I just inherited a 1982 Seca 550. This is my first bike, ive never ridden nor worked on motorcycles before. I was told all it needed was a fuel petcock and it would run. I got a rebuild kit and cleaned it up, now it doesn’t leak and seems to work just fine. However, I still can’t get the thing started.
As far as I know I’m doing it right, Run switch on, Clutch in, kickstand up, choke on, petcock to prime, fuel in the line, hit start, chuga chuga chuga nothing.
I pulled the air filter out and sprayed some carb cleaner into the intake, it will sort of putter and and run for abuot 2 seconds then die. Only seems to work when I spray the carb cleaner in. I figured then it must be Carbs. Pulled them off the bike.
Opened up the carbs, insides look very clean, no varnish really at all, very minimal in the float bowls and it wiped out right away. I pulled some of the jets and looked through them, don’t seem to be clogged. The float cylinders, not sure what they are called, but they are gold in color and have the needles on them, slide up and down ok, they feel ever so slightly sticky, I pilled off the tops and the rubber gaskets up top look good, pulled out the springs and those gold cylinders and looked inside. no gummy stuff or varnish, does look like there are some wear marks. Put everything back together.
I should note that I checked to see if the carbs were getting fuel by opening up the little drain plugs and plenty of fuel came spilling out.
Um, so I guess the question is, what is the basic check list of things to look at first? Not sure where to start, thought it was the carbs and it would be an easy thing to clean up, but they look good to my amateur eyes. Bike sat for 6 months under a tree. Tank was drained and plugged. Was supposedly running just fine before that aside from the petcock.
I’m waiting on the clymers in the mail, but still tinkering with the bike every day.
Apologies for the long winded explanation but I’m trying to cram in as many details as possible. Any help/advice would be much appreciated!
Hi Will – welcome!
I would bet you still have a carb issue. If you sprayed cleaner into the intakes and the bike sputtered then it follows that the bike is not getting fuel. I believe the Yamaha XJ550 has the same carbs as the XJ750 (please correct me if the pic doesn’t match up to your carbs, it’s from the XJ750 carbs). A very common clogging point in these carbs is actually in the bowl. The choke jet is a long needle like tube that goes down into the bowl. It goes into the hole in the bottom left of this picture (not the bolt hole of course, the one next to it). The bottom of this passageway clogs extremely easy and can be quite a PITA to clean. Pull off a couple of your bowls, drip some fluid down into the hole and see if it comes out at the bottom. I bet it doesn’t.
This is becoming quite the learning experience. So i squirted some carb cleaner in those little holes on the float bowls, and it did drip down and out through the other little holes. For some reason, and I’m regretting it now because it’s 12:30am and my carbs are in pieces, i decided to go ahead and boil the carbs in lemon juice just to clean em up. I figure might as well since i tore them off the bike. That went pretty well, but left a residue of gunk on the insides. I was working on cleaning the extra gunk out with shop towels but had particular trouble getting around those little brass flappers that are held in by two screws. I took one off to see if I could get things a bit cleaner, but I still couldn’t get it as clean as I’d like to. I’m trying now to put the dang thing back, but one screw is being very stubborn. It looks as though the threads have been mangled, though I don’t know how because all I did was take it out. That, plus the odd angle that the screw threads in at, has made this a very frustrating process. I’ve spent a good ten minutes trying to get that thing in without cross-threading it. I’m starting to think I may have to go to the hardware store to find a replacement machine screw, I really really don’t want to cross-thread anything on this.
OK. This is one of those learn the hard way situations. Those screws are peened over and not meant to come out. Makes sense, wouldn’t want one of those screws jiggling loose and flying through the intake. wish I’d known! solution in the works…
After boiling the carbs they need to be rinsed very thoroughly in a bucket of water (or sprayed with a hose) then doused with carb cleaner or wd-40 to displace the water. That will prevent them from being sticky from dried juice residue.
So you’ve confirmed the choke flutes aren’t clogged, you’ve held all 4 pilot jets up to the light and seen through the, and you’ve done the same with the 4 main jets correct? If those 3 passages are clean the bike should start and run. Other passages can certainly effect the running, bit those are the most important.
How old are your spark plugs and what do they look like?
Have you closely inspected your coils and plug caps/wires visually for cracks or crazing?