Topic: Troubleshooting a 550K. *New brass vs. old brass on page 4*

[Scott S]

  I bought a 550K from Brian/Whiteorbs. He had been having trouble with it fouling the plugs and we struck a deal.

 Here's his old thread:

http://forums.sohc4.net/index.php/topic,146912.0.html

 And here's what I've been doing with the bike:

http://forums.sohc4.net/index.php/topic,148099.0.html

 Today, I was at the point of hooking up the auxiliary tank and firing it up to set the timing and sync the carbs.
 Since the bike has been in my possession I have:
 -adjusted valves and cam chain. Saw nothing unusual.
 - oil and filter. Again, all looked fine.
 -installed Pamco. Set timing with a light.....dead steady and right on the mark.
 -trimmed back wires on original coils, installed new NGK 5K ohm caps and new NGK plugs.
 -had carbs professionally cleaned (ultrasonic, etc.), genuine Keihin jets. Good float height. Confirmed fuel level in #1 with clear tube. Right on the money.
 -new O-rings on manifolds.
 -vacuum synced carbs.
 

 The bike is running a little rough and something isn't right with #1. The plug was wet and fouled when I pulled it. While cleaning it (spark plug cleaner that hooks to my air compressor, followed by air, carb cleaner and holding a lighter to it), I stuck a dirty old plug in the cap and held it to the head. I am definitely getting spark, but it seemed weak and yellow. I even got a little zap through the cap when cutting off the kill switch.

 Opened drain plug on #1 bowl and confirmed fuel. Put clear tube in #1 bowl and confirmed proper level.
 Checked for air leaks all around carbs and manifolds and found none.
 I even removed the tappet cover on #1 intake and, with the kill switch off, turned the engine over and watched the valve actuation.

 I ohm'ed out the 1/4 coil and, with the caps in place, got 24.8 on my meter. That's 10k for the caps and 14.8 for the coil, right?
 I checked continuity between the black/white wire and the blue wire on the coil. I saw a reading of .005 on my meter, which indicates continuity, right?

 I'm leaning towards an electrical issue, but how can #4 seem to fire OK but not #1? The exhaust pipe gets hot, but not as hot as the other three (which are all within a few degrees of each other, according to my IR temp gun). It's almost like it's firing on #1, but erratically or not very strong.
 The 2, 3, 4 pipes all got up to ~165 degrees. Hot enough to make them sizzle with the spit test. The #1 is definitely hot.....you don't want to grab it and hold on....but doesn't exactly pass the spit test. Maybe ~105-120 degrees when measured at the same spot as the others. So....firing but not well?

 The coils are original and the only ignition component I haven't replaced. Is it possible for a coil to act that way?

[Duanob]

What's left? Maybe a weak plug wire? Maybe a plugged pilot jet? Happens a lot since the jet passage is super tiny it doesn't take much to clog it.

[Scott S]

 Luckily, in a way, it's #1. I can pull that bowl on the bike and pull the pilot jet.

[calj737]

I wouldn't expect a pilot jet to be the issue if the plug is fouled. If you vacuum sync he'd the carbs, how was the idle?

You say it's not running right, but does that mean at idle, under throttle, while riding?

[Scott S]

 Well....maybe not completely fouled, but it definitely had raw fuel on it. Idle was OK when syncing, and I always sync at ~2k rpm. I only had to adjust one carb, #4, and only slightly.

 The idle doesn't want to calm down, but then again it's only running on three....or three and a half. At first  I suspected a vacuum leak but there's none to be found.

 I only tried timing, sync and carb adjustments today. I rode it very briefly when I first got it and, honestly, it ran pretty well. I did all the above mentioned work preemptively, since Whiteorbs was having some trouble with it.

 I truly think if I could figure out what's up with #1 it would be just about perfect.

[turboed13b]

Swap 1 and 4 plug wires and see if it follows.

What do you mean the idle won't calm down? Is it hanging? 8 stroking?

If you can get a video or a very good explanation of what it is doing then finding a solution will be easier.

[Scott S]

 There's that term "8 stroking" again.....I'm not sure I know what that means.

 I can't get it to keep an idle at around 1,000-1,200 rpm. It has a bit of a hanging idle in that it can be slow to return to a low idle. I looked for vacuum leaks and can't find any. The O-rings on the manifolds are new. The pilot jets are genuine Keihin. Fuel level is correct. All the normal stuff I know to check, checks out fine.

 The timing is spot on at full advance. Steady and perfectly on the marks on both 1/4 and 2/3. The advance mechanism is one of the best I've seen. Very clean and snaps back nicely.

[turboed13b]

Try backing out the air mixture screw to 3 turns out. The idle should raise so back down to 1000 rpm. If it idles better and the hanging idle dissapears then you are rich on the pilot.

