder which I then open sourced on GitHub. I ended up supporting not just the EFI error codes, but water temp as well.

There were a few other go-fast bits we added:

  • Dan Kyle Linear Track Link & Ride Height Rod
  • Modified Ohlins TTX Mk2 rear shock
  • 848 rear wheel eccentric and forged aluminum 5.5″ rear wheel
  • AFAM quick change rear sprocket carrier off a 748
  • Constructors Racing Group Supersport Clutch
  • Woodcraft-CFM Clipons

Long story short, after many months of work, we finally had a bike!

Unfortunately, that’s when things starting going south. The motor that KC build for the bike blew up on the dyno during testing. He rebuilt that motor and it blew up again. And again a third time. The AFM race season was in full swing by this point and we were both desperate to get out on track and so we put in a motor that KC had been given by another customer that was just sitting on the shelf. We swapped the heads, so it wasn’t completely stock, but the bottom end was completely stock and we were bit down on horsepower. The first time out on track would be an AFM race weekend- not the best time for testing a new bike, but it would have to do.

That first weekend was really hard. Not just trying to setup the bike, but it had this bad habit of just dying on me while out on track and letting me either walk or catch a ride back to the pits. I also found the riding position really awkward because the custom subframe seating angle was too steep. After the third time the bike died on me in practice I decided the bike wasn’t safe enough to race and pulled out of the race weekend.

Back at home in the garage, KC figured out the problem was the tip over sensor bracket. We hadn’t mounted it straight up and down, and that caused it to stick and kill the engine while out on track. I took this time to also install a beautiful 30mm offset triple clamps from IMA Special Parts to improve the handling of the bike and KC modified the subframe to reduce the seat angle.

The next race round went a lot more smoothly and I was able to focus on dialing in the suspension and work on my lap times. By the end of the weekend, I felt we had made a lot of progress, but racing in superbike classes with a motor which wasn’t properly built was a bit frustrating since I was down on horsepower and I found the seating angle still too steep. In between rounds, I dropped the bike off so KC could hook up the vacuum sensor properly and put it on the dyno and see if he could put a better map in it and find a few extra HP to close the gap.

I picked up the bike from BRG on Friday afternoon on my way to Thunderhill Raceway for a track day that weekend to continue my development of the bike and see if KC’s work on the dyno paid off.

The first thing I noticed Saturday morning was the bike was really hard to start. Once I got it started, it didn’t want to stay running. I had to constantly blip the throttle like it was a two stroke. Well that seemed odd, but as long as it translated into more horsepower out on track, I could live with it. As I left the hot pits and out on track into Turn 1, the motor felt more like a bucking bronco then a fine swiss timepiece. By the time I got to Turn 2 I knew something was very very wrong and I ended up riding around the remainder of the 2.8 miles of Thunderhill with my hand up and trying not to crash because the bike was constantly surging and cutting out.

When I got back to my pits, I called KC and asked if he had any ideas what was going on… after all, he had just had the bike on the dyno less then 18 hours earlier. KC suggested checking the throttle bodies, so I removed the seat so I could remove the fuel tank and access the throttle bodies.

That’s when I found that the fuel tank wasn’t bolted to the frame. There’s two pins up front and supposed to be a bolt in the back holding it in place, but that bolt was missing. My first thought was it was a good thing I wasn’t riding normally or I would of likely crashed when the tank fell off the bike. When I finally removed the fuel tank and looked at the throttle bodies I immediately saw the problem- the “vacuum line” that BRG had installed on the throttle bodies to the vacuum sensor was the same kind of hose you find at Home Depot marketed for running water to an ice maker. This kind of hose is very soft and sure enough, collapses under vacuum. No wonder why it was running like crap. Lucky for me, I was able to hack around the bad hose issue and find a bolt to hold the fuel tank in place and save my track day.

To this day, I never got a good explanation how the bike was dyno’d with this hose in place of a proper vacuum line. The one thing I’m certain is that there’s no way the bike would run properly with that hose. KC told me that the missing bolt was a miscommunication between him and one of his junior employees. I suppose that’s believable, but sadly, that wasn’t the first time BRG had given me a bike which was dangerous to ride and so after about 5 years of working together I had to cut ties with KC and BRG.

When I got home and I started going over the bike with a fine tooth comb to verify everything was in tip-top shape for the final AFM round. That’s when I noticed a crack in the engine cases at the front motor mount. It turned out the captive spacer KC had made for it was expanding and cracked the cast aluminum. Lucky for me, my neighbor owns Pega Precision, an excellent fabrication shop and was able to weld up the cases and fix the crack so I could make the final round.

