So, after a few weeks of fiddling, I finally think I have the bike running as well as I can get it. Of course, that is a moving target, as you know.
Hopefully some of this information will help you.
I have open exhaust and pod filters.
First, I ordered gaskets, a variety of jets, float needles from Sirius Consolidated in Ontario. Chris was very helpful, as he own an XS400 himself. He put together a kit for me according to my setup.
I ended up with 160 mains, as the 150's I ordered were still lean. That surprised me, as 135 was stock. The jet needle is set all the way lean. I suppose a 155 would have been ideal but I made the 160's by drilling out some 145's using a #51 drill bit, and there was nothing in between.
The pilot is one step bigger, a 45.
The float measurement in the book is whack, so I just adjusted them to the point I figured was best. My needles must be longer or something.
I synced the carbs by eye as the manual says you can, but I still wasn't happy with that. I built a manometer with a yard stick, nylon ties and clear tubing filled with ATF. I couldn't believe how far they were out of sync. When I first started the bike it nearly sucked ATF into the right cylinder. I shut it off, cranked the screw a couple of times, and the left nearly sucked up fluid. Obviously a sensitive procedure. I finally got it to a point where I could move fast enough to make an adjustment while runnning, and with very slight adjustments, I got them even, and you could hear the difference right away.
If you have not done it yet, I highly suggest you try syncing. It actually almost solved one of my last problems, a dead spot at high rpm near redline. It is still there, but much better.
All in all the bike has never idled better, and will trundle along at 50kph in 4th gear no problem and still pull without loading up the cylinders. It goes along at highway speed much less frantically than before. It pulls really well through midrange.
Now what am I going to do?
Hopefully some of this information will help you.
I have open exhaust and pod filters.
First, I ordered gaskets, a variety of jets, float needles from Sirius Consolidated in Ontario. Chris was very helpful, as he own an XS400 himself. He put together a kit for me according to my setup.
I ended up with 160 mains, as the 150's I ordered were still lean. That surprised me, as 135 was stock. The jet needle is set all the way lean. I suppose a 155 would have been ideal but I made the 160's by drilling out some 145's using a #51 drill bit, and there was nothing in between.
The pilot is one step bigger, a 45.
The float measurement in the book is whack, so I just adjusted them to the point I figured was best. My needles must be longer or something.
I synced the carbs by eye as the manual says you can, but I still wasn't happy with that. I built a manometer with a yard stick, nylon ties and clear tubing filled with ATF. I couldn't believe how far they were out of sync. When I first started the bike it nearly sucked ATF into the right cylinder. I shut it off, cranked the screw a couple of times, and the left nearly sucked up fluid. Obviously a sensitive procedure. I finally got it to a point where I could move fast enough to make an adjustment while runnning, and with very slight adjustments, I got them even, and you could hear the difference right away.
If you have not done it yet, I highly suggest you try syncing. It actually almost solved one of my last problems, a dead spot at high rpm near redline. It is still there, but much better.
All in all the bike has never idled better, and will trundle along at 50kph in 4th gear no problem and still pull without loading up the cylinders. It goes along at highway speed much less frantically than before. It pulls really well through midrange.
Now what am I going to do?
