CBX Racing

[Warwick Biggs]

Thanks for asking Phil but it seems to be a very slow process. 2 months now and it still keeps me up at night and there is little improvement in movement. I still cannot make a fist but it is the left and I'm right handed. May have to stick to modern bikes with quick shifters. Maybe I could fit one to the CBX? There is a thought. Has anybody tried it, I wonder?

On a more positive note this enforced 'stay at homedness' has considerably improved my tennis and after having my lenses surgically replaced I can actually see the ball, which helps. I'll never be 16 again but am grateful that I can still move around the court OK. An 80 year old in our tennis club expressed the view that our seniors group are, "on the way down, not the way up" At the risk of sounding too bumptious, I had to disagree. Dylan Thomas put it well:-

Do not go gentle into that good night, Old age should burn and rage at close of day; Rage, rage against the dying of the light. Though wise men at their end know dark is right, Because their words had forked no lightning they Do not go gentle into that good night.

[Warwick Biggs]

OK, back to the CBX and some good news at last. The heat shrink tubing sealing the splits in the carb rubbers and the de-coke and re-seating and shimming of the valves still did not produce the clean running motor I was looking for. Ages spent fiddling with the slow jets did not help either. It was still spitting and farting around. The temperature gun showed #4 cylinder was not getting up to temperature.

So carbs off again and #4 carb triple checked. All jets (main, idle, air and choke) all removed and cleaned. All 6 main needles removed, cleaned and lifted by dropping a notch. #4 float minutely adjusted and float needle inspected under a magnifying glass. All orifices sprayed with carb cleaner and blown out with compressed air and choke circuit checked. Nothing obvious there. I had previously twice checked the spark plug by removing it, cleaning and gapping and then holding it against the head to see if it was sparking. Seemed fine. New leads. New Ignitech ignition, dual batteries showing 14 volts a piece but #4 still not coming up to temperature. With a total loss system and only 5 wires, no rectifier or complicating electronics there was little else to consider.

The middle carb rubbers (3 & 4) on CR Specials on CBX's are canted at quite an angle (all the rubbers are at different angles and lengths which is another defect with these carbs) but it does mean they each have to be in exact alignment but the middle 2 are very difficult to inspect being buried under the top frame mounts and bracing. Getting all six carbs evenly into the rubbers is a delicate operation with lots of rubber grease and wiggling them this way and that around all the obstacles with fractions of a millimeter precision. You don't casually pull the CR's off without allowing for some hours of patient finnangling and skinned knuckles. Maybe #4 carb rubber was not quite square and we were sucking too much air around the edges? More hours fiddling with every tool in the chest cos' its very hard to get in there to rotate the bloody things.

Finally back together and absolutely everything checked. Fire it up and #4 is still reluctant to fire properly. It had new plugs and leads but let's check them again. OK the crimp on the copper under the plug cap looks a bit loose. Re-crimp and let's put another plug in, just in case. Voila! It was the plug all along! Never overlook the obvious and always remember, appearances can be deceiving!

Now with minimal fiddling with the air screws it idles at around 1,000 rpm and it picks up crisply off a closed throttle. It's still spitting a little bit but that might be fixed by going from a #118 main jet to a #110. Finally it is running cleanly. It may not have just been a defective plug and it only takes one of the things mentioned above to be slightly out or blocked by dirty or stale fuel and you won't be racing. As Roly says, keeping one of the most complicated motorcycle engines running smoothly is a challenge and when you start trying to hot them up and keep them hotted up the task grows exponentially.

After that I velcro'd up the oil cooler into a better position, put tank and seat back on, everything torqued up and double checked the rider and static sag after fitting the new extended dogbone on the rear shock and it is now finally ready for track testing. Clunk! Can't get to the track because of the pandemic border closure. Nobody even noticed it was there until local politicians started trying to out do each other in hairy chested idiocies. Now its swarming with black shirts in baseball caps.

OK, drain the carbs, drain the tank and throw a dust sheet over the lump. But when we can come back to the track it is ready. I've provisionally entered Master of Mac Park and Round 3 of the SA Championship on 2,3 & 4th October. I'm cheating because I've entered the GSXR750 in Supersport (nobody can easily tell it is not a 600) and the NC30 is entered in Period 6 and the CBX can run in Period 5. Truth is, I don't think they will open the border b4 then. If they do I will not have the physical capacity to do all those races in different classes (20 laps at race pace and I start to wilt). But just in case, I have all my options open.

I still have a dodgy hand so clutch operation is an ongoing issue but Roly has offered me a VTR hydraulic actuator if I can find a good TIG welder to attach it to the clutch case it could help because I'm investigating a quick shifter modification. Who needs a clutch anyway. I only ever use it to get going, change down or stop and that can now be done without a hand lever. It goes on and on and on....

