Honda CB750 Sandcast
General Category => General Discussion => Topic started by: kp on December 18, 2018, 04:56:39 pm
-
Hey Everybody! Can we get as much feedback from registered members as we can on this topic. Whilst the subject has been discussed over the years in general restoration threads, I can't actually find a specific thread on this subject.
Who can comment on what tyres were fitted to the early Honda CB750. I have several front rims that have Nitto brand tyres fitted and I believe one of these is an original, but not certain.
Please, please, please add your comment, thoughts, feedback or recollections.
-
Hi!
My first CB750, a K0, VIN 24xxx, I purchased in 1970 had Dunlops like them you can buy from Yamiya. Pretty many of my sandcasts had same Dunlop front tyres when they arrived to me. Only one had its original rear tyre, also a Dunlop K87. This is the only I can support you with.
Best Regards Kerry and a Merry Christmas, Bo from Sweden.
-
Hi!
My first CB750, a K0, VIN 24xxx, I purchased in 1970 had Dunlops like them you can buy from Yamiya. Pretty many of my sandcasts had same Dunlop front tyres when they arrived to me. Only one had its original rear tyre, also a Dunlop K87. This is the only I can support you with.
Best Regards Kerry and a Merry Christmas, Bo from Sweden.
Thank you Bo and KP, as always, for your contributions keeping this forum alive and well.
i wonder if Dunlop tires were fitted to machines exported to Europe due to contractual agreements with Dunlop since they were out of Ireland (U.K.) and Bridgestone tires fitted for export to North America?
-
Hi.
Pretty many of my sandcasts are imported to Sweden from USA and most of them had Dunlop front tyres. Only one, also US bike, had its original rear tyre. Also a Dunlop, a K87.
Bo
-
CB750-1008054 (9/69 on VIN plate) still had its original Dunlop Gold Seal F7 front tyre fitted when purchased in 2010. It came from the USA.
Chris R
-
i wonder if Dunlop tires were fitted to machines exported to Europe due to contractual agreements with Dunlop since they were out of Ireland (U.K.) and Bridgestone tires fitted for export to North America?
The 69.4 parts list shows both Bridgestone and Dunlop tires so maybe Honda used whatever was available to them at any given time.
Pretty many of my sandcasts are imported to Sweden from USA and most of them had Dunlop front tyres.
Dunlop may have been a more popular replacement if it was cheaper or better.
Only one, also US bike, had its original rear tyre. Also a Dunlop, a K87.
Just curious, how do you know for sure that it was the original tire, oops, tyre?
I have a question about the K87. The parts list specifically shows the Dunlop K87 as on option for the rear. Do we know that the K87 of today is exactly the same as the K87 of 1969? I have a new K87 and it just seems too big.
I believe that the Bridgestone tires that were used were the Superspeeds. I haven't found any available tires that look close to the BS front tire with the distinctive straight ribs, which I think is part of the signature look of the CB750. I wish there was a contemporary replacement. That's why I'm thinking of putting a set of used, but not too badly, Bridgestones on #97 just for the correctness (just for show, not riding). If anyone had a set that looked better than the ones I have I would buy them. I guess what I'm saying is I'm still looking for a decent (better) set.
CB750-1008054 (9/69 on VIN plate) still had its original Dunlop Gold Seal F7 front tyre fitted when purchased in 2010. It came from the USA.
Does it look like the Bridgestone Superspeed front and how did you know it was the original?
-
interestingly enough, i have to say i have seen quite a few well worn, weather checked BS tires on CB750's.
-
How do I know front tyre on 1008054 was its original?
Other than carb tops and rear tyre, bike appeared to be as it left the factory in every respect. Recorded mileage of 10,836, front tyre worn to about 1mm of tread depth and very badly perished on side walls / between treads. Tyre therefore very old, and so likely JUDGED to be original based on overall patina of bike it was on. You are of course correct that I cannot KNOW!
I believe tread pattern is very similar to the Bridgeston equivalent, but do noy have one of those to compare directly with.
Chris R.
