Carbs leaking, starting problems (still)

Posted by alehman on Jun 11, 2012; 2:36am
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/Carbs-leaking-starting-problems-still-tp4022717.html

I have a very mysterious bike. Really, I have two issues, despite painstaking efforts: the #1 (and now #3 and #4) bowls will not stop leaking through the drains, and the bike simply won't start.

As for the leaking, I have done many things trying to solve it. I have cleaned and rebuilt the carbs. It's not the drain screws, I've checked that. I have checked the floats in gasoline, and they all work. I have cleaned the needle valve seats and replaced the needle valves. I have even adjusted the tangs on the floats slightly. After all those fixes I ran water through the fuel line to test if it still leaked and it didn't at all, but when I attached it to my tank it started leaking right away. The only thing I can think of is that there's junk in my tank that's getting into my carbs and messing with the seating of the needle valves. There's nothing large or visible but the gas is kind of rosy red like rust. Could that be my problem? Other than that, fuel delivery seems to be fine, so I'm ruling that out as something that would prevent the bike from starting.

To the second issue. A little background--- the bike has backfired before through the carbs, which leads me to think that either the valve timing or clearances is off if combustion gasses can escape through the intake valves. I have checked the valve timing marks on the cam sprockets, and they're pretty aligned with the valve cover surface as they should be. They're maybe a few millimeters off, but if I adjusted the chain a tooth, it would be even more off. So no problem there. I have also checked the clearances- they're pretty on spot. So it seems like compression shouldn't be an issue for the bike starting. I'm going to run a proper test soon, but I still can't figure it out why it backfired through the carbs.

I have spark, but it's pretty thin. Shouldn't it still fire with minimal spark though?

What seems to be my issue??