[Warwick Biggs]

And of course the major issue in adapting a quick shifter is that the bike has to be operating with an electronically controlled throttle. A conventional cable operated throttle can accommodate a single direction QS for up changes but who needs a QS for changing up anyway? Just back off the throttle momentarily and kick it through into the next gear, right? No clutch necessary. In fact when you are racing if you do attempt to use a clutch for changing up a gear you will quickly burn out your clutch because you cannot physically pull in and release the lever quick enuf' to avoid clutch slip on the release with the throttle wide open.

So the real challenge in setting up an 'auto blipper' or downshift QS for a CBX is controlling the throttle. This is necessary to match engine and gearbox speeds to avoid shearing off the dogs or crunching the gears. When effected electronically this process is achieved in micro seconds. Not something that even the cleverest monkey could manage by hand.

Some bikes do combine cable and electronics or ride by wire throttles and there has been some allusion to this on this thread in the past. So this is what I am currently investigating while working on my hand. All suggestions or observations as always welcomed.

[Rick Pope]

A long time ago, in a land far away, I think I saw a conversion where the shift rod had a switch built into it so as to break contact when pressure was applied. But, do I recall you've eliminated the shift linkage?

[Syscrush]

A long time ago, in a land far away, I think I saw a conversion where the shift rod had a switch built into it so as to break contact when pressure was applied. But, do I recall you've eliminated the shift linkage?

That would only work for upshifts, it would have the opposite of the desired effect for downshifts.

[Syscrush]

First, that's great news about the #4 cylinder!

I think that for downshifts you'd be much better off getting a slipper clutch in there rather than try to switch to ride by wire and a computerized quickshifter.

The APTC clutch as used by Ducati on the Monster 1100 EVO is a slipper clutch, and also includes some kind of mechanism that clamps harder based on the applied torque, so it has really light lever actuation. I'd suggest you start looking there as an upgrade path that could help mitigate your left hand issues.

[Warwick Biggs]

Yes, I have jettisoned the linkage but could reinstate it easily Rick. Most QS's work with spring loaded switches that involve more mechanical parts whereas my inclination is to reduce as many parts as possible. Some are more sophisticated but if you want both up and down (and why would you not?) things become more complicated because of the need for throttle control as I explained above.

The Ignitech TCIP4 ignition that I run has a number of ports that could be utilised to achieve this. However, it is the interface between the electronics and the throttle cable that I'm finding difficult to figure out. I understand that Yamaha have developed a combination of cable and electronics but with efi, not carbies altho' that may not be a relevant distinction. I have not yet found a good description of the Yamaha ride by wire system.

A slipper clutch may well assist Phil but the QS has so many advantages apart from dispensing with the lever that it remains my focus. The slipper on my GSXR750 is particularly useful in hairpins where you rely more on a combination of hard breaking and engine breaking. It still momentarily allows the rear to lock making the bike turn quicker as you can back it into the corner. Its good to know it is only momentary and does not lock up entirely and screw up your braking altogether. This also allows you to get into the powerband of a lower gear for the exit with less drama. For my local track I always gear the bike for the 2 hairpins to avoid having to drop into first because it is too easy to find neutral on the way thru'. If I can take the slow corners in second it reduces this risk. Faster tracks like Bathurst or Phillip Island I might gear for the straight.

So a slipper clutch is good but you still have a lot going on as you dive into corners under brakes and if you could eliminate the lever altogether that is a bigger plus and makes it that much easier. Typically, most circuits have around a dozen corners where you are braking, changing down and moving your body weight forward and to the inside. In tight corners the steering loads are higher too so you are pushing harder on the bars and if you are having to move your left foot and hand while focusing on maintaining a steady throttle approaching and thru' the apex that is a lot all happening at once. Multiply that 12 by at least 6 for a typical race and it is physically and mentally exhausting. Exhilarating too.

[Warwick Biggs]

The 2006 Yamaha R6 had the first ride by wire system in production. It utilised a small servo motor sitting on the throttle linkage that might readily be adapted to carbs. However, it relied upon a number of ecu's and sensors in conjunction with electronic fuel injection, so is not easily adaptable to the CBX unless the engine has an electronically controlled fuel supply.

As EFI is banned under our rules for Period 5 Historic Racing, for the moment I can't see how I could adapt a quick shifter to the CBX. In the meantime, I am fitting an adjustable clutch lever and perch off an FZ600. This should make it a bit easier to operate while I focus on physio. As always, adapting the rider is usually the cheapest performance option.

