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Joined: Apr 30, 2014 2:44:28 GMT -5
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Post by userix on Jan 13, 2015 0:32:22 GMT -5
What would cause an erratic idling when there is no apparent air leaks anywhere from the air filter of the carb to the intake manifold mounting point? After the engine has warmed up, sometimes at a stoplight, my idle would be around 2200 rpm and sometimes it would drop back down to 1900-2000 range. Sometimes at stop, it might drop way below to 1500-1700 randomly, but it doesn't stall out and would return to normal 1900-2000rpm. But there is no consistency with the idling. Sometimes it would keep around 1900-2000 when at stop. The scooter runs fine and I don't experience any performance issues from acceleration to WOT top speed running.
The pilot A/F screw setting is set right and throughout the ride, I never touched the idle adjustment screw. The throttle cable is in good condition and there is no slack or loose bolts.
When I got home, I performed the carb cleaner spray test and I practically sprayed the whole carb and the intake manifold where the carb connects and also where it connects to the engine cylinder. And the idle remains perfectly fine with no apparent dips or speeding up of the idle speed. I have also opened the carb and cleaned out the jets and the inside. The diaphragm at the top of the carb is also in good condition, no tears or leaks there.
It's just weird because my scooter used to idle consistently in the past and now it would have random times where the idle would be erratic.
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Post by geh3333 on Jan 13, 2015 3:36:24 GMT -5
Sometimes it seems like a new carb turns out to be the best option . I along with others have had problem with these stock carbs ,and no matter what u did to it the problem would not go away. I'm not saying it def the carb however I would def start there.
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Post by jerseyboy on Jan 13, 2015 7:18:48 GMT -5
Yeah I always keep a stock back up carb just in case I run into a problem where I know all jets/ports are clean with no air leaks and it still surges..how many miles on the scoot,,wonder if the crank seals are leaking?
I don't know enough about the enricher or ACV valve to say it may be them,,but I would check their functionality as well..
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Post by JerryScript on Jan 13, 2015 11:20:57 GMT -5
What is your idle speed set to? 2200rpm is enough to engage the clutch on stock setups.
Often times during the winter, when we have to adjust our carbs more rich for the cooler air, in the process the idle speed may have been raised. If it was raised enough, your clutch may be grabbing during idle. Over the course of a few days of this, it will begin to grab and slip (beginning to glaze over), causing your idle to go up and down.
If this turns out to be your problem, adjust the idle back down, and sand your clutch pads.
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Post by geh3333 on Jan 13, 2015 11:36:50 GMT -5
What is your idle speed set to? 2200rpm is enough to engage the clutch on stock setups. Often times during the winter, when we have to adjust our carbs more rich for the cooler air, in the process the idle speed may have been raised. If it was raised enough, your clutch may be grabbing during idle. Over the course of a few days of this, it will begin to grab and slip (beginning to glaze over), causing your idle to go up and down. If this turns out to be your problem, adjust the idle back down, and sand your clutch pads. Yeah it seems to me like the clutch was grabbing causing the scoot to surge forward. I once was adjusting my carb and I knew it was set too high but I forgot to turn the idle screw down , lol needless to say when i started the scoot it took off on me . I chased it for about 1/4 mile until it finally picked up speed and left me in the dust . it came back a couple hrs later and I never spoke of it until now . LOL , it was more like I started the scoot and it took off , went a couple feet and fell over. Luckily no one saw what happened. Lol |
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Freshman Rider
Currently Offline
Posts: 94
Likes: 3
Joined: Apr 30, 2014 2:44:28 GMT -5
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Post by userix on Jan 13, 2015 18:03:49 GMT -5
Yeah the crank seals are fine. I actually replaced a leaking one recently but before when it was leaking, there were no surges. As for the enriched, I actually sealed it off with jb weld a long time ago, so that's completely out of the equation. But I haven't had any issues riding back then. It could be the cold weather, which I assume colder air is denser which in turn leads to a leaner condition?
But the weird thing is that it doesn't always act up during my ride. It would only randomly surge at 2200 rpm at stop lights. As for my idle, even at 2200, my clutch isn't engaging or slipping. So it's not glazing my pads. I just find it awkward why it only randomly happens sometimes and not all the time, when nothing else has changed during the ride
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Post by rcq92130 on Jan 13, 2015 18:59:52 GMT -5
HA!
Scoots are just so rebellious and disrespectful these days. I'll bet hwatever it was doing after it left you in the dust you REALLY don't want to know.
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Post by jerseyboy on Jan 13, 2015 19:03:34 GMT -5
Yeah the crank seals are fine. I actually replaced a leaking one recently but before when it was leaking, there were no surges. As for the enriched, I actually sealed it off with jb weld a long time ago, so that's completely out of the equation. But I haven't had any issues riding back then. It could be the cold weather, which I assume colder air is denser which in turn leads to a leaner condition? But the weird thing is that it doesn't always act up during my ride. It would only randomly surge at 2200 rpm at stop lights. As for my idle, even at 2200, my clutch isn't engaging or slipping. So it's not glazing my pads. I just find it awkward why it only randomly happens sometimes and not all the time, when nothing else has changed during the ride It could very well be a bad batch of corn fuel,,where did you fill up last? Id run it a tank or two and see if it doesn't change...obviously try to get fuel at another station. Dump a few oz. of that Lucas fuel treatment in it as well,,that stuff is amazing...$4.89 walley world. |
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Post by JerryScript on Jan 13, 2015 22:41:45 GMT -5
Yeah the crank seals are fine. I actually replaced a leaking one recently but before when it was leaking, there were no surges. As for the enriched, I actually sealed it off with jb weld a long time ago, so that's completely out of the equation. But I haven't had any issues riding back then. It could be the cold weather, which I assume colder air is denser which in turn leads to a leaner condition? But the weird thing is that it doesn't always act up during my ride. It would only randomly surge at 2200 rpm at stop lights. As for my idle, even at 2200, my clutch isn't engaging or slipping. So it's not glazing my pads. I just find it awkward why it only randomly happens sometimes and not all the time, when nothing else has changed during the ride Correct, you need to richen your a/f during the winter, and lean it out during the summer. And yes, too lean could cause idle fluctuations. |
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