Topic: bogging down '78 cb550k

[egar]

I haven't posted in a while as I had the carbs off again for a good cleaning again. The bike's tank was rusty and despite flushing it, I could still see rusty hues in the fuel filter. I picked up another tank (painted an ugly blue but clean as a whistle inside) and finally go the carbs back on.
My problem. Bike idles fine, but once you get going down the road, it bogs down at anything over 30 mph. Turn the throttle all the way and it stays bogged. I've reset the points according to the manual, replaced the plugs, set the floats, cleaned all jets and bowls and this afternoon synchronized the carbs.
One note, would adjusting the tappets make any difference in this regard. They're noisy and I haven't attacked that part of the engine yet. I'm making progress, considering the bike was not running at all when I bought it in July, thanks to the help I've received on this site. I did a search on the site to look for folks with similar problems, but everyone's posting is a bit different in their particular problem.

[Bodi]

Sounds silly, but are the choke plates opening? I had a choke problem where the choke lever moved but nothing else happened, the result was exactly what you describe.

[KB02]

The other thing to check is the needles. A buddy of mine has a '78 CB400 (Hawk) that had a simular problem. What it turned out to be was one of the neddles wasn't lifting up when the throttle was opened. This was a result of the Press-fit washer on top of the needle coming off (I think it was on upside down to begin with - problem at the factory?), thus the slider was not lifting the needle. It idled just fine, but it would not accelerate beyond about 25 miles an hour.

I'm not sure how the needles are set into the sliders on the 550, but it might be something to check on. Remove the air filter(s) and look into the back of the carbs while you open the throttle. You should see all the needles raising, if you don't, you know what the problem is. This is also a good time to check the chokes like Bodi said.

Also check the throttle cable and make sure all connections are in place. Heck, you're there. Why not look at the obvious. 

[TwoTired]

The problem here is the description "bogging". One cannot tell from this if the bike is going rich or lean.  Knowing this would likely go a long way toward resolution of the issue.

I suggest looking at the deposits on the spark plugs.  Particularly at the center electrode insulator.  This will give you (and us if you relay that information) an idea of the mixture conditions during combustion.  For added focus, do a "plug chop" while the bike is performing the objectionable is behavior.

New plugs won't help if they are the wrong ones.  If they are something other than D7EA we need to know that.

Did you clean the carbs before or after you installed the internally clean tank?

Did you ensure all the tiny holes and passageways in the carbs were clear and flowing? Was the air jet circuit for the mains mixture cleared?

Does your "bog" improve or worsen when you apply partial choke?  What about if you remove the air filter?

Is the exhaust the stock 4 into 4?  Do the exhaust pulses feel even for each pipe?

Are the head pipes acheiving equal temp?

Adjusting tappets should be done before carb sync as well as all other carb adjustments.  In fact ALL other tuneup items should be addressed before mucking with the carbs.  (As stated in the FAQ)

Also, since your carbs have mechanically linked slides to throttle, noting the throttle position where the problems occur, help focus attention on that aspect of carburetor mixture.  Quoting speeds, while clearly an issue with the rider, doesn't tell us much without knowing the gear your in.

Finally, you will NEVER be able to snap the twist grip wide open to accelerate the bike.  Throttle position changes great than 1/2 will simply make the engine wheeze and perhaps die altogether.

What setting did you use the Idle mixture screws?

[egar]

Thank you for the responses. I will start with the spark plugs, Two Tired. I went to the local auto zone and they looked it up and gave me something other than D7EA. I'll inspect them for color and also tell you what brand they are. I cleaned the carbs before I installed the new tank. All the tiny holes were clear and flowing. I'm really familiar with them now (having taken the carbs off three times now for cleaning). I haven't tried running it without the air filter. The exhaust is stock 4 into 4 and I can feel the pulses for each pipe. They all seem OK.
The tappets are very noisy, however. I'm wondering if that could be part of the problem. I bought a feeler gauge set, but they're hard to bend and slide in there for measuring....idle mixture screws have been set at 1 1/2 turns.

[TwoTired]

Take a flat pair of pliers and put a 45 degree bend in the feeler gauge about 1/2 inch from the tip.

[egar]

Thanks, Two Tired.
By the way, the plugs Auto Zone gave me were Champion R8HAC.

[TwoTired]

Well, that is what Champion cross-references for the NGK D7EA.  But, it is a resistor plug intended for high energy spark systems.  Use it if you are desparate, or if you have converted your bike to have a High Energy ignition.  Or, if you have changed all the stock plug caps to ones with zero ohm resistors. Otherwise, get the correct plugs for your machine, rather than what the local parts mover wants to sell you.  I don't believe they will perform well in your machine, particularly as they age.
Cheers,

[Einyodeler]

Go to O`Relly`s Auto Parts or an Advanced Auto Parts store if you have any close by,they sell the NGKs

[egar]

Thanks. I have an Advanced Auto Parts here in town. I will get the correct plugs.
I adjusted the timing cam adjuster according to the manual (the good one that you folks referred me to, not my lousy Clymer's) and then tried adjusting the tappets according to the directions. The problem I notice is that regardless of how I set them, the arms themselves wiggle a tad, which allows the screw that I just set to still wiggle enough up and down to touch the tappet thingy. This would seem to negate any adjustment I make. This would explain why my tappets are so noisy. Has anyone experienced this problem and if so, what is the solution?

[hobieguy213]

What is the "good" manual?

[KB02]

How much Wiggle are you noticing on the tapets? Does the wiggle allow the tappet to open beyond the adjusted amount? Is it a side to side wiggle, or just an up and down?