Topic: EDIT: Starting attempt #2...SHE RUNS!!! No more issues!!

[Scott S]

 '71 CB500

 Got the carbs ultrasonically cleaned. Installed four new rebuild kits. Floats are set properly (they were all over the place). Bench synched.

 Tried to start the bike again today and no luck. Got a couple of backfires out of the 1/4 carbs, but it just didn't want to start. I had checked for spark before, but only on 1/4, the "easy" plugs. Pulled #2 plug today and no spark. Tried that plug on the #4 wire and got spark.
 Pulled the points cover and I don't see any spark on the 2/3 points. I plan on swapping the condensers tomorrow and see if it moves from 2/3 to 1/4.

 I checked the wires to the coils when I sorted the harness and had power. I'll also check the coils tomorrow and see if I can tell anything.

 I'm guessing it's bad points or condenser, but I really thought it should have tried a little harder to start.
 Can you think of anything else I should check/try to awaken this bike from a 28 year slumber?

[OldSchool_IsCool]

Key on, kill switch on, put a volt meter on the yellow wire under the points cover.  Does it read 12v or 0v?  Does it change as you SLOWLY rotate the crank?

[Scott S]

Key on, kill switch on, put a volt meter on the yellow wire under the points cover.  Does it read 12v or 0v?  Does it change as you SLOWLY rotate the crank?

 I'm by myself tonight and don't have enough hands to try all that. My Dad's coming over tomorrow morning and I'll give that a shot and let you know.
 What will that tell me?

[OldSchool_IsCool]

If the voltage jumps between 12v and 0v as you rotate the crank then your 2.3 points are working correctly.  Once we know that, we'll check points gap and static timing.  We also want to confirm that the blue wire is on the 1.4 points (left), yellow on 2.3 (right).  Need to also check that the blue wire is connected to the coil that fires 1.4 and the yellow connected to the 2.3 coil.  Getting those backwards could explain the occasional backfire.

If all this checks out, then its safe to say that ignition isn't the problem.  The lack of spark on 2.3 kinda tells us that there is.

[Mdub]

May not be your points at all.
You need to eliminate all the possibilities between the points and plugs.
I would start at the end of the chain.
Your plug wire ends may be (most likely) degraded.

All you need to do is trim the ends:
1.Mark the spark plug boot location on the spark plug wire.
2.Unscrew the spark plug boots and measure the distance from your mark to the end of the wire.
3.Cut 1/4" to 3/8" of an inch of the ends of all 4 plug wires.
4.Mark your wires with the measurement obtained in step 2.
5.Screw your plug boots back on all the way to the mark.
Doing this assures that the boot is screwed on (bottomed out) all the way.
A little silicone (dielectric) grease helps and staves off corrosion.

If you don't have spark then, move on to the wires between the points and the coils (check continuity with a multi-meter).
Then on to your points.
Doing this will assure that the coils will see the points make-break if/when they do.
Good luck,
Mike

[Scott S]

 Coils, wires, caps and plugs are new. I still plan on checking the coil and wiring to make sure I didn't screw up, but I was very thorough when sorting the harness and installing the new coils.

 I checked every wire on the harness to make sure it was good. I marked the old coils/wires carefully and followed the wiring diagram when installing the new coils. Still....I'll be checking everything from the points to the coils until I find the problem.

[Scott S]

 Let's say I get the spark situation figured out. What's the best procedure to start a dormant bike?
 Choke on? Off? Half way? Throttle cracked at all?

 I have oil pressure and oil to the top end.  I usually try the starter a couple of times and then start kicking it.

[JS550]

If the battery is weak from multiple starting attempts, that can make it not start also. Even kicking it over wont work. Yours sounds similar to my brothers 550, sat for a loooong time, no start, did fresh gas,points,plugs,wires,coils,checked fuses,we were almost to point of deciding to just part it out then wired in another kill switch control off of my 550. That was it. It popped & spat out a bunch of black sh!t down the side of my shed about two feet. He's been riding it every since. Come to think of it, I'm gonna need that switch back!
Jim

[Mdub]

Let's say I get the spark situation figured out. What's the best procedure to start a dormant bike?
 Choke on? Off? Half way? Throttle cracked at all?

 I have oil pressure and oil to the top end.  I usually try the starter a couple of times and then start kicking it.

When mine has been sitting awhile I turn on the gas and give it a minute while the bowls fill with gas.
Then choke all the way on (closed) and give it about 12 kicks with the key off. Then, after making sure the headlight is OFF, key and ignition on, I hit the starter with just a tiny bit of throttle (if any) and she generally fires right up.
If I find that I've flooded it, it's key off, and kick with the throttle wide open to purge the cylinders and try again. YMMV

[Scott S]

 SHE LIVES!! After sitting idle for 28 years, the old girl ran under her own power this afternoon.

Turns out that the 2/3 points were grounded against the points plate.
 Fixed that, checked the gap again and did a static timing check. Kicked her over and she fired!

