KymcoForum.com

Offroad => Side By Side => Topic started by: swalley on September 25, 2022, 03:44:38 PM

Title: 2008 Kymco 500 UXV hard start when engine is warm
Post by: swalley on September 25, 2022, 03:44:38 PM
Uxv 500 carbureted engine starts fine cold but after running and getting warm it’s hard to start back up any help would be appreciated
Title: Re: 2008 Kymco 500 UXV hard start when engine is warm
Post by: airshot on September 25, 2022, 04:43:58 PM
You will need to do some testing so we have some direction.  When it doesnt start....how is the spark ??  Spark plug wet with fuel?? Can you hear the fuel pump run ??  I fuel flow restricted ??  Air filter clean??
Title: Re: 2008 Kymco 500 UXV hard start when engine is warm
Post by: randyo on September 25, 2022, 06:32:36 PM
the ZS190 I put in my K-Pipe is the same, fires right up cold, even on a kickstart, first kick, when warm though, I have to give it throttle, a lot, and forget the kick start, after cranking 10-15 seconds on the electric start, it slowly starts running on it's own, then quickly revs

the way it starts warm, embarrasses me at gas stations
Title: Re: 2008 Kymco 500 UXV hard start when engine is warm
Post by: Stig / Major Tom on September 25, 2022, 06:44:50 PM
the ZS190 I put in my K-Pipe is the same, fires right up cold, even on a kickstart, first kick, when warm though, I have to give it throttle, a lot, and forget the kick start, after cranking 10-15 seconds on the electric start, it slowly starts running on it's own, then quickly revs

the way it starts warm, embarrasses me at gas stations
Fueling at home with a gas can might be better
Wonder what causes that?
Stig
Stig
Title: Re: 2008 Kymco 500 UXV hard start when engine is warm
Post by: randyo on September 25, 2022, 07:04:20 PM
Fueling at home with a gas can might be better
Wonder what causes that?
Stig
Stig

I do fuel at home, but with a 1.1 gal tank, I find myself low on gas away from home, my errands may be shorter rides,  but I've been on longer rides, last month when I went up Mt Washington, I had to fill up 4 times before I got home
Title: Re: 2008 Kymco 500 UXV hard start when engine is warm
Post by: swalley on September 25, 2022, 07:10:12 PM
Has good spark and I hear the fuel pump new air cleaner and fuel filter that’s why I’m confused
Title: Re: 2008 Kymco 500 UXV hard start when engine is warm
Post by: swalley on September 25, 2022, 09:13:53 PM
Air shot does that make sense by the way I replaced the plug while it was warm still had the same problem but it did start up on wide open throttle a little quicker
Title: Re: 2008 Kymco 500 UXV hard start when engine is warm
Post by: airshot on September 26, 2022, 10:34:32 PM
Air shot does that make sense by the way I replaced the plug while it was warm still had the same problem but it did start up on wide open throttle a little quicker
Did you try a brand new plug?  Wide open throttle to start sounds like it is rich...spark plug wet when it doesnt start??
Title: Re: 2008 Kymco 500 UXV hard start when engine is warm
Post by: swalley on September 28, 2022, 01:53:06 PM
Airshot the plug looks to be wet when removing it sorry im so long in repling
Title: Re: 2008 Kymco 500 UXV hard start when engine is warm
Post by: souzamoto on September 28, 2022, 04:03:25 PM
When was the last time the valve clearances were checked?
Title: Re: 2008 Kymco 500 UXV hard start when engine is warm
Post by: airshot on September 28, 2022, 05:17:54 PM
Along with checking the valve clearance, your carb might be in need of a rebuild. Being a 2002 your carb needle is probably hanging open and causing flooding when you shut it off, the fuel continues to flow, causing a wet fouled plug...thus the need to hold the throttle wide open to get it to start. Make sure your plug wire can jump a 1/4" plus gap!!  You could try running some heavy doses of Sea Foam thru it in hopes that it might disolve the crud, but in reality, probably time for a thorough carb rebuild.