So what does it take to update a Bimota db1 to some current specs?
It turns out a hell of a lot...
Starting 2010 I set out to put a Ducati M800 engine into my Bimota db1. This would fit into the F3 class for BEARS racing in Australia. My db1 was a 1986 vintage machine, it had been modified quite extensively for racing over the years. Firstly by BEARS stalwart Scotty Brown, and latter from 1999-2003 by myself. The final configuration for the bike was a bit like this....
Motor: Ducati 750 cc , 780 cc kit, Larger valves fully ported heads, 40 mm delorto carburetors, TT2 cams, Conti exhaust pipe
Suspension: Standard. Marrzochi M1R forks and Marrzochi rear shock
Wheels:
Front 17x3.5inch (TZ 250 3 stoke mag)
Rear 17 x 5.5 inch Campag, or 17 x 6.0 inch Marvic
Front brakes: 320mm disks (FZR1000), twin 4 piston monoblock calipers (YZF600)
Rear brakes: 210mm disk, 2 piston caliper from db1.
Fuel tank: custom aluminum 6 litre fuel cell.
Performance: 73.8HP at about 9000rpm
What we had planned....
Motor: Ducati 800 Monster, Power commander PCIII, custom bellmouths, exhaust 2 in 1 45mm system
Suspension:
Front: Showa 996 Trinitrde forks, in 900ss triple clamps.
Rear: Custom made Ohlins shock attached to modified PASO 750 swingarm
Wheels:
Front 17x3.5inch Ducati 996 Marchesini mag
Rear 17 x 5.0 inch Campag, or 17 x 6.0 inch Marvic
Front brakes: 320mm snowflake rotors, 4 pad Brembo calipers, 998 master cylinder.
Rear brakes: 210mm disk, 2 piston caliper standard db1
Fuel tank: custom aluminum 6 litre fuel cell, external fuel pump
Airbox: Custom unit to suit
Performance: (Target) 78HP at about 9000rpm
Weight: (Target) 145kg
The Bimota DB1 was always a sweet handling bike. My major hangups with it where the suspension, and the carburettors.
Gooses, bitch list.
Front suspension
The M1R front forks were good in their day, well that's what their defenders would say. So, you bunch of idiots, if they were so good, how come no one else has adopted the one leg for compression and the other for rebound strategy? Why? Cause it sucks. Add in the lack of adjustment, that works... So piss them off and add in a pair of fully adjustable Showa forks from a Ducati 996 with Trinitride coating. Mated to a pair of 900ss triple clamps. The forks where worked by Nick Dole at TekNick suspension, and sprung with 8.5kg springs. The axle, wheel and guard all come ex Ducati 996.
Rear suspension
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| Bastard child - parents: Ebay, Goose, Nick Dole |
The solution? Well it started out simple, as our Queensland connection who supplied the exhaust and triple clamps had also supplied a rear wheel and swingarm assembly they'd used in their 900SS engined db1. It took me and Mike King all of five minutes to figure out it was a 750 Paso rear end, and with ex-centric chain adjustment. As such it could go and get stuffed. Within a week we had sourced a 620M steel swingarm, pivot, axle and brake assembly (thanks Linden). These fitted on incredibly easily.
Using the interweb I found an Ohlins YZF1000R Yamaha shock on ebay. These are roughly the correct length for the db1 and come with full adjustment and most importantly a remote reservoir. Again a visit to Nick Dole at TekNick saw him produce a shock fitting our requirements, built on the original Ohlins specs.
Thats the back end sorted, bar the the fact the wheels do not fit. So income some spacers and modified rear calliper hanger.
Carburettors
Don't get me wrong the 41mm Malosssi's are good. In fact the units fitted by Gowanlochs were some of the best carbs I'd ever used. The problem was not so much the carbs but the fact that to adjust them you had to remove all the body work and fuel tank. This is laborious at best, at worst it will turn you into a homicidal maniac. Where's my knife? That's one of the reasons I wanted fuel injection, not having to take the body work off to tune. The other being as the injected Ducati's have both intakes in the V of the motor we could make an effective airbox.
Enter the M800 engine. Its EFI system uses twin 45mm throttle bodies, 4mm up from the carbs we had, and tunable via a PCIII. However, while we where looking at the injection, we came to the conclusion that the M800 dashboard and security system had to go, let alone the wiring loom which came in at 3.8kg. This was going to be problematic as M800 are fitted with Ducati's most advanced security system ever. In this system the dashboard is coded to the ECU, via a RFID (Radio Frequency ID) chip in the key. Basically this systems works by powering a collar around the key, which activates the RFID chip in the key. The code from the key is broadcast to the dashboard, which has the antenna and logic to inturperate this code. It checks this code against the code in the ECU and if it matches it allows the ECU to fire the bike. The code in ECU and dash are syncrohnized at the factory by a magic red key. What is a pretty decent system turns into a nightmare if your dash gets smashed. Frankly its a euro centric idea that when a dash is broken you'll wait by the road side for help. In Australia you'd be carried off by the Yowies long before the Ducati recovery truck turned up.
