CBX Racing

[Warwick Biggs]

Theory over practice, Phil? I can tell you that on all but a few high speed tracks I would trade horsepower for torque any day. A narrow power band at high engine speed with a lightweight crank can only be utilised by most riders on a long straight.

Any engine can be tuned for torque in the desired range over outright power and this can be further modified by gearing so, for tighter tracks you want the bike to jump off the corners. Very few multis of a given capacity and weight can match a relatively low revving single off a corner. Increasing the engine speed for more power will not be of great practical significance, particularly at extreme angles of lean where traction becomes more important. Witness: Yamaha's cross plane crank.

Where the Euro's have stolen a march on the Japs is paradoxically mainly in electronics. The current MotoGP bikes remind me of the period when Williams dominated F1 with computer-controlled traction and ride height. Ultimately, that led to the rules being changed to restrict that tech to enhance competition; observaby a significant factor in an increase in high speed crashes, culminating in the death of Ayrton Senna. The crash rate in MotoGP seems to be increasing (witness: M Marquez), a disturbing trajectory imo.

[Syscrush]

Theory over practice, Phil?

The theory and the practice are one in the same on this subject. This is probably more about me being an insufferable pedant.



Car and bike culture are so overflowing with misconceptions and misinformation about torque and horsepower I can't stop myself sometimes. My hope is that this is interesting, helpful, or at least amusing to someone.

I can tell you that on all but a few high speed tracks I would trade horsepower for torque any day. A narrow power band at high engine speed with a lightweight crank can only be utilised by most riders on a long straight.

You know a lot more than I do about what wins races - my track knowledge boils down to knowing what I like to have for breakfast before a track day and what beer I like to drink after. :)

But I would re-phrase that to say that you'd trade peak power for a broader spread of midrange power.

If you increase torque at a specified RPM, you also increase power at that RPM. Torque on its own means nothing, it always has to be discussed in the context of RPM - and the way we talk about torque and RPM together is by talking about power.

A 6.7L Cummins Diesel bus motor makes over 1,000 ft-lbs of torque - about 5x more than an F1 engine. Even ignoring the weights of the 2 power plants and asuming the gears could be dialed in perfectly, I don't think anyone would expect an F1 car to go faster if its 900 hp engine were swapped for the powerplant from a bus.

[Rick Pope]

Torque is measured, and horsepower is then calculated from that. If memory serves, (torque in lb/ft x rpm) /5252 + hp. Thus at any given rpm, a torque increase will cause a similar increase in hp. This is also why when you see hp and torque on a graph, those lines will always cross at 5252 rpm.

Simply put, you can't have hp without torque AND rpm.

[Warwick Biggs]

Haha! And, yes OK but....

You need to look at how the motor is working on a given track. A dyno will never replace that seat of the pants experience and is only a useful but rather limited tool.

We won't know about the new Ducati mono until somebody rides it and their raw peak hp claim tells us little about how useful that power may be. If you compare the torque figures the Vit makes more lower in the range. The extremely short skirt on the Ducati piston suggests it is designed to rev a bit higher, but so what?

I had the Vit out yesterday during a club coaching session and it acquitted itself well, up against mainly thousands. Nothing like charging down the straight at 120 mph with the visor up against your nose and being passed by a V4R or R1M as if you are standing still!

I did not have the time nor inclination to change the hard rear tyre, a dirty job at the track at the best of times but the Slovenian Mitas rear tyre actually performed well above expectations. Of course, it could not match the SC1 slick on the front but it seemed to handle everything except power out of the slower corners where it was at least predictable as it lost traction. I was riding it fairly hard albeit not quite race pace so I will look forward to seeing how the bike goes with a racing slick. The back needs more ride height too but a Nitron R3 costs almost as much as I paid for the entire bike so that might have to wait.

And I learnt a new trick too. holding the front brake through a flip flop to keep consistent load on the front tyre and assist the turn. Travelling from maximum lean on one side to the other very quickly is a far more aggressive and almost violent maneuvre on modern bikes than in the past and to do it without losing traction on the front requires a bit more technique than I have previously employed.

I do like the quick shifter, blipper and slipper clutch simply because it gives you more time to focus on a smooth and precise corner entry. Altho' I sometimes find it difficult to avoid automatically reaching for the lever.

The Brembo Z04 pads fitted to the front monobloc are so soft that they are worn out after as few as 3 track sessions and they are not inexpensive items. The single disk gets bloody hot too so fresh RBF700 racing brake fluid is essential every session to prevent boiling and consequent loss of brakes. The feel and control is worth it tho'.

All in all the Vit is almost the polar opposite to the Lump and it remains to be seen whether anything I might learn from riding a thoroughly modern mono will help me on a 40 year old 6 cylinder dinosaur. My next race on the CBX is likely to be in April or May '24. Not that far away, actually. How time flies!

[Syscrush]

Torque is measured, and horsepower is then calculated from that.