 There's still something up with the carbs (or maybe the timing?). She'll idle at 1000 rpm for as long as I let her. But if I give it any throttle the revs won't drop back down. I've checked the cable and it's not binding. Idle mixture screws are at 1.5 turns out.
 Two things I've noticed:
 A) The #1 cylinder is running cooler than the other three. Using an IR temp gun on the exhaust pipe, it's about 100 degrees cooler than the rest.
 B) When the RPM's get hung up, if I tap the top of the carbs (especially #1) it changes the revs.

 I suspect a sticky slide or something?

[Scott S]

 Oh yeah...I also have a tiny oil leak from the end cap on the right side of the head/valve cover. When I polished those end caps up, I noticed one of the O-rings was sorta wavy and didn't fit so well.
 Any tips and tricks on where to find an O-ring that would stop that leak without having to buy a top end gasket set?

[scunny]

if #20 then it's a 6x3 oring

[Scott S]

if #20 then it's a 6x3 oring

 Yep, I'm pretty sure that's why it's leaking. Can I find those at Lowe's or Auto Zone or whatnot?

[OldSchool_IsCool]

Congrats on getting her sorted and started!!  Great feeling, isn't it!?!?

As for the leak, it's hard to see in the drawing, but there is a soft aluminum washer, #16, that is also critical to keeping 'er from leaking.

[Scott S]

 The leak is very minor. I'm more concerned about what's causing the idle to hang....any ideas?

[Mdub]

Reluctance to return to  idle can be caused by:
(based on what you've covered already)

*An overall lean condition notwithstanding, air bleed screws  being screwed out too far, causing a lean idle mixture. Try screwing them in half a turn or so and see if it helps.
The service manual says 1 turn out +-1/8 turn.
Also make sure wires or fuel lines aren't interfering with movement.
If you had your carbs sonically cleaned I wouldn't think they're sticking.


*Leaking intake manifold tubes.

*lack of throttle shaft (that opens all 4 carbs) lube.

TT is the 500 guru maybe he'll chime in.

[Scott S]

Reluctance to return to  idle can be caused by:
(based on what you've covered already)

*An overall lean condition notwithstanding, air bleed screws  being screwed out too far, causing a lean idle mixture. Try screwing them in half a turn or so and see if it helps.
The service manual says 1 turn out +-1/8 turn.
Also make sure wires or fuel lines aren't interfering with movement.
If you had your carbs sonically cleaned I wouldn't think they're sticking.


*Leaking intake manifold tubes.

*lack of throttle shaft (that opens all 4 carbs) lube.

TT is the 500 guru maybe he'll chime in.

 The screws were out more than 2 turns. I set them to 1.5 and it still hangs. I'll try going in another 1/8 turn.

 I'll check for a vacuum leak today.

 Throttle shaft lube? Please elaborate. Where and how much? I'm sure it's very dry since it was just ultrasonically cleaned.
 
 I checked the cable to make sure it wasn't sticking, but I didn't think to look at the fuel lines, etc. I'll take a look at that today, too.

[Mdub]

 The screws were out more than 2 turns. I set them to 1.5 and it still hangs. I'll try going in another 1/8 turn.

 I'll check for a vacuum leak today.

 Throttle shaft lube? Please elaborate. Where and how much? I'm sure it's very dry since it was just ultrasonically cleaned.
 
 I checked the cable to make sure it wasn't sticking, but I didn't think to look at the fuel lines, etc. I'll take a look at that today, too.

The book calls for 1 turn +-1/8 so you still may be a bit lean at idle.
Carb cleaner spray helps to check for air leaks in the manifold tubes. Spray around tubes while engine is running and listen for changes. Honda use those little tin hose clamps that become fatigued and don't hold up so well after ~30 yrs. I.E. even when tight they leak.
I replaced all of mine with stainless hose clamps.

White lithium grease is what you want to lube the throttle shaft. If you had your carbs sonically cleaned while still on the carrier rack/plate that very well could be your issue. Have a look and you'll see the shaft running the width of the carbs.I think there are 4 areas where the shaft goes through a bushing cast onto the carb carrier rack.
You don't need much just a thin coat in each area. Loosen the shaft so you can slide it over a bit to lube the areas that go through the bushings

If you don't have a service manual, download one from here:
http://www.mediafire.com/?uznwn3ihx0i
Good luck, keep at it and you'll get it sorted.

[Scott S]

 I posted a little about it here: http://forums.sohc4.net/index.php?topic=71619.0

 I'm almost positive it's a carb issue. There's just something funky going on there. I've checked for spark, set the timing and points gap, adjusted the valves on #1 (twice) and there's something funky with that carb. The "chuffing" noise and the fact that there's fuel in the throat when it's running....plus, from time to time, it will run on that cylinder but I'm not able to determine what makes it run or what I'm doing that affects it. If it was a valve issue then it wouldn't go away like that, even if it was for a few seconds, right?

 I've been in touch with the guy that did the carbs. They're off the bike and he's going to go back through them for me.

[fastbroshi]

  B) When the RPM's get hung up, if I tap the top of the carbs (especially #1) it changes the revs.

 I suspect a sticky slide or something?

