Topic: 78 CB550K Cylinders 1&4 not firing

[natewatkins]

Greetings everyone. I apologize in advance that this may be a bit of a long post. I will describe my problem and what the process of elimination has been to get to my current question. I have used this forum for the answer to help ease my confusion, but alas my complete understanding on how to fix this problem eludes me.

First and foremost, I took the carbs off the bike. I made a post on this earlier in well last year on what I had. The carbs are stamped 627B and my understanding is these are off a CB500. I have what appears to be 100 mains and 40 slow jets. I pulled them apart and cleaned them up using carb cleaner. I Pulled the jets and the emulsion tubes out and made sure they were nice and clean. I made sure I could see day light through all the holes. The little O rings looked to be OK so I didn't replace. I cleaned up and made sure the floats were nice and free and not stuck, put new float bowl gaskets in and reinstalled.

The battery on the bike was completely dead so I jumped started the bike off a car and got her running. First thing I noticed (after 3 burned fingers later) that cylinders 2&3 are firing yet 1 & 4 are not. After some more poking around, I pulled the plugs, cleaned them, gaped and reinstalled. This time I filled a spray bottle with water and mist the pipes, 2&3 sizzle, and 1&4 still not firing. hmmmmmm

I pulled the plug on # 4 again and it didn't appear that at least Cylinder 4 was not getting any fuel. So I pulled the bowl off 4 and sure enough, no gas. I poke around again, wiggle the floats up and down 2 times and BAM, gas starts flowing. I made sure they would not get hung up again. So I put the bowl back on and proceed to check # 1, this was getting gas as the bowl was filled with fuel. I pulled the plug on the same cylinder and it smelled like gas but couldn't tell if it was fowled or not. I figure OK, I probably need new plugs before I go any further. The guy I purchased the bike from had 3 different brands of plugs in there (probably what he had lying around) and 2 different heat ranges. So I broke down, spent the $12 and got NGK D8EA plugs. Buttoned her back up and fired up again (this time with a new battery) but still, 1&4 are not firing. I pull the plugs for 1&4 and hold them against the case, and I can see that they are both firing so I don't see the coil for 1& 4 being a problem (maybe someone can confirm here).

Next down the line, I pull the points cover off. I crank the bike over again one more time and watch the points. I can see that 2.3 is sparking but 1.4, nothing. So I figure OK, maybe it is just a timing issue. I hop on here, read for about 2 days on static timing (I don't have a test light or timing light and am using the paper method). I first clean the points first to see that maybe they are just dirty and still, the same result.

I figure OK, time to make sure the timing is OK. I understand that you rotate the tank, and you wait until the largest gap is in the points and you set that gap. You do that by what I understand is adjusting this singular screw here, correct?:

If this is true, then OK, set the gap. The next step for 1.4 is that my understanding is when the 1.4 is at the F tick mark, the points should "just" be opening. If not you loosen the 3 screws on the main plate, shown here:

And you rotate the plate to achieve the gap. I assume the "main plate" is what the 1.4 points are attached to as well as the sub plate holding 2.3. So, here is where I am confused. When you rotate the plate, like shown below, is the "points" for 1.4 suppose to move with the plate? I mean, if I rotate the plate, the whole thing moves, I don't understand how I set it to where it "just" opens.

If one of you kind souls can help me out, I would really, really appreciate it! Thanks again.

[natewatkins]

Bump, any idears?

[OldSchool_IsCool]

I think you are right to suspect your 1.4 ignition circuit.  You've done everything right to get you r points in good shape though you didn't mention if you cleaned the faces of the contacts.  If they are pitted, get a points file (not sand paper!) and file them smooth again.  You'll need to regap and retime if you do this.  If the faces look good, take a clean, WHITE business card (non-glossy) and wet it with some brake cleaner.  Polish the points faces with the wet business card.

Do you get 1.4 to fire now? 

No?  Time to trace the blue wire.  There is a junction just behind the right side cover near the battery.  Are the connections clean and tight?  Next junction is under the tank at the coils.  Also check that the black/white wire is connected to BOTH coils. 

Still no spark?  We'll deal with this issue if you get here.  Have a multimeter handy.

[natewatkins]

OldSchool,

I checked the points, they don't look pitted at all. I cleaned them yesterday with a business card and just now I checked the blue wire off 1.4 and the bullet connector is clean and solid (it snaps into place nice and snug). Also, the black and white wire is going to both coils. If those were faulty, I wouldn't get a spark at all 4 plugs then correct? Because I have verified that I am getting a spark to 1-4

My question is:

A) If the points don't open at the proper time, a spark will not occur, is this correct? If that is the case, then I need to set it correct?

B) How do I adjust the timing statically based on the problem I mentioned above (how to adjust using the main plate)?

[hahnda]

A) you will get spark even if its at the wrong time as long as your points are opening and closing

B) First set gap when the points are open the widest. Set it with the screws at the points not with the plate. Do this first. Buy or make a test light to make it easier but paper will work.  Rotate to F for 1 and 4. Insert paper. Loosen plate screws and rotate until paper is let loose.  Use thin paper not business card. Tighten screws. This won't be real accurate but should bet you consistent spark at roughly the right time.

[OldSchool_IsCool]

Some coil basics, though you prolly already know this.  The black/white wire provides 12v to both coils.  The blue and the yellow wires provide a path to ground via their respective points for the individual coil.  Assuming good connections and clean points faces, current will flow through the coils when the points are closed.  The flowing current is building a magnetic field in the coil.  When the points open, the current stops and the magnetic field collapses.  A by-product of the collapsing mag field is the release of an energetic spark via the plug wires to the spark plugs.

Assuming all the above is working correctly, if your timing is off, the spark plugs will still fire, but at the wrong time.  to set the time, you must first set the points gap.  As you stated above, this is done when the points are at their max open.  The gap should be between .012 and .016 inches on a 550 if memory serves.  Use the single JIS screw head you have circled in pic #1 to hold the points in place once you have the right gap.  By the way, the notch in the frame and the two nubs just above the hold down screw are handy for making small adjustments while the hold down screw is moderately tight.  Set the gap on the 2.3 points after you get 1.4 in satisfactory shape.

Now to set the timing of 1.4 points.  As mentioned above, the coils will release the spark when the points open.  the trick now will be to rotate the ENTIRE points plate (the whole round disk) such that the points open when the "F1.4" lines up with the case pointer.  Easiest way to do this is with a volt meter or a test lamp.  

With a good battery installed, key on and kill switch on, rotate the crank until the F1.4 is in position.  Connect your test lamp between ground and the spring on the points frame.  Loosen the three hold down screws so you can turn the points plate.  Once the lamp lights (or goes out, depending on the direction you are moving the plate) clamp the points plate into position.

For the 2.3 points, you will be following very similar steps.  Rotate the crank so that the "F2.3" lines up with the case pointer.  Loosen the TWO screws holding the little sub-plate that the 2.3 points are riding on.  Now adjust the sub plate only (leave the main plate alone!) so that the lamp lights or goes out.