Thread: ct70 overheating?

I've learned a lot from this chat line, and thank everybody for the help. I recently stripped the kick start shaft, and drilled a 3/16" hole through the kick starter and shaft, and ran a steel shaft through it. It works perfect.
It starts great, runs perfect, but after about 20 minutes of riding, it starts smoking, starts cutting out, and then dies completely. Then I can't start it (that's what stripped the shaft in the first place) until it sits for about 4 hours, and cools down.
Any ideas?

It sounds like it is running lean which means too much air and that is not a good thing. Check your spark plug and see what it looks like. If it is burnt looking that is a sure sign of running lean. Running rich which means more gas to air ratio is better because it is not as hard on your engine. You may have to reset your carb settings or adjust the clip on the throttle valve needle.

You lost me on the "adjust the clip on the throttle valve needle". I don't recall a "clip" when I was working on the carb, and I replaced the throttle cable with a new one. Also, to make the carb richer, there are only 2 adjusting screws. What exactly should be done to them? I'll check the plugs this weekend.

The throttle valve is what your throttle cable is attached to.
You have to unscrew the part that goes into the top of your carb. You have to then disconnect the throttle cable. On your needle valve there is a half moon clip which can be set at different notches on the needle itself. Moving the clip down will make it richer. You may just have to reset your air screw and not mess with this at all. Wait until the engine is warmed up and a good sounding idle is heard. Then turn your air screw either in or out until you hear the idle increase to its highest point. Leave the air screw setting there. Then go to idle screw and turn it down a bit until an even good sounding idle is heard.

Thanks for the advise. You make is sound easy! I'll work on it this weekend, and sorry for the dumb questions.

Is there a plastic insulator between the carb and intake on your bike? This is to stop the heat from getting to the carb causing the fuel to bubble. One of my bikes had this problem. This can also be a cause of stalling. I`m not sure if theres a way to test to see if the oil pump is working or not, but thats a possibility. A bad pump or poor circulation.

Ian

When the oil pump isn't working, you'll know. Screeeeeech! Really, the oil pump is either working or it isn't, and when it isn't, neither is your bike. But I suppose something could be clogging up the channel the oil is pumped through to the head, but again, if that's the case, I'd think you'd sieze your piston in your cylinder fairly quickly.

Originally Posted by steampick

When the oil pump isn't working, you'll know. Screeeeeech! Really, the oil pump is either working or it isn't, and when it isn't, neither is your bike. But I suppose something could be clogging up the channel the oil is pumped through to the head, but again, if that's the case, I'd think you'd sieze your piston in your cylinder fairly quickly.

Yes I know thats a 'DUH' statement...but, someone here had a motor that didn`t have a pump that worked...if I find the post I`ll reply.

Here's the latest: I pulled the plug--it was not burned, but the insulator was black, and there was a light oil coating on it--along with a few black flakes. I went ahead and lowered the clip on the throttle needle. There are 6 spaces, the top one is lean, the bottom is rich. It was on the 3rd space, so I moved it to the 4th. After taking it for a spin, it cut out after 10 minutes, and wouldn't start again! I'm at a loss! It hardly even heated up!
Hey--one more dumb question. With the key switched to the headlight setting, should any of the lights or horn work, or does the engine need to be on in order to get lights?

Tailight, Brakelight, and horn will work at that setting. Headlight only works when engine is running. I would put the clip back to the original setting on the needle. Did you try just setting the carburetor like I stated before? How are the fins on the cylinder head? Are they packed with dirt or grime? What type of oil are you using?