CBX Racing

[Warwick Biggs]

The stiffer shock is now back in the Lump ready for re-setting the sag. Once that is completed and weather permitting I should be back at the track in 10 days time to try it out.

[Warwick Biggs]

A quote from EMS on the Prolink, "Yes, it is "progressive". That's what "Pro-Link" stands for. The ratio between axle travel and shock compression is indeed 2.78:1 at full extension changing to 1.92;1 at full bump." Is there an ideal ratio? How did the engineers arrive at this ratio? Who knows?

The original Wilbers shock length was 295mm with a 6mm extension. Whether the installation of the Wilbers changed the length or ratio compared with the original air shock is presently not to hand. However, it is reasonable to assume that lengthening the shock will have an effect on the ratio. Mostly, the ratio appears to derive from the respective lengths of the linkage struts but shock length has to be a factor. How significant is another matter. We have now extended that length 3 times (ie: I have 4 different length dogbones) to around 330-340mm. So, the shock is about 12% longer. The extent to which the longer shock changes the progressive ratio constitutes an interesting mathematical challenge but seat of the pants tells me it definitely has a disproportionate effect on ride height. I should have been recording it. In any event, the practical effect on handling is much easier to assess at the track.

Now Roly reckons that all my attempts to raise the ride height are anathema and the bike will be so unrideable that it will crash. Based upon the changes made to date, I beg to differ but we will know, soon enuf'.

[NobleHops]

I fear Roly is correct, and I hope we’re both wrong.

[Warwick Biggs]

I have only added a few mills from my last outing (8 mm still to play with) and I have reset the sag to the right range so I don't expect any great difference and I can still drop the forks a tiny bit to retain trail but I could not test it last track day because of wet weather and I don't ride the CBX in the wet, so the jury is still out. TBC.

In the meantime, I am playing with the Gunson color tuning.

[Warwick Biggs]

Fear is the only thing to fear Nils! if you think my ride height changes are extreme you should check out what is going on in MotoGP with their radical electronic ride height adjustments.

The Ducati/Lambo/Audi/VW Marrelli electronics are working a treat and you can see the 'spoon' is almost horizontal and touching the ground under acceleration where it almost looks as if the rear suspension has collapsed but then the back is way up high with the spoon at a much sharper angle on corner entry. Compare the Honda with Marquez repeatedly crashing and declaring the bike unrideable. A higher C of G does incline the bike to slide more and exaggerates rider weight shifting but provided adequate trail is retained by dropping the forks to compensate then so far, my experience is that ground clearance is improved without too many adverse effects.

It is all comparative however. To date the only chassis/geometry crash I have suffered is coming out of Siberia into the Hayshed at Phillip Island - a very fast front end wash-out after hitting the cases too hard and levering the front wheel off the deck due to lack of ground clearance. Part of that was my technique in not getting far enuf' off the bike but mainly it was a consequence of going from 18" wheels to 17" without adequate ride height adjustments.

Speaking of PI some discussions are underway to see if we can revive the Island Classic after it's Covid hiatus. The big question now is the effect of inflation and higher interest rates on potential entrant numbers.

[Warwick Biggs]

For those who don't know Oz's central bank the Reserve is tasked with controlling inflation within a narrow 2-3% range. It does this by controlling the wholesale interest rate that retail banks are charged. It has been fairly aggressive in hiking those rates and because Oz has a dysfunctional federal structure where the States are responsible for providing most services but the national government raises nearly all the taxes to cover those costs, the States have become dependent on their only main untied source of income that is stamp duty on real estate transctions. This has led to govt induced massive inflation in house values (= higher tax revenue) fueled partly by printing too much money during the GFC. So, the Reserve's monetary policy is having an exponential effect on mortgage borrowers who borrowed too much when money was easy and are now limited in their ability to fix their interest rate costs. 2024-5 could see a collapse in this market with flow-on effects to expensive sports like motor racing.

