Topic: Carb Problems

[billstron]

I have a '78 CB550, and the rubber boots that go from the air box to the carbs had a bunch of tears in them.  I got the bike just a few weeks ago, and it ran with those holes in the boots.  This past weekend, I took it appart and patched the cracks, from the outside, with sealer.  I also cleaned the exposed parts of the carbs with spray carb and choke cleaner.  A couple of questions about the job. 

First, how the F**k do you get the carbs off?  I was trying to take the whole assembly loose from the engine with the metal intake runners still attached to the carbs.  Is there a better way?

Secondly, last night I started it up for the first time after putting it back together.  When first starting, cylinders 2 and 3 weren't firing.  After a second restart, cylinder 2 was firing, but the exhaust pipe for 3 was still not nearly as hot as the others.  Do you think that it is just severley out of tune, or I clogged something with my indiscriminate spraying of cleaner, or something else entirely? 

Thanks,
Bill

[billstron]

As far as getting the carbs off Ive always had good luck with leaving the intake manifold attached to the carbs.  Just unbolt all the 10mm nuts from the studs in the block then, assuming the boots between the carbs and air box are still soft and plyable,  straddle the back end of the bike(like youre mounting it ) lay over the seat, and pull the carbs toward you until the manifold clears the studs, then tilt the manifold towards the ground and let off the pressure.  They'll slide right out after that.  Of course the clamps for the carbs to air box need to be loose.  I usually leave the throttle cables attached until after the carbs are free cuz theyre easier to get at then.  Same with installation, throttle cables attached before they go back on. 

That is what I was trying to do, but it took a lot of force.  Maybe I just need to work out more (or some)   

It may be time to give those carbs a good disassembled cleaning.  You may have disloged some crud when you sprayed.  Cylinders 2 and 3 run off the same coil, points, condenser so at first I was gonna say no spark there, but 2s running now.  You may still wanna test for good spark on 3 by holding the plug to the block with the wire attached while you turn the motor over just to rule it out.  Open the float drain for 3 and see if youre getting fuel there.  If so you may have a clogged jet.  What the the plugs look like.  Check your points/timing out.

I'll check these things, but how do you tell if you clogged a jet? 

Bill

[csendker]

Your slow jets have really tiny holes - #42's while the mains have 'bout twice the bore at #90's.  When you restarted, did you gun it or idle it?  Crappy running at idle could be crud in those tiny holes, which I'm painfully familiar with.  Running it at WOT would invoke the mains, which may not be/as clogged allowing it to run better.

[billstron]

Thanks for the ideas. 

First off, I am getting spark at #3.  That was the first thing I checked. 

I didn't think the carbs looked that bad.  From my records, it had a carb job 2 years ago, the outside looked pretty cruddy, but the inside didn't look too bad.  I have a feeling that I clogged something with my stupid spraying, though.  Can I clean the appropriate jets without fully disassembling my carb?  If so, can you recommend a way?  I am a noob, so I would like to avoid taking it all the way apart if possible. 

Thanks,
Bill

[Rsnip988]

 actually theres little to taking apart the carbs for cleaning (at least on my 76 cb750), I thought it would be extremely hard and parts would be lost but it was relatively simple after i got in there.

RKS

[jdpas29]

with regard to getting the carbs on and off i have one question for you...

have you ever seen a monkey and a football go at it?   

[Rsnip988]

Actually taking the carbs off the bike was the hardest part of rebuilding it,
it was rather like a monkey screwing a football yes.  "how do i get this D@#$ thing off, hit it with a hammer?"  haha no i didnt hit with a hammer but i wanted to after i stripped out both of the throttle pulley screws trying to get them off.

but all is well now.