Carb/revving issues

So I got the tank back on, idled a bit high, kind of hard start but that could be because the bowls were empty, revved it up and revved nice, no stumble up to redline, but after letting it idle a bit (maybe 3 mins.) the old stumble off idle was there. Once past that it would rev all the way up to redline no problems.

I should note there is no air filter inside the airbox, just a screen in front of the airbox boots. If I cover the airbox intake hole (air comes in) response is better but not as good as I'd like it to be. Next stop: factory air filter in the airbox!

Hopefully that will solve the issue.
As far as plug #2 is concerned, I haven't plug chopped yet. I may just replace them as a matter of preventative medicine anyway.

My compression tester doesn't fit the plug holes. The tapered rubber end is worthless as I can't hold it in tight enough to get an accurate reading.

Heaven knows I sure don't want to pull those carbs again to check the diaphragms...

[Steve]

If #2 plug is sooty, you likely have a bad diphragm in the petcock. It is evidently a small enough hole that you are able to pull enough vacuum to open the petcock enough to run the bike, but it still allows gas to go through, directly into #2 intake tract, richening the mixture. With a leak like that, it is also possible that gas can go through the hole, even when the engine is not running. This can drip into the crankcase, thinning out the oil. Check to make sure your oil level is not overly high (due to fuel being added) and check the odor to make sure it doesn't smell like gas. #-o

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Yeah yeah, everyone here has done the exact same thing I'm about to describe.

So my 84 Katana 750 was having a real hard time starting, then idling even when warm. Should I attempt to rev the motor it would immediately bog down. If I were lucky enough to "feather" the throttle and get the revs up, about 6000 rpm would hit a wall and bog down again. So I thought "hey, I bet something is wrong with carburetion". Easy way to check is to spray carb cleaner at the intake and airbox boots while the bike is running. This made no difference so I thought the next thing I should check is spark plugs. #1, 3, & 4 looked normal (tan, not sooty or oily, etc...) But #2 looked sooty, meaning it was running rich(?).

So I figure, well hell, I oughta pull those carbs out anyway and go through them, and upon closer inspection I found airbox boot #2 was missing the clamp, and wasn't fully seated around the carb intake. So I pulled the carbs (what a bloody stupid nightmare!) and found the internals to be clean and shiney. Nevertheless, I hosed all the ports and holes etc...with carb cleaner making sure it squirted out somewhere else, checked the float heights (all were good!) and reassembled the whole shebang. I figured that since I couldn't get the airbox out of the frame, thereby restricting access to the intake boots, and since the intake O-rings were undisturbed, and all the other rubber parts I had thus encountered were soft and pliable, I wouldn't replace those O-rings. (But it was mostly because I couldn't get to them). I may have committed a cardinal GS owner sin, but hey - we'll see what happens.

Now on to reassembly (ugh!). New fuel line, a new inline filter, and a few vent lines up and over the airbox (along with a remote choke cable pulley system) all conspired to make the job supremely pleasant and almost enjoyable. NOT!! After a few hours and many many choice curse words, I realized I'd have to disconnect the hydraulic clutch line (routed between #1 & 2 carbs, on the airbox side) and move it out of the way. So now I have to bleed my clutch in addition to getting these bloody stoopid nightmare carbs back on. Thinking it would be easier to get the airbox attached to the carbs and secured first, I did that. Then, realizing I wouldn't have enough flexibility of movement, I disconnected them, and shoved them into the intake boots, then reattached the airbox. Fun!

So, short story long, its all back together. Haven't had the chance to get the tank back on to see if I made any difference, but will update when I do.

Can anyone think of anything else that may have caused those start/idle/revving issues? Another thing I noticed was that it was smoking/dripping a little (minute amounts) of oil out of exhaust pipe #2 where it connects to pipe #1 underneath the engine. This on a stock factory exhaust system. Could it be a result of the leaky airbox boot on #2 carb, or I suppose it could it be blow-by thanks to poor rings/scratches on cylinder wall, etc... Should really do a compression test before I put that tank back on, I guess.

Any thoughts are appreciated.