Topic: Just can't get '78 CB550 to start

[DaveBarbier]

This is the kind of intake setup you have, right?




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1978 Honda CB550K

[Scott S]

 Yes, if you look in his build thread you can see pics of it.

 You say that removing the filter and blocking the plenum helps....this makes me wonder if you're idle screw is not adjusted correctly. Maybe the slides are lifted and you're getting TOO much air, until you choke it by covering the plenum opening?
 Sounds simple, but have you tried backing out the idle screw?

 And it wouldn't be the first time that someone had the choke lever wrong. But you ran the bike before, so that's a long shot.

[jaguar]

Have you checked that your fuel is good?
Modern fuel does some funny things when stored (more then 2 weeks)

[eigenvector]

I know you don't want to take the carbs off, I sympathize with you believe me, but everything sounds like the carbs need to be totally redone.  No, not torn apart and what not - but as Scott's saying - put the idle mixture screws back to factory, throttle adjusts back to factory, slides back to factory.  Put them back on - give it another try, then slowly adjust to correct for your air set-up.  It really shouldn't have too much trouble starting - even with no air filter. 

Lastly, it's entirely possible something awful happened - like the jet vibrated off and is now laying in the carb bowl (don't ask how I thought of this )  But in the end it's not a catastrophe, it's just some forehead slapping dumb thing out of whack.

[Duanob]

That's a silly response. What trouble shooting steps will a mechanic take that I cannot take? If the presentation of information isn't to your satisfaction then don't feel obligated to respond. Thanks.

It's not that you can't, it's just that you won't. You've been asked many times what the current plugs look like and you haven't posted that yet you keep posting. Until you verify whether you have or don't have fuel, all the rest is a moot point.

[strynboen]

is  fuel komming floting at a heigh speed from the tank
..and for long time..test it for some minuts..to be total shure it flow and staying floting..air trappt in the fuel line can blokk for fuel..inline filters can be a problem..try vitaut a filter..and open all drain in the floth hoysings...are the fuel still floting aut prober from all bovls..this is first test  for fuel problems

[shortbloke01]

Had much the same with mine. I got PD cards. Had them ultrasonically cleaned and it started first time with no choke. The brass tubes at the back of the cab were blocked.These give an initial squirt of fuel. I stripped them down and just had the bodies cleaned at a cost of £30. Well worth it, had no problems since

[Goldbug]

One thing that should be clear is I haven't been able to start the bike since getting the carbs back from Harisuluv. So whatever the problem is, it isn't just from sitting (with emptied bowls) for a couple seasons. The plugs from then look perfect. So what can cause a freshly rebuilt rack of carbs, from what was a running bike before the rebuild, to get fuel in the bowls but not into the cylinders?

[eigenvector]

Plugged idle jets.

[NobleHops]

Did you clean the tank? Are you running a fuel filter? If you put cleaned carbs onto a bike with a manky tank then it's time to pull those carbs back out friend. You may get away with simply unscrewing those jets and blasting them out.

You are not helping yourself nor those trying to help you by speculating, or asking us to. Go through the steps you're being advised to check before you speculate.

[harisuluv]

Yes, I had it running two weeks ago. Only thing that has changed is now I have a muffler. That should not affect fuel or spark.

Just want to clarify, so it was running, but things changed after you installing a new muffler?

[Goldbug]

I did get it to run roughly for about 20 seconds while covering the air intake with my hand. A couple hours prior to that I did spray ether in there and it would sort of start but not run. The time it ran for 20 seconds I did not use ether. But could there have been residual ether in there?

[Goldbug]

Pulled the carbs, trash in the bowls and clogged jets, probably from the tank. Cleaned, added fuel filter and synched. All seems good.

[harisuluv]

Thank you for following up, people don't always do that.  We all get resolution and learn something at the same time.  I agree that it sounds like your tank contaminated your carbs.  Here they are right before I sent them back to you

http://imgur.com/a/PleZo