KymcoForum.com
General => Technical | How To => Topic started by: YUL713 on December 28, 2018, 05:43:37 PM
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Hi everyone,
Since it is my first post and by way of introduction, I am from Mauritius and the proud owner of a Downtown 250i since October.
As from the moment I got the scooter I have always had a hard time with cold starts and always have to feather the throttle in the process. When the engine has been running for a while, no issues and it starts up just fine. The bike has 2500km on the clock now.
I have brought the bike a few time to the Kymco dealer and have had the MAF sensor changed, spark plug checked, idle speed checked, diag test machine found everything else ok. The problem however remains...
If anyone would have the faintest idea about what to look out for?
Thanks & Happy New Year!
YUL
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Try initializing: ignition off
Run/stop run
Open throttle to stop
Ignition on count 10 seconds, close throttle at 10 seconds
Ignition off
Then try to start, see what happens. Start should occur within two revolutions. Count seconds, "one thousand, two thousand, three thousand..." will be a lot closer than other count methods or use a watch/stop watch. This initializes the TPS and ISC so the mixture is correct at start. Throttle Position Sensor/Idle Speed Control
Tell us what happens. Downtown 250i? Dint know about that one!
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Hard starting is also associated with incorrect valve lash settings. Have the valves been checked?
But surely, your mechanic has already thought of that?
Stig
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Look at Mauritius on Google Earth! I'm tellin' ya, we in the wrong spot! YUL, that island is beautiful!
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Look at Mauritius on Google Earth! I'm tellin' ya, we in the wrong spot! YUL, that island is beautiful!
Yeah, wondered how the heck his scooter has a "cold" start!
Temps range from "hot to balmy"......poor fellow.
Stig
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Yeah, "cold start" ha, ha! Maybe a restaurant there has a big enough walk-in freezer....
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Hi Guys,
Thanks a lot for your replies. It is very true that the "cold start" issues could be re labelled mid-HOT start issues since we are now experience 34+ degrees Celsius everywhere around the island...
Karl, I have tried to initialise as recommended. I have had to do the procedure twice but on the second attempt, seems to work. However I am not home right now so I will only be able to give you a proper feedback in a couple of days.
Thank you all for your help. Will keep you posted.
Yannick
PS: Karl, the 250i is primarily intended for the Asian market. In Mauritius we have a (rather stupid) duty of 75% on motorcycles above 300cc. So the 350i is too expensive here and the agents that imports the bike prefers to order the 250i. We also have the AK550 on special order... but it would cost you approx. US$ 17K...
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Hard starting is also associated with incorrect valve lash settings. Have the valves been checked?
But surely, your mechanic has already thought of that?
Stig
Yul713, your "cold start" problem doesn't sound like a typical valve clearance problem, but whatever it's worth - I wouldn't hesitate to have a close look at the valve lash at your scooter. To my experience on other brands of engines, valve clearance adjustments as a first option to solve starting problems often saved a lot of time and energy....
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Wish I would have thought of what Stig and Scooterfan said!
$17000 USD?! Yow!
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Ak550 in argentina is 20.5k in cash and you add taxes and fees for almost 2k more!
Enviado desde mi iPhone utilizando Tapatalk
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Thanks guys! Will talk to the mechanic about the valve clearance setting and will let you know.
Wishing you all a happy new year with lots of fun rides!
Best
Yannick
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Thanks guys! Will talk to the mechanic about the valve clearance setting and will let you know.
Best
Yannick
Good luck ! They will probably do valve clearance adjustment, get the scooter going - but then deny doing anything about valve clearances.
That's how dealers normally roll - they don't like customers telling them what's wrong.
Happy new year to you too !
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As from the moment I got the scooter I have always had a hard time with cold starts and always have to feather the throttle in the process.
Small engines are always hard to start when cold. It's always been thus since the beginning of time. After a few minutes they warm up and run fine for the rest of the day. Don't worry about it.
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Now fellas ....ease up on the dealers....and a 250 is not a small engine in the scooter world. Bazillions of us in the below-300cc scooter world are enjoying easy start EFI engines all over this planet. Talk to any LIKE200I owner about how their scooter leaps to life on a frigid day! My smaller Piaggio EFI'd engine does the same.
This 250i Kymco engine needs sorting by the dealer. Kymco engine issues are so rare the solution doesn't always leap to mind.
Just my take....
Stig
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Time for an update!
Tried the initialising procedure. It helps on the first start but then once the scooter has been put aside for a while the problem comes back again... strange!
Will definitely talk to the mechanics about the valve clearance and will let you know. Sorry for the (maybe stupid) question but how does a valve clearance issue affect the engine startup only when cold?
Thanks
Yannick
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Time for an update!
Will definitely talk to the mechanics about the valve clearance and will let you know. Sorry for the (maybe stupid) question but how does a valve clearance issue affect the engine startup only when cold?