[Warwick Biggs]

I still haven't got around to testing the suspension mods to the Lump but I did take the NC30 out for a canter yesterday. Glorious sunshine at Mac Park, perfect conditions and over 100 riders to play with. As usual the little 400 was at the pointy end despite dragging it's 180cm/90 kg rider around. However, I was well and truly dusted off by Tim Campbell riding a poxxy 450 motard. Tim owns a Portland motorcycle shop and is related to Alec Campbell (decd) who was responsible for developing the very first Yamaha 700/4 2 stroke race engine that went on to great racing success. This is a little known footnote to racing hisory and an iconic race bike.

Alec had the Yamaha dealership in Portland in the '60's and 70's and was a top sidecar competitor, originally with Vincent motors and his own chassis but the Vincents were too slow and after stuffing around with a cb750 he decided to make his own motor by welding up 2 TD250 Yamaha twins and fitting a Norton Commando gearbox. This thing was fast and when Yamaha heard about it they sent 2 engineers out from Japan to inspect it at Mac Park. That led the factory to develop the first TZ700 which Alec took to the IOM and scored 8th outright on his first attempt. That then became the TZ750 and a racing icon was created.

He came back to Oz and was a regular competitor when I was racing and won a number of Oz Championships b4 being killed in a freak incident at Adelaide International Raceway in 1980. It was to be his last race having announced his retirement b4 hand but not in the way he had envisioned. He became tangled up with another outfit and they shot off into a steel guardrail at an unusual angle. I was working in PNG at the time trying to restore order after the first Bougainville War and did not hear of his death until I returned to Oz some 4 or 5 years later. He was a very well liked man and in many ways a typical local innovator and motorcycle enthusiast.

Here are some pics of that first engine taken at Mac Park (courtesy of Old Bike Magazine).

[Warwick Biggs]

Finally, the elements and life allowed me to get the Lump out to the track to test the suspension set up. Happy to report that it all went well and the rather extreme efforts to gain ground clearance appear to have worked with no obvious adverse effects, yet at any rate.

After some spectacularly severe recent storms the spring weather was sunny and warm in the mid 30's and I had the track more or less to myself. Only one other clubmate testing an FZR in readiness for the National Championships at Baskerville in Tasmania in November. I have not entered mainly because of the cost. The overnight ferry to Tassy is just ridiculously expensive.

Whilst my test was not race pace it was sufficient to tell me the back end was more controlled, less lively and better behaved. The fact that nothing touched down and that we completed a press button start and race distance on one LiPo battery was encouraging too altho' testing is not racing. Happily, the sharper swing arm angle was not so extreme as to cause any problems with traction on corner exit and I was able to get the power down fairy quickly and smoothly as I lifted the bike up.

I'm still not entirely sure if the chain is clearing the steel slider over the swingarm pivot with me on the bike. It certainly is not without my weight as the 'click-click-click' of the contact is very evident when pushing the bike around. I also noticed after the test when preparing for an oil change that the primary chain was particularly noisy at idle and this has me wondering how to get at the tensioner without having to completely strip the motor. Does anybody know?

[daves79x]

You can only service the primary chain and tensioner by removing the engine and splitting the cases. The top end does not need to come off.

Dave

[Warwick Biggs]

Thanks Dave, I suspected as much. Roly reckons to ignore it and that the triplex chain won't break. Perhaps not, but I don't like it.

[Warwick Biggs]

I can't believe that nobody knows the length of a stock Prolink air shock...

Here is a pic of the Lump at rest and soon to be Gunsoned.

Last long w/e I was at the track scrutineering the moderns. So many crashes, particularly the juniors. Is it my age? But I don't think 8 year olds should be racing and I certainly don't think 15 year olds should be racing with seniors. One kid no older than 10 had multiple bikes, flash leathers and a diamond ear stud. He crashed 4 times and was given a green popsicle to suck on. That is methoxyflurane and he was intermittently crying, laughing and singing in delirium. The medics sent the ambo off to the hospital with the patient suffering suspected fractures but he was back racing the next day. Dealing with the kids is one thing - they are just kids afterall, but their parents seem to be from another planet! Thinking about the legal implications for the club of a serious incident involving a junior gives me the willies.

