Exhaust Bubble Popping Sound

[Fojyie]

I was off for a month on other issues, but am still finding 1 and 5 rich and cooler on the pipe. I am pulling my few hairs out over this. It is running better after a few heat/cool cycles as suggested. Good comment. It stumbles on take off, like it lacks power, but 2500 and above it seems to smooth out and run much better. The carbs were rebuilt well. I checked numerous places: breather clear, spark in all lungs, cleared gas cap vent, compression check ok could be better, same with leak down, filter between carbs and tank since startup to keep crud out of carbs. It idles at 800-900 but hesitates on rev up. Sometimes dies at corner stop sign but restarts if I keep the revs up. Wonder about linkage and choke hang up and will try to see them. Any other thoughts?

[daves79x]

Hate to say it, but there is an almost 100% chance it's still the carbs. Were the pressed-in pilot jets removed and cleaned? Was the accelerator pump circuit checked and verified to work BEFORE carbs were reinstalled? Are your float levels correct? Lots of pitfalls with these carbs and most guys need two or three tries at it the first time they attempt it. Also, with the ethanol blend we get, I've found shimming the needles .020 inch is almost mandatory. Many CBXs, but not all, surge and stumble off-idle with the ethanol.

Dave

[ajs350]

Fojyie,
I was you 8 months ago. I had similar issues and had cleaned the carbs twice so was convinced it must be something else. Replaced coils, plug leads, plug caps, air filter.....................etc. The site experts continued to tell me it was carbs so off they came a again and again and eventually I got it right. Get the Mike Nixon book, follow his instructions and advice from Dave and you will get there.
Ross

[Fojyie]

Thanks for the suggestions. I had Mike rebuild these for me, so I expect he did what was necessary. I've tried to be careful not to introduce contamination to the fuel and have used a filter at all times. Drained the bowls and found them clean. Hate the ethanol curse we live with though. I try to use fresh fuel and small amounts at this point. Pulled plug 1 today after 15 minutes of running and found it wet. Suspect 5 is similar. No wonder it lumps at idle when two consecutive misses occur. I am so close, but feel miles away. May have to tilt and drop them out again for a careful review. Wonder if I screwed the linkage up in reinstallation? I will also get Mike's book.

[daves79x]

If Mike did the carbs, all the issues I suggested were addressed, I'm sure. Are you just starting and running the engine without actually riding the bike and getting it good and warmed-up? If so, that may be your problem. These things will foul plugs easily sometimes. I'd screw in new plugs and when you start it up, get it off the choke ASAP and get it moving. Sounds like it is really 'loaded up' as we used to say. After that, see how it goes.

Are you sure your exhaust for #1 and #5 is open? No mouse nests in there? I've seen that before. #1 and #5 are not connected electrically, so you haven't lost a coil, pulser or spark unit, most likely, although someone here reported losing 1/2 of a coil - can't remember the details on that. Very low compression (apart from the rest) will foul plugs also. Have you checked valve clearances since you've been running the bike? Possibly a couple being held open?

Other things would be to check all spark plug wire connections for corrosion. Unscrew the caps and look inside for corrosion. Screw them all back on very tightly.

But back to the carbs - if they have sat with this blended gas in them a couple of months, all bets are off on them. If they have attracted moisture, bad things result inside the carbs. Try running a little Seafoam through them if you can. Let us know how you are progressing and what else you find.

Dave

[Fojyie]

Thanks Dave, you guys offer great help. Yes, I believe Mike covered it and we have been in communication. Its hard long distance debugging, but today I made some progress. I removed No. 1 cap and sprayed some B-12 in and also added some Seafoam to the tank ~ double duty. I also decided to switch two coils to check them out. I found that No. 1 came alive today and the corresponding cylinder with the previous No.1 coil worked fine. No coil issue. Wires are new and caps are new. Found those old last month. Now, I pulled plugs and only No.5 is wet. I am working on removing that cap to spray also some B-12 Berryman's in thinking that made #1 healthy. Man, that is a tight SOB on the front screw. Still fighting it.

[Fojyie]

Hey guys, I finally got it hitting on all six cylinders! What a good feeling. Thanks to Mike Nixon and all of you for offering encouragement, suggestions and helping me get this one going. I have just a few little things to tend to, but knowing it runs well now is a big load off the shoulders. Thanks to all of you.

[daves79x]

Nothing special? You are being far too modest - that's a great looking '80! We'd like some more photos and a little of the story of what all you did to get it this way. May an Xpress article?? Well done!

Dave

[Fojyie]

Dave, I would be interested in telling the story. I, like many, took extensive photos along the way, made several mistakes and eventually got to the end. I have used some pictures for a local community class on restoration which turned out pretty good with other enthusasist. Let me know what I can do to provide.
Joe

[daves79x]

Joe:
Sent you a PM.

