Top speed of the first triples?

[1200ts]

I was just reading an article and it stated the first production motorcycle to have a higher top speed than a Vincent was the 1972 Kawasaki Z1. Laverda started making triples one month before Kawasaki started production so was Laverda the first bike (for a month???) to be faster than a VIncent? And a 750SFC which started production in 1971 is probably also faster? Top speed for the Kawasaki is supposed to be 130MPH.

The few road tests I have seen for the first triples is anywhere from 122MPH to 135MPH. And how fast was the first 750SFC?

 

[rocketonarail]

The first reliable ( electronically timed ) tests of the triple as far as the magazines were concerned probably took place around 1975 ..........

Dave Minton tried an early triple during a visit to the factory around `73 ...... It may have been the pre - production one with the additional rev counter or speedo fitted for verification purposes ...... and reckoned got 150 mph out of it ......... but he admitted that his personal comfortable limit was about 140 mph ......... anything over that and he began to feel out of his depth , so take that 150 with a pinch of salt ....... or as journalistic licence ..............

MCW took a 1975 3C(E) to a best electronically timed one way speed of 138.9 mph ...........

The Kawasaki Z1 they tested back in 1972 made 132 mph measured the same way .

The same paper recorded a best one way of 140.04 mph for the 1976 Jota , assisted by a slight tailwind ......... although I believe Roger Slater brought a selection of rear wheel sprockets along with him for the test .


As for the early ( pre `73 ) SFC`s ........ I remember one rider ( can`t remember who ) ...... saying it was really a bit of a carthorse as far as top speed was concerned .... it`s main advantage was that it had good high speed stamina .........

On the other hand , Gerrit Jongetjes reckoned his 1972 SFC was good for about 235 kph ... ( 145 mph ) ....... although he never measured it precisely .................... " but the engine ran at 7000 rpm " ........... " I haven`t the slightest idea what the gearing was ........ perhaps 36 teeth ....... and 15 or 17 on the engine ........ " .........

" I do remember that I drove on a short track with 38 and on a long track with 36 teeth " .

Boils down to horses for courses , I guess ............

 

[piranha-bro2]

Absolutely no way a 1972 SFC would have gone anywhere near 235 ... and 7000rpm wouldn't get it anywhere near that unless it was running about 32 teeth on the rear! Std gearing was always 19T front, twins and triples. I believe the triple has a higher primary gearing.

Batto's 917 racer would be producing a whole stack more ponies than a 72 SFC and that bike would be good for it (235) plus a tad more. Red's huge HP Mule is a good reference point for top speed speed claims.

Wasn't the Jota (so also 3C(E) claimed as the first ever production bike to exceed a genuine 140mph?

 

[The Sock]

Absolutely no way a 1972 SFC would have gone anywhere near 235 ... and 7000rpm wouldn't get it anywhere near that unless it was running about 32 teeth on the rear! Std gearing was always 19T front, twins and triples. I believe the triple has a higher primary gearing.

Batto's 917 racer would be producing a whole stack more ponies than a 72 SFC and that bike would be good for it (235) plus a tad more. Red's huge HP Mule is a good reference point for top speed speed claims.

Wasn't the Jota (so also 3C(E) claimed as the first ever production bike to exceed a genuine 140mph?

From Motor Cycle's August 21st '76 edition:


A similar MIRA Test (also in my archive) on an 750SFC, which John Nutting rode back from Breganze, gave a top speed of 118MPH

 

[sfcpiet]

Absolutely no way a 1972 SFC would have gone anywhere near 235 ... and 7000rpm wouldn't get it anywhere near that unless it was running about 32 teeth on the rear! Std gearing was always 19T front, twins and triples. I believe the triple has a higher primary gearing.

Batto's 917 racer would be producing a whole stack more ponies than a 72 SFC and that bike would be good for it (235) plus a tad more. Red's huge HP Mule is a good reference point for top speed speed claims.

Wasn't the Jota (so also 3C(E) claimed as the first ever production bike to exceed a genuine 140mph?

Tend to agree Quentin.

Some US triples had a 18T front sprocket, the smallest I know of. This may have bettered the standing 1/4 numbers a bit on a stock 40T rear, but won't help much in regard to Vmax. No space for anything larger than 19 either.

The "production bike" bit needs to taken with a pinch of salt as well, more of a "dealer special" at the time. Having ridden a multitude of twins and triples throughout my professional career, I find it hard to believe that a "stock" un-faired triple could nudge 140mph/225km/h. The Jota 1/2 fairing at least would be needed. Reckon most of the tired old dogs out there would be hard put to break the 125mph/200km/h barrier...

A lot of care and effort has gone into the engine of my own 3C, resulting in an estimated 105 ponies at the crank while remaining sort-of "legal" and streetable (the old, worn engine still put 95 on the dyno prior to the present upgrade). It tops out at a tad under 240km/h with a 3/4 fairing. A pretty small gain considering the effort, but it has to be remembered that wind/rolling resistance rises to the square of speed increase, so you need to dig deep in the box o' tricks when tackling in that region. The big problem with the Lav triples, and the twins even more so, is the lack of breathing at the top end, and it gets worse with rising cylinder volume. Heaps of grunt in the low- and mid-range, but they simply run out of steam at the top, wild cams are needed to counteract the poor port design and to get them to pull strongly over 8500. Chapeau to Red and Gijs, and a very few others, that have managed to get them to fly as they do! Battos' SFC runs on dope afaIk, that moves the goal posts a bit, but still quite the achievement.

The 500 4-valvers are a whole different proposition, they'll happily rev their nuts off until they self-destruct.

piet

 

[rocketonarail]

Gerrit`s comments about his SFC are taken from an interview he did with Laverda Club Netherlands sometime in the mid `seventies ...... which was then translated into English .......... Maybe some inaccuracies crept in there .......... more likely he maybe had some over fond or over enthusiastic memories of racing the SFC ! .........

Also , I guess the 7000 rpm he mentions would probably refer to the sort of engine speed he would usually operate around in the give and take of a racing lap ....... rather than the rpm showing when going absolutely flat out at top speed in top gear .


I`ve just remembered in Archive Stuff somewhere there is a MIRA test of an Ongar Motorcycles supplied standard 3C from 1974 , I think .......... which would give a more accurate comparison with a Z1 .......... I`m going to have to look it up now , unless someone can beat me to it ........ probably still quicker than digging out the actual paper itself ........

If I remember , this 3C maxed out at something like 127 mph electronically timed ........... which still put it behind the ( spot on ) 132 mph recorded by the Z1 ............. Roger Slater wanted the triple to be acclaimed ( and proven ) to be the fastest production motorcycle you could buy ......... hence the 3C(E) , which did that job ...... and then the Jota , which provided that little bit extra on top , with a timed 140.04 mph as shown care of Hamish`s post .


The John Nutting SFC article Hamish also mentions is again hidden away in Archive Stuff somewhere .......... going to have to find that now .... ( again , again ) .......... This was a 1974 " lowboy " framed points / disc , rather than one of the earlier ones , presumably with standard SFC gearing ..... ( whatever that was .... where`s that Green Book ...... ) ....... and it was being ridden back to England as a means of getting it run in as preparation for it`s entry in the TT production race.

 

[The Sock]

The John Nutting SFC article Hamish also mentions is again hidden away in Archive Stuff somewhere .......... going to have to find that now .... ( again , again ) .......... This was a 1974 " lowboy " framed points / disc , rather than one of the earlier ones , presumably with standard SFC gearing ..... ( whatever that was .... where`s that Green Book ...... ) ....... and it was being ridden back to England as a means of getting it run in as preparation for it`s entry in the TT production race.

I've got it reasonably handy, but it is newspaper so I'd have to scan it in bits or go down to the copyshop.

 

[rocketonarail]

After almost going dizzy scrolling up and down ...........

Archive Stuff .... Page 16 ...... # 301 ......... 1974 John Nutting SFC ........ RCJ 68M ........ Performance graph " for information only " .......

Shows 118 mph at 7200 rpm top speed ..... ( presumably two way mean average , though it doesn`t say ) ....... this was with silencers fitted ...... they reckoned with a racing two into one , 8000 rpm could have been reached , which would yield 128 mph ........ but more as a best one way , rather than mean average , I would think .........

They also say " standard gearing " ........ as in SFC close ratio internal gearing I guess .......... comparing the graph rpm versus mph through the gears , then the results do suggest higher gearing first to fourth , compared a graph for a `73 SF ........ which makes sense ........ top ( 5th ) should be the same , but the `73 SF graph suggests a higher ratio than that for the SFC in that gear ....... which doesn`t make sense , really ..........

But then I gather all 1000 /750`s came with a 19 or optional 18 for the gearbox ........ the SFC rear was 40 standard , with the option of anything between 36 - 41 .......... so who knows for sure what RCJ 68M was wheeled out of the factory with ...........


Archive Stuff ..... Page20 ...... # 399 .......... I shortchanged the 3C(E) earlier ........ best one way was 139.8 mph ...... not 138.9 ......... two way mean average was 133.3 mph ....... ( Which suggests the run " into the wind " was a rather lowly 127 mph or so .... but never mind ....... ) ......


Archive Stuff ....... Page 22 ....... # 437 ........ the 1974 3C .......PPU 40 M ........ 131.5 mph best one way , with a 128.5 mph two way mean average ........ both with a slight cross wind ........

Rider weight / size can have an effect when chasing mph of course ......... Testers were either John Nutting or Stewart Burroughs ........ details relating to them were also given as well as wind and weather conditions .........



John Nutting once told a story relating to performance testing of the then new Honda CB500 Four , not long after he joined the paper .........

They returned from MIRA with the results ....... Editor -in Chief Harry Louis took a look at the figures and said ....... " No , that`s not right ..... it`ll do more than that ..... try again ... " .........

So they took the CB500 back up to MIRA the following day ......... did the usual stuff ..... right hand with the throttle wide open , left hand clasping the bottom of the left fork leg , feet on the pillion footrests , or hooked up on the rear of the seat ........... and they got another 4 mph out of it ............

So Harry Louis was right all along ....... ..............