SOHC.co.uk Forums > CB500/550
Partially Restored 74 CB550
davidcumbria:
Thanks to Simon on this forum I now have the correct tacho fitted so all good in that department and I have a nice 750 tacho available if anyone is interested.
Bike was running ok / good as above but we like to fiddle don’t we? Changing the plug caps made no difference to sooty no 1 plug and digital thermometer showed it running a good 20 % cooler than the other 3. My first effort in (removing ) then replacing the carbs on a fully built bike went smoothly. Air box out and plenum minus rubbers in frame, carbs push onto engine intakes, plenum rubbers push into plenum from carb side with plenty of red grease then fit to carbs. Not the struggle I was expecting.
For peace of mind I rechecked the needle position which is the middle ( third ) groove on all so no slip up there. All main jets 100 and pilots 38. Thought there was possibly a small new blockage in no 1 idle circuit as the carb cleaner didn’t spray through cleanly at first attempt. Blow through with airline and all good. I went back to original needles and left the new Cruz in image needle jet tubes in place. I found No change to sootiness and bike idling worse ( hanging then stalling from 1100 rpm ) so probably should have left the Cruz in needles in and the possible pilot circuit blockage clearance didn’t nail it as I’d hoped.
Finally after the carbs were back on bike I managed to change the no 1 idle jet to 35. Seems to be running best it’s been with smooth idle, no hanging and good top end power but no chance to road test yet. Watch this space.
Btw this has been a very useful and informative thread on the subject for me and confirms my experience that the pilot jets and air screw setting are influential very significantly above idle indeed in a lot of the Rev range you might be using during running in.
http://www.sohc.co.uk/index.php/topic,25673.60.html
McCabe-Thiele (Ted):
Just read that old post by fogrider the link you posted from 2021 - it was very interesting stuff David.
davidcumbria:
Test rode the bike after stripping carbs, putting original needles back and replacing no 1 pilot 38 with a 35. All good, idles fine, doesn’t hang, no stuttering on pick up, revs cleanly to upper levels. No 1 plug still a little black coloured but not sooty and cylinder temperatures are closer. That will do for now - I’ll sync after a few more miles. Delkevich 4 into 1 is a bit louder than I would like……
Laverda Dave:
The bikes looks fantastic Dave and the colour really pops. It's always the final fettling that takes the time and is fiddly but worth it in the end. Great thread👍
McCabe-Thiele (Ted):
The exhaust noise might change with use?
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