Coleman 200CTUEX full throttle issue. Please help

T

TheSmanman

New Member
#1
#1
Hi, im new here and trying to figure out why my CT200UEX has a running at full throttle issue. Everytime I give it full throttle it keeps sputtering and won’t clear up. If I let off just a bit, it’s fine, but like I said at full throttle it is sputtering. It’s fairly new with only about 15 to 20 hours on it. Fuel is clean, carb bowl is clean also. The only mod I did was removing the throttle stop. The spark plug looks good as well. I thought maybe it was valve float, but I installed 18lb springs and it still does it.
Does anyone have any ideas of what is going on? D9BF16F7-B838-4F1D-97E7-07970B0B363E.jpeg
 

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Strigoi

Strigoi

#2
#2
Why'd you install 18lb springs? They do nothing if the governor is still functioning.

Are you sure it's not the governor that you're feeling?

edit: Just saw that you're running a stage 1 filter with the stock exhaust. You should really be running a header with that filter and the carb needs to be jetted for it as well. More air in = more air out.
 
M

Mariah

#3
#3
I'm thinking ......... defective, cheap, off brand, copycat, junk spark plug. Full throttle creates the most demanding conditions to fire a plug. Lots of us have been down this road before.
 
T

TheSmanman

New Member
#5
#5
Yes, running stock jet. Governor is bypassed using the zip tie mod but not tight. Bike tops out at 27. You guys are probably right saying it’s not enough fuel. But yes, when I give it full throttle it sputters like it’s running out of fuel. Hard to explain, it’s like a bap, bap, bap sound. I let off to say 3/4 throttle and all is well. I don’t think the jet can be replaced on this stock carb due to them grinding off the other side of the head so you can’t unscrew it.

What’s even more baffling is i have anothe UEX with the same mods and it runs perfec
 
SAS289

SAS289

Well-Known Member
#7
#7
Does it now top out at a higher speed? And you should see the RPM on your tach. You may be running too high RPM for the stock rod and flywheel. 27 MPH at around 4800 RPM isn't that bad, but once over 5K you should consider getting the parts to support the higher RPM. You'd be safer with the stock springs in there. Save the 18lb springs for after the rod and flywheel get replaced. I think the mod 2 cam calls for 18lb springs.

I don't even run higher than 5K RPM and my 196 and 224 have billet rods and PVL flywheel. They are better engines with them and are already in place if I decide to go for higher RPM later.
 
T

TheSmanman

New Member
#8
#8
SAS289 said:
Does it now top out at a higher speed? And you should see the RPM on your tach. You may be running too high RPM for the stock rod and flywheel. 27 MPH at around 4800 RPM isn't that bad, but once over 5K you should consider getting the parts to support the higher RPM. You'd be safer with the stock springs in there. Save the 18lb springs for after the rod and flywheel get replaced. I think the mod 2 cam calls for 18lb springs.

I don't even run higher than 5K RPM and my 196 and 224 have billet rods and PVL flywheel. They are better engines with them and are already in place if I decide to go for higher RPM later.
Click to expand...
Thank you. Yes I can go over 5, but what I did was control the top speed with the throttle screw stop. I filed off the weld and now I can adjust it. But now it runs great. I’m going to keep it below 5k. I have a 212 im going to build with the billet rod and flywheel. The head is also going to be ported and polished and I’m going to talk to the machine shop about milling the head a bit. We’ll see how that goes. I’m going to be putting that motor on a Motovox MBX10 that I want to stretch and put on the x18 10” wheels and the front end, but I need to find a donner x18 to do it though
 
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