KymcoForum.com
Scooters - 125 to 300 => Downtown 300 => Topic started by: avila2474 on January 28, 2021, 06:19:06 PM
-
Greetings community! I´m sorry for my bad English.
I have a Kymco Downtown 125 € 4 from 2017, which for a few days has had a problem, and that is that when I slow down to stop, the motorcycle idle (without transmission load), it stays slightly accelerated. That is, when I stop, the bike stays at 2200 RPM's and then progressively drops to 1800, which is its idle. I didn't do it before, so i have made the following checks:
1. Valve adjustment.
2. Check the throttle cable to see if it was stuck in any section of the sheath. Negative result.
3. Check the throttle body spring travel. I have lubricated it lightly with Oil 3 & 1 with the same result. It slides much better than before and the end of the race can be felt strongly.
4. I have reset the TPS and ELP sensors according to the motorcycle workshop manual.
5. I have cleaned the lambda probe with ultrasound. It has been quite good and has released charcoal.
6. I have loosened the engine drive belt and tested the engine idle (no load) and it does the same, it stays accelerated and progressively lowers to idle. The purpose of this is to rule out problems with the variator or with the clutch or pulleys.
The only thing left to do is disassemble the throttle body to see if it has any kind of dirt in the ducts or in the potentiometer.
Say that the filter you have right now is the 300 filter, since I have read that incorporating it improves behavior. The truth is that it does work, but it is a very subtle improvement so I will soon put the one on the 125 again. I imagine that the throttle body has probably gotten dirty or swallowed dust and blocked a duct.
In your experience, what can cause this type of failure?
-
check twist grip and throttle cable---little lube will not hurt anything.
-
What John said AND take your second key and open the gas cap the next time this happens. Do these two things before you take everything apart.
-
Idle speed control valve or air intake leak.
-
[quote author = john grinsel link = topic = 30716.msg215175 # msg215175 date = 1611866429]
Check twist grip and throttle cable. A little lubricant will not harm anything.
[/quote]
As I already mentioned, this is not because the cable from the grip to the throttle body spring does not get stuck. In fact, I applied some oil to the throttle body spring and now it glides much better, the stopper feels forcefully on the throttle. I have checked where the throttle screw stops on the throttle body and it is clear that it reaches the end of its travel.
[quote author = CROSSBOLT link = topic = 30716.msg215176 # msg215176 date = 1611870753]
What John Said And take your second key and open the gas cap the next time this happens. Do these two things before taking everything apart.
[/quote]
I do not understand this, if there is a possible clog in the gasoline filter, can it cause this type of failure?
[quote author = mousejunks link = topic = 30716.msg215186 # msg215186 date = 1611894297]
Idle control valve or air inlet leak.
[/quote]
Where is the control valve located? About the air leak, I take note.
-
According to this link, there are idle adjust screws you can change.
https://www.bike-parts-kymco.uk/kymco-motorcycle/125-SCOOTER/DOWNTOWN/DOWNTOWN_125_I_ABS_EURO_3/CARBURATION/177/8/0/177 (https://www.bike-parts-kymco.uk/kymco-motorcycle/125-SCOOTER/DOWNTOWN/DOWNTOWN_125_I_ABS_EURO_3/CARBURATION/177/8/0/177)
-
The vacuum operated fuel tank vent valves may stick. Opening gas cap will immediately correct your fast idle if that is the problem.
No disassembly required.
-
According to this link, there are idle adjust screws you can change.
https://www.bike-parts-kymco.uk/kymco-motorcycle/125-SCOOTER/DOWNTOWN/DOWNTOWN_125_I_ABS_EURO_3/CARBURATION/177/8/0/177 (https://www.bike-parts-kymco.uk/kymco-motorcycle/125-SCOOTER/DOWNTOWN/DOWNTOWN_125_I_ABS_EURO_3/CARBURATION/177/8/0/177)
According to the service manual, the screws with the reference 16170 cannot be modified, since they control the idle speed and are pre-configured at the factory. In fact, they have a cover that in the exploded view is 16112.
I will upload photo when possible. I will now go to the parking lot a to review what Forero Crossbolt said.
-
The vacuum operated fuel tank vent valves may stick. Opening gas cap will immediately correct your fast idle if that is the problem.
No disassembly required.
I have tested the bike with the gas tank open and the problem continues. So discarded.
-
Yes! You have discovered one thing that is NOT! Just as valuable.