Exclusive: Inside the new WorldSBK Fireblade with the men who built it

| | WorldSBK
Picture: GeeBee Images

Around 20 years ago I went to the traditional winter test for the top teams in WorldSBK at the venue for the first round of the championship in 2020, Phillip Island.

If memory serves me well, it was the first time the all-new and very un-Honda 1000cc vee-twin VTR1000SP had been on track with its peers. To my surprise, my request to have a closer look around the machine with someone from Honda saw me get an ad-hoc one-man guided tour around the utterly factory bike with – again if my memory serves me well - the ‘Large Project Leader’ Shuhei Nakamoto.

Once we got round the language barriers (him from Japanese to English, via a Psion PDA (remember them?) at times and me from Scottish to English to Japanese, with lots of pointing to things and saying, “… this part?”). I maybe got to know more about the bike in one afternoon than Honda had said all winter up to that point.

This year, with a new Honda CBR1000RR R Fireblade SP race spec bike officially launched in Japan a few days before, I got an inside line about the racing based aspects on the new (and much more typically Honda) FireBlade from two of the top men behind the new machine – the Large Project Leader for the Fireblade roadbike and WorldSBK project, Yuzuru Ishikawa and HRC’s General Manager of Race Operations, Tetsuhiru Kuwata.

No guided tour this time but in the HRC Honda team cabin at Phillip Island on Friday night the first details beyond those released at the official Milan show and Tokyo race team launch were revealed.

When you decided to come to WorldSBK with the new bike why was it an inline four and not a V4? Everyone always says that a V4 is the best engine for racing. Maybe if you made a modern day RC30/RC45, around the maximum 40,000 Euro limit, you could sell all of them? Was this decision more for marketing reasons or technical reasons?
ISHIKAWA: It is a completely technical point of view why we chose the inline. You know the inline four and V4 both had positive points and negative points. The inline four is more easy to have its layout keep space for some other units. Also try to make a balance with the machine. It’s better than the V4.

On the other hand if we want to go super, super high engine speed area from a power point of view, it could be negative point than the V4. The V4 is completely opposite. This bike is based on production bike, so first we have to consider a production bike. Now, for the production bike you know that we have many, many variations, especially emissions tests, etc. In that case, we have to have a space for some units, for the mechanisms. So that’s why with the in line four it’s more easy to find out the best balance over the machine.

This is also maybe good for the performance. If we will use the V4 with many unique system, is for example weight balance, it’s going to be not perfect for the production bike, but for the racing point of view also this will be problems. So then they decide to go in-line four. And this is image. In the past we have two kinds of engines for the high-end supersport. But now the V4 is more like extreme for racing use. That’s why MotoGP is using V4, because this is a prototype machine. You don’t need to consider for the regulations, etc. Just going for that speed or power or performance with the machine. So, this CBR is a production bike. We have to consider this.

KUWATA: This is my personal opinion. Already we have a brand, which is the CBR. It’s coming from many years ago. So we cannot throw away that this image is now, because we did build up the image since many, many years ago. So, the CBR was the CBR. It was the flagship model of Honda. So we don’t want to destroy this. This is one the point, but especially now if we want to have a very high performance machine, it’s like we have to make it with the regulations.”

In the past you can change many things in WorldSBK, now you have to engineer the racing part into the road bike, meet Euro 5 regulation and try to win on track against the others in WorldSBK. How do you make the balance between a consumer product with a warranty, and this race spec bike, which has to be more and more extreme in performance? How challenging was it?
KUWATA: It isn’t just how much difficulty to get to this level. What is a real question to a technical point of view? For me now, as you said, world superbike has many regulations. We cannot change so many parts.

So, if we want to use the production bike in world superbike, this base performance is quite important for the real link to the racing performance. If we can’t change a lot of parts, even if production bike performance is lower, but we can change, then you can get to some level of proper performance. But we cannot change so many parts now. But, everybody is trying to go into this level, so we should go to a higher level with production machines, because we have not so much room to improve the machine from the production specifications.

So then this new CBR, you know the catchphrase of the CBR is “Born To Race.” So that means that the target is more racing. So this world superbike was a massive production racer. So they need to keep that maximum performance of this bike. That’s why they are using many technologies that are a linked to MotoGP.

We see some similarities to the previous CBR, although more technology on this one. But the chassis seems very similar to the old CBR. You didn’t do something really ‘trick’. Was this a cost thing? I think people were expecting something more ‘special’ in the chassis, maybe?
ISHIKAWA: It looks like we don’t have the super, super new technology or something for the chassis side, but as I said, with this machine our target is the racing use. So it means that we need to have the proper geometry with chassis balance or weight balance and everything for racing use. So it means that this chassis specification is quite similar to MotoGP.

So looks not so special, but they made a lot of effort to keep that same functionality of MotoGP but had also adjustability of the machine. With all of the things it’s quite linked to MotoGP. So they are forced to the focus from this area for the chassis.

Have you started with the complete stock chassis or already have you made some extra bracing, strengthening or additional material, like you are allowed to under the rules?
ISHIKAWA: The main frame is completely the same as the stock frame, because this production machine with this new frame has been developed with slick tires already. Already we put on that stress for the frame in racing use.

So that target is racing. So at this moment we don’t need to modify the main frame. Sure swing arm, where we can play more than the frame by regulation. So now we are using the different swing arm. Completely different. And completely different fork yokes.

For a race bike here, it’s different - weight, etc, from GP. Did you use a ‘copy’ of your GP experience for the yokes or go a different way?
ISHIKAWA: It’s basically not copies. We have a lot technical transfer between the other sections and HRC now. So we gave to them a lot of data about the MotoGP machines. But sure, they understood what is important for the racing machine from this data. Some essence will be used for that machine. But as you said, engine specification is different between inline four (WorldSBK) and V4 (MotoGP).

