Topic: Plug chop reading.....help?

[sinister902]

OK, so I've had pods on my CB550 for 4yrs now, and EVERY season it changes to being too lean or too rich. I am experiencing symptoms that full within lean AND rich it seems. I've just done an oil change, new filter, fresh d8ea NGK plugs, valve clearance, points gap, and cam chain tension in preparation for Vintage Motorcycle Days next weekend. I thought the bike might be running rich, so I yanked the pods and threw some peices of screen over the carbs with zipties to go for a spin. I KNOW how everyone feels about pods.....I am in fact ditching them and have ordered Steel Dragon Velocity Stacks......which I'm sure I'll need to re-tune for anyways....but back to the issue I'm having TODAY.

Borrowed from the Carb FAQ (bold is what I'm experiencing)

>>>Typical lean conditions:
Poor acceleration - feels flat
Engine doesn't respond when throttle is snapped open - picks up speed as throttle is closed
Engine runs hot, knocks, pings and overheats (end result- hole in piston)
Engine surges or "hunts" when cruising at part throttle
Popping/ spitting through carb when throttle is opened, or popping and spitting through pipe on acceleration with a closed throttle (classic lean pilot circuit symptoms)
Engine runs better in warm weather, worse in cool
Performance gets worse when the air filter is removed

>>>Typical Rich Conditions
Acceleration is flat, uneven
Engine will "8 stroke" as it loads up and skips combustion cycles
Throttle needs to be opened continuously to maintain acceleration
Engine works better when cold
Black smoke from the tail pipe
Poor fuel economy
Engine performance improves when air cleaner is removed
If the pilot screw is overly rich, idle is rough and the engine won't return to idle without blipping the throttle
Black sooty plugs, sooty exhaust pipe

OK, now....to describe some riding conditions:

-Cold starts are INCREDIBLY DIFFICULT. I do not even try to use the electric start because the battery would be dead before it would be running. I spend on average 5-7mins kicking the bajezus out of the kickstart until it hobbles to life. I have tried starting fluid a few times in the past, but this doesn't seem to make any difference (leads me to believe rich?)

-Hot starts are a quick tap of the start button and she's running (as should be).

-Once up and running, up to 1/4 throttle feels fine to me. 1/4-half is I would say normal-ish, possibly a little sluggish. rolling on into 3/4-full feels very flat, acceleration is steady yet very slow at full throttle. If I whack the trottle from 1/2 to full it bogs RIGHT down and acceleration is nearly non-existent...at which point if I back of and roll back in it is much better (this leads me to believe lean?)

-While cruising along in 5th gear at posted speed limits, the bike will sometimes surge, make coughing/hiccup type noises, and sounds like possible light backfires through the carbs. (Leads me to believe Lean)

-fuel economy is fairly terrible in my opinion. maybe 80-90miles per tank (stock tank).....(leads me to believe rich?)

-Last season I changed plugs.....the ones that had came out were QUITE sooty, I thought the bike was rich......I adjusted needle clip position at the time and the idle screws a bit and the rest of last riding season she ran pretty good. This season I've got roughly 1000 miles on and I've been pretty unhappy with performance....so I thought maybe the plugs were fouled up again so I bought new ones to replace.

These are what came out:





What I find confusing, is the tips themselves look to be light brown, which should be GOOD, possibly a touch lean.....while the metal housing surrounding the electrode is pretty black and sooty(rich?)

so I put fresh plugs in, and pushed the bike down my street a good ways......fired it up, and went WOT back towards my house in 1st,2nd,3rd and pulled in the clutch/hit the kill about 3 houses away, and rolled the rest of the way into the driveway. pulled plugs and they look like this:





These to me look lean......am I correct? if I swipe my finger across the tip a tiny amount of very white powder/dust is left on my finger.

I'm running 115 mains, stock 38 pilots on stock keihin carbs, 1975 CB550. needle clip is currently second from bottom, and idle mixture screws at 1/4 turn out from bottomed.

-engine is stock, exhaust is shortened stock mufflers. Elevation here is about 650-700ft above sea level. Temperature here has been about 85-90 consistently lately with roughly 60-70% humidity ( I think I've covered all the variables here lol) I have to say, that I would find it QUITE surprising to be lean at 115 mains with very light exhaust modification and just pods.....which is why I'm consulting the SOHC4 brain trust, this is my favorite place on the web.

Thanks in Advance for help/thoughts/guidance.

[Jerry Rxman Griffin aka MuthaF'er]

Looks good to me but I'd question if that last plug/picture is firing. Think your problem (which I don't have time to read now) is elsewhere.

[sinister902]

Thanks Jerry, seems you might be right, that plug is the only one without a touch of black on the ceramic part down inside.....I just went at all four with my in-line spark tester and all 4 plugs have spark. I think I have to break the carbs back down for a thorough cleaning/inspection yet again.

