CBX Racing

[Warwick Biggs]

Experimenting with the carbs proved interesting. Going UP a notch on the needles reduced the tendency for the engine to die when the throttle was lifted off idle.

This was the reverse to what I was expecting because the plugs were still showing sooty suggesting it was still overly rich. I now suspect that with the choke issue identified (altho' not necessarily 100% fixed) the 118 mains may be too SMALL for the motor. It originally ran 120's but because it was showing rich (probably because of the leaky choke) we went down a size. Fix the bypass leak and its being strangled by small main jets. Perhaps!

Without a dyno its all hit and miss guess work but that is all I can do.

[Rick Pope]

Your tenacity sir, is staggering.

[Warwick Biggs]

Rick, when we all raced 2 strokes (H1R's, TR's & TZ's) we spent an inordinate amount of time re-jetting the sensitive wee things. It drove me to distraction and to this day I loathe the things. Having to go thru' this with a 4 stroke and SIX carbs is just cruel and unjust punishment. But as some of my Middle Eastern friends are wont to say with that resigned shrug, 'What can you do?'

Here is an update on the approaching Island Classic with the Yankees making another big effort and with a woman in the team too:-

http://islandclassic.com.au/latest-news ... ge-assault

Now these FJ Jamjar hot rods that they and the Poms are allowed to bring, do not qualify under our period rules because the bikes they are loosely based on were built in the mid 80's when our rules cut out at '82. But because Phillip Island is owned by a trucking magnate who makes up his own rules, the playing field is not even. I last competed a few years ago and sadly will miss this upcoming event because the CBX is just not ready yet. Even tho' these 300 kph (200 mph) replicas somewhat out class the CBX it can still run with them without being embarrassed and that is a testament to the machine. We were showing a wheel to the Team USA TZ's in '18, when we crashed.

I finally fixed the tacho oil leak with a combination of rubber O rings but they won't last long in hot oil so I think I will lash out and buy one of those Speedhut electronic tachos that you recommended Phil. Life is too short...

[Warwick Biggs]

Latest update is that Roly thinks the jets may be too BIG. He runs 110's in the Beast. So I'm doing a vox pop of all the racing CBX's to see what others are using. Just out of curiosity because our engines are in different states of tune.

Meantime, it is hard to ignore that the entire eastern seaboard of Australia is on fire. Millions of hectares are just ash. The beautiful property I put 30 years of my life into with it amazing biodiversity is about to be obliterated.

Racing motor bikes is a huge indulgence and it comes with a number of price tags. Including an environmental price tag that none of us want to confront. The planet is dying big time. Here in Oz we have the highest extinction rate in the world and corrupt governments stacked with politicians from the fossil fuel industries that merely reflect our indulgences.

To say its' not sustainable is passe`. We've been hearing that for years and nothing has changed. We may have passed that point. If anybody has seen the film 'On the Beach' with Ava Gardner, I sympathise with the character played by Fred Astaire. It was a serious role for a dancer. A very serious role.

[Syscrush]

the chassis changes look promising.

Wonderful.

[Warwick Biggs]

Just retiurned from a busy couple of days at the track. The slicks did not arrive in time for the GSXR750 and the CBX is awaiting a dyno tune so I took the little NC30. My times were woeful. A good 10 seconds off my best and I was very ginger, still shy after my recent crash.

But on the 2nd day I adjusted a few small things and tried a few new things that seemed to work. It didn't improve my times dramatically but I felt a lot more comfortable, especially when I started passing riders on bigger, more modern machinery. I was amongst the slowest in the fast group and was the fastest in the slower group so all in all we did OK.

Better than Wag's, who was next to me in the pits and the owner of this 1959 JAP. He crashed his modern superbike and ended up in hospital. Those tubes that look like Harley or Triumph pushrods are actually shafts for the desmodromic valves developed by Prestwich. These old engines can be made to produce prodigious amounts of power and were used by man, including John Britten in his Daytona winning bike pictured earlier in this blog.

