Topic: Need Some Advice on what to do next - 1975 CB550

[quidger]

I'm kind of at at loss and looking for guidance on my barn find.

I can't get the bike to start after having success starting it last week. Had the carbs off last week and cleaned them up. The bike started after that but now, no cigar with starting.

So I have clean carbs, new spark plugs, new points & condensers and the bike is now statically timed. I checked for spark at both the plugs and the points and all is well. I checked to make sure that the float bowls have fuel. And she still won't start. Kind of a mystery since it started last weekend. Now it cranks and cranks with no sign of starting.

I checked the plug caps by putting screw driver into plug cap and cranked the engine...good strong spark against the cylinder head.

Gas is a few weeks old.

Plugs seem damp with gas after trying to start. I assume that is normal.

The jets should not be clogged because I cleaned all the jets and checked the floats a week ago. Tank was de-rusted a month ago.

After I cleaned the carbs a week ago and put the new points and plugs in, the bike started and ran. It was not running perfectly but the only issue of any consequence was that I was getting an exhaust backfire on #4.

I got a timing light and was going to electronically time the bike and now I cannot get it started.

I hate to take the carbs off again but maybe that is the next step.

What about trying to adjust the air screws?

Could that be something worth trying.

Anyway I'm looking for suggestions.

Thanks.

[Laminar]

I doubt the air screws could be responsible for a start/no-start situation.

Have you set valve clearances?

What do you have for an air filter? One that's severely clogged could prevent starting.

[the technological J]

i also had a barn find and i was told that there is a possibility that the needles have some grooves in them from being pressed closed.. so if i were in ur shoes i would get some starting fluid and  see if she fires on that if she does u know ur prob is in the carbs... if thats  the case double check the float hieghts and that thier set up right

 and ive heard if the air cleaner is more thatn 6 months old u need a new one ....do a search on the foam ones they supposed to be where its at

[bender01]

Have you adjusted the idle Knob so that its too closed to run? Sitting on the bike with right hand turn it clockwise a turn or two.  Is the petcock on? Do you have enough fuel in the tank for on? Try reserve setting on petcock. Good luck.

[bikebitzofvt]

Hmmm...  Timed ignition, fuel delivery, and compression.  That's our simple recipe.  You say you've only cleaned the carbs once?  You'll find numerous posts here joking about how well the bike runs after the third (or fourth) trip through the carbs.  Did you line the fuel tank or simply remove the rust?  Fuel valve cleaned and new lines installed?  Not knocking your work, but it's the most likely culprit.  Been there, done that!

 
Good luck, and keep us posted!
Tom

[1timduke]

Kill switch position?   I did this for hours...felt really smart when I figured it out.

-Tim

[quidger]

I have not changed the air filter. I have a 1978 CB550 that has a foam filter in it that is newer. If it fits the '75 I will put it in and see if that makes a difference.

I have not adjusted the valves as yet.

I de-rusted the tank using the electrolysis method - zinc bolts on the battery charger with PH pool chemical. Seemed to clean it up preety well.

[bozo4onion]

My 75' 550F ran fine until I cleaned my tank, ran some Seafoam thru it. Cleaned the tank right into the needle seats. Yep....after another cleaning, my 3rd, it runs great. If you have an air box, and you should get one if you don't, carb removal can get tedious and at times painful. Good luck.

[quidger]

Are you saying that by running the Saefoam thorough your tank that it freed up a bunch of gunk and flushed it into your carburetors?