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Still on the cam sprocket bolts

valiantkiwi

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Apr 20, 2022
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Nelson New Zealand
It seems hard to get a definitive answer on whether the silver 350 cam sprocket bolts are okay. I have one coming that claims/appears to be nos and the part number is correct but it doesn't have 11 stamped on the top. Did Honda use a couple of different types or different hardness ratings as the models progressed? Or were they all black with 11 and the silver ones are something different altogether? Does anyone know for sure?
 
Moved to 350 Engine and Transmission section.

Comparing part numbers from CB350K0 to CB350G/K5, the bolts are the same for every year after serial number 1131116 on the K0. So the only 2 sets of part numbers shown are 90081-286-000 (Knock Bolt) and 90085-286-000 (6x14 Hex Bolt) for the early K0, and 90081-312-000 (Knock Bolt) and 90085-312-000 (6x14 Hex Bolt) for all models after that. No mention of color, though we do know they're hardened.
 
Interesting how the fsm mentions the cam sprocket bolts as having a '9' stamped on the top, which is what the silver bolts appear to have rather than '11' which the black bolts have. I expect this means that the manual was printed in conjunction with the KO models? Most likely, as you may already have said that the silver '9' bolts were simply superseded by the '11' bolts as the models evolved and improved.
 
That would be my guess, Honda was always improving things even during a production year, which is why so many parts changes refer to frame or engine numbers that fall within a series instead of beginning at the next one (like starting with 2000001). When they saw a need they took care of it.
 
Interesting how the fsm mentions the cam sprocket bolts as having a '9' stamped on the top, which is what the silver bolts appear to have rather than '11' which the black bolts have. I expect this means that the manual was printed in conjunction with the KO models? Most likely, as you may already have said that the silver '9' bolts were simply superseded by the '11' bolts as the models evolved and improved.

The earlier silver bolts (zinc or cadmium plated) were stamped "9" and the later black bolts (black oxide coated) were stamped "11". Those are tensile strength ratings. Here is a chart from the Honda General Service Manual, showing ratings for "8.8" and "10.9" bolts (approximately "9" and "11")



They used Kilogram Force per square millimeter to rate the bolts, which can be expressed in psi or pounds per square inch, if desired, by using an on-line calculator. Whatever units are used, the numbers look really big, but you have to bear in mind that the bolt is very small.

Whatever units are used, looking at mid-range values for the two bolts, the "10.9" is about 22% stronger than the "8.8" bolt.

The bolts are supposed to be single use items -- replace but do not ever re-use. Eight years ago, I reused my original bolts on my CL350 and have run that bike 11,900 miles since then with no problem. The bolts were NLA at most places back then. One forum member found a dealer who still had a supply of the bolts and bought them all. He then tried to sell them at a premium, which upset most people on the old forum. Looking back, he wasn't offering such a bad deal at US $25 including shipping for the pair of bolts.

Back then, I bought a KA tensioner from Bore-Tech, who are now out of business. They also sold me a pair of the black bolts for a cheap price, but they said these were "good used" parts. I decided that I knew where the bolts from my bike were from, so I used them instead of the unknown ones. I still have that pair that came from Bore-Tech. I also have a pair of silver ones from the 1970 SL350 K0 basket case I am working on.





In all measurable respects, the bolt dimensions are the same. Since the black ones are supposed to be stronger, I guess I will go with them. Time will tell.

It's a little spooky to do a Google search on the part number of this knock bolt and come up with a lengthy post I made 8 years ago when I was dithering over how much torque to apply. So far, so good.
 
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