Dear Dogs, I need some help...
My wife's 2006 Honda CBR 125R (carb model) is driving me crazy. The thing starts with/without the choke, and when warm, you can rev it until even Marques feels sorry for it. Idles perfectly, no issues. When you ride it and go through the gears to build up speed it's perfectly fine. When, however, you are at a constant speed, let's say 70km/h in 4/5/6th gear it feels as though something is constantly opening and closing the throttle ever so slightly - losing power, gaining power, losing power, gaining power. If you drop a gear and pin the throttle it picks up speed easily until you run out of space on the rev counter. If you go faster/slower it's a little better, but the jerkiness is still there.
What I've done so far:
1. Spark plug - I have 2 new plugs, both at different heat settings and gaps set as recommend by the Haynes manual. Both do it.
2. Replaced the ignition coil and plug cap - both new and old do the same.
3. Replaced the vacuum petcock at the bottom of the tank. Glad I did as the seals were busted and the filter element was cracked. Did not help.
4. Replaced the fuel and air lines running from the tank to the carb.
5. Replaced the fuel filter.
6. Replaced the air filter.
7. Took the carb off and gave it a good clean inside and out. I did not replace any needles etc.
8. Valve settings were checked in the first lockdown.
Could the 2x vent pipes under the fuel tank have anything to do with it? They are not pinched and I can blow through them. Running with the fuel cap on/off doesn't make any difference.
Any ideas?
My wife's 2006 Honda CBR 125R (carb model) is driving me crazy. The thing starts with/without the choke, and when warm, you can rev it until even Marques feels sorry for it. Idles perfectly, no issues. When you ride it and go through the gears to build up speed it's perfectly fine. When, however, you are at a constant speed, let's say 70km/h in 4/5/6th gear it feels as though something is constantly opening and closing the throttle ever so slightly - losing power, gaining power, losing power, gaining power. If you drop a gear and pin the throttle it picks up speed easily until you run out of space on the rev counter. If you go faster/slower it's a little better, but the jerkiness is still there.
What I've done so far:
1. Spark plug - I have 2 new plugs, both at different heat settings and gaps set as recommend by the Haynes manual. Both do it.
2. Replaced the ignition coil and plug cap - both new and old do the same.
3. Replaced the vacuum petcock at the bottom of the tank. Glad I did as the seals were busted and the filter element was cracked. Did not help.
4. Replaced the fuel and air lines running from the tank to the carb.
5. Replaced the fuel filter.
6. Replaced the air filter.
7. Took the carb off and gave it a good clean inside and out. I did not replace any needles etc.
8. Valve settings were checked in the first lockdown.
Could the 2x vent pipes under the fuel tank have anything to do with it? They are not pinched and I can blow through them. Running with the fuel cap on/off doesn't make any difference.
Any ideas?
