A few things bugging me...rich idle, residue

Good day folks,

Bike has been running pretty good lately but I saw some seafoam on sale and decided to mix in 3.5 ounces with a fresh tank of fuel. I now have small backfires on idle (Rich, yes?) that I did not have before. I can get the choke lever down a bit more during warm up which would also indicate it is running more rich than before, yes?

My carbs were cleaned, by me several times, then by a shop just short of two months ago. I wouldn't think that putting some seafoam through the tank would open up the pilot that much more than several cleanings would have...
Think I should be ok to open up the air screws a bit on the carbs to even it out?

Also, while you're here, hoping to prevent another thread...
I replaced my fuel gasket a while back because the old one was shot. Ever since I replaced with a new rubber gasket on the fuel cap, I get what looks like residue running down the sides of my tank after each fill up. The residue will return after each ride or if the bike is sitting in the sun until the fuel gets down to maybe 1/2 or 1/3 tank. Any ideas on what this is or why it is happening?

I'd run the tank empty then fill it to see what happens. Did you clean out the breather passage in the cap?
Steve

I'm probably half way through the seafoam tank. Will post back after I refill with any changes.

Breather passage?
I removed the old gasket and put the new one on, I scraped off some rust but nothing else.

Edit - Looked up gas cap breather and nothing looks anything like the cap I have. I did unscrew the part mounted on a spring to be able to get the gasket around the lip, then screwed it back in place.

You might want to check it out. I made the mistake of filling it to the top and ruined my new paint job. Got behind the badge and created gas filled bubbles in the paint.
Steve

An update -
I ran through the rest of the seafoam tank. It was popping slightly all through the tank on idle. I took the bike for a nice long ride about 10 days ago, mostly highway speeds 60-70MPH and the bike ran great with a passenger.

The bike then sat for about four days. The next day I rode it seemed a bit "off" on my way to work. I thought it was just traffic trying to kill me and the stiffer setting on my rear shocks. Later that day leaving work the bike was acting like it was running low on fuel. I had to hold the RPM at red lights to prevent it from dying. It died as I pulled into the gas station.

I filled it with fuel, premium no ethanol, but only got 2.5 gallons. Weird... Normally from "running out of fuel" I get 3.5 gallons. It rode fine back to my house.

Later that same night I took it out and parked it for about an hour, petcock on, then rode home. Normally I turn the petcock off when parked but I forgot. On my way home, I pulled on it pretty hard up to 70mph for only about a mile and it started to give me the problems again. It wanted to die at low RPM, there was backfires in the exhaust and coming through the pods. It finally died on me when I tried to get going from a red light. I changed the petcock to reserve and let it sit for a minute.

The bike started back up but was bogging down with any throttle. I made it another mile, and it died on me again. I pulled into another gas station, .7 gallons of fuel and I'm back off. I made it up the hill and through the neighborhood to my house. The bike died as I pulled into my driveway.

Questions - I've read others having issues with premium fuel. Could the premium be an issue for me? Think it would help to remove the fuel and replace with standard? My sparkplugs aren't fouled, yet bogging on throttle is usually a rich condition yes?

Sounds like pilots. Fuel filter?
Steve

Yes I have an inline filter. My previous issue is that it was running lean. I had a shop rejet for me and it was running good. I could see it running a tad rich from the seafoam opening up the jets a bit, but once the seafoam was gone its acting like something else is wrong. Popping at idle and at cruising, popping through the pod filters, bogging on throttle, those are all rich conditions yes?

Sounds lean. Pics of plugs?
Steve

Definitely check the plugs.
Switch to 87 octane, your bike with a stock engine is not meant to run on anything higher unless you experience knock in warmer weather.

Have you checked valve clearance?
synchronized your carbs?
Timing?

If all that stuff is looking good and you still have rich/black plugs you may just need to turn the air screws out some.

A quote from Wiregeorge back in 07 on the 76 kz900 vm26 carbs

" Turn the screw out to 1 3/8 turns and see if the spark plug on that cylinder burns sooty. If it does, turn it out another 1/2 turn. If you still have soot, then you can conclude your cleaning efforts were not adequate or there is another reason for the soot (electrical, timing or valve related). "

I've run it a few times, here are my findings.

It runs well for about 10 minutes, then acts like it's running out of gas. I stop, open the cap, let it sit for a few. Runs again for a few minutes before acting low on fuel again. I don't have a vacuum petcock and I don't hear a vacuum when I open the cap.

Have you tried running it with the cap ajar?
Steve

I haven't. I might try that tomorrow.
I ordered a new petcock and some new filters. I am sure it's the way my fuel line is run and maybe a dirty filter.