Author Topic: '75 cb550 tuning questions  (Read 923 times)

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bluecb550

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'75 cb550 tuning questions
« on: August 11, 2007, 08:19:45 PM »
Well since my last post when I finished my LED taillights I've been having issues with the bike. Stumbling at higher revs and random dieing. Good news, all is fixed, mostly. Turns out some wires were crispy coming from the field coil, chopped and replaced those. And reset the gaps on the regulator. As far as the stumbling, carbs were gross. Previous owner said they were rebuilt recently, doubt that. After two cans of carb cleaner and lots of cleaning they are running extremely better. I do have a few tuning questions.

I'm afraid to let the revs fall below about 2500 rpm, sometimes it dies after that sometimes not... Slow jets? Keep in mind I still need to take it to get the carbs synched by a mechanic. Also I have a weird slapping noise at my rear wheel. I obviously thought the chain was out of adjustment. I have adjusted it 3 times now and still does it. Could my sprockets be worn so much that one side is longer than the other, like an oval shape kinda? Its just kinda strange and I can't seem to put my finger on it. And lastly, I get a lil bit of a surging feeling when holding constant speed. Under accel it feels great but I can feel it surge a lil under decel or constant speed. Could it be carb or chain related??? 

Thanks for all the help guys. I have learned A LOT just from reading old posts here. Slowly, but surely I'm breathing new life into this 30+ yr old machine. I think the previous owner wasn't very kind to her. He had her running on a car battery. Yea, had alot of wiring that I replaced...

bluecb550

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Re: '75 cb550 tuning questions
« Reply #1 on: August 13, 2007, 07:48:54 PM »
Anyone?

Stevien1

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Re: '75 cb550 tuning questions
« Reply #2 on: August 13, 2007, 08:58:52 PM »
You might want to consider a complete carb overhaul.  This means replacing the jets, air screw, needle jet, float needle/seat, and cleaning every passage out with solvent.  Look around ebay, you can get 4 carb kits for around $60 shipped.

After you get the carbs sorted out, adjust the valves prior to having the carbs sync-ed.