I've been offered a road registered SV650 as a direct swap for my KTM Duke but I'm not sure. A mate is also building a Husq'y 701 track bike for me too, so I'm very uncertain about the KTM's future. It is a great bike festooned with high end gear including expensive fully adjustable suspension, rider modes, Marchesini's, Brembo M50's, etc but a horrible riding position. It has adjustable bars and rear sets but it is that banana seat that doubles as an airbox making it difficult to modify. Later models had a much flatter seat and cut down suspension. Maybe I could learn to love it and I should get it out to the track again and give it another go.

[Warwick Biggs]

The 2 siudes of Juniors racing are illustrated in the following pics. First is an exotic bike built for Cameron Rende, winner of last uyear's Junior Oceania Cup and living and racing in Spain for the past year. It was built especially for him to contest the Super Twins class in Europe and he was circulating within tenths of the top unlimited superbikes during the weekend. The cost can only be speculated as it is a one off piece of exotica.

[Warwick Biggs]

And this bike was brought in to be re-scrutinised after at least 2 crashes, the last, terminal. The little kid riding it was high sided off after blowing a big end out of the bottom of the sump. After displacing it's rider the bike continued on to square hit a 200 year old stringybark tree, well inside the infield. Even the rear monoshock was snapped in half. The kid's leathers were destroyed but he was still wandering around looking for another bike to ride.

Some of these kids could be in MotoGP on multimillion dollar contracts within a few years but most will eventually lose interest and their parents' huge financial risk will be wasted. The kids are keen but some of the parents are keener and you have to question the motives and values at 'play'.

[Warwick Biggs]

Of course, that is just my opinion about the involvement of juniors and it is not shared by many of the powers within the sport who point to similar situations in other sports.

However, the strong commercial links such as Yamaha's bLU cRU involvement sits uncomfortably with the obvious dangers. Some may see it as exploitation of the vulnerable while others will complain about the 'nanny State'. Eventually and inevitably, it will be determined in a court of law.

[Warwick Biggs]

Meanwhile another of our juniors, Senna Agius has just been recruited to one of the top Moto2 teams and Oz also has 2 juniors in Moto3 so they keep coming thru. Hopefully he will be better suited than Wayne Gardner's son, Remy who won the Moto2 world championship only to squander the opportunity when he moved to MotoGP with some ill judged remarks. Jack Miller who originally moved to Spain so that he could race at a very young age is likely to retire soon now that he himself has a young family but there are heaps of young Australians racing in Europe and the States, many still in their teens.

Here is a pic of our current garage. A 650 Single, a straight 6 and a V4. People often ask how I can switch between such different bikes. The biggest change is a later apex on the heavier bike and more aggressive body movement and weight transfer in flip flops. Speed and braking distances are obvious but less technical. The lighter bikes with greater ground clearance can maintain higher corner speeds and are easier to turn and both have good torque to jump out of the corners whereas the CBX has more outright muscle and speed altho' it too has good grunt and amazing pickup mainly due to the way the lightweight crank spins up so quickly.

I have some track tests of replacements for the KTM coming up soon. Currently both a 701 and an SV650 are being built with me in mind. Both are eligible in the modern Limited class with the former also eligible in the super mono class altho' I just want a cheap track bike that I can also ride on the street. Both are ideal candidates for that, albeit with some modifications. Modern supersports and superbikes are too expensive to run ($1,00 at least for every track outing in tyres alone) and the G forces too hard on my aged frame.

The trouble with the KTM is that banana shaped seat that can't be modified because of the airbox in the tail. It locks the rider into an upright motard riding position that is hopeless on anything but a go kart track. A pity really because it is a bike with high quality componentry and nothing grunts out of a corner like a big bore single. The 701 is a better platform with similar motor and componentry but better racing ergonomics, while the little SV is a sweet little V twin with the same power (70HP), light weight and nimble handling. We will see... In the meantime, I must get back to tuning the Lump using the Gunson colourplug.