I recently installed a brand new Honda GXH50 engine from smallenginewarehouse.com on my bike (to replace its Hua Sheng 142F). I installed a very nice throttle control linkage that I bought from a guy here on the forum.
I now have just over 100 miles on the engine. Up until my last couple of rides, the motor ran great. But now it's acting a bit quirky.
The engine usually starts on one pull; it wants full choke to start, but I can turn off the choke completely immediately after starting the engine. It idles smoothly. But when I give it throttle, the motor seriously bogs down, and doesn't recover. When this bogging first began happening, it was always after I had ridden a few miles. But now it happens right after I've started the engine.
I can get acceptable performance (enough to ride home from wherever I've wandered) by giving the carb about 1/2 choke. I don't get full power under these conditions, but I can do at least 25 MPH. The engine always idles nicely; before and after putting it under load. And the engine hasn't ever stalled under any circumstances.
I'm using a new gas tank, lined with a Caswell novolac epoxy kit. I've got new fuel lines with a new sintered bronze inline filter. My 87 octane gas is fresh, and treated with Sta-Bil. I've checked the tank's gas cap for proper venting.
Right now, I'm suspecting that my problem may be related to the Honda carb's air/fuel mixture screw. The design of the mixture screw doesn't allow much adjustment at all (as seen in the photo below). Turning the screw within its limited range of motion doesn't seem to make much difference in how the engine runs. I'm guessing that the funky screw head must pop off to reveal a normal head beneath it, but I'm hesitant about getting too agressive with this adjustment screw before I hear from somebody with experience! I'm also guessing that limiting the mixture screw's range of motion has something to do with Honda controlling the engine's emissions...for the U.S. E.P.A.
Any ideas?
..................................
UPDATE:
This morning, after writing the query above, I took out the bike, started it up, and rode 12 miles. She ran superbly the whole time; from startup to kill switch. I got up to 34 MPH a couple of times. I figured I'd ride until the bogging started, but she wouldn't.
I did nothing differently from yesterday: no changes to anything on the bike, same roads, same gas, etc. The only thing that I can think of that's different: this morning, it was about 64F with VERY low humidity of 37% (southeastern Connecticut shoreline). In recent days, we had a serious humid streak around here.
So, I'm cautiously optimistic...
I now have just over 100 miles on the engine. Up until my last couple of rides, the motor ran great. But now it's acting a bit quirky.
The engine usually starts on one pull; it wants full choke to start, but I can turn off the choke completely immediately after starting the engine. It idles smoothly. But when I give it throttle, the motor seriously bogs down, and doesn't recover. When this bogging first began happening, it was always after I had ridden a few miles. But now it happens right after I've started the engine.
I can get acceptable performance (enough to ride home from wherever I've wandered) by giving the carb about 1/2 choke. I don't get full power under these conditions, but I can do at least 25 MPH. The engine always idles nicely; before and after putting it under load. And the engine hasn't ever stalled under any circumstances.
I'm using a new gas tank, lined with a Caswell novolac epoxy kit. I've got new fuel lines with a new sintered bronze inline filter. My 87 octane gas is fresh, and treated with Sta-Bil. I've checked the tank's gas cap for proper venting.
Right now, I'm suspecting that my problem may be related to the Honda carb's air/fuel mixture screw. The design of the mixture screw doesn't allow much adjustment at all (as seen in the photo below). Turning the screw within its limited range of motion doesn't seem to make much difference in how the engine runs. I'm guessing that the funky screw head must pop off to reveal a normal head beneath it, but I'm hesitant about getting too agressive with this adjustment screw before I hear from somebody with experience! I'm also guessing that limiting the mixture screw's range of motion has something to do with Honda controlling the engine's emissions...for the U.S. E.P.A.
Any ideas?
..................................
UPDATE:
This morning, after writing the query above, I took out the bike, started it up, and rode 12 miles. She ran superbly the whole time; from startup to kill switch. I got up to 34 MPH a couple of times. I figured I'd ride until the bogging started, but she wouldn't.
I did nothing differently from yesterday: no changes to anything on the bike, same roads, same gas, etc. The only thing that I can think of that's different: this morning, it was about 64F with VERY low humidity of 37% (southeastern Connecticut shoreline). In recent days, we had a serious humid streak around here.
So, I'm cautiously optimistic...
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