Stupid fuel leaks on the PC800

I rode my Honda Pacific Coast PC800 motorcycle to work today.  It’s been running well enough the last few months but I hadn’t really taken it on a long jaunt.  As I was going through Sherwood, I started smelling gas.  By the time I got to work, the bike was peeing out gas.

I disassembled the bike behind the office to try and fix the issue.  A little premium gasoline and some seafoam, and I was able to get the float valve unstuck that was causing the float bowls to overflow and dump fuel out of the vent port on the back side of the carb.  However, I can tell this problem is going to keep coming back.  It’s time to search for a new carb.  I’ve rebuilt this carb enough times that I’m getting sick of it.

A surprising gas leak on the PC800

Tonight when I came home from seeing The Hateful Eight at our local Alamo Drafthouse, I smelled some gas. I went down and checked on my fuel injected PC800 to find a small puddle of a mix of gasoline and oil under the bike. I immediately started draining the tank while I removed some plastics to try and determine what was going on.
 
No leaks around the fuel sensor. No leaks around the fuel pump/filter/gas tank outlet. No leaks around the piping going up to the throttle bodies. No leaks on the injectors. But wait a minute…
 
When I took the airbox off, some gas sloshed out of the airbox! It turns out there was quite a bit of gas in the airbox. Some of you might remember that I connected the vent line from the high pressure fuel pump to the airbox. It appears that the airbox and air intake were sucking gas up from the pump the last time I ran the bike (a couple weekends ago). This gas stewed in the airbox eating away at some RTV sealant until it leaked. Or maybe the gas got into the engine oil via the crankcase breather hose and leaked out somewhere lower on the engine (I’ve got a slow oil leak that’s been with the bike for the last 30,000 miles).
 
I’ll do a little more sleuthing tomorrow once the residual fuel evaporates around the bike to find the place where the leak came out to make sure it was some RTV that I had used to seal a hole on the bottom of the airbox and not something else.
 
Luckily I have a California-style gas cap (the one with the hose barb) laying around that I can plumb the vent line from the fuel pump to. That should solve that problem, assuming that was the problem.
 
Always something exciting in my garage!

The complete fuel injected PC800

I made a 20 minute long video walking through all of the many modifications that I have made to my PC800 over the years including the custom fuel injection system running on a MicroSquirt ECU. I’m contemplating selling my bike or the fuel injection system to get ready for the next big project that I have in mind.  If you’re interested, please get in touch with me.

A partial list of the modifications includes: