CT200U jetting

[Fisher1983]

I was tuning on the CT200U today, and am wondering where I should be with jetting. First, I ditched the stock EPA carb and got the non-EPA carb from OldMiniBikes Warehouse, along with their underseat header and screw in muffler. The stock pilot jet on this carb is .016. Dug out my pin vise set and went to the #76 bit (.020) and I still have to choke it on a hot restart. I haven't messed with 196's before, only 212 Hemis which seemed fine with a #77 or #76 to cure the hot start issue. I also adjusted the air screw per the instructions and am around 2 and 1/4 turns out (fastest idle, then bring it to spec with the throttle plate idle screw.) Do these 196's like more pilot jet? I haven't touched the main yet, trying to solve the hot start problem first. TIA for any advice!

 

[sparkwizard]

Is the idle mixture adjustable with a screw?
On my carbs that do not have a mixture screw, I still need to choke to start about 50% of the time.

Sorry, I just read your post again, you do seem to have adjustable idle mix. rather than drilling the plastic jet, I play around with the idle mixture to richen it up for easier starting.

 

[Fisher1983]

Is the idle mixture adjustable with a screw?
On my carbs that do not have a mixture screw, I still need to choke to start about 50% of the time.

Sorry, I just read your post again, you do seem to have adjustable idle mix. rather than drilling the plastic jet, I play around with the idle mixture to richen it up for easier starting.

I had already done that and it did nothing. Even after drilling the jet it still needs choke to restart when the air mixture is set correctly.

 

[SAS289]

"cure the hot start issue."? I wouldn't call it an issue. Starting on choke was a habit for me. It was somewhat rare for me to turn the engine off hot, then start it again hot.

I don't think the 196's need more pilot jet. Never did anything with the pilot jet or mixture screw on any of my 196's, even after build. I did open up the pilot jet on my 224 to .018" to help with startup and idle. I guess I didn't see the need to tweak the mixture screw when they ran so well. What matters to me is what happens when I twist the throttle, not how rich or lean it is at idle.

The very best thing about the stock carbs is the one pull starts. Whether it was my Greyhound 196 or the Hisun 196, I thought something was wrong when they didn't start on the first pull. Most often was because I left the kill switch on.

I no longer use stock carbs. I traded one pull starts for up to three pulls to start with the VM22 carbs. But the tradeoff is worth it.

 

[Fisher1983]

"cure the hot start issue."? I wouldn't call it an issue. Starting on choke was a habit for me. It was somewhat rare for me to turn the engine off hot, then start it again hot.

I don't think the 196's need more pilot jet. Never did anything with the pilot jet or mixture screw on any of my 196's, even after build. I did open up the pilot jet on my 224 to .018" to help with startup and idle. I guess I didn't see the need to tweak the mixture screw when they ran so well. What matters to me is what happens when I twist the throttle, not how rich or lean it is at idle.

The very best thing about the stock carbs is the one pull starts. Whether it was my Greyhound 196 or the Hisun 196, I thought something was wrong when they didn't start on the first pull. Most often was because I left the kill switch on.

I no longer use stock carbs. I traded one pull starts for up to three pulls to start with the VM22 carbs. But the tradeoff is worth it.

Starts one pull cold....no problem. Choking to hot start has always irritated me. I guess I'm just used to my old Hemis and them starting hot after a jet tweak. It runs great otherwise....good response, no flat spots or hesitation. Need to read my plug soon and see where the main is and that's it.

 

[panchothedog]

I have built 4 212's and 2 196's, all running stock style carburetor. ( ease of starting and crisp throttle response ). I am in California, so none have an adjustable air screw. I drill the pilot's to .020" and the man's to .036" or .037".
Seems to work good on both engines. I am at sea level but always use the choke to start hot or cold. Doesn't really seem to be a lot of trouble.

 

[Fisher1983]

I have built 4 212's and 2 196's, all running stock style carburetor. ( ease of starting and crisp throttle response ). I am in California, so none have an adjustable air screw. I drill the pilot's to .020" and the man's to .036" or .037".
Seems to work good on both engines. I am at sea level but always use the choke to start hot or cold. Doesn't really seem to be a lot of trouble.

Hmm. Ok, well guess I'll have to get used to it. .036-037 main....was that with significant mods? I just have the under seat header and bologna muffler at this time.

 

[sparkwizard]

Does it run well after you get it started? If so, I would leave it alone and ride it.

 

[panchothedog]

Hmm. Ok, well guess I'll have to get used to it. .036-037 main....was that with significant mods? I just have the under seat header and bologna muffler at this time.

