Valve setting 81 cb750k dohc

X7eater

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Good work.....we learn so much from these old bikes. Just need time and patience! #3 at .003" looks a bit tight, and if you had a smaller shim to bring it up to .005"-.008" then just change that one....but if not, I'd ride it as-is for another 1-2000 miles and them check them again.
 

fg1972

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Just checked my notes from when I did mine. Target was 0.127mm (0.005") with min/max range of 0.102 - 0.152 (0.004" - 0.006"). So yes, definitely worth proceeding with getting the gaps within tolerance. The fun part, you can try playing musical chairs by rearranging what you have to get as many as possible in spec, then just replace the ones you need. There was a guru on here "AMC49" who was a wealth of knowledge on these bikes, sadly I think he stopped contributing due to some kind of issue with another member(s) however many of the useful posts are still here.
 

Rampton

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Just checked my notes from when I did mine. Target was 0.127mm (0.005") with min/max range of 0.102 - 0.152 (0.004" - 0.006"). So yes, definitely worth proceeding with getting the gaps within tolerance. The fun part, you can try playing musical chairs by rearranging what you have to get as many as possible in spec, then just replace the ones you need. There was a guru on here "AMC49" who was a wealth of knowledge on these bikes, sadly I think he stopped contributing due to some kind of issue with another member(s) however many of the useful posts are still here.
Thanks 👍☺️ for the advice have been reading threads and noticed this guy from America, he knows some stuff and would be a hero to this site it's a shame he isn't contributing anymore. Thanks again for the advice will finish valves and put covers back on. Then start on the dreaded carb problem haha 😃. What doesn't kill you makes you stronger. See you around me old pal. 🇬🇧🇭🇲🇺🇲
 

Rampton

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Good work.....we learn so much from these old bikes. Just need time and patience! #3 at .003" looks a bit tight, and if you had a smaller shim to bring it up to .005"-.008" then just change that one....but if not, I'd ride it as-is for another 1-2000 miles and them check them again.
Yep going to order them, the clearances will be bigger than I wanted but if I can get the carbs sorted and get her out on the road for a good blast then check the valves on a regular basis change them out if they alter ( more wear). Thanks for the great advice keep up the good work. It's nice that bikers help each other to keep these old birds on the road. Stay safe🇬🇧🇭🇲
 

Rampton

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Just checked my notes from when I did mine. Target was 0.127mm (0.005") with min/max range of 0.102 - 0.152 (0.004" - 0.006"). So yes, definitely worth proceeding with getting the gaps within tolerance. The fun part, you can try playing musical chairs by rearranging what you have to get as many as possible in spec, then just replace the ones you need. There was a guru on here "AMC49" who was a wealth of knowledge on these bikes, sadly I think he stopped contributing due to some kind of issue with another member(s) however many of the useful posts are still here.
IMG-20210919-WA0003.jpg
 

Rampton

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Good work.....we learn so much from these old bikes. Just need time and patience! #3 at .003" looks a bit tight, and if you had a smaller shim to bring it up to .005"-.008" then just change that one....but if not, I'd ride it as-is for another 1-2000 miles and them check them again.
IMG-20210919-WA0003.jpg
IMG-20210919-WA0003.jpg
 

Rampton

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Good work.....we learn so much from these old bikes. Just need time and patience! #3 at .003" looks a bit tight, and if you had a smaller shim to bring it up to .005"-.008" then just change that one....but if not, I'd ride it as-is for another 1-2000 miles and them check them again.
Hi x7eater hope all's well. Just letting you and fg1972 know that tappets all done started bike and still got same problem. So I am going to start a thread in the carb section asking how to strip and clean the carbs. As always your advice would be greatly appreciated 😊👍 stay safe🇬🇧🇭🇲
 
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Rampton

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Putting carbs back on can be a pain as you know. A trick that makes it a lot easier is to heat the rubbers with a heat gun. The jet under the rubber plug is the troublesome low speed or idle jet. They are either pressed in or have a slot in the top which can be unscrewed. Putting the guitar string in there and also in a tiny hole just in front of the throttle flap with lots of carb cleaner. Not sure if have this carb manual that is really useful. http://www.cb750c.com/publicdocs/SeanG/Honda_Carb_Manual_revG.pdf
Hi fg I've tried opening the carb manual you sent me but it won't open!!!?
 

Rampton

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Putting carbs back on can be a pain as you know. A trick that makes it a lot easier is to heat the rubbers with a heat gun. The jet under the rubber plug is the troublesome low speed or idle jet. They are either pressed in or have a slot in the top which can be unscrewed. Putting the guitar string in there and also in a tiny hole just in front of the throttle flap with lots of carb cleaner. Not sure if have this carb manual that is really useful. http://www.cb750c.com/publicdocs/SeanG/Honda_Carb_Manual_revG.pdf
Input the link manually, everything I need to know is there thanks fg! 42 pages just finished reading them there's a lot to take in but there's a lot more than I did when I changed jets and other. A lot more cleaning to do especially on idle circuit. Thanks again brilliant 👍😊.🇬🇧🇭🇲
 
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