Author Topic: Kymco dt125 engine surges downhill  (Read 633 times)

Kevin newbie

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Kymco dt125 engine surges downhill
« on: June 16, 2017, 11:25:24 AM »
Hi all, new to the forum. I have a DT125i, am experiencing a curious problem with the engine. This problem only came up after an accident last year in Italy, when I was rear ended by a car. Since then I have used the  bike and had this problem, but it only happens when I ride downhill for a bit. I try to accelerate and the response from the engine is jerky and somewhat delayed. The problem can go on for several minutes after the downhill run, even when I'm riding on flat roads again. We have had a look to see if the rubber joiner at the air intake to the cylinder is okay and it appears to be tight. Can it be the shock from the accident has caused a problem for the efi? Otherwise it runs fine i.e. Uphill, or on the flat.
I really love this DT125i. It is a dream to ride and I would like to find a solution to this erratic problem.
Cheers. Kevin.

MJR

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Re: Kymco dt125 engine surges downhill
« Reply #1 on: June 16, 2017, 04:42:50 PM »
If you have a rollover sensor it may be a problem or the mounting maybe bent holding the sensor at the wrong angle causing it to trip.
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Stig / Major Tom

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Re: Kymco dt125 engine surges downhill
« Reply #2 on: June 16, 2017, 05:49:31 PM »
Also, are you maintaing some forward power (throttle) when riding down hill....or are you "coasting" down the hill (using gravity while engine is at idle) ?
Some throttle power from engine to rear wheel will prevent jerky sensation after,or during, a down-hill run. My scooters do not like to coast down a hill!
Stig
« Last Edit: June 16, 2017, 05:51:43 PM by Stig »
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Kevin newbie

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Re: Kymco dt125 engine surges downhill
« Reply #3 on: June 17, 2017, 09:56:21 AM »
Hi all, MJR & Stig, thanks for your replies. Not sure if it has a roll over sensor, will check that out. When I ride downhill it's usually steep and hairpin turns, so yep, I use some gas and sometimes not, doesn't make any difference to the problem. Curious is that it doesn't happen at any other time than on a relatively steep downhill run, then it continues on the flat for a while. But no problem accelerating on flat roads or uphill. I use the gas and it seems like a 2 or 3 second gap until the gas comes then it starves again and then the gas comes back again.
Before the accident this problem never existed!! Never had a problem just coasting down from big mountains, the gas response was always immediate.
We've checked all the vac hoses etc, cleaned air filter, checked the rubber joiner after the efi unit etc.
The bike was on its side on the road for a few minutes after the accident.
I stripped the bike down and made all the repairs myself, all cosmetic fairing parts etc.
Is it possible that the air cleaner unit has a crack and allows too much air in creating a negative pressure or maybe the efi unit has an issue after the crash?
It was a fair whack in the rear end and moved the bike from stopped position about 20ft 7mt. Most of the impact was taken by the rear wheel.
Cheers.

Stig / Major Tom

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Re: Kymco dt125 engine surges downhill
« Reply #4 on: June 17, 2017, 12:39:20 PM »
Ok, after your latest....I,  too, am thinking your roll over sensor is acting up...or ...?
Aught to be a way to jump electric around its cut-off feature.
Pretty certain most modern scoots have these things.
Wiring diagram will show its location.

Or, get the rear elevated, at idle, and start messing with stuff under the seat bucket. Anything make it cut out?
Interesing issue....
Good luck.
Stig

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