Dare I ask how near original Sand Cast are you gone a do your model?
Now this discussion about short throttle springs. As the original setup could not close properly!
Don't for sure know exactly what change did the difference. Thicker cables or the higher slides some 2/100 mm smaller in diameter
I could use the weak springs for years afterwards without any problems.
Though changed to double cables when that was possible.
Some in this Forum insist on 28 carbtops. Are they modified for 6mm cables?
Do someone still want to use the shorter slides?
Apparently more than me had a problem since Honda gave away new parts which indeed cured the problem.
And I for one never came about to complain.
I shall not tell anyone what to do, but apparently 6mm cables and the 46mm high slides would do, and that still with weak springs!
       Youers Erling.
P.S. Some 10 years ago appeared here in Danmark a Motorcycle History Book (Danish).
In the chapter about our Honda, the author claimed all 4 slides could stick wide open simultaneously!!
I had never a problem with more than one at a time, and do not remember if it was the same every time. It took some time to rectify of cause. But it did not happen that often.
Only the one time outside the camping in Milano (Italy), to start the 1000 mile ride home, all luggage had to come off again, but girlfriend could hold the tank though.
      Erling.

It is some time ago E17xx was said to be introduction of finned oilfilterhousing.
erling.

So I'm not the youngest with 45 in 6 months time as Sandcast owner/user, though after some 10 years on a BMW R69S. and of cause the legal age even before.

1941wld asks for a Rickman and a low vin donorbike. What about CB1676 engine 1638? (last 2 ciffers half ditto frame vin!) and a Seeley frame born to take the Sandcast. Though we shoehorned a CBX750 engine into it 25 years ago. Do not really know the diffrence to the Rickman except my Seeley was delivered in black paint to my demand. Am a little shy to let anybody know what bike I´m on. Got a Fireblade in ´96. The Seeley was a match to it up to say 70-80 MPH. Then the stability of the Blade is superior. This on little twisty country roads. But it has not been running for some years now. Friend with an R90S BMW  got a VFR Honda. BMW and Seeley were equal on power. A problem might be I do´t know about pictures, and even less how to put them into this forum. Only got one rearwheel. Got new brakeshoes some 10 years ago. O-ring chain was new with the CBX engine. The original sandcast lasted a chain some 1 or 2 K km. The Blade wears out a O-ring chain in some 30 K km. Mileage is not known. Speedo was only on for the autumn 1969 i.e. August-Oktober. Next year the Münch brake of my previous BMW was on for a trip to Italy ordering a 4 shoe Fontana brake. Frontwheel still stands with original 1969 tyre! Speedo shows 6655km. Though now frontwheel is an 18" comestar double disc. In a way I have to sell both at the same time. Some parts will be missing for both to be roadworthy. Have to face the fact I´m but an owner and user certainly not on leavel with what I see in this forum. The engine do turn, I us the the kickstart from time to time. Have a diecast engine for it too. Enlarged to some 8xx cc. A firce cam made it difficult to dial in, so the CBX was an easier choise.
Youers Erling.

 Happy New Year. Maybe just to destinct myself: How many are we in this forum to have posesed ouer precious Sandcast since day one?
         Youers Erling.

Back to Sandcast: Mine left more oil, where it was parket just the first month, than the previous R69S BMW in 8 years! Now 43 years ago. And I come straight to these lines from "unread posts".
        Erling Denmark.

Wednesday August 20 1969. Got a Honda CB 750 1001676 5/19 E1638. Round oilfilter house 14m bolt. Sunday after in Sweden met 2 other Hondas. They had finned filtre houses! Engine 23xx. Do not remember when I got finned one, and it is black, have just looked to check for the 14mm bolt. But the round one reached an age, where it had at least 3 cracks from the center hole. Don't know where it has gone. Normally I have kept things. Even the massive rubber cusions from inside the rearwheel, and 28 . carbtops. Original engine has not been in use for the past 35 years eather' as a diecast second hand one was acquired for 8xx cc enlargment. And the original should be as was for my old age run about on the first CB 750 to be licensed in Denmark. Wife denies i'm so far jet. And like someone else in this forum says: I'm not qualifyed to do restauration work like described here in the forum. I'm the owner and was the user untill years ago, but it is more fun to ride the fireblade.  Diecast Engine 19216 has 12mm bolthead and grey finned house. If they are reinforced or not I've no idea.
Youers Erling.