A 20000rpm red line. Amazing for the period. I think this 125-5cylinder, was basically formed from the Honda 50cc twin, in order to demonstrate the art of miniaturisation. I think this machine had an eight speed gearbox. What I like about Honda, is they are never affraid to go beyond existing bounderies in order to make new levels. Many love Ducati for their Desmotronic engine and say Honda isn't anywhere close, but they have done things Ducati has never even tried.
Honda sold a street bike - the CB160 - that had a 10,500 rpm redline. In 1965. And unless I'm wrong, the video shows th bike revving only to about 12,000.
@@caribman10 maybe learn more about the difference between redline and powerband? this 125/5 has ultra narrow powerband, to put in layman perspective, that's narrower than a virgin teenagers.
@@caribman10 I am in the process of restoring one of those old CB160's. Lovely little bikes. I've ridden a JDM market CBR250RR from the early 90's that rev to 19,000rpm. What amazes me the most is how reliable they are. My co-worker bought one after lusting after my VFR400R for a couple years. It's got over 40,000km on it and runs like a peach. Nothing has been done to the internals maintenance wise, not even valve clearances. I was lucky to take it out a couple of times. A small displacement 4 cylinder engine that revs that high is certainly a different approach to today's learner bikes, which is extremely unfortunate. It's something else to experience riding one. I can only imagine how cool the 250 6 GP bikes would be to ride.
@@caribman10 Watch the video closely and you will see the red line on the tacho is near the 20,000 mark. Very near the end of the video the mechanic revs this engine right up to that red line at approx 20,000 rpm.
@@caribman10 With a larger screen, you will be able to see the rev counter rising to 17,000 with every twist of the throttle & indeed hits over 20,000 at the very end.
I thought that was very disappointing for a 5 cylinder machine. Then I realised it was the starter! Awesome machine, just a pity we don't race small cc multicylinder bikes anymore. Bob
The RC147 had a five-cylinder 125cc engine that produced 32bhp and revved to 19,500rpm .Shoichiro Irimajiri , a brilliant engineer who worked on Honda's GP racing bikes of the 1960s is also responsible of the developpement of the rc147 and later for the CBX 1050
Forgot to mention this in my previous post. I'm sure many people noticed that the Tachometer on this Bike starts at 5000rpm. When you consider the average automobile's redline even for V8's was around 5600rpm, it makes this motorcycle engine all the more incredible. Too be able to stay together in RR's turning as high as 20,000 rpm and barely going below 12 to 14 grand in many races is a testament to the amazing engineering and quality made parts for these machines. There reliability was astounding; you rarely ever heard of them blowing up which wouldn't surprise anyone turning that kind of RPM
Its all about stroke, mate. Shorter stroke easier to rev but struggling at lowest. The longer the stroke the higher the rev, it will destroy the ring and liner because of its piston speed.
Longer Stroke engines do not rev high rpm. Case in point BSA B34 Goldstar undersquare at 85mm Bore x 88mm Stroke. If you raced them consistenly past 7600rpm, then you rebuilt the bottomend multible times during the race season or they just broke a Rod wiping out the main cases. Same scenario with H-D's old Racing KR 750cc Flathead/SV engine, undersquare long stroke, they didn't want these engines reving past 7000rpm. Both engines had roller bearing lower ends. Current Alloy XR750 is being reved to almost 10 grand on Grand National Caliber engines and needs a bottomend rebuild almost every race. Engine originally designed in the early 70's with 10-1 compression and 8000rpm redline. Now running close to 10 grand with the aid of titanium valve and lighter valvetrain components and having close to 13-1 compression ratio, they have become gernades and too expensive for privateer riders to maintain. Even causing 2 Former GN Champions to jump to INDIAN'S new FTR750 for the 2017 race season. H-D team will field their new XG750R. Both these engines have strokes around 65mm with Indian having a 53 degree V angle. Their Redline is right at 10 Grand...
steve matz its not really that impressive considering its only 125ccs. 25cc per cylinder at That! I mean that's a weedwacker. comparing the rpms in this to a 5000cc+ v8 with valves and considerably more strain on components really dosent make much sense to me.
As I was getting ready for a practice lap on my G-50 at the 1966 IoM TT I saw the Honda team with one of these 5cyl 125s. It wouldn't start as they had apparently flooded the engine. A mechanic simply picked up the front end of the bike and held it vertical until the excess fuel drained out of the carbs. That's how light and compact they were.
This and the 297cc 6cyl were Honda masterpieces and I feel so lucky to have seen the likes of Hailwood, Bryans and Taveri ride them in anger. You could here them from far away above all the other bikes.
Parts on this bike seam similar to the Honda cr93 I am currently restoring it has a very similar suspension but is a twin carb and has moto guzzli exhaust two on either side, I was told mine was used in racing back in the day so it's a mix of the best Hondas of the time :) great sound as well
@alna1287 I was unsure what you meant, but I thought I'd mention the NR500. Honda's CVCC engine was also remarkable, but never went into production for the motorcycle, but worked quite well for the car as it never needed a catalytic converter for the regulations of the day. Also their rotary engine which was adopted for the CB125, never made it because it failed on the emissions (I think the NOxs where to high).
