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Old October 9th, 2019, 09:00 PM   #1
NewtoNinjettes
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Engine slow to fall the last 2000k rpm before idle.

So long story short. Just picked up an all stock 2007 pregen. It had no key, so I was just able to try to start it today when I received the correct Ignition switch. Cleaned the carbs, airbox, petcock and flushed the fuel tank with fresh fuel, before trying to start it. Airfilter foam had crumbled into breadcrumbs so that had to be removed and cleaned.

Upon starting the bike for the first time it ran at 5k rpm with the coke on, and wouldn't dip below 3k rpm with the choke off. Checked choke to make sure it was fully disengaging. Added a make shift air filter foam and lowered the idle speed and it runs great except on free rev decel the rpm drop is slow from 2500 rpm to 1200 rpm where it idles nicely. It's not a big problem but would prefer for it to function correctly. Any ideas?
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Old October 9th, 2019, 09:12 PM   #2
BoBO
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The carburetor might be out of sync assuming that your carbs are clean and your valves are in spec. Also, you might want to check for vacuum leaks by spraying water after the engine is warmed up. Could be the hoses or around the air box. Hopefully you find out what it is and let us know.
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Old October 10th, 2019, 07:21 AM   #3
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I agree - sounds typical of a vacuum leak.
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Old October 10th, 2019, 06:30 PM   #4
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I've found the 2 vac hoses between the carbs, or 3 hose points at top of decel valve can be loose and prone to leakage when hot....check those specific areas.
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Old October 10th, 2019, 07:07 PM   #5
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Yeah, I zip-tie those little hose-ends onto carbs to keep them from opening-up and leaking when warmed up.
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Old October 16th, 2019, 03:08 PM   #6
NewtoNinjettes
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Ok going over all of the hoses with a fine tooth comb now. First odd thing I noticed is that of the three hoses exiting the back of fuel tank, blue, black and red, the red one which is attched the furthest to the shifter side of the bike and running to the inlet on the 4 way connection to the evap cannister labeled "tank" had a significant amount of water drip out of it when I took it off. Is this a water drain line for the area around the fuel cap? If so why is it connected into the vacuum system that leads to the carbs? Sounds like a bad combo to me, or is it hook to the wrong tank outlet? Is water normal in that line?
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Old October 18th, 2019, 06:44 PM   #7
NewtoNinjettes
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Appears I had it hooked up correctly according to the diagrams I found. Also I guess I have a Cali bike because it has an evap cannister system which I guess maybe was unique to the California model? Anyways went over all the lines. Can't find a Vacuum leak and still having the slow rev down issue, even tried bypassing the evap/vapor recovery system to see if it was somewhere in there. No change. Now I'm back to thinking carb issues. No sure what to do next.
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Old October 19th, 2019, 12:14 AM   #8
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Quote:
Originally Posted by NewtoNinjettes View Post
Appears I had it hooked up correctly according to the diagrams I found. Also I guess I have a Cali bike because it has an evap cannister system which I guess maybe was unique to the California model? Anyways went over all the lines. Can't find a Vacuum leak and still having the slow rev down issue, even tried bypassing the evap/vapor recovery system to see if it was somewhere in there. No change. Now I'm back to thinking carb issues. No sure what to do next.
Try replacing the o rings on the mixture screws under the carbs at the Botton of the float bowls. That was where my was leaking.
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Old October 19th, 2019, 12:57 AM   #9
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Also make sure needle jets aren't backwards.
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