Dave

[steve murdoch icoa #5322]

You have a beautiful bike, Joe.
What did you discover was causing the poor running?

[Fojyie]

Steve, I did a number of things to find out what was wrong, but the final steps were to switch coils and determine if the problem moved. It did not move. Before starting the bike, I also added Seafoam to two fresh gallons of fuel and lifted the cap on No. 1 and sprayed Berrymans B12 into the top of it. So, I can't say for sure what it was, but that cylinder came alive immediately, so I suspect I had a small piece of something affecting the fuel ratio. It was basically flooding that cylinder. Knowing this, I went to No. 5 and tried to lift that carb cap. Uh, what a hassle, in fact, I couldn't raise it all of the way, only enough to spray B12 on top of it similar to No.1. Closed it up and it also came alive. I now suspect that I had not cleaned the fuel tank adequately and perhaps something condensed in the carbs. Regardless, I probably spent way too much time chasing an electrical ghost that wasn't there. Surprising considering the 32 year old components. I'm sure one day in the future I will need to change coils out and maybe the igniters. I can't give Mike Nixon enough praise for staying with me through this. He offered tons of suggestions and offered to take the carbs back, which I resisted for obvious reasons. You just can't get that kind of support from most vendors. I am now a believer that these bikes are exceptionally sensitive in the carb area and will give that high respect. I really am concerned about how to store it this winter. I will use Stabil, but don't know whether to run till dry and drain, or leave alone. The conditions just don't let you ride often here in January, but you never know. I usually find at least a few days to fire them all up.

[daves79x]

Joe:
Glad you have it running properly. When in doubt - its carbs, carbs, carbs! I've had a few sets that I rebuilt, test ran even and sent back to the customer that acted this way. Every one of those sets had sat either on the shelf or on the bike withoout running for weeks or more. I'm guessing you introduced something into them inadvertantly that partially plugged #1 and #5 pilot jets. Mike would have certainly made them right, but I'm glad he steered you through fixing them. I've taken a couple of sets back that I had to clean completely all over again due to so much rust and crap from a dirty tank. I'm sure yours was pretty clean, but it doesn't take much. I've also had carbs so crappy that they SEEMED clean and test ran OK, but sat for a while and some remaining varnish that had partially softened had re-hardened and plugged a couple of jets. If put into service right away, this seems not to be an issue, and running them completely cleans this out.

I'd run yours as much as you can this Fall, then drain the carbs and fill the tank - no stabilizer. I've had a couple of disasters with stabilizer a few years ago and now only fill all my tanks with gas - no stabilizer - for the winter. With the carbs drained - no varnish can form and a full tank will not go stale enough to cause problems over the winter. But PLEASE, drain the carbs completely and goose the throttle several times to clear the accelerator pump circuit. You will have no problems for years by doing this.

I assume you still have the vacuum valve functional on the carbs? If so, when starting the bike in the spring, or after any long lay-off during the season, just locate the vent line from your vacuum valve (usually routed over the right side of the airbox and down near the carb drain on the right side. Blow into this line and hold pressure for a few seconds, then repeat a couple of times for empty carbs. Then full choke and no throttle. The bike will fire up like it was run yesterday, every time.

Dave

[Fojyie]

Dave, I will follow this procedure to clear them. Great to know how. One other thing, now that you mentioned it, I had received my carbs far in advance of actually starting it, about a year longer! That probably didn't help the situation either. Anyway, it's a marathon as so often projects can be. Got two smaller issues to address yet: weeping at brake seals (all rebuilt with new kits, disappointing) and speedometer that is slow responding. The fun continues.

[NobleHops]

Dave, I will follow this procedure to clear them. Great to know how. One other thing, now that you mentioned it, I had received my carbs far in advance of actually starting it, about a year longer! That probably didn't help the situation either. Anyway, it's a marathon as so often projects can be. Got two smaller issues to address yet: weeping at brake seals (all rebuilt with new kits, disappointing) and speedometer that is slow responding. The fun continues.

Joe,

Bravo, the bike looks fantastic! Get some tank badges though, willya?

I had trouble getting a caliper to seal, resorted to my local independent, who fessed-up what they do: They have a (MotionPro?) kit with rotary brushes that they use to polish the bores of master cylinders and calipers, and that aides in them sealing. I have not personally tried this myself, but when I looked into it one of the things I found was this:

https://www.benchbuddy.com/

Re the speedo, I've read that they will sometimes free up after a few miles of use. If it does not and you can't live with it, then you might look into companies like North Holywood Speedometer, I'm pretty sure Jesse (pitfighter) used them on his resto and was pleased with the results.

Good luck!

N.