That's true on some dynos (load cell or brake type engine dynos) but not true on the inertial dynos that are by far the most common in use today. If you don't hook up the tach signal to those dynos, you get a graph of hp vs road speed - no torque at all. The tach signal is required to calculate RPM, which is then used to calculate torque from the measured hp.

If memory serves, (torque in lb/ft x rpm) /5252 + hp. Thus at any given rpm, a torque increase will cause a similar increase in hp. This is also why when you see hp and torque on a graph, those lines will always cross at 5252 rpm.

Yup. Put another way, torque in ft-lbs = hp * 5252 / RPM. The two statements are equivalent. If you have torque and RPM, you can calculate hp. If you have hp and RPM, you can calculate torque. But there are many, many other ways of measuring hp.

And ultimately, the only thing a modern dyno actually measures is voltage from a variety of sensors.

Simply put, you can't have hp without torque AND rpm.

For motorcycle and automotive applications, that's true. But a 1500W toaster has neither torque nor RPM but would be rated at just over 2hp, as 1 hp = 550 ft-lbs/sec which in metric is 746 watts.

It's worth noting that the ft-lbs in this hp definition (a force of 1 pound exerted through a distance of one foot makes a unit of work) is different than the ft-lbs in the other hp definition (a force of 1 pound exerted at a normal to a lever of length 1 foot makes a unit of torque), which I think likely adds to the confusion.

[Syscrush]

I had the Vit out yesterday during a club coaching session and it acquitted itself well, up against mainly thousands. Nothing like charging down the straight at 120 mph with the visor up against your nose and being passed by a V4R or R1M as if you are standing still!

And I learnt a new trick too. holding the front brake through a flip flop to keep consistent load on the front tyre and assist the turn. Travelling from maximum lean on one side to the other very quickly is a far more aggressive and almost violent maneuvre on modern bikes than in the past and to do it without losing traction on the front requires a bit more technique than I have previously employed.

Sounds like an amazing day at the track!

I did Michel Mercier's racing school a bunch of times, and something he always drilled was how braking and accelerating change the geometry of the bike. He always talked about how compressing the forks by trail braking gets the bike ready to turn, and then getting on the throttle after the apex turns the bike into a cruiser.

He had us do braking before we did anything else, which is interesting when compared directly to Keith Code's approach of not allowing any braking at all until the 3rd or 4th session of the day. I'll never be a racer, but I like a track day now and then, and I find it helpful to stick to the "no brakes" rule for my first lap of every session to make me ease into it instead of being over-excited and getting in over my head. Other than that, though, I turn more like what MM taught us and I trail brake even when doing low-intensity street riding.

[Warwick Biggs]

Talk about torque versus HP gives me brain fade. In the real world give me a gear, any gear but preferably the right one to overcome the moment of inertia exiting a corner.

Another track session on the white arrow over the w/e but now fitted with slicks resulted in a PB but some missed gears going thru' neutral with the street gearing (16/40). I've said it b4; wherever possible avoid 1st gear at the track. I took another set of sprockets (15/42) to fit in case it rained. Luckily it didn't because I had some great dices with one of our fastest racers on his Ninja.

Lucky for another reason; changing wheels and sprockets on road bikes as opposed to race bikes is a pain at the best of times, much less in the pits. I can pull off and refit the back wheel of my Honda NC30 in 2 minutes flat whereas the little Swede took me over 2 hours in the workshop yesterday mainly due to the designer's failure to provide a decent location for the axle spacer and a diabolical grease seal. OK, so I dispensed with the seal. Just extra weight anyway.

The Prolink also has a fiddly design with 2 poorly located axle spacers, mainly held in place by a lot of messy grease (exacerbated due to my mods to the ZZR rim to align the chain). I wish somebody would market a ratchet device that can be mounted on a stand and that fits under the wheel like a stirrup so that the wheel can be accurately raised into the caliper and the axle holes perfectly aligned. Pit Bull do a scissor lift but it only fits their stand and raises the wheel at an angle. Looks like I will have to make something myself (sadly, my last attempt with an inflatable inner tube from a wheel barrow wheel was a failure).

Conclusion from track tests of the 701 Vitpilen so far is (that in my hands at least) it is faster than a hot GSXR750. Now I have to pull the back end apart again to fit the longer WP shock off a 690 Duke to provide more ride height. My Alpinestars boots are too expensive to keep having to repair with Sikaseal. Here we go again....

[Warwick Biggs]

This is my low tech solution for locating the rear wheel of the Lump so that the axle lines up with the swingarm during wheel changes.

On my Prolink I have to align the axle with the Kawasaki brake caliper as well as the 2 spacers, one on each side of the wheel, while also making sure the disk fits between the pads. Usually everything takes a while to get precisely into place and then one of the spacers will drop out. The last item to be fitted is the chain on the sprocket. Luckily this tool is a close match for fitting the rear Vit wheel as well.

