CT70 has good idle but bogs down on throttle, I've tried everything but can't fix it

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Ranch120

Member
I know this topic has been covered dozens of times but I am stuck. Good idle on my CT70 but bogs on throttle pretty bad. Cleaned carb twice very very thoroughly, good fuel flow from tank to carb, have proper sized jets, choke works fine, needle on the middle slot, no vacumn leak.

It's still runnin lean. Can anyone think of anything that I am missing?

Thanks everyone!
 
R

Ranch120

Member
hornetgod said:
Did you adjust the fuel mixture screw? If not, 1 1/2 turns out from lightly seated is a good starting point.
Click to expand...

Yes, I have adjusted the air screw as you mention with no change. Also, I forgot to mention the float is set accurately (as far as I know) approx .75 inches from carb body.

---------- Post added at 08:06 AM ---------- Previous post was at 08:02 AM ----------
hondaman said:
Move the clip on the throttle needle down another notch.
Click to expand...

I have adjusted the clip as you mention with no noticeable difference in performance. Maybe I should adjust it two slots. Would that create other problems?
 
fatcaaat

fatcaaat

Well-Known Member
How long has the bike been sitting? My guess is the carb is still gummed up and your jets are not perfectly clean.
 
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Ranch120

Member
fatcaaat said:
How long has the bike been sitting? My guess is the carb is still gummed up and your jets are not perfectly clean.
Click to expand...


Bike was running pretty good, just a bit slow on idle, I adjusted the idle screw to compensate for this and that is when it started having problems. So, it had not been setting for extended period.

---------- Post added at 10:16 AM ---------- Previous post was at 10:14 AM ----------
extremajoe said:
Have you checked the timing? what about valve lash?
Click to expand...

yep, the timing and lash are both good, the bike was running before this demon spirit decided to invade it, it was just a bit slow on idle, bike has not set for extended period
 
fatcaaat

fatcaaat

Well-Known Member
Well, you started having problems after you adjusted the idle screw. Well, perhaps then, this is where the problem lies? If it ran good and you messed with nothing but the screw, chances are you need to readjust the screw right?
 
R

Ranch120

Member
fatcaaat said:
Well, you started having problems after you adjusted the idle screw. Well, perhaps then, this is where the problem lies? If it ran good and you messed with nothing but the screw, chances are you need to readjust the screw right?
Click to expand...

Yes, your correct, a point that I did not mention though is that when I adjusted the screw, it quit running completely even after adjusting the screw BACK to the original position, then when I opened the carb to clean I found the main jet completely unscrewed from its base. So, to be clear, when I adjusted the screw it stopped running completely, even after trying to re-adjust back to the original position.
 
85CTrider

85CTrider

Member
Hey ranch,
i am having the identical issue; - see thead http://lilhonda.com/webboard/f6/checking-oil-level-9955/

goin on right now. I messed with the idle screw and airintake screw and since then the bike is a mess. It idles great even revs great in neutral, but when i ride it, it bogs down, sputters, stops and starts and rides like a bukcing bronco. i took the carb off 3 times, cleaned it ( so i thought ) cleaned the jets, the bowl the tubes, everything, checked the pug, the intake the air can etc... still cant figure it out.. i am running to lean as well... maybe its the idle screw or air intake screw... i never took those off when i cleaned the carb. those stupid screws were probably not adjusted in 20 years untill i messed with them.. have you made any more progress???
 
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goldenboy81

Member
Just a question for both of you (which I think I already talked to 85CTrider about). How have you both arrived at the conclusion that you are running to lean? I thought 85CTrider mentioned in one of his posts that his plug was ashy black? This would indicate that you are running too rich. See link on Reading Spark Plugs

Have either of you tried moving your clip on your throttle needle up? If not, try it. I went through the exact same thing both of you mentioned and my clip is at the very top, which completely fixed my problems. If you have done this already....sorry to waste your time.
 
85CTrider

85CTrider

Member
GOLden Boy and all,

please correct me if i am wrong. my bike is a 1985 stock, carb is original 1985 carb. i did not see the talked about "clip" on the throttle cable. when i unscrew the throttle cable from top of carb and take it out, there is the angled cylider which goes into the hole on top of the carb, then on top of the angled cylider there is a spring, then the screw cap that screws on the top of the carb, never saw any clip. please advise if this clip should be on my throttle assembly ot not due to the year.. maybe i am missing a CLIP.. >>!@#$%^
 
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goldenboy81

Member
I realize this isn't for your year....I couldn't find one for an 85....However, it should be similar. Carb Diagram
Part #3 in the diagram. There is a "W" clip on top that holds the slide needle down. You want to move the little round clip (below the "W") that is set onto the needle (also in diagram labeled as #3) upward on the needle. The needle will have grooves notched into it to keep the round clip in place allowing you to adjust the clip to different settings. As you move that clip up, you allow less fuel into the carb, making it leaner. As you move that clip down, you allow more fuel into the carb, making it richer (some experts can correct me if I am wrong but I think I have it right).

Easiest way to remove that little round clip is take a pair of needle nose pliers and grip the end opposite the open side and simply pull away from needle. Careful placing it back onto the needle, I have dropped this little booger a couple of times and it is a doozy to find on a garage floor.
 
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hondaman

Active Member
Try it at different settings and see what happens. You can always put it back where it was if nothing changes.
 
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R

Ranch120

Member
85CTrider said:
Hey ranch,
i am having the identical issue; - see thead http://lilhonda.com/webboard/f6/checking-oil-level-9955/

goin on right now. I messed with the idle screw and airintake screw and since then the bike is a mess. It idles great even revs great in neutral, but when i ride it, it bogs down, sputters, stops and starts and rides like a bukcing bronco. i took the carb off 3 times, cleaned it ( so i thought ) cleaned the jets, the bowl the tubes, everything, checked the pug, the intake the air can etc... still cant figure it out.. i am running to lean as well... maybe its the idle screw or air intake screw... i never took those off when i cleaned the carb. those stupid screws were probably not adjusted in 20 years untill i messed with them.. have you made any more progress???
Click to expand...

No, Im almost afraid to touch anything else until I get a more firm understanding of the physics involved, I wish I had racerx's brain sometimes!
 
85CTrider

85CTrider

Member
this is crazy. i will go back and look at the w clip. \

do i have to undo throttle cable to access the W clip?? or can i adjust it with throttle assembly in tact??

BUT if the engine revs full throttle in neutral but bogs in gear.. could it still be that clip causing the problem???
 
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hornetgod

hornetgod

Well-Known Member
Remove the needle from the slide assembly. You'll need to remove the throttle cable and return spring first. Once those are removed look down inside the slide, there should be a "W" looking retainer holding the needle in place. Remove the retainer and the needle will fall right out if the slide is turned upside down. Once the needle is out, you will be able to see the "C" clip on the top of the needle with 5 slots to choose from. I hope this helps.
 
Haas

Haas

Member
85ctrider,

Are you reading all the advice that's given to you? You're asking if you have to undo the throttle cable to acces the "W" clip, but a day or so ago, I already provided you a link that showed exactly where that is, and how it's supposed to be installed.
Correct me if I'm wrong, but it doesn't seem like you're taking all the advice, and steps given to you.
 
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