SOHC.co.uk Forums > CB500/550

76´CB550F, born to run, currently rehabing

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Green1:
Oh yea forgot to mention apart from the misfire.Agree with oddjob a good tune up works wonders.
If it doesn't sound like it's chewing it's head then it's not a 70's Honda.

Mick

K2-K6:
Hello Bigbird and welcome to the forum.

The first thing you should do is change the oil and filter if you are at all unsure of the oil condition/quality that's in there. You can argue with people  for ever abut what oil should be in there and get 100 different answers but what ever it is, if it's been diluted with petrol from crappy running, then it will be no good for the engine.

Pod filters basically change the vacuum that is pulled at the intake to the carb and it's the difference of the vacuum compared to atmospheric in the float chamber that causes the jet to flow a set amount of fuel. Change the vacuum and the jet will flow more or less fuel......but, and it's a big but.....the engine requirement didn't change, so wrong fueling and crappy running is the result. A quick reality check can be made by wrapping some porous rags (polishing cloth/muslin or similar) round the pods and see if the restriction improves the running.

Bigbird:
And now i´m back to let you know i can really shake em down.

Thanks for the warm welcome, and astonishing response. Getting back to the Honda-project for a while now. My aim has been a longdistance (4000km) trip in the end of summer, but that´s really in the grey now, as i´m growing to the needs of the bike.

I Did:
- tank
- points
- timing
- chain tension
- valves sounds ok, so i left them as is

Now cleaning carbs, which didn´t look too bad, except thin white deposits on the two leftside carbs. One needle had a bad screw and i tried to bore it out but didn´t succeed, so now i´m looking for a single needle and throttle slide, if anyone near Copenhagen has such a thing I´d be happy to pick it up very soon. I think I´m keeping the airfilter for now, as an airbox is hard to get by.

Oilpressure-light, which comes on gradually as the bike heats up.
I´ve been carefully listening to the engine, and the sound changes of course when it gets it´s heat on, but that I figure is normal. No bad sounds, other than when it gets really hot from low speed city driving, it stumbles and using the kickstarter feels heavier.
I ear-synched the carbs, and it runs alot better, almost no stumbling when hot. Can´t remember if the heavier kickstarter remained or not.

As for leaks
Topend looks moist most of the time, drips from back of block once every 5-10 minutes when hot. Filled it up with oil 400km ago, and i can hardly tell its changed. Engine bolts are a bit rusty, so there is rust trails on the enginecovers from the top and down. Suspecting leaking carb here, as oil tends to a gasoline smell again, so i´ll change the oil again after the carbs are back on hopefully without a leak. Using 10w40. While changing the oil I´m fitting new gaskets to sidecovers of engineblock.
Checked for airleaks with both starterspray and a small gas blow torch. None.

Plugs (fairly new)
Cleaned and checked gap; and again black sooted after run, which points to a rich running, but it should be running lean as i haven´t rejetted yet. Needles where set to second highest which would make it even leaner. Will try to resitrict the filters as soon as the carb is back on and synched. So, can the black plugs point to oil burning? Bike is said to have 45000km on it, is it time for a top end service? Guess i´m going to do a compression test to see what condition the pistonrings are in.

Exhaust
Has been white at one or two occasions. Clean when idle, black when revving.

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