[Warwick Biggs]

That should have been 'many', not "man". There was a bit of drama when somebody slowly immolated their R1 after an oil filter came loose. He didn't realise is was actually on fire until it melted the radiator hose spaying glycol all overr the track. Eventually he bailed out and it was totally engulfed in flames but not b4 he's sprayed the track with very slippery glycol. That took a while to clean up. I was out next. So, here I sit waiting to take the tyre warmers off and not knowing what was causing the delay. Not another pick up?

[Warwick Biggs]

I stripped the carbs again, sprayed copious amounts of carb cleaner thru' the emulsion tubes into the choke passages and dropped the needles another notch. Reassembled and running it was back to blowing unburnt fuel and mis-behaving. The choke mechanism is now so stiff that the arms are bending and I have to close them individually by pressing each plunger rod down with a screwdriver.

The carbs will have to come off again and I will have to strip them again. The slow jets are 70's and one size over size so I will have to see if the chokes can be re-built and try to get some smaller slow jets.

Sometimes buying second hand items is a false economy. I could try re-fitting the bored out CV's but I imagine they will need re-building after sitting in a box for 2 years. So I may as well persevere with the CR Specials. The CBX will not be a runner in the 2020 Island Classic, unfortunately. Very disappointing.

[Warwick Biggs]

This week end we are hosting the State Historic Championship for South Australia. Because of the carb problems on the CBX I am not competing. Am I sorry? Yes and no. It was 35 degrees when I left the track during Friday's practice but it was a pleasant 25 degrees with a sea breeze by the time I arrived home. The temperatures have gone up since then. Climbing in and out of leathers in temperatures over 100 degrees F is not my idea of fun. Especially at this time of year. Let's hope 2020 is a better year than '19, that our leaders find some courage to meet the challenges and we get the CBX running properly after a year in the doldrums.

[Warwick Biggs]

Apart from dealing with bushfires we have been in the workshop fiddling around with the CBX. I pulled the carbs off again and this time extracted the tiny jets in the bottom of the float bowls and cleaned them as well as the air jets and passages. Then I replaced the slow jets (70's) with 68's.

According to Keihin these jets control the first 30% of the throttle and are critical to the off closed response. This is where I have a problem so, we will see if that makes a difference.

I have been talking to UK CBX racer James Fisher who has just enjoyed a good season on his jigger - at last. Good to hear that somebody is doing well with a CBX. Now James has Kawasaki carbs on his bike and reckons they are so heavy that he keeps breaking cables so we have been thinking about how to make them lighter. He thought CR's would help but they are still quite heavy and require very robust cables.

It occurs to me that this was the main reason Honda opted for CV's but they used conventional Keihin round sides (22 mm) on the RC 166 so I'm curious as to what sort of linkage they used because they still would have been heavy on the throttle hand and strip cables. They must have had a fix??? Keihin say they do not make different diameter cams for the cables to attach to. Can anybody on the forum post a pic showing the linkage Honda used on their racer?

[Warwick Biggs]

I found this pic from the Honda Museum that looks like they used a largish round wheel attached to the actuation rod. I would like to see how the cables are attached.

[Warwick Biggs]

Does anybody in ICOA own or have access to an RC 166 K model?

[EMS]

Does anybody in ICOA own or have access to an RC 166 K model?

What do you mean? An original RC166?? Or a plastic/metal scale "model".

[Rick Pope]

I only know of one in private hands, and it belongs to Team Obsolete.

[Warwick Biggs]

I'll take that as a 'no' EMs and thanks Rick. I will attempt to chase it up. I am aware they are rare but I never cease to be amazed at what some enthusiasts manage to acquire.

We have a Harris TZ with a history falling out of the tree here in Oz as I type. A Klimt turned up the other day and it could be a Caravaggio tomorrow. You never know,...
R.