Most of mine are pretty heavily built. But even a bone stock engine with a header pipe and a free flowing air filter will need the main enlarged to run properly. I find that they start easier with the pilot opened up to .020". None of my engines seem to want to start without the choke.. Even when warmed up.

 

[SAS289]

I just tested what we are talking about here.

I had to down tune my bike for new riders for a family outing. I removed the 224 and put in a stock 196. It has the stock air box, 31 main jet, and the 224 muffler. I did a short warm up in the yard then did a full throttle run down the street and back. Shut it off then started it without choke. Was only one test but it did start. I'll eventually try it again with a hotter engine.

The massive difference in torque made me laugh. Still fun to ride and I don't have to work so hard to keep the front tire on the ground. Kept the torque converter and 60 tooth on it.

 

[sparkwizard]

The only stock type carb I ever found that didn't need choke to start came from Tillotson. I am not sure if they still make it, but it was called blueprinted stock. It was jetted rich, had idle mixture screw the venturi was bored as large as was "legal". It was made for a 212, but I ran it on several engines. I can't remember where I got it, and I can't remember where it went. On a stock Predator 212, it would wheelie a CT100U coming out of a corner at 10 MPH and hold the tire up for about 30 feet. (TC yes) It did puff black smoke when you yanked the throttle but it was a fun carb.

 

[RobertC]

On a stock Predator 212, it would wheelie a CT100U coming out of a corner at 10 MPH and hold the tire up for about 30 feet. (TC yes) It did puff black smoke when you yanked the throttle but it was a fun carb.

That'll put a grin on your face !

 

[Fisher1983]

I just tested what we are talking about here.

I had to down tune my bike for new riders for a family outing. I removed the 224 and put in a stock 196. It has the stock air box, 31 main jet, and the 224 muffler. I did a short warm up in the yard then did a full throttle run down the street and back. Shut it off then started it without choke. Was only one test but it did start. I'll eventually try it again with a hotter engine.

The massive difference in torque made me laugh. Still fun to ride and I don't have to work so hard to keep the front tire on the ground. Kept the torque converter and 60 tooth on it.

.031" is a #68 bit in my pin vise. I also have a stock airbox, and the short under seat header with bologna muffler. Though, I'm thinking about finding a 224 muffler for less noise. Gives me a good place to start, thank you! EVERY 212 Hemi I have ever owned....the first thing I do is jet it....even stock. I open the pilot up to .018" or so, and I read the spark plug on Rec fuel to jet the main. I forget where it usually ends up. But, every one has hot started without choke after that. Glad you see what I mean Massive difference from the 196 to 224, huh? I love torque but not sure I need THAT much now..... Off topic but I was originally thinking of running this 196 for a bit, swapping to a 224 with different gearing, and giving the 196 to my best friend for his mini.

 

[sparkwizard]

I like to leave the governor working, use a stock type carb, stock airbox, higher lift rockers, thinner head gasket, NGK plug, header and then always install a torque converter. I have used that simple formula on several bikes of my own and several more for my "customer-friends". They have all been surprised and a little scared the first time they rode my quiet, very stock looking CT200U. Some of these old farmers got such a kick out of it, they went right to Tractor Supply and bought their first mini bike to ride around their fields.
I recommend this carb.
https://www.gopowersports.com/stage-2-196cc-212cc-honda-clone-style-carburetor/

 

[SAS289]

.031" is a #68 bit in my pin vise. I also have a stock airbox, and the short under seat header with bologna muffler. Though, I'm thinking about finding a 224 muffler for less noise. Gives me a good place to start, thank you! EVERY 212 Hemi I have ever owned....the first thing I do is jet it....even stock. I open the pilot up to .018" or so, and I read the spark plug on Rec fuel to jet the main. I forget where it usually ends up. But, every one has hot started without choke after that. Glad you see what I mean Massive difference from the 196 to 224, huh? I love torque but not sure I need THAT much now..... Off topic but I was originally thinking of running this 196 for a bit, swapping to a 224 with different gearing, and giving the 196 to my best friend for his mini.

I ended up putting the stock jet back in. If I quick snapped to full throttle it would break up a bit then recover. It did restart warm without choke with the stock jet.

I like the 224 muffler. It's not loud but does have a more aggressive sound than the stock 196 muffler. I had to use it with this setup because the stock 196 Coleman muffler is too tall to fit in the frame. The engine riser I'm using raises the engine 1 3/8".