Runaway RPM's when shifting

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mash2378

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I have been experiencing a strange situation recently with my 72 Commando where when I pull the clutch in to shift the RPM's seem to spike or at least remain elevated. I am also seeing this when I slowly roll on the throttle while in gear, especially first. The only solution when I have this happen between shifts is to keep the clutch lever pulled in and quickly roll hard on the throttle. That quick spike in RPM will usually calm the bike for lack of a better term. I am suspicious that it may be the slide sticking in the carb which may explain why a quick blip of the throttle would help it unstick. Anyone else ever experience this or have thoughts? Thanks very much.
 
Check for air leaks, ie: loose carb and manifold fasteners and cable for snagging routing on loose carbs or throttle cables. A good Norton Snort tends to pull things together for teasing intervals.
 
Do you have points ignition? The automatic advance mechanism can stick on them making them run fast.
 
yes - slide sticking most likely - can happen to amals if their overly tightened thus causing distortion of the body to the slide , or to amal / mikuni carbs from using ethanol fuel in a fiberglass tank and the fiberglass melting as a result and gumming up the slides - you can try taking them apart cleaning (do they have a thick reside on them if fiberglass tank?) and put back on (tighten lightly) and see what happens

the
mash2378 said:
I have been experiencing a strange situation recently with my 72 Commando where when I pull the clutch in to shift the RPM's seem to spike or at least remain elevated. I am also seeing this when I slowly roll on the throttle while in gear, especially first. The only solution when I have this happen between shifts is to keep the clutch lever pulled in and quickly roll hard on the throttle. That quick spike in RPM will usually calm the bike for lack of a better term. I am suspicious that it may be the slide sticking in the carb which may explain why a quick blip of the throttle would help it unstick. Anyone else ever experience this or have thoughts? Thanks very much.
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You said carb, not carbs, so are you running a single carb like a Mikuni? When I had one on my bike I used one of my old Amal springs inside the Mikuni spring because the slide would hang up. Many others with Mikunis have experienced this problem.

Russ
 
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