-
How do I know front tyre on 1008054 was its original?
Chris, just so you know, I wasn’t challenging your opinion. What you say is logical. I’ve had many times where I wondered if something was original or not.
I’m pretty sure that the Bridgestone tires used on the early CB750s were the Superspeeds. Can anyone confirm this?
(http://cb750sandcastonly.com/coppermine/albums/userpics/10002/20181223_174901.jpg)
Here’s a pic of the tread on the BS front tire. Does it look anything like the Dunlop?
(http://cb750sandcastonly.com/coppermine/albums/userpics/10002/20181223_175148.jpg)
-
Looks pretty similar to the Dunlop that I can see.
I also have a really nice rear wheel from a K2, which appears to have its original tyre still fitted - and that one is a Bridgestone Super Speed R2.
Chris R.
-
i don't think there's any reason to not believe Bridgestone tires were fitted in the beginning.
-
Yes I agree that Bridgestones were used but my question was were the Superspeeds used on sandcasts.
-
Yes I agree that Bridgestones were used but my question was were the Superspeeds used on sandcasts.
Why wouldn't have Superspeeds been used on sandcasts?
-
Maybe Superspeeds were all Bridgestone made back then so maybe it's a stupid question. I don't know. Just trying to confirm that is was the Superspeeds used on Sandcasts. :)
-
Mark, these are good questions. i would not say they are stupid. Probably some research into the manufacturing history of these Dunlop and Bridgestone tire companies would be helpful. what i remember when i got back from my trip to California early June 1970, the tire and chain were both gone; the dealer did not have the chain or tire designed for the 750 and he told me he could not sell me a tire or chain that the factory did not recommend. as i recall i had roughly 4,000 miles on the odometer. i have NO idea what tire was on 4779 from factory new; what i do know is a tire specific for the CB750 was unavailable in California (the dealer at Vallejo told me he had no tire (or chain) for the CB750 and therefore to not ride high speeds on the way home from California to Nebraska.)
Sometime around the time the CB750 was to begin production, the factory had their undies in a wad with the motorcycle manufacturing section of Bridgestone; it is fact that Honda told Bridgestone they'd quit buying tires if Bridgestone didn't quit making motorcycles. my understanding is the Honda factory had the chain and rear tire manufactured to spec to meet the until then unheard of performance the CB750 was capable of. and i have that memory of Art Olsen at Olsen Brothers Honda/Triumph, Sioux City, Iowa telling me i would have to wait for a chain and a tire for 4779; given Art saying i would have to wait for a tire and chain tells me that tires and chains fitted to Trident's were not suitable for the CB750. (Art had Trident's on the showroom floor and if i recall correctly both Trident's and Rocket III's were fitted with K70 front and K81 rear. the K81, if i understand correctly, was designed specifically for the Commando and the triples...)
maybe asking other questions such as the following could shed some light on if Superspeeds were on early sandcast vins... "What evidence exists that Superspeeds were fitted to early vin sandcasts? "What dates did these special Dunlops and Bridgestone tires first become available?" "Was the relationship between the two factories (Bridgestone motorcycles) so strained that Honda was not at the time purchasing tires from Bridgestone?" "Did demand for the Superspeed exceed supply?" -or- "Was Bridgestone even fully tooled up to begin production of Superspeeds prior to or very early during CB750 production?"
Mark, your questions are on target. if i understand correctly i think your question is, "Were Superspeeds were fitted to the very early CB750 sandcast vins?" Another question could be "What is the earliest sandcast vin that a Superspeed tire is found on a sandcast vin?" However, finding answers to other questions such as i pose might answer your primary question.
-
so then there is this thread, it seems we established the Brighton bike, 2110, had Superspeeds on it.... http://cb750sandcastonly.com/smf_forum/index.php?topic=281.15 (http://cb750sandcastonly.com/smf_forum/index.php?topic=281.15)
-
In the August 1969 issue of "DAS MOTORRAD" (A German Bike magazin) a sandcast had been tested.