[EMS]

A much lesser effort to ease clutch pulling can be done mechanically. Harley Davidson mid-90s Sportsters were notorious for high clutch effort due to a ramp/roller design pressure plate. I installed an EZ Pull on my wife's bike to enable her to pull the clutch on a 300 mile ride. It is a little getting used to, but works quite nice.

[Warwick Biggs]

I have stock CBX springs in the clutch. Not a particularly heavy clutch then. For more powerful motors some people use K1 springs that are a bit heavier but really that is not necessary for the lump. A longer lever is the obvious solution to a heavy clutch altho' there are limits. Not compared to a 10" diaphragm spring on a Norton, for example. We used to tape a spare cable to the clutch cable for quick changeovers on the road on Nortons because eventually the nipples would strip. A better pushrod design is the answer to that problem.

My issue is not so much a weak hand and heavy clutch but restricted movement. I can barely get my fingers into a hook much less make a fist but I'm working on it. Spending a bit of time on my tredley just practicing holding onto the handlebar grip.

[Warwick Biggs]

This is my temporary expedient. An extendable lever and physics at its most basic. I looked at TIMS' hydraulic conversion kit but he is out of stock and I'm investigating a Crake hydraulic conversion which has a fine adjustment for weight from a one finger pull. Magura do some for MX bikes that would need modifications.

[Warwick Biggs]

In preparation for the SA Championship races in a few weeks I plan to return to the track for practice this w/e.... finally, after the easing of restrictions and the second wave was crushed by 3 months of lockdown.

For practice I will use the 750 GSXR and I took it in to a local muffler shop to cut the cat off and fashion up a new pipe connection. I had to load it back into the trailer which is always a tricky operation because my trailer is rather high off the ground. Helpers pushing are always a hazard as they put more muscle than direction into their efforts. So I ask volunteers to stand back and I load the bike on the clutch as I walk up a ramp next to it. This is a real test for my left hand as I have to slip the clutch by modulating the lever. The gixxer clutch is very light and I had no problems, which is encouraging.

Many years ago I rode a Norton Commando over 1.500 miles thru' floods and ice from Sydney to Adelaide with no clutch and it takes a bit of technique to master, especially on icy mountain roads. Some bikes with really good gearboxes can be operated without using the clutch at all altho' sooner or later the selector forks or bearings will be damaged. I certainly won't be spending any longer on the track than my clutch hand can handle tho'. Heh, that's a pun.

The cat weighed over 3 kilos. That equates to 3 extra hp so if the hand works OK my times should be a bit quicker.

[Syscrush]

This is a real test for my left hand as I have to slip the clutch by modulating the lever. The gixxer clutch is very light and I had no problems, which is encouraging.

That's wonderful news - very glad to hear it. Can't wait to read the report on your weekend shenanigans.

[Warwick Biggs]

The best laid plans...

When I originally spoke with the surgeon we were heading into a long lay off and my words were, 'I want to be race fit for the National Championships in November'. Then they were postponed until 2021 and later the State Championship unexpectedly opened up a month earlier. And the operation did not go as smoothly as we hoped.

Well, ride day yesterday to test things out. I managed 3 sessions on the gixxer. Crikey! What a weapon it is and much sharper after I replaced the plugs and set up the suspension properly. But the rider was jerky, riding the brake (a very old, very bad road bike habit) and awkward with the throttle. 'Rusty' is not an adequate description of how bad it felt. New boots were just an added mistake and a few light showers on slicks didn't help. Wooden and clunky is closer to the mark but eventually I climbed up onto the tank and got more aggressive.

That took the morning by which time my hand was aching, both wrists were aching and I was counting down the laps. After lunch I did another session as the sun was appearing for longer and the spring weather improving but the pain was too much, so I packed up. After long soul searching and the heavy foot of the Voice of Reason descending later that night I decided to withdraw from the races next w/e. Much as my determination and perseverance has served me well in the past, my hand was seizing up and I was going to be a danger to the other riders as well as myself. The VOR had a compelling point and I had to accept that her anxiety was too high a price for my block headedness.

None of this was helped by the death of Vonnie the day b4. A champion racer, club mate and contemporary who was actually 2 years younger than me. Spine crushed by a malfunctioning auto entrance door in a servo, not while racing. Cruelly mundane. The Club will commemorate a Trophy in his name for it's signature race event. Vale Vonnie.

So on the w/e I will don a fleuro jacket with a big sticker proclaiming me a COVID MARSHAl and stalk up and down the pit lane. Instead of enjoying the heat of battle I will be forced to watch others enjoying themselves. And the Club will be seen to be doing the right thing even if it is mere tokenism. Try telling an excited racer when they come in after a torrid race that they are not properly socially distancing? Oh yeah! That might work - not.

[Syscrush]

Sometimes discretion is the better part of valor. Here's hoping that you're able to rehab that hand.