Thanks
Yannick
Let me explain the other way round - valve lashes which are too small normally cause “hot start†problems (not “cold startâ€problems). The reasons are as follows :
When the engine is cold and there is no lash between a valve stem rocker arm and the rocker arm is j-u-s-t touching the valve stem, the valve will still be closing completely and the engine should start easily when cold.
But when the engine heats up heat expansion takes place and the valve stem will start stretching slightly. When the valve stem starts stretching, the valve will not close properly and will start leaking. Which means:
1. Engine compression will start dropping.
2. A mixture of exhaust fumes and gasoline will be sucked into the combustion chamber.
3. Air / fuel mixture inside the combustion chamber will be incorrect.
Therefore it becomes difficult to start the engine when it is hot - the valve stem will still be slightly stretched and the valve will still not seal properly.
But when the engine cools down again -the valve stem will “crimp†again, the valve will seal again, and the engine will start easily.
You seem to find yourself in a warmer climate, and the lash between your scooter’s rocker arm and valve stems might be right on the edge (zero) - which means the engine might still behave quite strange in a “not so cold†climate when the engine never actually gets that “coldâ€.
Having said all this -if the lash on your rocker / valves are about zero at the moment, you should also experience a starting problem after a ride - when the engine is still hot. Therefore my initial comment “ your ‘cold start’ problem doesn’t sound like a typical cold start problem but...........â€
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Hi Yannick,
It shouldn't - poor valve clearances are usually associated with hot engines, where the slight expansion of the valve means it doesn't seat properly and compression is reduced.
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Hi Yannick,
It shouldn't - poor valve clearances are usually associated with hot engines, where the slight expansion of the valve means it doesn't seat properly and compression is reduced.
Thanks ;)
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Hi Yannick,
It shouldn't - poor valve clearances are usually associated with hot engines, where the slight expansion of the valve means it doesn't seat properly and compression is reduced.
Not to contest your thinking - but time and again I've read that many do not check the valves until the scooter becomes hard to start. That is how long so many PCX owners wait - and it is how long they're told to wait by their forum gurus. "Leave the valves alone until it becomes hard to start." (a PCX is a pain to get to the valves!)
Stig
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If ever that can help, here are 2 engine starts, the "hot" one just after a 30Km commute this afternoon and the "cold" one after a 2 hours rest! Speaks for itself...
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COLD one now
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Rats! Won't play! Where are you? I'll be right over!
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Here we go again:
HOT : https://youtu.be/ymdiOv2PQ7Q
COLD : https://youtu.be/zEugrkgjpws
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Here we go again:
HOT : https://youtu.be/ymdiOv2PQ7Q
COLD : https://youtu.be/zEugrkgjpws
Starts hot and cold?
So, it healed itself....or, what?
Cool dash!
Stig
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Starts hot and cold?
So, it healed itself....or, what?
Cool dash!
Stig
To my understanding from Stig's response the videos actually shows "pretty normal" results about engine behavior on Kymcos with EFI systems. Maybe other owners with EFI scooters should confirm ?
I think this rather looks like a possible fuel supply / air mixture "problem" though.
I just did a quick Google search, and stumbled across some info which is actually not Kymco related :
https://mechanics.stackexchange.com/questions/5643/motorcycle-with-efi-not-starting-well
Looks like you should also get the battery tested, or maybe you need a diagnostic tool to solve the problem.
If the agents are not able or willing to do anything about this, I guess you need to live with the scooter as is - or you need to trade the scooter on a carburetor model.
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Not visible in the video. ....are you touching the throttle when starting?
EFI is a "hands off" start, in 99% of all situations. Scoots and autos.
Maybe a heartbeat or two longer wait before using start button. Give all systems a chance to get fully pants-ed for their days work! (Although, most EFI systems are even American Driver Proof....😊)
Stig
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Hot start = no compression
Cold start = normal compression
My conclusion: first suspect is valve clearances too small.
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Here we go again:
HOT : https://youtu.be/ymdiOv2PQ7Q
COLD : https://youtu.be/zEugrkgjpws
Something doesn't look right. By comparing the two rev counters on the two videos, it looks like after a "cold start" the engine Rpm's are lower just after the engine started - then the Rpm's start creeping higher after a few seconds.
I think this might point at a pressure problem in the fuel line, (i.e. dirty fuel filter, faulty pressure relieve valve, faulty fuel pump, etc) or faulty sensors in the EFI system.
Another question which might be important : What was the ambient temperature during the two tests on the video ?
Maybe this is a Choke-related problem ?
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I was going by the hot start cranking sound: very fast with very little if any variation. The cold crank was like my almost broken in DT300i two turns and run. Good videos on utube by the way!
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Starting a cold engine requires more fuel, less air, which is why we had chokes on old carburetor engines and a cold start circuit on modern EFI engines. I suspect there is a cold start injector or enrichener on your scooter engine that is not working properly.
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I listened and watched the cold start video again just to be sure it started and it did. Not nearly as brisk since it made about 3 revolutions before starting but it started. I still say check and adjust if necessary all valve clearances. .1 mm/.004" and then see what happens.