Topic: 550F Tune Up Time *Updated 4/20...please read*

[Scott S]

 OK, I'll have to pick up some new plugs. I can unplug the headlight, and I have a pigtail on all my bikes for a trickle charger. It wouldn't hurt anything to have the charger on it while doing that, would it?


 And what will this test tell me?

 When I had the air screw removed, I could put my finger over the hole so that it was either completely open or completely plugged. No change at all in idle or engine sound or anything.

[flybox1]

plugged or not, if you have spark, you'll get combustion to some degree.  you may or may not 'feel' it.
you're using plug color as your gauge to get close to a proper mixture and the best burn possible.


another thought is to check your pilot jets again.
did you change them at some point? did the PO?   Are they all Keihin?  Do the holes look the same?
are they the same length?  if you swapped one into the #1 carb, does the rich condition follow?
If your pilot jet on #4 is slightly different, this might account for the rich cond, and no matter the setting of your air screw, its pulling in too much fuel

[Scott S]

 The jets are all genuine Keihin. I can't say that I looked at every single jet, but I did confirm that they are stock size, including the numbers on the needle. If I had to bet, they're all stock....but....

  I don't know if the problem would follow the pilot or not....guess that's something I can try.

 Yeah....I understand reading plugs. I just wondered what the chop would tell me. I already know it's rich on #4; this would tell me which circuit is the possible problem?

[flybox1]

to rule out the pilot jet itself, (after visually checking all pilot jets are similar, set all air screws the same, put the #4 pilot into #1, new plugs on 1&4, and idle.  check plug color to see if richness follows to #1. 

if it does not follow, visually inspect/compare #1&4 air screws (spring/washer/oring stack), swap, and retest.

[Scott S]

 OK, I think I may have found something....

 The pilot jet is genuine Keihin, #38, and seems to be perfect.



 I pulled the air screw again and blew carb cleaner back and forth both ways, through the hole for the pilot, and through the pilot itself.

 Then I pulled the main. It was a tight, snug fit with the O-ring. While doing some searching on here, I've seen a couple of threads that talk about which way the main jet goes in. I was going to replace the O-ring again because I KNEW someone would ask about it.
 I have a pack of O-rings and replacement Keyster #98 mains. That's when I noticed that the O-ring was in different grooves. I searched the site and found conflicting answers....which way does the O ring go?
 There's a thin ring and a fat ring. One side of the jet is shallow, the other deeper. The O-rings on the aftermarket jets are opposite of what came out of #4. Where does the O-ring go and which side face UP (toward the needle) and DOWN (towards the float bowl)?

[Scott S]

 Looking at an assortment of old jets that I have, and the "witness marks" on them from pliers or whatnot when being removed, the thin ring/shallow end goes UP.
 That would mean that this jet has been in upside down, right?

[flybox1]

Yeah, just posted on your other thread.  the OLDER of the two jets below has the o-ring in the wrong recess,
as search of many images on the interwebs can confirm...
o-ring sits nearer the small end

[flybox1]

Tell us that the older jet, the one with the end marks, came out of #4!!! 

...because if it was, with the o-ring in the wrong slot, it may allow fuel to bypass, even at idle 

[Scott S]

 Yes! It came out of #4. It's a genuine Keihin jet. I installed a new O-ring on the other side and flipped it.
 The air screw still doesn't have that big of an effect on that carb, but it seems like maybe it's doing *something* now.

 I'm on my way to get a new plug for #4. The other three have maybe 300 miles on them and have a nice, tan, proper color to them, so I'll just replace #4 and see what happens.

 If it EVER stops raining here, I'll put some miles on it and see how it goes.

[flybox1]

Even looking at the pictured o-ring, it looks pinched and too big to fit/seal properly.
I think you're on to something 

[Scott S]

 Seems to run fine now, but it usually took a couple of tanks to foul the plug. New NGK D7EA installed. The rain is supposed to finally stop tonight. I'll try to get in some riding this week.

 I hope that it IS something this dumb! This bike is a really great survivor and, other than this issue, a great bike. I love it and want to be able to ride it like it deserves to be ridden.

[flybox1]

Nice.  what does the #4 plug look like after an idle/rev?
...fingers crossed!

[Scott S]

Nice.  what does the #4 plug look like after an idle/rev?
...fingers crossed!