Are the slows NOS or just cleaned? I never reuse old jets and here is why. Even if they look clean there are not. I have a stack of 38's and looking through them all and each look different. These things are 40+ years old and most of these jets have been subject to corrosion or just impossible to remove varnish. I have had a ton of problems trying to reuse old jets and the problem cured with aftermarket new jets.

Same with the carbs. Most of my carbs have corrosion pits and the worse ones always run really rich. For example on one of my cb550 uses a 35 slow with a 100 main with pods and exhaust and runs perfect. I can throw another pair of my carbs which are pretty clean with no corrosion and it runs perfect but has 110 main and 38 slow.

[Scott S]

 Swapping the plug wires is a little easier said than done. They're a little stiff and have been routed like this since 1975. They're also about as short as I'd like them to be, after cutting off ~1/4" to get to good wire inside.




 They're the only original part of the ignition system left, so I may replace them anyway if this problem persists.

 

Try backing out the air mixture screw to 3 turns out. The idle should raise so back down to 1000 rpm. If it idles better and the hanging idle dissapears then you are rich on the pilot.

Are the slows NOS or just cleaned? I never reuse old jets and here is why. Even if they look clean there are not.

 My experience is exactly the opposite (and I think you'll hear from others that feel the same way).  The bike only has 6,500 miles on it, so I doubt the jets are worn out. The brass bits rarely wear anyway. And these ARE clean, I feel sure.



 That said, I will be pulling the bowl to make sure a piece of trash from my auxiliary fuel tank didn't get in there. Or something even weirder, like a loose main jet or something.

 And I once chased a lean/hanging idle problem on a '71 CB500 for months. It turned out to be crappy, mis-sized aftermarket pilot jets. I've used nothing but genuine Keihin since then.

[Scott S]

 I put the bike on the charger overnight. I plan on double checking all the wiring, from the Pamco to the coils and everything in between. I'll also try swapping some plugs around.

 I've been offered a couple of new aftermarket coils. I may try rigging one up and see if the problem goes away.

 I'll also pull the bowl on the #1 carb and look for trash or anything funky.

 And I'll quadruple check for vacuum leaks, even though liberal spraying with carb cleaner around the intake manifolds (carb and engine side) and around the carb bodies revealed nothing. I also went back around after the engine was warm and tightened/checked all the clamps.

[RevDoc]

Scott, when I first started the rehab on Angie I was chasing the cause of a crappy idle and fouling plugs. Especially on #1. Cleaned every part and circuit on the carbs in ultrasonic and carb dip. All Keihin brass. Would idle better but still not smooth & fouled plugs in about 12-15 miles. Finally tracked it to a couple problems. Apparently some jackass had drilled the low speed jets which caused rich mixture plus the valve stem seals were worn just enough to cause oil fouling on the plugs.

New Keihin pilot jets & valve stem seals...problems solved.

[turboed13b]

They will bend just go slow and remove them from the clips on the engine. If the problem follows the coil then your problem will be solved with new ones.

If the problem doesn't follow the coil I would swap slow jets #1 with #4. Again this is to eliminate all possibilities one at a time.

I looked through the old thread and I do see some pitting in the #1 carb. The pictures are not clear enough to see how bad but I wouldn't dismiss it.

[Scott S]

I was able to swap the wires as well as the plugs. Same issue. I pulled the bowl on #1 and removed the pilot jet and air screw. Sprayed carb cleaner through the carb passages and checked the pilot. No trash....nothing plugged. The pilot did seem to maybe have a tiny bit of damage on the very tip, but if anything it was widened out a little; not crimped or blocked.

 I didn't try swapping the pilots from 1 and 4 yet.

 I also checked thoroughly for vacuum leaks again and found none. I even checked to make sure the exhaust was tight at the header and I removed the tappet cover and watched the rocker move on the exhaust side, too.

 I looked through my stash for another pilot jet to try. I'll look again, but I only have 40's. This carb uses 38's. Should I still swap them out and give it a try?

 It seems like it's running on #1, just not like the others. The temp is about 20-30 degrees cooler than  the other cylinders.

 I'm uploading a video....I'll post it soon.

[Scott S]

 While we wait...pics of the 1 and 4 plugs. Overlook how rich #4 appears. The bike has been idling in front of a fan in the garage. Cylinders 2, 3 and 4 all seem to run fine.

[Scott S]

 And the video. At around 37 seconds you can hear the idle change and see it on the tach. My temp guns battery is dying, but you can also see the ~30 degree difference on the #1 header.

 The carbs I pulled the 40 pilot jets from also use the open tip air screws. If I try the 40 pilot instead of the 38, I ought to be OK, right? Just to rule out a bad pilot jet?
 While I had the jet out, I spray cleaner up into that passage. And when spraying down through the air screw passage, I get a stream of cleaner.

