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Scooters - 125 to 300 => Downtown 300 => Topic started by: PiotrKymco on January 17, 2026, 05:34:39 PM

Title: Downtown 350i wont start
Post by: PiotrKymco on January 17, 2026, 05:34:39 PM

Hi there
Just bought fir my son downtown 300i 2018 in not working condition Well think easy to fix but I stuck. Engine crank and from time to time fire up for second or two and dies. And again.
1. Coil spark plug ok
2. Timing marks ok
3. Compression 11bar
4.injector ok ( gives to much fuel in my opinion but it is nice mist)
5. Changed TPS no change
6. Battery perfect

Now have no idea what to check or what that could be. Need help.

I connect tester unit and there is no fails nothing suspicious. And that is totally not understandable.

Title: Re: Downtown 350i wont start
Post by: Ruffus on January 18, 2026, 11:26:30 AM

Welcome here!
Pls check scoots KILL- switch whether its on or OFF.

Ignition key to ON, do you hear fuelpump running?

Check are brakelights on when you pull lever/s

Then check voltage at battery during starting process, all under 10.5 VDC is too less.

Under this level, jumpstart from a car battery.
STARTS = change battery to LiFePo4

Title: Re: Downtown 350i wont start
Post by: PiotrKymco on January 20, 2026, 10:45:40 AM

Hi
I check everything according what you wrote and all is ok and engine still do not start up. It fires up from time to time for second and that is it. Have no idea, all is ok and engine does not start up. That is weird and do not know how where to looking for.
It starts to be a little annoying.

Title: Re: Downtown 350i wont start
Post by: Ruffus on January 20, 2026, 11:57:48 AM

Has this scoots engine beeing worked on?
Could be that timing is 180° wrong!
Coil, cable and plug really NEW and in functional condition.
Used ones are not good enough!