 :/

[lucky]

QUOTE:

"so I put fresh plugs in, and pushed the bike down my street a good ways......fired it up, and went WOT back towards my house in 1st,2nd,3rd and pulled in the clutch/hit the kill about 3 houses away, and rolled the rest of the way into the driveway. pulled plugs and they look like this:"

I am not surprised at how that plug looks.
That new plug did not even run long enough to tell you anything.

You are not clear on the concept of plug chops.
When you do a plug chop run the bike for a while ,ride around town whatever.
Then come home and pull the plug and see what it looks like.
"PLUG chops" are done to tell you if midrange or WOT are performing correctly.
If you are doing a plug chop for WOT just get the bike up to speed in high gear
on a deserted road and get up to WOT and then stop, and wait for the engine to cool down a little bit before pulling the plug or you run the risk of pulling threads out of the cylinder head. Use anti seize on the threads to help prevent damage.
For mid range do the same. Run the bike and cruise at midrange and the do your plug chop. Remember to let the engine cool a while to prevent pulling the threads out of the cylinder head.


But BEFORE any of this fine tuning could take place you need to get basic drivability performed FIRST.

LEts get all the facts:

CB550, 1975.
EXHAUST- "Light exhaust modification" Means nothing
Intakes pods now, and stacks later. (tuning will be almost the same for both).
Main jets #115 mm.
Idle jets #38 mm.
Needle clip 4th groove from top.( Always count from the top).
Mixture screw 1/4 turn out.


I see no way this bike could be running correctly.

I would have to know exactly what the exhaust system is.
The stock jetting would be #100 main jets.
#38 Idle jets.
Clip on slide needle 4th form top.
Idle screws 1.5 turns out.

I just cannot tell you anything until I know what kind of exhaust system you have.
FORGET about plug chops right now.

So the exhaust is a 4 into 2 aftermarket.
Good enough. Thanks for posting the photo. Very helpful.

So this is what I would do based on my own knowledge and some other forum members results with this year of CB550 with similar set ups.

Exhaust 4 into 1 aftermarket.
 #105 mm main jets.
#40 mm Idle jets.
Clip on slide needle 4th form top.
Idle screws 3/4 turns out.

Of course all other issues must be taken care of first and the float levels need to be done by the book. Float needles not leaking .


 

[sinister902]

the exhaust is an aftermarket 4-2 that I shortened the tubes on. the mufflers themselves are unmoddified.

here's what it looks like, I THINK they were a MAC set to start with, I got them second hand/used

[dave500]

what plugs are they?are they resistor plugs and you also have resistor caps?

[sinister902]

the local shop was all out of d7ea, so the old timer sold me DPR7EA-9 plugs.....said they just have a tiny bit more protrusion from the threaded part for a more full-burn spark.

I know the plug wires aren't equipped with OEM ends......at some point the original tips were cut off, and the crimp-on ends like for a car were installed with the rubber shields.....been that way since I got the bike in '06 (done by a previous owner)

[DJ_AX]

the local shop was all out of d7ea, so the old timer sold me DPR7EA-9 plugs.....said they just have a tiny bit more protrusion from the threaded part for a more full-burn spark.

I know the plug wires aren't equipped with OEM ends......at some point the original tips were cut off, and the crimp-on ends like for a car were installed with the rubber shields.....been that way since I got the bike in '06 (done by a previous owner)

It would be much better to put proper caps and plugs on there.
And of course a stock air box  is the simplest fix. Take the guess work out.

And maybe that old timer meant you well but on more than one occasion at more than one shop they tried to tell me "these plugs are the same, just different number" ... they're not.

[sinister902]

understandable, but the bike was running the same with the previous d7ea plugs......so the issue seems not to be with the plugs themselves. I'm patiently awaiting Lucky's take on my carb setup. I'm feeling like my needle might need to come up (move clip down to last notch), I probably need #40 pilots, and might have to change up the mains. (sucks, no way to get these parts by thursday)

[bollingball]

Just how old was that old timer?  But if you don't have resistor caps then you need resistor plugs. Are you using the part that screws on the plug where the wire slips on?

[sinister902]

Just how old was that old timer?  But if you don't have resistor caps then you need resistor plugs. Are you using the part that screws on the plug where the wire slips on?

if your referring to the thread-on tips that go on the end of the plug so the wires can clip-on, then yes I'm using those.

[BAchvytrk]

understandable, but the bike was running the same with the previous d7ea plugs......so the issue seems not to be with the plugs themselves. I'm patiently awaiting Lucky's take on my carb setup. I'm feeling like my needle might need to come up (move clip down to last notch), I probably need #40 pilots, and might have to change up the mains. (sucks, no way to get these parts by thursday)

let me know what jets you need and i'll see if i have any in my shop to help ya out, i'm close to you.

[sinister902]

I've sent an email to JetsRus to see if I can get 105 mains, 110mains, 120 mains, and 40 pilots by wednesday......heading to Vintage Motorcycle Days on thursday afternoon.....if you have any of those, it would be an incredible help!