[Scott S]

 AND  I just did a compression test on a slightly warm engine and #1 actually has about 5 psi more than #4!

 It seems to be getting fuel,  by looking at the  plug. And I'm getting spark. What next?

[turboed13b]

You can run the 40's but you will have to adjust the air screw out.

Have you tried adjusting the air screw out with the 38's in? It seems to me that all your cylinders are rich and to compensate you have have to adjust your idle screw way open. When you do this you loose the vacuum to pull in fuel which cause a lean state and high idle. eventually the slows will catch up and flood out the carbs and this is when you see the idle go back down.

In the picture it looks like the plug on the left is not igniting because it is so clean. Last time I had a plug like that it was from the carb flooding out because of a small rust particle that was blocking the float needle.

[Scott S]

 OK, I swapped the 38 for the 40. No real change. In this pic, you can see the damage at the end of the 38 pilot. Maybe nothing, but I thought I'd try it.



 I have tried adjusting the air screws out. Cylinders 3 and 4, you can really tell an effect, but they still want to be right at 1.5 turns, which is factory. Cylinders 1 and 2 don't seem to have as big of an effect, and #1 doesn't do much at all.
 I even tried turning #1 out 3 rounds (six turns) and that didn't really do anything. I also checked for vacuum leaks again....nada.

  I'm definitely getting fuel to #1. And I'm definitely getting spark. While the bowl was off, I pulled the main, pilot and air screw and sprayed carb cleaner through. Getting a good stream. All jets were clear.
 I guess I could pull the bowl again, drop the float and make sure nothing is stuck on the fuel valve.
 I don't *think* it's flooding out, as the exhaust isn't blowing out black smoke or anything, but....

[Tews19]

38 looks chewed up. Let me check my stash and if I have a 38 spare I will send it your way.

[turboed13b]

See those little dimples at the other end of the jet? That's corrosion if it is that bad on the outside then the inside is probably bigger than a #38 now.

If the idle screw has no affect then you are extremely rich as you already know.


If the carbs are in similar condition as that jet then it is going to run rich and you are going to have to start the jetting game.

[Scott S]

 If I could just get #1 to act right, I think I could tune it out.

 I was looking around and saw this on the sync screws:

 From left to right, #1 and #2


 #3 and #4


 The carbs were bench synced and the first time I put the gauges on them I only had to adjust #4. I put the gauges back on, made SURE that the tubes/rubber O-rings were tight and set the idle screw to hold 2K rpm. Made very minor adjustments to #1 and #3. I can get these things dead even.

 I tried running 2 turns out on all four air screws.
 I tried running without the advancer cover, just in case it was keeping something from snapping back. It all looks good under there.

 It's hard to NOT get everything loaded up when it's idling in the garage in front of a fan. I removed my auxillary tank and rode up and down the street until the bowls started to get low. Twice. It actually runs out pretty good and I'm getting some heat in the #1 pipe, but it's still consistently less than the other three. I'm also starting to show a little carbon on #1 plug, just like the rest.
 There's no popping, snapping or backfiring, just an unwillingness to hold a good idle long enough to continue tuning. I may have to wait until I get the tank back from the painter and try riding/tuning at the same time.

  When I reinstalled the sync screws, I dug around and found four good washers to go under them. If there's a vacuum leak, I'll pay any of you $20 to find it for me.

 I just can't seem to get the idle to act right or stay in one place. I backed out the idle screw until it wasn't lifting the arms at all and tried going from there. I've about had enough for today. Me and the bike are both hot and stinky. It's time for a cool shower and colder beer.

[Scott S]

38 looks chewed up. Let me check my stash and if I have a 38 spare I will send it your way.

 That would be awesome. Putting the 40 in didn't seem to do TOO much, but I'd rather have the proper jet.

 And if you do, I'll check operation of the fuel valve as turboed13b suggested, but...

 I've already opened the drain screw on the bowl and confirmed fuel. I blew through the overflow in the bowl and it's open. I did the clear tube method on #1 and confirmed fuel level. I'm NOT getting anything out of the overflow tube that routes under the bike.
 All that said, I WILL check operation of the fuel valve the next time I have the bowl off.

[Scott S]

 I checked the valve adjustment today. After seeing the post explaining the timing marks, I redid all of  them. I used to use the space between the 0 and 5 degree marks. Set them all today at the 0 degree mark. Just minor adjustment was needed and they were a little loose, not tight.



  I triple checked the timing. I put my gun on #1 and #4. Also checked #3 while I was there. The timing is dead steady when advanced. I would say that it's possibly a little advanced. Maybe the width of the mark past 31.5 degrees, the green mark in the picture. I would have dialed it back but I'm working by myself today and really needed an extra set of hands. Would 1-3 degrees advance cause the issues I'm having? It still wouldn't explain the temperature difference on #1.
 Which, BTW, was closer today, but still consistently cooler. If anything, the OTHER three were running a tad cooler and #1 was the same as it has been.

