Topic: Carb trouble with CB 650 SC "RC13"

[HenrikPoulsen]

Hey all.

After having a few problems with my blink relay and horn etc Im finaly done assembling the bike again now with the electrics sorted.

Having been standing still for the last 4 years I thought I would empty out the carbs and fuel tank before filling it with some fresh fuel. I notice that between the two carbs on the right side of the engine there is a tobe on the connection, this tube is not connected to anything on the other side and Im thinking that it should go somewhere else than on top of the crankcase. Is this a fuel supply line to the two carbs?

Tha bike would not start after putting the fresh fuel in, (I took the tank off to empty it completely) so I might try cleaning out the fuel petcock when the battery is fully charged again.

Any good advice on this matter?

Regards
Henrik Poulsen

[HenrikPoulsen]

Nobody knows if the carb setup on a 650 nighthawk requires one or two fuel connections?

Regards
Henrik

[Laminar]

Nobody knows if the carb setup on a 650 nighthawk requires one or two fuel connections?

Regards
Henrik

My '83 Nighthawk 550 has a single fuel input to the carbs, but a couple tubes coming from between carbs 1&2 and 3&4 that are vents of some sort.

http://www.bikebandit.com/houseofmotorcycles/honda-motorcycle-cb550sc-1983-carburetor-assy-link/o/m1971sch31694

I'm talking about item 6 in the above diagram.

If the bike sat for several years, the carbs will probably need a good cleaning. My carbs sat for less time than that and they were very gunked up on the inside.

[HenrikPoulsen]

damn I was hoping I didn't have to take off the carps, they really is a pain to fit back on

It did run a few days ago though so im still hoping that with some new fuel (Old fuel was very clean no gunk there) it´ll fire up once full again

[Laminar]

I've found that the carbs are much easier to get in and out if I pull out the rubber boots between the carbs and airbox. I can pull the carbs in a matter of minutes, the trick is rocking them up and down.

[cb650]

Sounds like your describing the vent tubes.  T from 1/2 and 3/4 to another T then to airbox.

[HenrikPoulsen]

Vetn tubes you say, hmm just dont really see anywhere on the airbox where the tube fits, but ill have to keep looking I guess
Does it do any harm if the vent tubes does not go back into the airbox?


The problem is not so much getting the carbs off the bike, more getting them back in, tried it once and nearly went crazy doing it, it is very difficult I think

Regards
Henrik

[cb650]

I cant remember exactly were it went on the airbox.   On mine with pods I just ran a hose down behind the engine.  Dont make it too long or the air at speed will play with the floats.

[HenrikPoulsen]

Hey all

I figured it out today, the tubes from the two t-joints just go down on top of the engine. I had no need to pull the carbs though, found out that my fuel filter vas placed in a way that the fuel had to travel upwards towards the fuel filter, this it couldn´t do so I took out the filter and two seconds later it was purring like a kitten I could never tell that the bike have been sitting in a garage for the last 4 years without having been used, it just goes like a dream now