RaWarrior
Well-Known Member
So once again I'm balls-deep in the annoying world of "making an old carb 2 stroke run well", this time it's for my FL350 Odyssey.
Little background:
329cc single cylinder, air cooled, reed valve 2 stroke mill
STOCK carb was a 32mm Keihin PE round slide, #142 main #58 pilot
Motor compression is perfect book spec at 130psi
The p/o said the main jet snapped off in the original carb when he took it apart to clean it, so he replaced the whole carb with an "equivalent" Mikuni. It would start and idle and rev up OK, but under load it would fall on it's face and wouldn't rev past 4-4500 or so. He said the jetting was probably wrong and I agreed. The plug was really black and wet, and it seemed like it was just flooding out when you got on the gas. Looking up the conversion table, a #142 Keihin jet is about equal to a 125 Mikuni. There was a 250 in the replacement carb, I swapped in the 125. Better but far from perfect.
Idle is OK, about as good as you can expect from an old 2smoke. Hangs out at about 1000rpm or so. To get it "off idle", you need to "tickle" the gas. Slowly pressing on the flipper results in it bogging out and stalling. Once it's revved up, quick stabs at the gas are snappy and responsive, but if you press it past 3/4 throttle or so, it falls on its face. With the 250, anything past 1/2 throttle would just make it sputter and fart and bog and not really go anywhere (but not kill it...just wouldn't have any power or pick up RPMs)
Out driving it, it seems to run great between 1/4 and maybe 90% throttle. Push it that last tad to WOT and it's as if you hit the kill switch, goes from screaming to dead, back off and it recovers instantly.
Someone wrote "32" in sharpie on the carb bowl, I measured the ID of the motor side and got 34mm(which I guess is a common replacement size). Looking into some other forums, people report their setups for this carb run anywhere from 310(stock) to 450(piped ported) mains.....how can that be if I'm mega-rich with a 125? And with the 250 in there it ran like total crap.
The plug is a darkish gray with maybe a hint of tan in there. It's usually wet, and the exhaust smells rich. Here's the weird thing....pulling the choke (bypass valve like on the vmax) makes it run better. The bogging gets better, and hitting WOT doesn't kill it anymore. Similarly, dropping the needle(to try and lean it out), makes everything worse....best case was with it on the lowest/richest clip.
So I'm kind of stumped here....this doesn't add up. I went through the carb, and I couldn't find anything out of place...float valve didn't leak and was set properly, no jets backed out, nothing plugged, the carb looked almost new.
Anyone good with these 2 smokers? Any ideas?
Little background:
329cc single cylinder, air cooled, reed valve 2 stroke mill
STOCK carb was a 32mm Keihin PE round slide, #142 main #58 pilot
Motor compression is perfect book spec at 130psi
The p/o said the main jet snapped off in the original carb when he took it apart to clean it, so he replaced the whole carb with an "equivalent" Mikuni. It would start and idle and rev up OK, but under load it would fall on it's face and wouldn't rev past 4-4500 or so. He said the jetting was probably wrong and I agreed. The plug was really black and wet, and it seemed like it was just flooding out when you got on the gas. Looking up the conversion table, a #142 Keihin jet is about equal to a 125 Mikuni. There was a 250 in the replacement carb, I swapped in the 125. Better but far from perfect.
Idle is OK, about as good as you can expect from an old 2smoke. Hangs out at about 1000rpm or so. To get it "off idle", you need to "tickle" the gas. Slowly pressing on the flipper results in it bogging out and stalling. Once it's revved up, quick stabs at the gas are snappy and responsive, but if you press it past 3/4 throttle or so, it falls on its face. With the 250, anything past 1/2 throttle would just make it sputter and fart and bog and not really go anywhere (but not kill it...just wouldn't have any power or pick up RPMs)
Out driving it, it seems to run great between 1/4 and maybe 90% throttle. Push it that last tad to WOT and it's as if you hit the kill switch, goes from screaming to dead, back off and it recovers instantly.
Someone wrote "32" in sharpie on the carb bowl, I measured the ID of the motor side and got 34mm(which I guess is a common replacement size). Looking into some other forums, people report their setups for this carb run anywhere from 310(stock) to 450(piped ported) mains.....how can that be if I'm mega-rich with a 125? And with the 250 in there it ran like total crap.
The plug is a darkish gray with maybe a hint of tan in there. It's usually wet, and the exhaust smells rich. Here's the weird thing....pulling the choke (bypass valve like on the vmax) makes it run better. The bogging gets better, and hitting WOT doesn't kill it anymore. Similarly, dropping the needle(to try and lean it out), makes everything worse....best case was with it on the lowest/richest clip.
So I'm kind of stumped here....this doesn't add up. I went through the carb, and I couldn't find anything out of place...float valve didn't leak and was set properly, no jets backed out, nothing plugged, the carb looked almost new.
Anyone good with these 2 smokers? Any ideas?