So we decided to ditch the dashboard and standard ECU. This lead us to buying a NEMESIS type 3 fully programable ECU made in the UK. With this we could discard dash, keys, and PCIII. Less is more, but more expensive also.
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| Le original F1 motor, 780'ed etc |
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| db1 frame, all 4.5kg of it! ready for paint... |
So off we go....
Stripping the Db1 down was pretty easy, and given all we wanted was the frame and rear suspension linkage we had a very large pile of bits left over to store. Forks, wheels, swingarm, ahhhh, everything else, including the motor. The engine mounts on all Ducati engines are in the same location, so fitting the motor in was extremely simple. All that was required was to bore the frame mounts out from the 10mm used on the F1 engine to 12mm for the monster. After we dropped the frame over the engine we found a little problem with width of the throttle body assembly. Aka it did not fit, being to wide. A touch of creativity was required by Mike and some cutting tools, reducing the width by 20mm overall to squeeze between the Bimota frame rails.
With the motor indexed to the left of the frame with 5mm spacers the chain run was surprising true. This came as a real shock as the swingarm was not from the bike, nor the rear wheel. The axle spacer on the left needed to be 3mm wider, and we could still use the standard brake hanger from the M620. Well use, only after a massive amount of electric putty, aka aluminium welded to it to move the calliper mounts inward by 15mm to suit the 210mm disk. A quick machining job latter the rear calliper mount was done, and a 3mm spacer welded to the wheel side of the hanger made it all fit. This was of course the 6inch rear wheel, from which we'd hammered out the spacers inserted to take the db1 20mm axle fit.
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| 800M engine with 620M swingarm in situe |
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| Something is not quite right.... |
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| Mike welds up the new linkage mounts |
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| Linkage mounts in place. |
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| Highly modified rear caliper hanger - donor 620M |
Wheel it out boys.
The other rear wheel we wanted to use was a super trick Campag 5.5inch magnesium unit. This proved more than a little bit difficult due to the bearing sizes in the wheel. It had been fitted with 42mm OD bearings, and avoid a lot of machining, we'd have to use a bearing with the same OD but a much increased ID from 20mm to 25mm. Thankfully Mr SKF made some bearings (#61905) which would suit our needs. However this would require all new spacers in the wheel and sprocket carrier. Frankly a nightmare, so out with the lathe, and lots of measuring later we had our dry weather rear wheel up and spinning. Oh those bearings are 4 times the price of a 45mm OD x 25mm ID bearing.
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| Mock up rear wheel to get some alignment going |
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| Trumpets... yum! |
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| Clearance is a perpetual issue on the db1, we had to reduce the width of the throttle bodys |
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| This is 20mm narrower than stock! |
Coming up for air.
As mentioned previously I really wanted an airbox. With the throttle bodies in place Mike give me the go ahead to buy some bell mouths to suit. Some web research later I'd sourced some 45mm ID aluminum bell mouths of the right length to clear the front frame rail. Roughly 60mm high once we'd adjusted them. The whole airbox, filter idea took on a new meaning as we saw the location of the rear cylinder bell mouth. Aimed toward the front wheel, it gave it the best chance of catching a rock, or a small bird I've ever seen. I had envisioned the airbox was going to enclose the throttle bodies, but this made fitting it extremely hard. Mike came up with a great idea to put the bottom of the airbox over the top of the throttle bodies and all their relative hardware, plumbing etc, aka like a Ducati 4 valve.
The floor of the airbox would be in two parts. A vertical section that would form a place to seal against the front bell mouth. This would be glued to a horizontal plate stretching to the rear of the airbox and provide a seal plate for the rear bell mouth. We cut the standard rubber trumpets up to provide a mating flange for each bell mouth, and used 996 intake seals to cover the gap from airbox to trumpet. MIke carefully welded a flange to each trumpet to keep the seals under tension.
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| trumpets in place |
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| Flange to load the 996 airbox rubbers. |
The back of the airbox is a simple vertical wall secured via captive nuts to the floor, and its a tight fit to lock the floor in place both vertically and horizontally. The side panels not only box in the two top frame rails down to the forward cross member, but include a crankcase breather chamber on the right, vented into the airbox. The entire structure was made from HIPS (plastic) sheet. The bottom of the fuel tank would provide the airbox roof.
A filter element was next in order. Due to the front trumpet length this had to be a long way forward. We finally boxed in an area at the front to hold a screen of steel mesh and plastic element. The sides of this area where enclosed by 1.2mm aluminum sheet, mounted by screws to a floor extending forward from the front frame cross member. Mike decided on aluminum as it was less likely to fail under any stress caused by the front wheel coming up and hitting it. This was a forgone conclusion, and was going to happen no matter what. Future improvements will see us try to duct the air it from the high pressure area at the front of the fairing, and remake the rear assembly from carbon fibre.
