CBX Racing

[EMS]

Like I said in your other post: It is an issue of liability to say your part is OK for use on the street.

[daves79x]

Phil - I had a Lectron carb on my '76 TT500 Yamaha single way back in '76. It worked superbly, and I did a lot of hill climbing where low and mid-range performance was paramount.

Dave

[Syscrush]

They seem very popular for singles. The only applications they sell for multis are drag-only velocity stack configurations. They don't say off-road only, they say "drag only".

I suspect that if you ran them open on the intake side and had a 6-into-6 exhaust there's no reason why they wouldn't work just as well as they do on singles, but that's not a direction I'm interested in going.

[Warwick Biggs]

Another thoroughly enjoyable Seniors meeting with all riders over the age of 45 but definitely not 'over the hill' and some well known names competing.

My best effort on the Lump was 12th in a field of 31 but I was consistently in the top third in the unlimited class and finally broke into the 20's, a 3 second improvement and almost as quick as my PB on the NC30. What a relief after all this time!

More importantly I had some fantastic dices with a competitor on an immaculate Wes Cooley replica Suzuki 1150. My starts were woeful all w/e and I was getting swamped by 30 bikes piling into the 180 degree first gear corner after the start and had to work my way back thru' the field to eventually catch up to the Suzuki. I knew we were neck and neck down the straight but I was able to use my superior track knowledge to latch onto his back wheel coming thru' the double apex onto the straight and slipstream him, only pulling out just b4 the braking zone at the end to slingshot past and outbreak him.

This happened in at least 3 of our races and he was nonplussed and frustrated until I pointed out the difference in our brakes. Like all the other P5 bikes he runs single piston Brembos. Floaters and multi pistons are banned under the GCR's - unless fitted as original equipment. Step forward the Prolink. Once I was in front he could not match the big 6's grunt out of the remaining corners to the flag. Hopefully, One of the pro photographers will have captured some of the action and I can post some pics of the battle.

Until then here are some of Fran's shots taken from the same old spots near the pits.

[Warwick Biggs]

And coming over the water tower hill...

[Warwick Biggs]

The small fairing might have helped; I didn't notice but lowering the dash means the trailer roof doesn't hammer my tacho anymore. The last one is over the line and heading up the short straight b4 the aforementioned 180 degree corner.

Mac Park was packed with a long waiting list for garages and scores if not hundreds of marquees out in the camping area. Covid seems to have given road racing a shot in the arm if you will forgive the pun. Whatever the reason, the atmosphere was magic and everybody was totally absorbed in this strange racing world of focused aggression, with broad smiles everywhere and the 'family' simile used repeatedly during the trophy presentations as now lubricated competitors became emotional.

[Syscrush]

My best effort on the Lump was 12th in a field of 31 but I was consistently in the top third in the unlimited class and finally broke into the 20's, a 3 second improvement and almost as quick as my PB on the NC30. What a relief after all this time!

This is wonderful news and an amazing accomplishment, Rick! I can't tell you how glad I am to read this update.

It's so heartening to see your persistence and determination paying off like this.

How's the hand?

[Warwick Biggs]

Thanks Phil. The hand is still very stiff and a bit useless first thing in the morning but with a bit of stretching and some regular exercises with a strongly sprung welding clamp it is good enuf' to race. My clutch lever mods help but nothing helps with finding neutral when hot.

It just wants to slip past into first or second. This means starting with a hot clutch that I have to ride while waiting for the lights after the warm up lap and the NC30 is not much better. Its' a major cause of my poor starts. I have to work out a better fix than switching off the ignition, selecting neutral and then starting it again. Its not very safe doing that on the starting grid which is the most dangerous place on the race track. It also drains the battery that is powering the coils thru' the race.

Any suggestions from the brains trust?

[Warwick Biggs]

Here is an example. On the grid, clutch in looking for neutral. Incidentally the fellow in front of me is Louis Pitman on his TZ engined LC, a lap record holder and 20 years younger. It was a tough field.

[Warwick Biggs]

I had to include this pic of my club mate Rob chasing me on his modern Ninja 400 in one of the lightweight races. Sorry about the quality but it was taken with a mobile phone.

His modern bike had more grunt out of the bends than the 30 year old NC30 but I have an extra 4,000 rpm up top so it was no contest for poor old Rob. A note for more mature ICOA members; Rob is a sprightly 73 and was part of the legendary Mike the Bike's (Hailwood) works GP team when he was a young fella. A really lovely gentleman, conservationist and still strong competitor who scored a life membership of the Mount Gambier Motorcycle Club during the trophy presentation.

[Warwick Biggs]

And b4 anybody suggests selecting neutral; while the bike is still rolling - I tried that but there were other factors too.

Because I was entered in around 30 races on 2 very different bikes I had multiple grid positions that I had to search for each time while forming up. There were so many I had a length of gaffer tape stuck to my petrol tanks with the various race and grid numbers written down. However, new positions were being allocated while still on the dummy grid due to crashes and late scratchings so there was rarely the opportunity to coast up to a fixed known spot while trying to find neutral.

Racing is full of these annoying little things that can make a big difference to the result. On very rare occasions you might get a race where everything just seems to click into place and go smoothly. As rare as hen's teeth in my experience.

[Warwick Biggs]

Nobody has any suggestions about improving the rolling selection of neutral?

Then I would like to attempt to dispel a number of common myths about the Lump and CBX’s in general.

First myth, that such a massive looking engine must be humungously powerful when tuned. Wrong! A 2 valve Suzuki engine of the period is easier to hot up albeit proportionally to it’s life. A Bol Dor of the same period or CB1100R are much better prospects for tuning than a CBX.