 I also tried different air screws on #1; an aftermarket one and a genuine Keihin. Nothing really helped.
 
 I did the clear tube method again on #1 and #4. They are so close to the pictures I've seen, such as this one, that I wouldn't dare touch them. The level is basically at the bottom of the lip on the bowl, just like in these pics.
 


 I also removed the overflow tubes on the bowls and watched for fuel.....nothing.

 I checked the advancer by snapping the rotor on the Pamco back and forth. I also checked the advance mechanism when I had it off and it looked great. I used a light film of grease on it.

 I'm now suspecting something electrical.....maybe....
 Sometimes, it will idle just like it should and then immediately die, like someone hit the kill switch. Always starts right back up. Other times, the idle wants to rise and fall.....hang for a bit, but then die when I back off the screw.
 I can find a single thing sticking on the throttle, cable, rack, etc.

 Could it be running out of gas? Maybe, but the fuel valves are new, float levels set, checked with a vacuum gauge on the bench and the clear tube method on the bike (on #1 and #4, anyway. Any time I open a drain screw, I get fuel). Plus, it doesn't stumble and slowly die, like when you need to switch to reserve. It just dies.
 And if the high idle is because of a lean mixture (low fuel), why is it random?

 This thing is really kicking my ass. I think I'm going to replace the coils, just so I can rule them out.
 I also have a set of 087A carbs that are for the STF2 bike. They came off a running bike (rode it for thousands of miles with them) and have been in my spare bedroom for a couple of years. I think I'll pull a bowl or two, check for any residue or dried up O-rings, and slap them on if the coils don't fix it.
 

[turboed13b]

I really think you are just running extremely rich on all carbs.  When riding with just fuel in the bowls and when they start getting low it leans out and runs better so that confirms that you are way too rich.

I am still betting the carbs just have a lot of pitting and letting fuel past places where it use to seal. On all of the cb500 and 550 carbs I have seen that were somewhat taken car of #1 and #2 always had the worse corrosion. This is because when people drain bowl 1 and 2 when over on the kickstand it still holds plenty of fuel and you have to tip the bike up to remove all of it. This is why on worn carbs 1 and 2 always have the problems. Mostly #1 because it will hold the most gas even when the drain screw is opened so there is more corrosion.

Did you clean the slow jets? If you didn't clean them personally I would just throw them away because you don't know if someone poked around in there with a hard metal and gouged them bigger.


Once you get your tank do a few more test with the petcock shut off and if it always gets better then I would rule out anything electrical. However that one plugs is pretty clean which is telling me it is only firing intermittently. Is it from way too much fuel or no spark? I guess we will find out once you can give it a good test ride while manipulating the fuel flow.

[Scott S]

 Well, the coils didn't fix it. 

 The only thing I can get this bike to do consistently is run poorly.  I installed another 38 pilot jet in #1 carb. While I was in there I checked the operation of the fuel valve....works properly.
 Installed new coils today. The entire ignition system is now new.....coils, wires, caps, plugs, Pamco, battery. The bike fires up instantly and initially settles into a decent idle. In the garage, #1 cylinder runs cooler than the other three and the plug looks slightly wet.

 I checked timing again today. Dead steady and perfectly on the marks.

 Eventually, the bike starts acting up. The idle will sometimes jump up high. All the known causes of that check out.....fuel level, timing, vacuum leaks, air leaks, etc. All good.
 But sometimes it will sit there and idle normally, only to cut off like someone turned off the key. No coughing, stumbling, spitting, dying, etc. Just OFF. Then it'll fire right back up.

 I'm now leaning towards a carb problem. And I believe that it's in #1 alone.
 Today, I unhooked my auxiliary jug and rode the bike up and down the street with just the fuel in the bowls. It runs GREAT. Pulls strong....feels stronger than my 550F or even the XS650.
 It won't run too long before the fuel level gets low and it starts acting up, of course, but when it's on the needle and the main, it runs really well. I checked the cylinder temps after a ride like that and they're even. Or really, really close.
 This leads me to believe that there's something wrong with the low speed circuit of the #1 carb. Probably something internal.

 I've tried three different 38 pilot jets and a 40, I've tried three different air screws. I've checked fuel valve operation and level using the clear tube method. I've synced the carbs twice. I've done the full 3,000 mile tune up twice (minus the oil/filter....only once).

 I guess my next step is to pull the carbs and see if there's anything obvious I can see with the naked eye. I have a set of carbs that belong to the STF2 bike. I ran them on a different 550 engine for many, many miles. I'll try swapping them over and see what happens. If that doesn't cure it....well.....