You can also see on the bench the new high tension leads I'm making for the CBX. They are aptly named as they take a lot of patience to make. First you have to measure the various lengths. Then cutting and crimping the connectors tightly enuf' so they don't fall apart when you are pulling the leads on and off. Then fitting to the coils with those silly plastic friction screws. So the job is proceeding at a snail's pace. I would prefer a modern coil over plug setup (my kingdom for a good sparky!). The way the HT leads screw into the Honda coils is SO primitive. The coils are too big, too heavy and have too high resistance for modern digital ignitions and the system for locating the inner cable with the spike on the end of the coil is very hit and miss. It's a miracle any voltage gets to the plugs at all. Then there is the connection of the cap to the plug and all of it has to be completely watertight.

[Jeff Bennetts]

Cheap insurance.

IMG_5066.png

[Syscrush]

Usually everything takes a while to get precisely into place and then one of the spacers will drop out. The last item to be fitted is the chain on the sprocket. Luckily this tool is a close match for fitting the rear Vit wheel as well.

Can you switch to captive wheel spacers?

[Warwick Biggs]

Yes, Phil but they would have to be especially turned up on a lathe. Roly suggested machining a lip into them ages ago, something he did on The Beast. However, not sure exactly how he did it and I don't have a lathe. It is one of many minor annoyances that is easily forgotten and therefore, never properly addressed.

Funnily enuf' I was watching the final round of the Oz Superbike Championships at The Bend yesterday (another world class track not far from me in South Australia) and one of the many returned young Oz internationals Tom Toparis had his R6 wheeled off the starting grid in the final 600 Supersport session when they had trouble fitting a fresh rear slick because of problems locating the axle spacer.

That race was won by another young international Harrison Voight in a stunning display of elbow scraping, on the limit riding. The SS title was actually won by a young local in Cameron Dunker, on his 16th birthday! One of my young club members and a veteran of the class had just the day b4 announced his retirement from 600's at the ripe old age of 21. This is the way of things here with the racers getting younger and smaller, many of them unable to hold a driver's license but circulating around race tracks at over 200 mph.

To be successful at the top level these days you really have to have started racing b4 the age of 5, be super fit and weigh under 65 kgs or 140lbs. This is legally problematic because it is well below the age at which contracts can be executed either by the riders or their parents.

[Rick Pope]

Interesting. One of our farm tenants' daughter just won the Mid-West sprint car series, at the age of 15, the youngest one can be to drive in that class. She's the youngest, first female, and first rookie, to hold that title. Some of the older folks in the class are a bit jealous. These aren't go karts or midgets. They're the 410 ci alcohol cars.

[Warwick Biggs]

What I find difficult to grasp is the parents' attitude. All adult racers know the risks inherent in racing and accept them. We all sign contractual waivers acknowledging and accepting those risks. Children do not understand and are not emotionally mature enuf' to do this and the law does not allow them this right until they are at least 18 years of age.

In many jurisdictions the parents or guardians are also prohibited from doing so on behalf of the child because they have a responsibility to safeguard the child. Regrettably, some parents and guardians do not fully grasp that responsibility whether it be on the race track or more generally.

Enuf' proselytising and skip to CBX news:-

Phillip Island is currently being re-surfaced and tarted up in readiness for WSBK and MotoGP in 2024. Prior to WSBK they have scheduled the first round of the ASBK in late February. In early February one of our largest road racing clubs has secured 3 days and will be the first, dare I say, 'crash test dummies', to test the grip of the new surface with the first round of their State Championship. Included with the moderns are some historic classes and because I am giving up the SA Championship to help celebrate my crew chief's (Fran's) 70th birthday I have been granted the consolation of competing at the iconic circuit in early February.

I built the Lump for this high-speed, flowing track. It is considered by many racers to be the best race track in the world and it is certainly my favorite. Considering my age, Covid and the demise of the Island Classic have conspired to frustrate that original purpose with ever declining possibilities. So, the opportunity to have another crack at it is very welcome as I haven't raced there since 2018. That will probably be my next outing with the CBX and if I can reassemble my full crew from past attempts I will be over the moon.

[steve murdoch icoa #5322]

That sounds great, Rick. Happy for you and The Lump.
One of your crew has to sort out an on-board camera.

[Warwick Biggs]

Thanks Steve. We will see.

There is a new faux historic series in Oz for the larger Period 5 & 6 historics called the Masters. It is commercially sponsored by an aviation firm and runs in association with the Oz Superbike series (ASBK). It is televised and live streamed with the ASBK and I can provide a link if anybody is interested.

When I enquired, I was told that they would like to see the CBX on the grid but I would have to commit to racing every round as the ASBK travels around the country. Oz is a big country and I don't have that kind of racing budget. Also, the riders are mainly young professionals and past world champions and the bikes modern replicas. Not that that phases me because I have competed with quite a few of them in the past. However, realistically it is not a place for elderly club racers like me who are just riding for a bit of fun. Altho' they all say that, I don't believe them! There is serious money and a lot of marketing involved.

I would need a race transporter with full on board workshop and comfortable accommodation and that would cost more than all my bikes put together, much less the running costs. Naturally, I had to decline.