81 550T not starting after maintenance

[TreverGreen]

Hi everyone. This is my first post here so if I'm not in the right topic for this question let me know.

This is my first motorcycle and I'm having a heck of a time getting it running again. When I went and picked it up from the PO it started up instantly while cold (I checked the exhaust pipes). The only thing I noticed right away was the petcock leaked, and the owner said the carburetor leaked as well, but I couldn't see what he was saying. After having gotten it home it would not start, which I found to be the battery. While I waited to get a new battery I figured I would do some general maintenance, ex. change oil, filter, clean carbs, etc.

After getting a new battery, and reassembling the carbs (with new gaskets & orings) while following a YouTube video on the exact same carbs (Brickhouse Builds), I noticed that one of the cylinders was firing intermittently (#1 I think?). I tried adjusting the air screw on the carbs to no avail. Then other cylinders started firing intermittently until the bike wouldn't start anymore.

I checked spark, which seemed good with strong blue sparks, compression which was eh (1- 115psi, 2- 110psi, 3- 95psi, 4- 109psi), fuel (fuel on spark plugs, but cleaned before trying to start again, and air (has pod filters, which I wish it didn't). I tested the ignition coils, and found one was bad, and replaced, yet still wouldn't start.

​​​​I checked the valve clearances and they were all within spec, so I'm completely stumped at this point and could use any troubleshooting tips and tricks.

This is my first bike so I just want to finally get out and ride. Thanks!

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[Baatfam]

Start here: Top 10 Newbie Mistakes

Read all of the them, but be sure and take note of 5) and 5b)

Good luck...

 

[TreverGreen]

Well I know it's not a fuel issue because if I spray starting fluid in the intake with the carbs off it does nothing. Occasionally I'll head a pop like it's wanting to start, but it never does.

I'm not sure if it's an electronic ignition problem, but I'm going to clean up all the bike's connectors when I get home today.

Thank you!

 

[Mr.humbucker]

On the heels of Baatfam's suggestion, try rigging up an auxiliary fuel tank/line. If it works or is much better it will tell you your petcock is the issue. In all of my restoration/rebuilds, I buy a new Suzuki petcock ... old ones fail, and aftermarket variations that kind of fit are crap.

Also, when you did your tear down on the carbs how did you clean your jets? From my experience (which isn't huge) I have found it is crucial that the pilot jets are completely clean and the small orifice on the tip/bottom is clear. I use a thin gauge guitar string.

 

[TreverGreen]

Well, I've made some progress but have ran into another issue.

I re-did a bunch of connectors on the wiring, and replaced any wires that seemed suspect. After having done that I thought to switch the coil wires around because the new coils I got didn't have any instructions on them so I just matched what the old ones were like. Sprayed some starting fluid in the intake while turning it over and it started to fire. So I threw the carburetor back on and the pod filters.

It took some babying, and cleaning off fouled plugs, but it started up on all cylinders! It even idled well too at about 1100rpm. At that time it was about midnight, so I cleaned up my tools and called it a night with the intent to take it out tomorrow for a ride. THEN, the next morning trying to start it was a pain, and I could only get it started after putting a teaspoon of oil in the cylinders, and it was only firing on 3 cylinder. After playing around with the fuel screw a bit it then only was firing on 1&4. I know the coils are good because I tested them on both sides.

I know the petcock is good because I replaced that right away, I just forgot to mention that in my original post. And I've cleaned the carburetors twice now, spraying out all the jets with carb clean and an air hose.