Exhaust Bubble Popping Sound

[Fojyie]

I have just started a 1980 bike that has been idle for well over 10 year, maybe 15 years. I have gone through it pretty thoroughly, but did not break into the engine since it has 17,400 miles on it. On my first startup, I heard a weird sound like bubbles under water or like you might make with your mouth sound before it started. Is it possible one of the valves is sticky or burnt? I only ran it a brief 3-5 minutes with the exhaust pipes off. I cruised through this area, but didn't see any similar sounds. Nothing metallic sounding and the engine ran well without missing, of course, this is my first experience with this engine. I've been on this for nearly 3 years and hope that I won't have to take the head off. Thoughts? Thanks in advance.
Joe

[NobleHops]

Maybe crank it a bit with plugs out, to prime the oil pump and passages? I'd be tempted to drop the oil, inspect, reinstall. Tough with pipes off though, not a normal listening environment to say the least

[Fojyie]

Before starting, I primed the oil pump until the light went off, then I proceeded to start it. Like I said, the sound was like a bubble popping. I think I will do another start of the engine to see if it repeats this. I'll record it also. Everything else seems fine. Mike Nixon did his magic on the carburetors and it took little to start, only a couple of puffs of starting fluid the first time. Maybe I should do a cylinder compression test across the bank. I did do some small valve adjusments.

[spencer]

I have heard similar sounds from an engine with no exhaust system and there was nothing wrong. Put an exhaust system on it and then see if it sounds normal.

[Fojyie]

Okay, I'll do that. It was a weird sound I have never heard an engine do before. As you suggest, I'll install the exhaust and will see if all is well.
Thanks Spencer.

[steve murdoch icoa #5322]

Did it sound anything like this?
http://www.youtube.com/watch?v=EVheMtylYyM

[Fojyie]

Not quite, but I love the colors! I managed to set off my garage smoke alarm when doing my inital start. At first I thought the bike had a beep, but then I realized it was by the back door along with my dog crying at the sound. I taped it also http://www.youtube.com/watch?v=-d6xyoNqe00 for your humor.
I put the exhaust on today ~ lovely chore for me by myself, about four hours. Will add tank and will try again maybe tomorrow. I hope the "wipple" sound goes away, otherwise, it seems fine.

[NobleHops]

Not quite, but I love the colors! I managed to set off my garage smoke alarm when doing my inital start. At first I thought the bike had a beep, but then I realized it was by the back door along with my dog crying at the sound. I taped it also http://www.youtube.com/watch?v=-d6xyoNqe00 for your humor.
I put the exhaust on today ~ lovely chore for me by myself, about four hours. Will add tank and will try again maybe tomorrow. I hope the "wipple" sound goes away, otherwise, it seems fine.

Well, that's awesome, that your bike is so close to being back on the road.

Two things please:

1: Photos! Let's see the project!

2: What do you need to complete it?

N.

[Rick Pope]

Your bike sounds normal, for a bike w/ no exhaust pipes. I'd be a little leery of running it much though. With no pipes, when you shut it down, the cool air has direct access to those hot valves.

[steve murdoch icoa #5322]

Now there are a few sounds that you usually don't hear in a CBX clip.
A fire alarm, a howling dog, popcorn popping and classical music. Excellent!
Sounds fine, lets hear it with the exhaust.

[barryadam]

Now there are a few sounds that you usually don't hear in a CBX clip.
A fire alarm, a howling dog, popcorn popping and classical music. Excellent!
Sounds fine, lets hear it with the exhaust.

plus the sound of someone stomping on a fire alarm to silence it.
Twice.

Sounds just like a bike we ran with no exhaust. Same bubbles popping sound.

[daves79x]

It would not be uncommon for a few valves to not seal properly upon first start-up after a long layoff. Symptoms of this would be popping back through the carbs. Run it through several heat/cool cycles - with exhaust on please - and the valves should reacquaint themselves with their seats, if they are going to. I've treated a couple of engines this way and they soon ran just fine.

Dave

[Fojyie]

I know I provided some entertainment to all of you by my initial start and directorship 101. Yes, that was me trying to push some air past the smoke alarm with a T-shirt and my dog howling in the background. Classic music to calm my nerves. Can't some things be simple?

I got the exhaust on and am anxious to see if that burble goes away or is masked by the exhaust. I only ran it a with that small tank once. Speaking of exhaust, what a pain to install.

I will get the painted parts on this weekend despite the 102 heat predicted here and will then get some pictures for all. Nothing special other than a clean machine. At this point, the only thing I am still working on is a breather for the crankcase tube which I ran over the airbox to the rear. I may look at still using the tank for dripping, but maybe nothing will rise that far (no experience there). It will be less exciting (I hope) than the startup.

Joe

[steve murdoch icoa #5322]

"Nothing special other than a clean machine"...blasphemy, they are all special. lol.
If i have music on in the garage it is to drown out the swearing. Nothing is ever simple with these brutes.

[Fojyie]

I agree. I put it all together yesterday and I lost #1 and #5 fire in the hole. Now doing electrical checks. Sniffing around the ignitor feeds and wires over the air box ~ I tighten those two bolts before adding air cleaner cover bolts during final assembly. Those were the last two bolts I needed a home for and are probably guilty here. Maybe the coil current wires were "crunchy" after 31 years and need to be replaced. More trouble shooting before ecstasy of riding this guy.