[BAchvytrk]

i will look and see what i have, i know i have 110's.  are the pilots press in pilots or screw in?

[sinister902]

pilot jets are thread-in, mains are push-in:



I have two sets of stock 100 mains, I'm considering drilling out one set to 105 and one set to 120 to see if I can get the bike running better while I wait to see if I can get my hands on jets before wednesday

[Rookster]

The first thing you need to do is to isolate the difference carb circuits so you know where to make changes.  You do this by marking your twistgrip at 1/4 intervals.  The easiest way is to mark 1/2 throttle first then 1/4 and 3/4.  You can do a plug chop at any of these intervals to determine exactly what the plugs are doing for each of those carb circuits.  Here is a chart for the CB750.  I assume the CB550 is similar.



To do a plug chop make sure the motor is warmed up, put in new plugs and hold the throttle at whatever position you want to check.  It would be helpful to be going slightly uphill.  It doesn't matter what gear you are in or what speed you are going as long as the thottle position is constant.  After 10-20 seconds at the same throttle position pull the clutch and close the throttle.  Pull over and start checking plugs.  It helps to carry 3 seperate sets of new plugs for each throttle position.  Use a legnth of hose to unscrew and hold the hot plugs.  I would bag each set of plugs and write on the bag which throttle position they were chopped at.  Don't make changes on the side of the road, wait until you get home to really examine and determine where and what you need to change.

Scott

[BAchvytrk]

i've got a set of 40 pilots you can have here, all the push in mains i have are 100's.  i get alot of jets i need from pioneer motorsports in sardina, they have a great selection, i'm just not sure if these push in mains were only on hondas or not. I'm not sure where in buffalo you are, but you could try hamburg honda, they may not have any new jets in stock, but you could talk to Fred in service, he may have some. if you want these pilots, pm and i'll give ya my #.

[sinister902]

PM's ya BAchvytrk! You might have just saved my whole week lol.

I drilled out my stock 100 mains to 120's, plan to try them out tomorrow. I'm also going to replace the o-rings that connect the intake manifold to the head as they look extremely flattened out and I'm worried I could have a vacuum leak there causing my lean conditions. Also going to remove and inspect my petcock and replace the in-line fuel filters to make sure fueling is as it should be.

[bjbuchanan]

The old timer wasn't wrong he just didnt say enough. With his new plugs, that are resistor plugs and non resistor type spark plug boots he should be around where he needs to be ohms wise to not burn his points up quickly. If those new plugs and old boots were used it would be too much resistance, too little if the new boots with old plugs. His porridge is just right

[BAchvytrk]

how'd ya make out?

[sinister902]

bike won't run now. found all kinds of crud in the fuel lines, the "t"s between carbs 1/2 and carbs 3/4,  cleaned the heck out of everything, bench-synched, and put everything back together. went to do some kickstarting and just got a couple crackles and pops....got tired of kicking, so I went out to the street to push start it (this works like 98% of the time ont hsi bike) and the battery went dead. I'm confused as to how the battery got low while I was rebuilding carbs.....but it's on charge now. I'm praying to the motorcycle gods that tomorrow this thing just runs so I can hook up my vacuum gauges and sync them up and be done. If it DOESN'T run tomorrow, I'm going to be incredibly let down that I'll have to miss VMD mid-ohio due to something stupid.

it was 9pm when I got it back together, I gave up for the night at 10 after all the kickstarting and trying to push-start it. Was too dark to really go through anything (garage is full of other projects, have to work in the driveway)

going to check fuses and some wiring connections tomorrow, check for spark again, and see where I'm at.

[sinister902]

Well, I got up early and messed around before work. Was able to get the bike running, seems like its still wrong up top.....idle is great, part throttle is great, everything till 3/4 throttle is great.....the second I got Full throttle it bogs out. going to sync the carbs after work and see if it improves, but at this point I'm leaving it alone until after I get back from Vintage Motorcycle Days.

for referance due to previous comments....here's my spark boots (by previous owner)



and I pulled a plug this morning after riding around the block two or 3 times. this is what it looked like.




current setup:
022A stock carbs
UNI pods
40 pilots
115 mains
mixture 3/4 turn out
needle 4th notch from top
DPR7EA plugs

[lucky]

So it runs good?
It has good throttle response from idle?

Try some 105 mains instead of the 115's.

In high gear will it just keep accelerating steadily upward to a higher speed?

If so then you are done.

You are getting closer now.

[BAchvytrk]

def sounds like you've almost got it, glad the pilots helped out. Have a good time at VMD.

[bollingball]

and I pulled a plug this morning after riding around the block two or 3 times. this is what it looked like.
 Well this does not mean much. You said it runs good at every thing but WOT
 and I pulled a plug this morning after riding around the block two or 3 times. this is what it looked like.


 idle is great, part throttle is great, everything till 3/4 throttle is great.....the second I got Full throttle it bogs out.

 Going around the block will not give you a plug chop for WOT. So that is useless.
 Stay focused. Or you will continue to go in circles
Ken