Four-stroke 125 with five cylinders in line, transverse. The distribution, lubrication, and ignition systems were not substantially altered. The central exhaust tube passed under the others and then emerged under the saddle. Two cooling radiators were mounted on the lubricating circuit, housed inside the fairing. In 1966 the Honda 125 five-cylinder proved to be the fastest 125 that had ever entered world championship racing, and the championship was hotly contested that year. Suzuki was the reigning champion and Yamaha had its new RA 97 in the field, but Honda won the 125 title with its new motorcycle. Motorcycle: Honda 125 Five-cylinder Manufacturer: Honda Motor Co. Ltd., Tokyo Type: Racing Year: 1966 Engine: Honda live-cylinder, four-stroke, with two-shaft overhead geared distribution and four valves per cylinder. Displacement 124.8 cc. (33 mm. x 29.2 mm.) Cooling: Air Transmission: Eight-speed block Power: 30 h.p. at 18,000 r.p.m. Maximum speed: Over 135 m.p.h. Chassis: Double cradle above, tubular, engine suspended. Front and rear, telescopic suspension Brakes: Front, central drum, four shoes, four-cam; rear, central drum, double cam
@veevum True. If the desmo was so advantagous over the conventional conterpart, then most manufacturers would make regular use of it. You're right, I think Ducati continue to use the desmo as their much loved trade mark. Admittedly, I love the desmo concept.
the idea was to maximize power from 125 CC, so they doubled up on cylinder's to stretch the powerband out. it was the same with the 250 six cylinder. Benelli, and MV did the same thing. Then the japanese 2 stroke's came out and changed everything.
@alna1287 I don't think the 5 cylinder 125 had oval pistons, but the NR500 of 1979 did. Regulations of the day did not allow V8s, but Honda wanted a high revving four-stroke. An engineer was sat at a set of traffic lights in his car and noticed eight lights in an oval. He then thought of the idea of eight valves and four oval pistons, thus allowing a high revving 500cc four-stroke V4. Each piston has two con-rods, enabling the rpm of a 500cc eight cylinder. The NR didn't defeat the two-strokes.
@schlusselmensch Yes you are quite right. I was mistaken. I knew it was the 450 as I read abit about it a couple of years ago but thought of the 400 as that was more common. The 450 didn't sell in huge numbers if I not mistaken. Was the 450 the one that had the torque converter? The torsion bar system is a good idea and so is the desmo, but nearly all engines still use coil springs so the other two ideas must have their drawbacks. Honda had a proposed CX360 but never produced it
I propose making 2 precise replicas of this engine and give them to Allen Millyard so he can make a lovely little 250cc V-10. I know, I know...but it would be a hoot.
@1100HondaCB You're right, Honda has built engines that Ducati could only wank over (and I very much like Ducatis). Desmo is a marketing feature, nothing more. People should have a read of the technical details of the small Honda racing multis. Quite incredible.
@1100HondaCB Yes, I'm familiar. I wasn't suggesting that this machine had oval pistons, just agreeing with you on Honda's technical acheivments and using the oval pistoned machines as an example of that - should have clarified, sorry.
Reportedly at the time the 125/5 was a most difficult bike to race because when the throttle was closed between gears with so little flywheel-effect the engine would just stop harking back to the Kriedler 16 speed 50cc 2-stroke single where below something like 10000rpm the motor would 'oil-up' the spark plug and over 11000 it would fly apart.
I would understand better : Below 10000rpm the motor would oil-up the spark plug, but over 11000 it would fly apart...? I cannot understand... May you explain better this point? Perhaps you would write 21000 rpm... Best regards Angelo
@@angelor9377 With the technology and the materials at the time, 1950's/'60's single cylinder Kriedler 50cc 2-stroke was tuned to the nth degree which compressed the 'power band' right up to the limits of reliability where bhp was everything and torque (if you can call it that with only 50cc) was sacrificed leaving only a very small window of power of a 1000-or-so revs. Lubrication was measured to keeping the engine 'happy' at high revs whilst somewhat over-oiling lower down. As far as I can remember the final gearing was an 8 speed gear train plus a 2 speed rear axle. Luigi Taveri the Swiss rider was capable of riding it well but very few others. If anyone cares to correct me I'll be pleased to receive such.
the stroke of the engine is 29,2 mm. So 29.2 mm x 700 strokes = 20 440 mm per seconds. 20 440 mm per second / 1000 = 20,44 meters per seconds. 20,44 meters per seconds x 3,6 = ( so does pistons run at) 73.584 km per hour. unimaginable, you say? That here is un-unimaginable =D
It wasn't as if BSA couldn't have done this sort of stuff, but rather that they got hamstrung both financially and by the smug concietedness of their massive previous achievements. But, heigh-ho...
If BSA could have engineered an engine like that , they would have done it , but i think Hondas ideas and engineering R and D were far greater and years ahead of any of the british marks , our attitude was stick to what we know , like you said, thank the big wigs who run these firms that killed our bike and car industries.
@@leegraves101 My (Japanese) Enya 36 model aircraft engine has 21mm bore (17mm stroke) but only revs to 13000 - and is only 2-valve of course. But they were "mass produced". Just under 6 cc and 0.6 hp - which, as I can testify, is quite enough to send you to hospital with sliced-up fingers.
Where would racing be now, had the FIM not restricted the development of these wonderful machines. We would surely be watching something better than the computer controlled 'Moto GP ' rubbish we now have! Might as well dispense with with the riders altogether, and as for the circuits; do Cleethorpes sands look familiar?