So they cannot fully copy from the MotoGP. But there are some philosophies of like chassis geometry or some other parts, but it will be used in this CBR but not full copies. This essence is in the CBR, but after that, they try to modify, they improve with this essence for the in-line machines. The stresses are different. We cannot say whether the superbike is softer or MotoGP is harder. No general rule.

So, for example, some parts will have similar stiffness. Some parts will be softer. So it will be also just try to get the true performance from this machine for that configuration. We are playing a lot around this area.

On the engine you used a large 81 millimetre bore for make the revs, as the revs here are another performance balancing limitation. You need the engine bore this size?
ISHIKAWA: MotoGP is using this a current diameter. It’s the same diameter as CBR. Their concept is they want to use the free technical things for the engine specification. We transfer from MotoGP to this CBR, because its diameter is also affecting many things. Like combustion.

At MotoGP we are using this bore and have lot of know-how. And that leads to the higher level of performance from this specification. They want to use directly this know-how on the CBR. That’s why they are using the same diameters. It means that they have no question marks to go to the big or small diameter.

Do you already make the crankshaft inertia maximum lighter? You can make it lighter but do you wait for some development?
ISHIKAWA: This is still tuning item. We can play. This is at the moment I cannot say. There are possibilities we will change the specification though the season or next few years. So it depends. Maybe it’s getting the data from this year with the new machines.

Why no split throttle on the roadbike, which means you cannot have a split throttle on the racebike? Five years ago everybody needed split throttles?
ISHIKAWA: At the moment he said it’s current requirement for the rider is a lot of specifications, this requirement is coming from that, like performance of the racing feel. Still we can reach to that requirement with this full throttle valves, via electronics, a lot of technology. Now we have that different know-how, the technology in electronic control. There are many things. So at the moment we don’t need to use a split throttle. So that’s why they keep four.

The throttle body almost looks like it is mounted inside the cylinder head, and very close to the inlet valves. What’s the advantage?
ISHIKAWA: It’s a quite similar specification of the MotoGP machines. So if you want to get the quite high performance of the engine and also good response of the engine… Also if you can put the throttle body very close to the head, also you can make more volume in the air box. We can play…

What else on the bike is special, things that you realize you needed on the bike to go WorldSBK? What’s special about this engine that maybe we don’t see obviously? Treatments, maybe?
ISHIKAWA: For the engine point of view, it’s valved the same. Its material for example, the material of the piston is quite high quality. And also for the coating of the camshaft, anti-friction. This is quite high technology. This is coming from the racing field.

But you have to make this work for a road bike, in the winter in Norway and in the summer in Thailand, with racing material also. Was this a big challenge to adjust the racing material on the road rather than the racing material on the race engine?
ISHIKAWA: It’s basically that a process for the manufacturing for this kind of racing technology is quite complicated. So it means that if we want to have one piston or something for just one day, it’s no problem. For racing, one piston for just one day is OK. But for production it is a compromise point.

It’s for a production bike. Of course, timescale is one of those things. Also I think cost. If we can put on a really expensive price, it could be possible to do anything. But also we have price capping for these regulations. So this is also around your point. They are thinking, developing to find out the best compromise point from racing to production machines.

Why did you decide, OK, we have to come to WorldSBK for this bike? This bike is ‘every bike you race’ with the exception of MotoGP. So it’s very important to get this bike correct, we would imagine?
KUWATA: I think the answer is this is a world championship. It’s a world championship for the base production machines. BSB is basically like a national series. Top level of that category, it’s our understanding, is WorldSBK, and also other manufacturers are concentrating on this category. If we want to show the people the performance of the new CBR, we need to go to the top level of the category. So that’s why we decide to go to WorldSBK.

With HRC, not just with another team? Last year you were HRC, but this year bike, everything new. But why no staff from last year? Why you make such a complete re-start?
KUWATA: Last few years we provided the machines for the current MIE Althea Racing Team. But they have their way, we have our way. Also this is a factory team. It is also same time as the launching of the all-new CBR. This is no joke. Just we try to give all the people our passion for how important this CBR is for Honda and also how much important it is for this championship.

How advanced are your electronics now, even from this strategy? Are you running in the level already of the level like MotoGP and more? Many people tell me that electronics is still mostly look up tables. Not so many PID feedback loops, eve though the general strategy can be very sophisticated. Are you moving things forward in electronics more than the others? Will you?
ISHIKAWA: Basically, this is all our own software. This is coming from the past. It is a including MotoGP and some other categories. So my understanding this is our best control strategy there. So as you said, we have room to develop areas. You know Honda. Honda has never stopped. So if you have some idea and you think it is necessary, you just go. So of course in some parts we are using a lot of closed loops.

This is true. We need to more stable on the performance for the riders. Sure, we need a closed loop. Just now it is not a simple closed loop. We try to feel the more natural closed loop for the riders. When they closed the loop means that we see the feedback. Everybody knows this. Feedback means something happens, and then we react. So sure we have a delay there.

But if the rider feels this delay, sure they don’t like it. So we try to discover, try to reduce this delay, so didn’t feel for the rider. Just for example also we are trying to introduce some feed forward systems.

Whether you have one sensor/data input, ten inputs or many more, ultimately you finally have ignition, throttle opening and fuelling that affects the bike. Can you predict in those areas?
KUWATA: We try; we are trying. This is the super-difficult part. But, if we don’t have any technical challenge in the racing field, we would never come to here. So what we’re always trying to find something challenging here.

We have to handle the 5,000 parameters or something. Around the performance of the electronics, it’s not only control performance. It is how long you need to meet that maximum performance level. You need one week, one month…? How much you need to set up electronics to reach full performance.