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| Airbox floor in place |
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| Forward airbox section |
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| Airbox rear panel being mocked up. |
Completely Forked
After the suspension bill was paid. I picked a stunning looking rear shock and the showas from Nic at Teknick. The work on the forks had been extensive. The cheep forks from eBay turned out to have the internal preload spacers, a rolled steel tube, completely ruined. Along with the plastic caps at the bottom. The cause of all this according to Nic is way to much wheeling with hard landings. To remedy this Nic made up aluminium spacers from 3mm thick tube and new bottom bushes from nylon to suit. A far more robust setup. We sprung her with .9kg springs as these were the lightest Nic had in stock at the time.
Bolting them in for the first time 2 weeks out from racing proved a shock however. Not only was the top clamp hole not big enough, but the bottom was to wide! Both me and Mike very nearly gave up at that point. I ripped the top clamp off and we shimmed the bottom with 1mm aluminum to get an idea on stance and front wheel clearance to the engine. This also necessitated the fitting of the rear shock and positioning at roughly the right ride height to simulate a tyre on the bare rim. The stance itself was a guess at best. We measured both bikes available in Mikes shed, Ducati 888 and 748R making note of the height of the engine mounts. We rock the db1, back and forth on shock and forks until we reached the same height. 520mm on the front and 500mm on the rear mounts. Will it work? Me not sure, only time and a track will tell.
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| It took a lot of mucking around to get these in!! |
I take the top clamp out to Ben at Xtreme creations (www.extremecreations.com.au ). Ben threw it in his CNC Mill and took the top plate out to the required 53mm. Thankfully the 900ss clamp had enough meat on it for this to be done. Two days later the top plate was back on and the rotary steering damper was mounted up as well. We had to use a rotary damper as the standard plunger type would foul the air box we'd designed. I personally love the position of the rotary damper on the top clamp, side mounted ones are so easy to damage in a simple fall.
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| MSC rotary damper out of harms way |
Time to get tanked!
Going from carbs to EFI can be a bit of a mission, and the db1 provided more than that for us. The simple lack of size of the machine kept playing against simple solutions for many things, the fuel tank included. As we had closed the space in the V for the airbox we were left with no low point into which we could place the fuel pump I'd sourced from an 848 Ducati. All options were considered, including putting the tank under the seat and even under the motor. The lower point being critical to keep the pump immersed, running your fuel pump dry is a good way to wreak the pump. Our solution was to make a pump housing to be placed low under the seat, while a upper tank would line up with the existing hole in the body work. Total capacity would be 7 litres. We plumbed the top to bottom tank together with CRC quick release connectors and clear fuel line so that we can see the fuel level easily. The bottom tank would be rubber mounted to the triangle seat stays, while the top unit would be held on by big elastic bands and rubber mounted to avoid vibration. The whole tank assembly including aircraft filler comes in under 2KG.
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| Surge tank, aka Pump housing |
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| Nearly complete, just needs a whole for the gas to go in! |
A body of work.
Lets not mince words the db1 is a tiny bike, and the body work as small as it is weighs a tonne. The primary reason for this is that the body work is used as a monocoche struture that supports the rider. Effectlively placing all the riders mass through the seat which is in the standard config held up by the tank. With the tank gone, my arse was hanging in midair. To save time we stuck with the old body work, cleaned it up and made the decision to not fit the integrated belly pan that would cause lots of exhaust clearance issues. As a result we built added to the main body work two forward lower sections to blend this into the original front fairing section. Once completed we painted most of it black again.
Piping up.
With scan time left before the first round in 2010 Mike adjusted the pipe we had from the the Queensland connection. This proved slightly tricky as it was ceramic coated, and given we'd gone to a new swinging arm added complication. Mike added a lamb point into the rear pipe, and the 45mm diameter 2 into 1 system was hung from the right rear fairing mount. Ugly? You bet. This will be replaced later in the year with a two into two reverse cone megaphone unit. The dyne showed this pipe working pretty well, but the different header lengths have a negative impact on the rear cylinder with a hole in the fuelling at 5500rpm. Repeated runs with more and less fuel, and engine timing had no impact on removing this dip.
Our finished unit... (Bike finished at 3am for me to drive to Broadford practice started at 9am!)
DB1 Beta EVO Mk1
Motor: Ducati 800 Monster, NEMESIS EFI, custom bellmouths, exhaust 2 in 1 45mm system
Suspension:
Front: Showa 996 Trinitrde forks, in 900ss triple clamps.
Rear: Custom made Ohlins shock attached to 620M steel swingarm
Wheels:
Front 17 x 3.5inch Ducati 996 Marchesini mag
Rear 17 x 5.0 inch Campag, or 17 x 6.0 inch Marvic
Front brakes: 320mm snowflake rotors, 4 pad Brembo calipers, 998 master cylinder.
Rear brakes: 220mm disk, 2 piston caliper (monster 620)
Fuel tank: Custom aluminum 7 litre fuel cell, with 848 pump and filter assembly.
Airbox: 4 litre Custom unit to suit from 4mm plastic sheet
Performance: (Target) 78HP at about 9000rpm (Actual 77HP)
Weight: (Target) 145kg, Actual 150kg
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