  I've run into this issue twice on 550 carbs, and I've only worked with three sets of the 067 variety.  I think this same style has different numbers on them sometimes, anyway... 
 
  I noticed when breaking them down the throttle valve or slide was hanging up at the end of the bore and wouldn't come out.  It was the same on both carbs I had problems on.  After a bit of careful fiddling they both came out and after inspection it seems the valves had burrs on the bottom edges that were hanging them up.   So if I were to use them in operation, I wouldn't have noticed any hanging at the top as the valve doesn't go that high.  But I definitely might've noticed some kind of lean condition (revs staying high) down at the bottom if the slide didn't want to drop all the way when letting go of the throttle.  This was easily fixed with a rattail file and a light abrasive brush on a Dremel.
 
  That being said, running lean causes higher temperatures, not lower.  If your cylinder were running lean, the temps would definitely be higher, not lower.  It sounds like it may be intermittently firing or just getting too much gas. 

  You said you tapped on the top of the carb body and the revs dropped.  In what other cases does tapping on the carb affect a change?   The floats.  You said someone else did your carb cleaning.  Did they set the floats correctly, and to what level?  Might need to double check that.  These being off can affect the bike's running drastically.

[Scott S]

 You said something that I totally agree with.....getting too much gas. We (me, my Dad and Pamco Pete) all feel like it's getting so much gas that it's just flooding that cylinder.

 There's a guy near me that rebuilds carbs. He sells them on ebay and does it for individuals like me. I've been to his shop, and he has a stellar reputation. I feel like he knows what he's doing. That said....who know?
  He set the floats at 21.5mm. When I put the vacuum gauges on, the bench synch was damn near perfect. I'll tell him to check the slide(s) and float setting again. All four carbs have a new rebuild kit in them, but I've seen brand new needle/seats be bad in Weber carbs.

 Does the mixture screw having no effect on #1 tell me anything? At one point during all this, we could make the "chuffing" come and go with the mixture screw, but then lost that, too.

[fastbroshi]

  Sorry I just read your first post again and saw you said the floats were set right.  Have you checked that plug and is it oil/wet?  Maybe try changing that plug, or at least checking to make sure it's the right one!   Did you check the sparkplug gaps by any chance?  If you replaced them all at any point, remember they have to be gapped, they won't come that way.  Shot in the dark.

  I think I ran into that chuffing before and IIRC it happens when that cylinder doesn't fire.  The mixture screw having now effect could be akin to that circuit not functioning = clogged?  

[Scott S]

 Plugs are new and gapped by me. I have spark on that cylinder. Set the timing yesterday with a timing light. Points gap is correct.

 That plug looks like it's getting fire from time to time. It's not oil or gas soaked, but the other three are sooty and black (remember, this is just idling in the garage....can't really go by the plug reading til I can take it up and down the road). The #1 plug is cleaner, but dry.

[fastbroshi]

Have you check the bowl vent hoses?  Maybe that one got kinked or is clogged.  I've read some stories of them causing all kinds of head scratching.

  If all else fails, just to rule it out, maybe you could take off the bowl on #1 and check the float's motion.  It should go up and down very easy with no tight spots.  When rebuilding mine I very lightly polished the brass pins they hinge on to try and avoid any problems there.

  If that doesn't yield anything, maybe try going around the carb with WD 40 while it's trying to idle and see if you get any unwarranted blips of the throttle.  If it jumps up while you're spraying, it's ingested some and you've got a leak somewhere, say around the intake manifold O-rings.

[Scott S]

 I sprayed all over the carbs and manifolds with carb cleaner yesterday. I can't find a vacuum leak anywhere. I know they can be particularly difficult to find sometimes.
 What I DID find odd is that I can actually make the bike stumble and die sometimes by spraying carb cleaner on the carb tops. But not always.

 The carbs are off and will be dropped off this morning to be checked out again. I'll be extra careful when re-mounting them to get a good seal on the manifolds. I'll also mention polishing/deburring the slide and double checking the float height and needle/seat. I'll let you know how it goes...

[Scott S]

 I love it when it's something obvious!!

 Just got back from the carb guys shop. Pulled the float bowl on #1 and found the slow jet loose and hung up around the float.
 He still has all the original jets and will clean and inspect them and re-use them if they pass muster. The O-rings in this kit are already showing signs of getting soft and goopy, too. He has an assortment of the proper fuel resistant O-rings and will replace them as well.
 He's going to re-check the float height, bench synch and check the springs in the linkage holder arms. He soda blasted the carbs and wants to make sure there's nothing in there that would be keeping the RPM's from dropping back.

 I'm pretty sure it's ALL related to the lack of slow jetting in the carb.

[Scott S]

 Back together and smooth as a top! Well, as smooth as I can get her on the centerstand in the garage. As soon as I get the master cylinder kit in, I'll rebuild the brakes and take her for a spin.

 Idles well and sounds good now!

[fastbroshi]

Cool, glad you got it sorted.  It was beginning to sound like an odd one.

[Don R]

Carquest matched my 750 o-rings, I have 12 more there waiting for me now.