kymco ck1 idles then dies

[legand]

I bought a second hand ck1 2017 model that had apparently been sitting for about a year in a garage. All seemed good when I was testing it up and down the road near my house, apart from that petrol was leaking out around the keyhole in the fuel cap. I took the cap apart and switched the O ring out for a new one.I couldn't find the exact O ring so I got the closest match, which was ever so slightly fatter. All seemed okay, the leaking problem had stopped. Then I took it for my first proper ride on it, and when I was downshifting the bike cut out. It then wouldn't start, it would idle and die. If I put throttle on it would die instantly, if I just let it sit it would idle down until it cut out. I should mention that it did have half a tank of old fuel in it, and I thought I should drain this out but then I got told to just top it with new fuel and that it would be fine. I'm completely new to bikes so I didn't really question this. I'm not sure if this could have caused the problem or if switching the O ring out has caused it. Or if its just a dirty carb from sitting for so long.

[Stig / Major Tom]

How does it run if you remove the fuel cap?
Stig

[CROSSBOLT]

+1

[Kansas kymco]

Usually with a dirty carburetor it doesn't want to idle. Those are the smallest passages in the carburetor.  Fuel tank has to have a vent or it will pull a vacuum.

[JJJoseph]

If I put throttle on it would die instantly, if I just let it sit it would idle down until it cut out. I should mention that it did have half a tank of old fuel in it, and I thought I should drain this out but then I got told to just top it with new fuel and that it would be fine.

Your CK1 is OK. We're close to a solution.  Old fuel can be a real nuisance.  Here's a bit of trivia.  Auto fuel deteriorates with time and can leave crud in the caburetor innards.  On the other hand, aircraft fuel is totally stable and never decays.  If you're able, disassemble the carb and soak everything overnight in toluene, then blow out all the innards and jets with air or brake-cleaner.  Carefully (VERY carefully) inspect the vacuum diaphram for leaks or damage, and re-assemble VERY carefully! Replace any gaskets that look suspect.  Check all hoses for tightness. Don't be afraid to ask your dealer if you don't understand any of this!

[legand]

Hi, so I took the bike to a garage and he cleaned the carb out, he said it didn't seem to be dirty but when he put it back together the bike was working fine. I have been using it for a while now without any issues until today. I was riding at about 45mph (probably the fastest I have taken it so far due to most of my area being 20 - 30 residential zones) and it just cut out and died. I pulled over and tried to start it and it wouldn't start, so I opened the fuel cap and then it started up. I then rode around for a while at lower speeds and it seemed fine. Later on I went to the same stretch of road and hit the same speeds, and again the same thing happened. Bike died and I tried to rev and it was like it was not giving any fuel to the engine. Is it likely to be a problem with the fuel cap? It just makes me think there is some issue with either the tank or the cap, as it started up okay when I opened the cap, and also with the initial issue where the fuel was leaking out of the key area. Maybe I have blocked airflow with the fatter O ring? I'm not 100% sure how the fuel cap works or even if the CK1 does vent through the cap. It's hard to find any information on this bike online, and I can't seem to find a manual anywhere either.

[legand]

Well I took it out on the same route today, this time with the cap open when riding. Got up to 60 with no issues and went up and down the road a few times and it was fine.

[CROSSBOLT]

Every scoot and motorcycle has a vacuum operated gas tank vent valve. Many stick shut and cause this problem as Stig suggested. Replacing the valve with even an improved part is no guarantee it won't happen again. Venting the cap fixes this permanently.
A small hole must be drilled in the gas cap. Small means 1/16" or smaller.

[legand]

Hi, on my bike I have a tiny hole in the back of the lock when you open the gas cap, and then inside the tank there is also a hole. I attached a photo not from my bike just one that I found on google where the hole inside the tank is in a similar position to the one in mine. My grandad had a look at the bike and he blew into that hole with a straw and he said it was blocked, and then he poked inside it and said something was there and that it is clear now. I took the bike out and got up to 60 with no issues. Do you think its likely that this was the problem?

http://www.ducati-upnorth.com/forum/attachment.php?attachmentid=3934&d=1243511824

This looks similar to mine except mine doesn't have a plastic cap coming out of the hole.

I'll definitely drill it if it happens again. Just not sure if a blockage in that hole could cause this issue or if it is just working randomly now and it might happen again.

[Stig / Major Tom]

Do you think its likely that fixed it?

Yep. Give grandpa a hug!
Stig

[CROSSBOLT]

Absolutely! Old guys rule! Like Stig said, give Gramps a hug! He da MAN!

[legand]

Hi, unfortunately the problem came back. Again I opened the cap and the bike started up. I noticed a whining sound coming from the fuel cap area. I switched the O ring inside the cap back to one the size of the original one that was in there (I had switched it out to one that was slightly fatter). I then took the bike out and it was fine, no fuel bubbling out of the keyhole and it didn't cut out. I am thinking that when the fuel was bubbling out of the cap, it was caused by the hole being blocked that my grandad cleared, and that changing the O-ring in the cap stopped it bubbling out but created a venting issue causing fuel starvation. I'm hoping that it is fixed now.

I was looking at the tank and I noticed a tube coming out of the bottom and down towards the floor that seems to act as an overflow tube. Is this the only purpose of this tube or is it used for venting too? I was thinking of looking to that if I still have the problem. When I blow into that tube its like air flows completely freely through it, even when the tank cap is on. Is this normal?

[legand]

The latest update is that I managed to get hold of a cheap second hand fuel tank in awful condition. I took the fuel cap off and had a look inside it to see if I could compare it to mine. Looking at it, it had two holes where mine has none. One hole was where the ball bearing sits and another was at the end of what looked like an airflow line. When I inspected the same part on mine, it looked like it had markings for these holes (small indents) but that they hadn't been drilled through. I drilled it and I'm hoping that this fixes it. I wonder why mine wasn't drilled.