Warwick Biggs wrote:A Klimt turned up the other day and it could be a Caravaggio tomorrow. You never know,...
Paintings are MUCH easier and more profitable to forge than motorcycles - and the art world has a vested interest in accepting fakes. Motorcycle enthusiasts tend to run the other direction. :)
I know I mentioned this before, but is ride-by-wire completely out of the question? If you make the case that it's strictly there as an accommodation for an older rider's physical limitations and that it offers no performance advantage, maybe you could get it cleared?
Phil in Toronto
A cool guy deserves a cool bike, a dork needs a cool bike... Pics of Perry, my '79.
Warwick Biggs wrote: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.
Well... the Klimt always existed and it was stolen and got lost and reappeared. No real surprise there. There was a definite number of RC166s made and the whereabouts of these are really not in question.
A minor point: The Team Obsolete 250cc 6-cylinder is a RC165, not the later, more successful incarnation.
Owned by Team Obsolete’s Rob Iannucci, the "Six" is the only surviving RC165. Jim Redman first rode it, followed by Stuart Graham before Mike Hailwood took it to victory in the 1966 Czechoslovakian Grand Prix.
The 297cc, which dominated the 350class was actually dubbed RC174
Points taken. I don't think there are any RC's racing. They, like the art works have derived value as not just rare but unique collectibles. I wouldn't push the analogy much further than that. Yes, replicas are possible but they are not necessarily forgeries and this takes us back to Theseus's ship and the special value that the original carries.
I just want to see how Honda did it originally so as to get some idea of whether I can replicate the function, if not the form.
As for an electronic throttle Phil, I could do it but with 3 coils running on total loss I just don't have the juice for much more electronica. I am looking into the possibility of Lectrons tho'. As far as I can determine nobody has ever tried them on a CBX.
The TZ I mentioned that is for sale in Sydney is one of 3 in the same ownership and I think the motor and frame came from the US. Might have belonged to Don Vesco??? One of the 3 did. The motor has been up-dated in Oz by ex international Barry Ditchburn who makes cases, cranks, power valves and just about everything else for TZ 750's. It is said to be putting out over 165 rwhp and the bike is in full racing trim. I might be tempted except the vendor is asking $60K and I have my hands full already.
I would guess that you could drive the throttle servo with a dedicated Li-Ion phone battery and not raise any eyebrows in tech. It's just part of your RBW system.
Phil in Toronto
A cool guy deserves a cool bike, a dork needs a cool bike... Pics of Perry, my '79.
Would a phone battery keep lifting 6 CR's? They are pretty heavy. I have never tried an electronic throttle on a bike so its unknown terrain for me Phil. Food for thought tho'.
Warwick Biggs wrote:Would a phone battery keep lifting 6 CR's? They are pretty heavy. I have never tried an electronic throttle on a bike so its unknown terrain for me Phil. Food for thought tho'.
I did a bit of searching and couldn't find good info on the electrical draw for a RBW servo. It's not clear to me how to find that info other than buying some and experimenting. Another option would be to look at aftermarket cruise control systems like this one. Contacting the manufacturer or doing some other research might get you specs on the servo.
Li-ion battery packs come in a wide array of sizes, voltages, and capacities - if something the size of a phone wouldn't do it, then one of the batteries that I use in a 20V circular saw or impact driver sure would. I expect that there's something suitable somewhere in between.
Phil in Toronto
A cool guy deserves a cool bike, a dork needs a cool bike... Pics of Perry, my '79.
All the RBW systems that I have found in my searches are designed to operate with EFI Phil. I thought it might be possible to adapt an Yamaha R6 RBW which has a reasonably quick action suitable for racing but after looking at it I really don't see how it could be done.
I mean, I couldn't adapt it. I'm sure somebody with better skills than I could come up with something.
I can't even make a bigger cam to improve the leverage on the cable, much less re-design an electronic throttle. I'm still struggling to get the bike running properly. There is a guy in my club who is pretty good with carbs and I'm hoping he can give me some guidance.
Thanks EMS and Rob Ianucci and Seth Rosko for the following pic that shows clearly that Honda used a simple round pulley of about 20-25mm in diameter (1") to achieve the mechanical advantage to satisfy their riders. This pic is of the carbs off Jim Redman's bike.
Because the basic design of the carbs is the same as the CR Specials this would be a useful modification for all those CBX owners running CR's that find they are too heavy on the throttle hand. It will not ovecome the load on the cables that still require careful routing but should improve throttle feel and control.
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A couple of interesting things to note about these 22 mm Keihin carbs.They are bespoke flat sides and note the rough sand casting of the magnesium throttle bodies. Honda must have been at the pointy end of development of this material in the early 60's.
The nuts are all drilled for lock wiring - an aircraft engineering approach. The jets are all positioned to maximise access for tuning and the carbs appear to have 'ticklers', a carry over from Amal carb design, something Keihin quickly dropped when they developed the separate choke plumbing that can be so problematic. Give me ticklers any day.
R.
In regards to ticklers..I’d guess Honda would never use ticklers, too crude for them oil/ fuel leaks
it’s a British tradition I thought that I had to mark its spot on the ground each place it stopped
Couldn’t resist!
Honda used the same principle but in reverse, Rick. CV carbs use a gas vacuum as opposed to fluid pressure.
One of the problems with early hydraulic brakes on bikes was a lack of feel. A 4 leading shoe drum brake had a sort of self servo so that it gave excellent feel at the limits of adhesion. Cable operated disk brakes were OK on scooters and light weight bikes but too weak for faster bikes and it took a while for Yamaha to get hydraulic disks to work well on their TZ's and then RD400's. British hydraulic disk brakes of the period were often quite wooden.
I can't imagine any hydraulic system that would allow you sufficient control to feather the throttle. RBW is good but really a high end engineering solution better matched to EFI and the increasingly sophisticated electronics of modern bikes.
I'm recently advised by a race mechanic who was active in the late 70's early 80's that a pulley modification similar to the RC166 was used on the RC Bol Dor endurance racers. They removed the diaphragms from the CV's for better throttle control and then fitted the pulleys to the side of the bank, rather than the middle, to reduce the effort at the bars.
As for synchronising 6 carbs I think they would have done it by eye/ear Phil. It is possible to drill holes in the velocity stacks to fit vacuum gauges but that would interfere with gas flow and provided they are all opening and closing together the performance at full throttle would be unaffected.
Perhaps somebody else knows? I will ask Seth how he does it with Redman's bike.
R.