Text says that tyres are in Japan produced (lizence) Dunlop "nylon cord".
I have no idea what those are.
-
Wow, a lot of good info on that thread. I had forgotten some of the posts I made. :o
-
it could make sense the p-p bikes had Superspeeds and the production bikes did not. only 4 bikes vs. thousands of bikes, contract agreements, who knows what else personalities, politics and ego's may have been in play at the time. what 'evidence' we have points at Dunlops being on early prod.vins and while i could tend to believe Bridgestone tires were not on early sandcasts and may not have been on any sandcasts, i suggest the necessity of staying on the look out tire types on any new sandcast acquisitions anyone might have.
My now owning a 1967 Bridgestone 350 GTR, having read a bit of information about Bridgestone, the story of Honda threatening to quit buying tires from Bridgestone, from what i have read may be true and happened during the time Honda was working on the CB750. Bridgestone quit production 1971.
-
a bit of Bridgestone history:
While production at the Bridgestone site was busy the motorcycle production side was more of a side line to the tyre manufacturing and profits earned didn't stay within the motorcycle division but were absorbed by the tyre division. Unconfirmed rumours spread that other Japanese motorcycle manufacturers made it clear to Bridgestone that if they pursued their competitive attitude in motorcycles on and off the track they would find themselves with no home market for their tyres, the big four had the view they were putting money into a competitor by buying their tyres. A perhaps more plausible reason was the company’s decision to focus on its tire business rather than invest in the technology needed to meet new clean-air and noise standards. The dealer and sales network in the U.K. had already gone by then, and the demise of the network in other countries swiftly followed. Both tyre and motorcycle production took place in adjoining sections of the same crowded factory and expansion of one would be at the expense of the other, the alternative was heavy investment in a new factory, also the increasing value of the yen against the dollar was cutting into profits and didn't bode well for the future either.It soon became apparent that corporate interest in continued motorcycle development was slowing with late sixties "new" models that were merely painted over variations of earlier ones or given high pipes, chunky tyres and called scramblers i.e. the 350 GTO. Dealerships began bailing out and then there was the environmentalist pressure against two-stroke engines in the U.S.Following the 1971 model run Bridgestone closed the motorcycle division at Ageo with most of their tooling sold off to a Taiwanese firm named BS Tailung.
-
As sometimes happens (seems more and more ::) ) my memory was incorrect about the size of the Dunlop K87. Here’s a pic of a new Dunlop K87 on the left and a used Bridgestone Superspeed on the right. They are amazingly close in dimension (width and diameter) and tread pattern. :o
(http://cb750sandcastonly.com/coppermine/albums/userpics/10002/20181228_170534.jpg)
-
one major problem with the new Dunlops, they are good for less than 2,200 miles max of normal riding; i.e., no smokies, no burn outs, no stop light to stop light drag racing, no sustained high speed; just rpm's occasionally up to 6,500 - 7,000, mostly under 6,000.
-
My pre-2000 bike was purchased with what I believe were original fitment Dunlop Gold Seals, F3 front and K87 rear. I think the F6’s came in as a later replacement for the F3’s early to mid 70’s. These tyres are the ones mentioned on the later K0 rear guard decals as well. My bike had 8000 miles on it so if they weren’t original, they were likely replaced same for same. I’ll post pics shortly of the tread patterns.
Here’s a pic in the meantime of a Tyre decal from a spare K0 Guard I have. This shows both Dunlop’s and bridgestone mentioned too.
-
Steven, that "tire decal" on a pre2xxx bike is, at least to me, an interesting detail. clearly appears faded brown and original to bike. i was always under the impression those "tire decals" appeared post-7414...
-
Indeed the decal is from a K0 guard Steve, not from my sandcast. Sorry if it wasn’t clear. I’ve amended my post. I included the pic to support the tyres that were on my sandcast.
-
Indeed the decal is from a K0 guard Steve, not from my sandcast. Sorry if it wasn’t clear. I’ve amended my post. I included the pic to support the tyres that were on my sandcast.
gotcha, thanks !