CT200U-EX - Stalls Under Load

[ak_attack]

I swear I searched for this issue. Found the exact issue twice on reddit, but oneguy couldnt get an answer & the other solved with a new engine. He even replaced the carb.

video of the same problem

Any thoughts would be appreciated.

Bike
Coleman CT200U-EX,
Tractor supply, Camo
Stock Hisun 196cc engine
2020 purchase

Issues
Start quickly with choke on, 3-5 pulls when cold, 1 when warm
Idles a little rough, but come on its not a BMW
Turn off choke, roll on throttle, bike stumbles & then dies
Can roll on power with choke, but no power
Only restarts with choke ON
If i lift the bike onto sidestand, will run at full throttle

Troubleshooting
Removed and cleaned carb
- Including pulled main jet (even tho obnoxiously "security" thread for one direction, ez-out bit worked wonders)
- Including fuel/air "plug" & jet
- Get good flow of carb cleaner thru all passages
- Cleaned float, float valve & float valve seat
Cleaned petcock
Checked fuel flow, good

To-do
- Add a fuel filter. Have but doesnt fit with linkage, need a smaller one
- Check shaft key didnt shear?
- Bad clutch?
- pull plug and see if oil in cylinder?
- f*&%ing gremlins?

 

[Lizardking]

Welcome....

When did the problem start? Usually for idle problems it's a dirty idle jet. The problem you described could be caused by too much air or not enough fuel. Check for any air leaks between the carb and engine.

 

[SAS289]

After checking for air leaks be 100% sure the main jet is clear, then check to make sure that the e tube is clear.

I had this exact symptom start while riding and I went right for the main jet. It was clogged with what looked like a piece of plastic from the tanks fuel filter. I was just yard riding and was close to tools. Couple minute fix.

When the throttle plate starts opening you start calling for fuel from the main jet.

 

[ak_attack]

Welcome....

When did the problem start? Usually for idle problems it's a dirty idle jet. The problem you described could be caused by too much air or not enough fuel. Check for any air leaks between the carb and engine.

Started on a cold day - just about freezing. Bike kept inside.

I'll try a spray between the carb and intake & maybe a little gasketcinch.

 

[ak_attack]

After checking for air leaks be 100% sure the main jet is clear, then check to make sure that the e tube is clear.

I had this exact symptom start while riding and I went right for the main jet. It was clogged with what looked like a piece of plastic from the tanks fuel filter. I was just yard riding and was close to tools. Couple minute fix.

When the throttle plate starts opening you start calling for fuel from the main jet.

I'll pull the carb again. Anybody have pics of where they crammed a inline fuel filter?

Also, any diagrams of the throttle linkage?

 

[Lizardking]

Started on a cold day - just about freezing. Bike kept inside.

I'll try a spray between the carb and intake & maybe a little gasketcinch.

I have used bread tie wire to clear any buildup on the small holes on the jets. If it sat for a while and was running good before then a proper cleaning of jets/carb is in order. Make sure the small holes on the jets are cleaned with a small wire if you only sprayed cleaner the first time.

 

[SAS289]

You could remove the main and e tube without pulling the carb off.

The fuel filter in the tank is sufficient. I've never seen anyone add a fuel filter with the stock tank and stock carb.

Your startup choke on then choke off to idle tells me your stock linkage is working properly. You should leave it as is until you want to make a purposeful change.

 

[ak_attack]

I have used bread tie wire to clear any buildup on the small holes on the jets. If it sat for a while and was running good before then a proper cleaning of jets/carb is in order. Make sure the small holes on the jets are cleaned with a small wire if you only sprayed cleaner the first time.

Understood. Have a few other full size bikes - 70s hondas, etc that all have a few more carb circuits. This carb is clean as far as i can tell.

Also damn please i dont have to sync a 4-bank set of carbs.... lolol

 

[ak_attack]

I have used bread tie wire to clear any buildup on the small holes on the jets. If it sat for a while and was running good before then a proper cleaning of jets/carb is in order. Make sure the small holes on the jets are cleaned with a small wire if you only sprayed cleaner the first time.

guitar strings work wonders.

i'll poke a bit more and post an update in a few days. thanks!!

 

[ak_attack]

You could remove the main and e tube without pulling the carb off.

The fuel filter in the tank is sufficient. I've never seen anyone add a fuel filter with the stock tank and stock carb.

Your startup choke on then choke off to idle tells me your stock linkage is working properly. You should leave it as is until you want to make a purposeful change.

cool- thanks for the insight.

 

[BrownStainRacing]

cool- thanks for the insight.

You can safely open the main jet up from .028" to .031" with a 1/32" drill bit. That .028" is way too lean from the factory anyway.

 

[ak_attack]

You can safely open the main jet up from .028" to .031" with a 1/32" drill bit. That .028" is way too lean from the factory anyway.

Really? sounds good to me...

My main jet has the one-way slotted screw top. Pain in the ass

 

[sparkwizard]

When you drop the bowl, make a note to look for water in the bowl, before you dump it.
Your comment about your main jet is confusing.
You are looking inside the bowl, in the center where the bolt holds the bowl on, correct?

 

[BrownStainRacing]

Really? sounds good to me...

My main jet has the one-way slotted screw top. Pain in the ass

I've heard there's carbs out there that you cannot change or remove the main jet. I havnt ran into one yet.

 

[SAS289]

Yeah sorry. I forgot about the carbs with the main jet they don't want us to remove. Some guys just buy another carb. I would do whatever it takes to get it out and buy a main jet.