Coleman CT200u-ex quits on full throttle - stage 2

[alexi]

Hi, I have a CT200u-ex with a stage 2 kit installed and a torque converter. Starts alright and runs strong but sometimes when WOT lets say on the beach, the engine quits as if I pressed the kill switch. I let go of the throttle and as it slows down the engine kicks in again. If I keep it up to 50% throttle it'll run normally, as soon as I add more throttle it'll "quit and restart" again. Where should I start looking?

Sometimes it'll start right up if it doesn't revive itself while coasting, other times it'll take a minute for it to start. Don't know if its the spark, fuel, or some other issue.

TIA

 

[darwin]

Sounds like it's running out of fuel at WOT. Try running it with the gas cap off and see what happens. Fuel bowl might not be getting replenished enough in time. Everything seems to be working fine, just not at WOT. I'd start there. What parts did you change for a stage 2 kit?

 

[Sidewinder Jerry]

A tale tale sign is if it operates better at half choke. Then it's an air/fuel/leak issue.

 

[Wyvern]

I recently built a 224 with a VM22 carb.

As soon as I went past 1/2 throttle it would face-plant/die and restart if I was moving.

I started jetting-up sizes on the main, it was worse! I then started jetting down until it was running great at 1/2 to full twist.

In MY case, I was running way too rich, as if it was acting like I flipped the choke on full.

I ended up at #95 which is TOTALLY wrong, as I should be in the 110-120 range, but cheap chinese jets aren't always accurately labeled.


However, a lean condition or a bowl float issue (mentioned by others here) can also cause this problem.

Always try jetting UP sizes before jetting down, rich is safe, lean is death.

 

[Amwicr]

I've had very similar problems with my whizzer. Turn the throttle too fast, and it would die. Once I got going fast enough, I could slowly add throttle. It behaved slightly better with choke half on, but still pretty bad. I tried valve adjustments, a replacement carb, a cdi...no luck.

I'm pretty sure now that it was a lean bog. but yeah, yours might be rich. The question is, why? In your case, you've done some mods that probably caused it. For my whizzer that was 100% stock (down to the air filter!)? Who knows...

 

[alexi]

This is the stage 2 kit I'm running https://www.ombwarehouse.com/stage-...-coleman-ct200u-mini-bike-196cc-or-212cc.html and also the flywheel https://www.ombwarehouse.com/pvl-flywheel-for-clone.html. The issue seems to start after riding a while, like after 20 - 30 min on the beach.

I'll try the above mentioned options next week and will report back.

 

[Hunter]

The issue seems to start after riding a while, like after 20 - 30 min

Seems to me like your tank isn't venting fast enough so it creates a vacuum and the gas cant reach the carburator. I had the same problem on my Honda Grom clone.

 

[Wyvern]

Seems to me like your tank isn't venting fast enough so it creates a vacuum and the gas cant reach the carburator. I had the same problem on my Honda Grom clone.

As soon as he said after X-amount of time I was thinking that too.

Maybe vapor lock, if he's giving it the beans the whole time.

 

[Chainlube]

Is there a low oil shut off? Cut the wire.

 

[alexi]

I haven't had it happen again, the issue just disappeared.

I do get white smoke on idle and startup, attached is an image of the spark plug. My compression shows 60psi pulling the cord, it's 196cc honda clone and might not build pressure till higher rpms? My carb is a stock non epa but I don't thing I can adjust air/fuel on it.

With the plug being black, is it buring oil (explains white smoke), running rich, or both? What other tests to run?