I decided to do the Friday track day before the race weekend to get more practice in. Just after lunch, the front fairing stay that KC had built for the bike snapped at one of the welds. Sigh. Nothing a few heavy duty zip ties wouldn’t fix. I continued to work on my lines and especially my braking- the Brembo RCS master cylinder and Brembo monobloc calipers really work!

On the first practice session after lunch on Saturday I noticed my boot was really shiny. A closer inspection indicated that I had oil all over my boot… where was it coming from? From my bike of course. Turns out the way KC wanted to bolt the engine into the motor mount- by using helicoils in the engine cases to bolt the motor to the mount was causing too much stress on the cases and literally pulling the two halves apart. The result was the motor was leaking at the centerline- right where the cases split for servicing the bottom end. Thus ending my first year racing with my Duzucati.

I swore 2014 would be better. I knew I had a few things had to change in order to get ready though:

  1. I needed a new motor mount which was properly designed to treat the engine as a stressed member
  2. I needed a new motor which put out good power and was reliable
  3. I needed a new front fairing stay and subframe
  4. I needed to replace the custom rear sets KC had made because I was dragging the rear brake lever…
  5. which meant I needed to find a thumb brake because Ducati mounted the rear brake master cylinder and lever off the engine, not the rear sets

I ended up picking Gregg Spears of Spears Enterprises to build my motor. There are other good engine builders out there, but Gregg was the most professional and took the time to listen to my concerns and was able to explain to me how he would meet all my requirements. We had a lot of problems with the DL1000 throttle bodies and so we ended up replacing them with bored out SV650 throttle bodies. The result was the bike started easier, idled better and made plenty of power.

I started asking around to find someone who could re-design the motor mounts I had and make them better. Through Gregg, I ended up talking to John Stark. John at the time owned Stark Fabrication and was interested in building a single out of a Ducati 1098 motor and I still had the perfectly good motor from the 1098 sitting in my garage. John proposed a trade and I gladly accepted. It turned out, Ed Lloyd (the guy who lent me the 848 a year prior) worked for John and would be doing most of the work designing the new motor mount and programming the CNC. The new motor mount brackets are not only stronger and better functioning, but a work of art as well. Most importantly, they allow the motor to act as a proper stressed member and use two bolts which compress the cases rather then four short bolts which screw into the cases.

The fairing stay and subframe were probably the easiest- there’s so many aftermarket parts for Ducati’s. In the end, I ordered the parts from a local company: Motowheels. The rear sets were also an easy choice since Woodcraft is one of my long time sponsors. They make great parts for a very reasonable price.

The hardest part turned out to be the thumb brake. There aren’t many thumb brakes sold for road bikes and surprisingly, some companies didn’t get back to me when I contacted them for more information. In the end I went with Hudson Performance Engineering which even though they’re in the UK were very prompt in answering all my questions. Finally, Galfer USA made me a custom brake line for the thumb brake.

While I had all the bike apart in pieces, I decided to grind off all the unnecessary tabs from the Ducati frame and have it powder coated bright yellow to go with my newly painted fairings. I also had Pega Precision weld on heavy duty SpeedyMoto frame tabs to replace the flimsy OEM ones which bend very easily in a crash.

You’d think after all this work everything would be perfect! Nope.

I found out that when I changed the gearing for racing at Sonoma Raceway (aka Sears Point) I destroyed a chain. How does a bike making less then 90HP destroy a top of the line DID 520 chain? By causing the o-rings to literally pop out! I was able to get another chain and finish the races that weekend, but I took the bike back to Gerry Piazza to see what was going on. It turned out that the alignment of the front and rear sprockets was off by a few millimeters and that was putting a lot of lateral stress on the chain. I had Gerry engineer a spacer for the front sprocket which fixed that.

Since then things have been pretty good. The bike handles great and it’s been reliable. I’ve been able to setup the geometry for my liking and I love the fact that swapping the rear wheel (a common occurrence at the track) a painless and quick process. I’ve started designing some custom parts for the bike and Ed has done a great job making my designs into reality.

The last important modification I made was switching to the Woodcraft GP Shift lever cam. Last year I ended up crashing in a race and the crash caused my motor to be seriously damaged (required new engine cases) because the shift knuckle made contact with the ground. The Woodcraft GP Shift lever allows me to rotate the shift knuckle 180deg so it is pointing up and adds a lot of much needed clearance to prevent that from happening again.

So there you have it… the not-so simple process of building a custom race bike.

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