Thread: Throttle issue - Engine runs at full throtle

Hi. I'm new to bikes and just got me a ct70. It was running great but was really dirty inside and out. So I broke it down and gave it a good cleaning also removed carb and cleaned it really well. now that its all back together I have a sticky throttle cable. Its fine when I have it disconected from the carb. The spring is in fine shape and when disconnected it retracts all the way to idle. but when I install it in the carb - I'll crank it up and it runs all out at full throttle no matter what i do with the grip. When I screw it into the carb the spring is compressed to far. It seems like the pin or needle setup wiht the cylinder surroundign it should sit further down into the carb, even though I have hte grooves lined up with the notch in the carb. Still seems like it needs to go further to have the spring stretch out enough to pull on the throttle grip. Any ideas on what I can do here?

thanks a bunch!

You have your throttle valve in wrong. Keep turning the throttle valve until it falls all the way down into the carb body. If it is in correctly the top part should screw on easily to the top of the carb.

well I for sure did at first and I may still have it wrong. I finally figured out that I had to get the grove in the outer cylinder (is that the throttle valve?) to line up with the notch in the carb. So it slid down in there another half inch or so but I couldn't get it any further in. it seems like with teh way the notch and groove fits there would be no more turning to do but I could be way wrong on that. it really does seem however that it should fall deeper in the "chimney" type part of hte carb. is there further twisting i need to do?

If it fell down another half an inch or so it should be right. The top cap should go on pretty easily now. Your throttle should operate smoothly if it is in correctly. Try it and see what happens. Just be ready to shut it off in case it is in full wide open throttle mode. If it still does it then try it again until it falls further but it sounds like it should be in right now.

After taking my carb apart (rebuilt and put in new needle and seat) and replacing it, I had the same issue. Was not at full throttle but was pretty high. I found that I needed to remove the boot on the top of the carb/cable and adjust the cable adjusting nut. I actually took the carb off to find that by looking into the intake. At clear closed throttle I could see light thru the carb so I know it was not seating correct.

I have in the past put the assembly in wrong but turning it around should cure it quickly if that is the only issue.

The slide (a.k.a. throttle valve according to Honda) has a long narrow slit on one side that runs from top to bottom, and a wide slot that has a "ramp" in it that only runs part way up the body. That wide slot should line up with the idle speed adjustment screw on the left side of the carb. The slide should be nearly to the bottom inside the carb when everything is right. If the idle speed screw got screwed in too far when you were putting things back together that could cause the revved up idle. Just one more thing to check.

-kevin

thanks everybody for the help. I finally got it working properly. I was dropping it in the wrong way cause it was the only way it would fit. apparently the side of the carb that accepts the slot that runs all the way down the slide has a piece to accept the slide thats made of some type of polymer. it must have melted when I used the carb cleaner and spread out a bit. I just took a knife to it and cut it to thin it back to the size needed for the slit to slide up and down on it. Works fine now. thanks miniac for letting me konw the propper orientation.

My problem now is that after revving the engine and releasing throttle the engine pops and sputters. If someone could point me to a good guide on adjusting the carb so I get the right mixture I would be much appreciative. Thanks!

Originally Posted by 0o0o0

My problem now is that after revving the engine and releasing throttle the engine pops and sputters. If someone could point me to a good guide on adjusting the carb so I get the right mixture I would be much appreciative. Thanks!

From Honda. Yeah I ain't figured out how to determine the 1300 rpm yet either.

Originally Posted by Flash

From Honda. Yeah I ain't figured out how to determine the 1300 rpm yet either.

Harry,

Have you ever heard of a vibra tach, a.k.a. a Treysit Sirometer? I got to play with one when I got sent to Germany on business, and it's the neatest little thing. According to the guy that was demonstrating it they cost less than 20 Euros and they're extremely accurate when used properly. Unfortunately, I was unable to find one in Germany before I had to leave. Take a look:

TREYSIT Sirometer, revolution-meters, frequency-meters, resonance-meters

If I can ever figure out where to get one I'll let you know how I like it, . . . and where I got it. I figure that someone in the US must have one. My latest lead is Briggs and Stratton PN 19200; it's supposed to be just what I'm looking for, but the lawn mower shop I visited last week was staffed by some sort of alien life form that doesn't understand words or numbers. Or maybe it's an IQ thing?

-kevin

i woulda guessed the throttle stop screw was all the way in.

Originally Posted by 0o0o0

thanks everybody for the help. I finally got it working properly. I was dropping it in the wrong way cause it was the only way it would fit. apparently the side of the carb that accepts the slot that runs all the way down the slide has a piece to accept the slide thats made of some type of polymer. it must have melted when I used the carb cleaner and spread out a bit. I just took a knife to it and cut it to thin it back to the size needed for the slit to slide up and down on it. Works fine now. thanks miniac for letting me konw the propper orientation.

My problem now is that after revving the engine and releasing throttle the engine pops and sputters. If someone could point me to a good guide on adjusting the carb so I get the right mixture I would be much appreciative. Thanks!