Hello All - my first post on this forum, with what’s to me a Maddening Issue:
Bike revs well for about 14-20 seconds when started stone cold, then only idles. When you twist throttle, even slowly, engine stutters, bogs, backfires - will not increase rpm. Will not rev again until having sat for some hours or overnight.
Background:
Friend who owns bike bought it at a swap meet in Austin TX, said it did same thing upon purchase.
Things done:
Cleaned carbs and installed 45 pilot and 117.5 main jets to account for our 7000’ elevation and pod filters. Floats set to 22mm height. Pried off idle screw plugs, found them to be set at 3.5 turns out, turned in to 2 turns, idles a bit better but no effect on “no rev when warm” problem. Slides move up and down freely, tho springs seem a bit strong.
Checked coils both cold and hot, same resistance 3.5 primary, around15k secondary.
Shows bright, robust spark on both sides with plugs laid on heads, cold or warm.
Ignition advance turns freely, springs back quickly when released.
Shows compression of 110-112 psi on both sides, normal - commensurate with x .8 altitude factor.
Left plug remains dry, tiny bit of gas on right plug.
I am accustomed to CDI boxes either working or no spark.
Left to wonder could it be signal generator? How does one test it, if that’s possible.
if I’m missing something, hoping someone can point me in the right direction, thanks!
Bike revs well for about 14-20 seconds when started stone cold, then only idles. When you twist throttle, even slowly, engine stutters, bogs, backfires - will not increase rpm. Will not rev again until having sat for some hours or overnight.
Background:
Friend who owns bike bought it at a swap meet in Austin TX, said it did same thing upon purchase.
Things done:
Cleaned carbs and installed 45 pilot and 117.5 main jets to account for our 7000’ elevation and pod filters. Floats set to 22mm height. Pried off idle screw plugs, found them to be set at 3.5 turns out, turned in to 2 turns, idles a bit better but no effect on “no rev when warm” problem. Slides move up and down freely, tho springs seem a bit strong.
Checked coils both cold and hot, same resistance 3.5 primary, around15k secondary.
Shows bright, robust spark on both sides with plugs laid on heads, cold or warm.
Ignition advance turns freely, springs back quickly when released.
Shows compression of 110-112 psi on both sides, normal - commensurate with x .8 altitude factor.
Left plug remains dry, tiny bit of gas on right plug.
I am accustomed to CDI boxes either working or no spark.
Left to wonder could it be signal generator? How does one test it, if that’s possible.
if I’m missing something, hoping someone can point me in the right direction, thanks!
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