At considerable expense you might achieve somewhere between 125-135 rwhp from conventional tuning max. The Lump at it’s strongest was around 120 hp at the rear wheel. Currently I estimate it is making a little more than 100 hp – maybe 105 and with more time with jetting on the dyno, maybe 110.

The generally accepted reason for CBX tuning difficulties is the limitations imposed by the basic head design and more particularly the oddly and unequally angled inlet tracts.

Second myth, that CBX’s are heavy. Wrong! They might look heavy but the Lump in ready to race condition currently weighs 205kg or 450 lbs with 106/99 front to rear distribution. That is with 6 litres of oil and a quarter of a tank of fuel. That is about the same weight as most contemporary superbikes. You might think ‘ yes, but the Lump is an exotic racer’ but again you’d be wrong. It is as close to a bog stock Prolink as you can get; simply with the unnecessary road gear removed and ordinary junkyard 17” wheels fitted – in this case an old Kwacker ZZR600 rear wheel and a VTR front. I could knock a further 20 kilos off just by fitting a set of Dymags and cast iron disks. Crikey, I could save another nearly half a kilo just by replacing the heavy chrome lockable fuel tank filler cap.

The CBX road bikes were lighter than many of their competitors of the period too.

Third, that more hp equates to a faster CBX. Certainly not at the race track where grunt, handling and braking make for faster lap times. It is in these 3 areas that the Lump and CBX’s shine. I am talking the B and particularly the C models. Arguably, the first and most collectable model was released too early and was not really fit for purpose. This is good for those people who are more interested in how the machines actually perform than how they look because Prolinks are relatively cheap and accessible whilst being technically and dynamically superior in every way.

It is easier to increase speed on a CBX simply by reducing the weight. This includes the motor. Lionel Brancquardt, developer of the 20,000 rpm CBX ascribes its ability to rev nearly 100% faster than the stock motor by meticulously reducing the weight of every component, particularly the valve gear.

When I acquired the Lump it had a 630 chain fitted, something Brunel might have used and completely excessive and unnecessary. Do you know how much difference it makes just by replacing it with a 520? A lot, I can assure you.
I think you can probably guess in which direction the continued development of the Lump will proceed. Simple things are often the best.

[Warwick Biggs]

How many times has this happened to you? At the track on the w/e and a guy comes up and says something like, 'Yeah I used to have a CBX but the twin shocks were the best. They were the quickest and handled better..." Right. You immediately know the fellow does not know squat about CBX's and probably is spinning you a yarn about having owned one too.

The first models were undoubtedly faster in a straight line and Honda's marketing went awry with the C model - the Prolink but the later model was definitely the quicker bike, irrespective of less power and more weight, Simply because it handled and stopped way better.

Clearly there was some confusion in Honda marketing of the CBX that ultimately nearly bankrupted the company. Below is an advert from British Bike magazine of December 1981. Please note, no panniers and a continuing focus on speed and sophistication. undoubtedly this was the pinnacle of mass produced air cooled motorcycle development. Unfortunately, its conception was already out of date and harking back to the past Honda racing glories of the 60's. HRC never saw it as the basis for production or endurance racing.

On the other hand it was a lot more than a poseur's wet dream as often suggested by the motorcycle press of the day and justifiably remains as the pinnacle as we approach the end of mass produced internal combustion engines.

And harking back to another shibboleth - the power versus handling balance - I had my modern gixxer track bike out at the w/e. It has 130 hp at the rear wheel and a lightweight chassis. It took me 3 full sessions and a shredded rear slick to get it into the 20's and it still wasn't as fast as the Prolink CBX or the NC30 that only has about 50 hp. I was exhausted at the end. Trying to keep the front wheel in contact with terra firma and stopping it pushing wide exiting the turns under power were the main problems and ultimately I had to ride it around 2 gears higher and away from the power band to get it to go fast.

[Syscrush]

I'm a twin shock die-hard, but I understand the benefits/improvements on the Pro Link models, and I am glad that my friends with those bikes are happy with them. If I was racing a CBX, I would for sure want the bigger forks, better brakes, and wind protection of the later bikes.

As for unsolicited pontifications on our bikes... the CBX is the 6th bike that I've owned and ridden on the street over 20 years of riding. It is the ONLY one that pulls old dudes out of the woodwork every single time I hit a gas station or parking lot. "I had a CB750 Nighthawk!" "My cousin had one of those, said it would go 200!" "My high school buddy took me for a ride on his CB550 once... He always wanted a CBX." "Wow - 6 cylinders, eh? Must have LOTS of TORQUE!" The truth is that I like the enthusiasm and most days I like the attention, too - but I don't really get into trying to correct/educate strangers about the strengths and weaknesses of the different flavors of CBX, or even what mods have been done to mine.


Your experience with the vintage heavyweight, more recent flyweight and relatively current welterweight bikes on the same track are very interesting. I don't think that there can be any doubt that the GSX-R has the highest performance envelope, but it goes to show that different riders will have better experiences on track with different bikes - as on the road. IMO it really puts the lie to the whole idea of having a literbike shootout with 5+ bikes and then wringing hands over 0.5s differences on a road course.

[Warwick Biggs]

"...unsolicited pontifications..."

Did I do that? An opinion is not a pontification Phil, unless perhaps you happen to disagree. But I'll admit at 69 I'm definitely opinionated and sometimes perverse but where were we...? Are yes, The reason the gixxer was such a pig was I'd dropped the front forks 6 mm and put a heavier spring in the rear to try and stop the belly pan scraping.

So the forks are now back to stock and the belly pan is waiting for surgery. Why didn't I think of that to start with?

Here is what happened to my old carbs now fitted to James Fisher's CBX racer, one of only a handful in the world regularly competing. Great sound.

Nope. The site won't accept a video. Sorry. Is there another way beyond posting a link I wonder?