Service Bulletin No.15

[AshimotoK0]

Read this SB no. 15 and it highlights the ludicrous  obsession to detail some people have. Those 'No.28' carb.  caps are one of the 'Holy grail' items for CB750 Sandcast owners but were the subject of a safety recall in 1970.

You can image the same types  in 25 years time looking for original front mats for a Toyota. You know, the ones that can jam under the pedals 

Cheers ......  AshD

[ Guests cannot view attachments ]

[Johnwebley]

interesting comment Ash,

 I consider my CB500 95% original and standard, the parts that are modded  are those which improve,and make safer/better,
such as H4 Halogen headlamp,Peter Furlong enclosed chain case,twin Discs,electronic ignition,

my thought is how Honda would have added as the model continued,

could you imagine any having a 1940's Spitfire ,with out certain mods,to make it faster,safer etc,like  the famous "Mrs Shillings orifice "

[Erling]

To me not the actual 28 carb tops were at fault but the sliders a bit larger on diameter and some 5 mm less high tend to stick in carburettor thus letting the cable nibble drop down out and pulling that slide a nibbles high higher up! Never all 4 at one time as I've read in a book to be the case. Do not remember if it was the same every time it happened. And indeed it was not that often either.
       Youers Erling.
       

[AshimotoK0]

To me not the actual 28 carb tops were at fault but the sliders a bit larger on diameter and some 5 mm less high tend to stick in carburettor thus letting the cable nibble drop down out and pulling that slide a nibbles high higher up! Never all 4 at one time as I've read in a book to be the case. Do not remember if it was the same every time it happened. And indeed it was not that often either.
       Youers Erling.
     

Please introduce yourself here Erling!

And welcome aboard in advance from me!

http://www.sohc.co.uk/index.php/board,112.0.html

[Erling]

I'm a bit nervous for this, being an original owner e.i. not a collector nor a restorer! First bike a '61 BMW R69S then the first to even ask for a four cylinder Honda when a spy photo revealed its existence. August 14 '69 5 arrived in København. 2 remained in town. Dealer wanted one for himself. I happened to have the cash. Next week the new BMW R75/5 was announced! Got one for the '71 season. Still have them both though CB750 was transferred into a Seeley frame in '78 with a die cast 8xx ccm KO engine, to be superseded by an '85 CBX 750 engine gently shoehorned into the Seeley frame where it still is. '96  got a fireblade which keeps me happy whenever riding. Remaining in use from the original CB750 is the rear wheel and other little parts, to make the Seeley a complete bike. Had to be member here as for answers in forum said some thing was only for members and answers are interesting to me as I know hardly anything about the bike i've owned for more than 45 years now!
 Erling.
P.S. Wrote in the US Sooc under members bikes the first year on a SC not long ago.

[AshimotoK0]

May be translation but no need to be nervous on here....You will be the only original owner of the first 750 Sandcast  on here, to my knowledge anyway. So we would love to hear your experiences. bet UKPete would as he has a sandcast &an early Diecast and I have an early diecast too.

Cheers ...Ash

[UK Pete]

Hi Erling,there are a few of us that post regularly on here that own the early cb750,s, probably many more who observe the posts but choose to remain quite, this forum is for all .owners restorerers , novices, potential buyers, and just Honda lovers, if you have not done an introduction yet that would be a good start
pete

[Erling]

Thank you for the kind receiption. Would of cause answer if someone had a question I might be able to answer on. But can't give any technical comment as such. It was just this about the 28 carb tops. I changed them myself, even still have the original ones laying about some where. And believe to have had experienced the need for them, though rather the slides, as I see it. Have never heard any official side to the story. Tried the stronger springs, but found them too much, the original weak ones did the job well, together with the new 6mm cables. Ok, when double cables came about I did change to that figuration.
      Erling.

[UK Pete]

Erling do yourself a favour and get those 28 carb tops on ebay, they fetch good money, if you dont do ebay then i can try to sell them for you
pete

[AshimotoK0]

Hi Erling,

I raised the post and seems that caps alone were not the safety issue but I suppose if you saw those caps on a bike you could be forgiven in thinking that the safety recall had not been carried out. Or were there dots stamped near the engine number or on the back hub?
Your first hand 1969 experiences are precious to us. I was a mere schoolboy when the sandcast came out and three years later I was aspiring to a meagre  C200 90 'sports'. Please join us on here, we are a friendly bunch you know  .

Ash

[Erling]

Hallo Pete and Ash.
There are no dots on my engine or rear hub, as it was never to any kind of service! Changed the thing myself. Thats why I still have what was in surplus. To me the 28 carb tops belong to my E-vin in case I could sell the lot. Problem is Honda was donor bike with parts needed to complete the Seeley! and are of cause still missing there, as Honda has not been on the road since '78. Friends tell me to put the old Honda together again, which sounds reasonable, but knowing a next owner would tear it apart first thing, it seems a waist of time, and I'm no good at it either. Once upon a time I believed one day to come to an age where the happiness in life would be to just ride on an old Honda to meet other Honda owners, but alas I'm still not that far, only concerned about riding a bike (biased it's a Fireblade) . In case I manage to sell, it would have to be both, and next owner can then fight for parts for the Seeley, or sell it. Though there are two engines for that one, any other part could of cause be whatever! My experiences on the old Honda were limited to daily use. There were no one else around in the day with whom to talk issues. The package about the 28 carb tops: Original gas cables were 5mm and replaced by 6mm ones, so new carb tops with larger diameter holds for these. Carburettor slides were 5mm higher and to my measure 2/100mm smaller in diameter, and springs were stronger, too much for me. They were only tried and then changed back to original weak ones. No problems ever afterwards. Thats why I believe the slides were the problem though frankly speaking I did not try with thinner cables and old 28 carb tops! As Pete suggests I'm no good at ebay or computers, how do you think to help? Have in vain tried to put in a picture. Friends have explained how to but my page does not always show the camera silhouette below. Some day maybe?
          Erling.