Categories: all aviation Building a Biplane bicycle gadgets misc motorcycle theater
The old fashioned, down-home jettin' blues
Jetting a carburetor, for all intents and purposes, sucks.
That's where the CL175 is now. I've tackled the big, gross problems, and I'm starting to move onto the smaller, subtler problems. In this case, jetting.
When I rode the bike into work a few weeks ago, it was fine, but I noticed it seemed to lack power going up a hill. Other than that, it was ok, and I figured maybe I was just getting used to it. Then I started riding it with a more critical eye toward the problem, and discovered that it was losing power at full throttle. Not just "You're riding a wimpy bike" losing power, but obviously "This bike should be making more power, but something's holding it back."
So, with a bit more research, I decided that it must have a fuel flow problem. It felt exactly as if it could sustain full throttle for a moment, but then it would run out of power, as if gas just wasn't arriving at the carburetor fast enough. If I let the throttle go, so that it was using practically no fuel, I could get another momentary burst of full throttle before it went all feeble again.
I pulled off the tank, and rattled around a length of chain inside it, trying to knock all the rust off. I flushed it with gasoline, through a series of coffee filters until there was nothing else showing up (and got a goodly collection of rust flakes and crud in the process). I pulled the petcock and carefully cleaned it out and blew compressed air through every passageway, although it was already pretty much spotless. I pulled off the carburetors, and checked the float height, which seemed to be spot on.
After all that, I went and rode it. It was, if anything, worse than before. I don't know if my expectations changed, or if the carburetion got even worse, but it was just terrible now. It'd run at a cruising speed and with mild acceleration, but anything close to full acceleration sapped its strength something fierce.
So, tonight, I pulled off the carbs and cleaned them thoroughly, getting off all the crud and making everything as beautiful as possible. I unclogged jets, and set float levels properly, and did everything. I even fixed a pinhole leak in one of the floats (although I also dented it, so that was definitely a "one step forward, two steps back" kind of operation). After all that, I went out and rode it up and down the block, and.... The exact same problem.
So now, I'm kind of stumped. It's acting exactly as if it's running out of fuel, but I've done everything I can to make sure it's not (even including filling up the tank). If I run it much more like this, I'm going to damage the engine from running too lean.
I've got a couple of carb rebuild kits on the way, but I don't think they'll solve anything -- the wear and damage in the current parts should be making it run too rich, if anything. The adjustments I've made should also be aiming it much more at the "too rich" side of things, yet it persists in running too lean.
When it has fuel, it runs really well (so I think the jetting is actually about right), but all too quickly, it seems to run out of fuel in the float bowls, and the game's all over. Very, very frustrating.
Posted at 09:14 permanent link category: /motorcycle
Categories: all aviation Building a Biplane bicycle gadgets misc motorcycle theater