Japauto 960 cc SOHC CB750 Honda 4 cyl. and Florida doppleganger

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Fire-medic

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An interesting read. The largest European Honda dealer builds big-bore SOHC 4 cyl endurance racers after the release of the 750-4 in Oct 1968, making this the 50th anniversary in Oct. of what was the archetype of what became known as the Universal Japanese Motorcycle (UJM).

https://www.motorcycleclassics.com/...-motorcycles/1975-japauto-1000vx-zmcz18sozhur

Here's a similar build re-done at the Florida shop I frequent, no, the color scheme isn't one I would have chosen. It was the owner's idea. The bike is a vintage street racer based on a SOHC 750-4 Honda but is now a cool 1,000 cc displacement. If you were around in 1968 when the SOHC 750-4 was released, you recall what a BIG deal it was. The only transverse inline-4's were MV Agustas, and you had a better chance across the USA of seeing a flying unicorn farting rainbows than seeing a 4 cyl MV Agusta on the street. The Honda 750-4 gave us a disc brake, SOHC valvetrain w/a high redline, four cylinders, big displacement, five speeds, and typical Honda leak-free build quality. There were bikes before this that had one or the other, but the Honda 750-4 well, you got it all, baby! You bet your bippy it was a big deal! Verr-y interesting! A selling price of $1,400 made it priced well-under the British Isle triples.

The Triumph Trident 750 cc triple cyl/BSA Rocket III was for a few months the performance king, before the Honda 4. You really had to love Triumph/BSA to pay more, for less, in the specs, though the British triples had success in racing, too (see Slippery Sam https://www.ridersdomain.com/magazi...the-most-famous-production-racer-of-all-time/ ) and was the basis for one of the first factory efforts to pay homage to the chopper craze, with the release of the Triumph X75 Hurricane, which actually used the BSA engine instead of the Trident's 3 cyl., for packaging reasons. It was a design by Craig Vetter, yes, he of Vetter Fairings. https://www.motorcycleclassics.com/classic-british-motorcycles/1973-triumph-hurricane-x75

Though built back in the 1970's, this Florida 1,000 cc bike had been off the road for over 20 years, where it had previously been used for street racing, after the original build. The owner gave it to the shop, with the request to make it operable again. Because of the layoff from the street, and the condition the shop owner found it-in, the cases were split, the head and the cylinders were off, the head went to the machinist to be checked-out and repaired, if-needed. No major repairs were required, though the gearbox was problematic, after a circlip failed after the first go-through. That required a second tear-down, and replacement of all possible gearbox parts that weren't replaced the first time.

Another problem was excessive oil use, though the rings were replaced during the first tear-down. The cylinders were OK, the rings were too, though rings for the overbore size were only available from one source. The head was re-checked and found to be OK. It was finally traced to a scavenging oil pump not performing (dry sump system) and once the pump was rebuilt, that cured the problem.

The bike sounds more-like an overbored Kawasaki Z-1 with a Kerker 4/1 than it does a CB750-4. The owner should be very happy when he gets the bike back. Maybe he will replace the yellow seat cover with a black one...

The basis for this 1,000 cc bike is a circa 1977 CB750-F. Note the struts, it wasn't built for comfort.
 

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I think that seat probably more than compensates for the lack of shocks on the banana yellow CB750F rocket . As for the X75, I cant help but to think trials bike while looking at that side view with that one piece body work. Didn't the Triumph twins fire both pistons at once?
 
The X75 Hurricane is a 3 cylinder engine. Without looking it up, I suspect the Triumph twins were 180 degrees apart in firing.

The Vetter X75 bodywork, with its wasp-waisted tank/seat, & side covers was a radical departure for a stock big displacement bike. The premium Triumph charged for it pretty-much doomed it in the marketplace as it was a whopping 50% more than the 750 twin Triumph. Before this bike, factory customs were non-existent. It took H-D another four years to make a 'custom' Sportster, the XLCR, widely reported to be the first bike wholly-designed by Willie G Davidson. It too was a sales disappointment, because it was so-far out of the normal Big-Twin styling, being a cafe-racer look, dealers didn't have the foot traffic to be able to move them, and the commonly-used term to describe their time on the sales floor was 'languishing' there. They only lasted two years in the sales catalog, and for years after, you could find them NOS, still crated, at dealerships. Nowadays they are collectible and are a frequent site at big shows. In perhaps the greatest compliment, people are now making 'clones' of the XLCR, ironic because of the sales bust they were when first released. Here's a thread by a friend of mine who has spent considerable time restoring a true XLCR. http://www.motorcyclistcafe.com/forums/showthread.php?21939-Harley-XLCR It's very entertaining to read.

Getting back to the X75, Tracy fiberglass had been making a replacement one-piece seat, side covers, and tank bodywork for the Japanese streetbikes. It looked very similar to Vetter's X75 bodywork. Both were to emulate shorttrack racing bodywork in the brevity of their appearances. http://fueltank.cc/blog/tracy Be sure to check out this catalog of Tracy designs, it's very entertaining.

My friend who is now retired from General Motors Tech Center in Warren MI where he was a stylist had made and sold a small number of similar bodies as the Tracy piece, for the Honda SOHC 750-4. Ironically, his streetbike was a Triumph Daytona 500 which he had flown to England to purchase at the factory in Meriden, and then spent a couple months riding around the UK and Europe before bringing the bike back ti the USA. The Daytona 500 was a successful bike used for roadracing in the 1960's in AMA competition. When the Triumph co. went to the reviled oil-in-frame design for their larger twins, the Daytona 500 continued to use the early design frame, which endeared it to the Triumph faithful.


https://www.cyclenews.com/2017/07/article/archives-harley-davidsons-cafe-racer/

http://craigvetter.com/pages/Motorcycle_Designs/Hurricane_Pages/Hurricane history intro.html

https://advrider.com/f/threads/1971-triumph-bonnevilles-what-to-look-for.763542/

http://www.classic-british-motorcycles.com/triumph-bonneville-oil-in-frame.html
 

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