01 Sportster LE Carb loses power between 6-7k rpm?

[bkwashby]

I have an 01 Sportster LE Carb with the 951 engine. Rebuilt two years ago, carbs too. Wear ring/impeller is new, carbon seal is new. Replaced check valve in RAVE system and RAVE's are clean and operating smooth. Doesn't foul the plugs and cylinder compression is 130psi pto side and 128psi mag side. Gas is pre-mix 40:1 and fuel filter is new. Whenever I get into the 6-7k rpm range it doesn't have power. If I turn the wheel the back pressure against the pump is enough to cause the rpm to go down to between 6200-6500 rpm then goes back up when I straighten the wheel but doesn't stay constant like it used too, it tops out at about 6800rpm instead of 7000rpm like it used to also. Started last year near the end of the summer. Thought it was bad gas or water in the gas but I've used gas line antifreeze and gone through about 6 or so tanks of gas since and it's still doing it? Any suggestions would be greatly appreciated. Could it be the solenoid valve for the RAVE system? The stator or the ignition coils not pumping out enough of a spark? Could it be that the switch in the throttle cable isn't working properly to advance the spark at 80+% throttle?

 

[Dr Honda]

I would check the reed valves. You may have one that is cracked. Also... if it's getting to 6800... then that's about right for an engine with some time on it. Your compression sounds ok... but it is a little low. A new engine would be 135psi... and a slight loss in static compression would show up as a slight loss in power.

 

[bkwashby]

I figured it out. The threads on the fuel filter assembly were stripped and not making a good seal so air was being sucked into the fuel lines. Also rechecked the compression, this time I remembered to open the throttle full like I was supposed to the first time and got 132psi on both cylinders. Replaced the plastic fuel filter assembly with a metal inline filter because plastic filters are not legal in an inboard motor application (at least in Ontario). So everything is good now. 7100 rpm with no loss in power on turns and 51mph top end again.

 

[drjack]

I'm interested in your metal fuel line filter. Where did you find that part?

 

[bkwashby]

I'm interested in your metal fuel line filter. Where did you find that part?

I just went to a place that does boat repairs and they had one hanging on the wall so I grabbed it. It's just a standard inline fuel filter. Nothing special about it.