 Maybe a tad rich, but so does the "old" plug in #1. Then again, it's mostly been idling in the driveway or no more than second gear around the neighborhood.
 If you look back at the first post you can see the plugs 1-3 have a nice tan look when ridden normally. Never fouled any of those three, either.
 Full tank of fresh gas and a long ride soon.

[Scott S]

 I need a few more rides before I declare victory, but that sure seems to have fixed it. I filled up before my test ride and got 25.3 MPG with the old set-up.
 I rode for a couple of hours, took it out on the interstate, ripped her up to 90 MPH one time, cruised along for several miles between 65 & 75 MPH. Then, I took her on my loop through the country. Sweeping back roads, mostly 4th or 5th gear. Threw in a little in town stuff getting between those two places.
 Filled up and it returned 30.6 MPG. That seems a little low, still, but I sure wasn't taking it easy on the old girl.
 Plus, that's 5+ MPG better and about the best I've ever seen with this bike. I'm sure if I got into some 5th gear, 55-60 MPH stuff, it would easily net mid-30's.

 It seems maybe a tad sluggish when rolling on the throttle, but not really bad. Just not super crisp. I had set the air screws at 2 turns out. I'm going to try a method that Two Tired suggested and slowly dial back on them and see how it feels. I've already closed the a 1/4 turn. I'll keep experimenting and see how it goes.

 I didn't do a plug chop, but I did compare the #1 and #4 plugs. After just riding it into my neighborhood and into the garage, both were slightly rich looking, but the same. I've seen #1 with an even, tan color after a plug chop. I'll definitely be doing that again soon and keeping an eye on things, but so far, so good!

[flybox1]

good news, so far  its a good sign 1 & 4 are similar.
dialing in the air screws is certainly important, but because of the overlaps of the pilot, needle jet and main jet, you really should do your WOT chop first, then a 2/3rds throttle chop for needle position, 1/4 throttle for pilot, then the fine tune the idle chop with the air screw. . .

[Scott S]

good news, so far  its a good sign 1 & 4 are similar.
dialing in the air screws is certainly important, but because of the overlaps of the pilot, needle jet and main jet, you really should do your WOT chop first, then a 2/3rds throttle chop for needle position, 1/4 throttle for pilot, then the fine tune the idle chop with the air screw. . .

 Right. But I'm hoping that since the bike is stock except for a UNI filter in the air box and a Pamco instead of points, there shouldn't be a need for anything other than stock settings/jets.

[flybox1]

OK! keep us posted! 

[Tews19]

Every one of my 550s had relative mileage of 35 mpgs. I have read all the time on here people getting 45-60 mpg but never believed it. Plus i would rather guesstimate low for rides because if I push it to 45 mpg i may find myself on the side of the road out of gas.

[Scott S]

 I was pushing her pretty hard today.  I can see picking up a couple more mpg.

[reddyvv]

I usually get about 37 when gently cruising around, maybe 35ish winding it up a little bit now and then. I find that my bike accelerates smoother with the idle circuit on the leaner side than richer. I think that relatively speaking those old carbs are not as good at atomizing fuel as newer ones so rich mixtures can tend to "wet" the plugs.

[reddyvv]

Not related to your carb issues but one thing I noticed is that you are using NGK D7EA plugs. Those are non-resistor which are fine if you are using the original 10K plug caps but if you are using the newer caps they are only available in 5K. So I prefer to use the NGK DR7EA as those have 5K resistance which brings you back to the original 10K resistance value. My bike ran fine with the non-resistor plugs but just a little item if you want to get it to original spec.

[Scott S]

 The caps have been changed. I *thought* I used resistor caps, but you say they're not available? It would be easy enough to check the resistance. I can do that by going across the 1 and 4 caps and won't have to unscrew one, right? Just check total resistance, including the coil?

 What effect does having the lower value have on performance?

[reddyvv]

Resistor caps are available but only in 5k, not 10k. So 5k plugs to make up the difference. I don't remember the resistance of the coils to subtract from the total but better to test each part individually. If I'm not mistaken having the correct resistance gives you a longer spark duration.

[Tews19]

What's the verdict Scott? Problem solved?

[Scott S]

 So far, so good. I did a mini-plug chop as I pulled up to my neighborhood the other day. If anything, a tad rich....but the same on 1 and 4. I've been riding it a good bit and mileage varies, but it hasn't fouled the plug yet and seems peppy.