SOHC.co.uk Forums > CB350/400
'77 CB400F - it runs!
mattsz:
See subject heading...
First start - fired right up on the second button press, with a barely-there puff of smoke - not surprising, as there was oil in the cylinders. All 4 cylinders heated up quickly and uniformly. No obvious oil leaks, yet. With a bit of juggling choke lever and idle screw, I quickly got it down to a steady 1200 rpm idle with the choke off.
The front end sounds very rattly - is this a loose timing chain? I know it's hard to hear sometimes on a video, but I've posted a couple. Would you guys check them out and give me some opinions?
The first one is the start video (because I had to!), just over 1 minute long. It ran until I shut off the choke and it stalled:
https://youtu.be/PoMMEqoxnK0
The second video is a shorter (about 25 second) "running" video to highlight the noise. It's running without the choke at this point:
https://youtu.be/fzLM4dWA_lE
Nurse Julie:
Sounds like cam chain rattle. Well done for all your work so far, it's great to hear it running.
mattsz:
--- Quote from: Nurse Julie on August 31, 2020, 07:23:09 PM ---Sounds like cam chain rattle. Well done for all your work so far, it's great to hear it running.
--- End quote ---
To be honest, I'm shocked it went so smoothly! But I'm not there yet!
I tried to adjust the cam chain tension using Bryanj's method of "putting pressure on the [crank] so that the engine is just about to turn but not quite turning." I don't know if I did it right, or if the adjuster isn't working correctly. Any advice on how to proceed? Dare I follow Honda's recommendation and let it adjust itself while the engine is running?
Nurse Julie:
--- Quote from: mattsz on August 31, 2020, 07:27:58 PM ---
--- Quote from: Nurse Julie on August 31, 2020, 07:23:09 PM ---Sounds like cam chain rattle. Well done for all your work so far, it's great to hear it running.
--- End quote ---
To be honest, I'm shocked it went so smoothly! But I'm not there yet!
I tried to adjust the cam chain tension using Bryanj's method of "putting pressure on the [crank] so that the engine is just about to turn but not quite turning." I don't know if I did it right, or if the adjuster isn't working correctly. Any advice on how to proceed? Dare I follow Honda's recommendation and let it adjust itself while the engine is running?
--- End quote ---
Yes, I would have a go Hondas way. If it doesn't make any difference to the rattle, it would diagnose either a cam chain stretched well beyond spec or a seized horse shoe pivot, or even both.
mattsz:
Thanks Julie!
I did investigate the function of the tensioner based on the advice of another forum member. I did get some results, but I never got an answer as to whether my results were normal. If you wouldn't mind, would you take a few minutes and read this short post and the three which follow it to see what was suggested, and my results?
http://www.sohc.co.uk/index.php/topic,17461.msg205855.html#msg205855
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