Engine and throttle acting weird

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cnodie1

New Member
Jan 27, 2010
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Baton Rouge, Louisiana
(I originally asked this question in the chat box, thats why its formatted like this)

I have been having problems lately with my bike...

-it seems like when my engine is not running my throttle seems very responsive and "springy" (throttle slaps right back closed once i let it go)

-but when my engine is running i would describe it as like throttling through syrup... not responsive (doesnt slap back closed, just slowly moves back)

-im not sure what the problem is but i can tell its taking away from my top end speed. last week I could get it up to 35 mph after a little while but now i am struggling to get it passed 30

I am thinking it may be a carb problem and it could be because of my recent modifications. Does anyone think this may be a problem? I really hope not because I love it :D

Thanks for any help the community can provide!
Clark
 

bairdco

a guy who makes cool bikes
Aug 18, 2009
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living the dream in southern california
as long as your choke is opening and closing fully, it shouldn't be a problem.

if you took the carb apart, i'd go back through it and check it, make sure it's all back together correctly, and that you don't have any air leaks.

also, if there's a lot of pressure on the choke, it might be pulling at the carb, which could be creating an air leak.

the best thing to do, is if it worked fine before the choke mod, start there. put it back to normal and see if it works right. if it does, then figure out where you went wrong.
 

cnodie1

New Member
Jan 27, 2010
60
0
0
Baton Rouge, Louisiana
as long as your choke is opening and closing fully, it shouldn't be a problem.

if you took the carb apart, i'd go back through it and check it, make sure it's all back together correctly, and that you don't have any air leaks.

also, if there's a lot of pressure on the choke, it might be pulling at the carb, which could be creating an air leak.

the best thing to do, is if it worked fine before the choke mod, start there. put it back to normal and see if it works right. if it does, then figure out where you went wrong.
Ill give that a try asap... today when i was riding the throttle was still acting up. I would go to accelerate somewhat quickly and it would almost bog down and would accelerate very slowly when i let off. i still got it to 30 mph but it took a long time. Im stuck here

edit- ok I just rode it back to my house and it started doing something different: it was still taking a little bit longer than normal to get it up to speed but when i was at about 30 mph the engine would start sputtering and surging. now i really dont know what to do. im gonna take apart my mod and see if that helps
 
Last edited:

cnodie1

New Member
Jan 27, 2010
60
0
0
Baton Rouge, Louisiana
as long as your choke is opening and closing fully, it shouldn't be a problem.

if you took the carb apart, i'd go back through it and check it, make sure it's all back together correctly, and that you don't have any air leaks.

also, if there's a lot of pressure on the choke, it might be pulling at the carb, which could be creating an air leak.

the best thing to do, is if it worked fine before the choke mod, start there. put it back to normal and see if it works right. if it does, then figure out where you went wrong.
OK i just went and did some trouble shooting and it turns out my choke had vibrated loose (again!) and had been intermittently blocking air flow. however i still wasn't getting maximum speed and it was bogging and surging. i have heard something about the needle placement and that my mixture may be too rich but i have no experience in that matter. do you?

Next I have the problem of my choke nut vibrating loose... WHAT CAN I DO ABOUT THIS!?! it has come loose half a dozen times and im not sure what to do about it.
 

bairdco

a guy who makes cool bikes
Aug 18, 2009
6,537
264
63
living the dream in southern california
after i tightened up the nut on the choke, i crushed the threads with a punch and a hammer. you gotta take the carb off and support it well so you don't smash anything else. basically, i made a ding in the threads where it contacts the nut. so far it's holding.
(loc-tite may work, but i'm anti loc-tite. just personal preference...)

as for your needle setting, you need to check your plug and see what color it is. black and oily is bad, tan is good, white is deadly. you want a nice cocoa color.

if it's black, it's too rich, and you need to move the clip on the needle up. ride the bike, hit top speed, then shut it down and turn the gas off.

WAIT TILL IT COOLS before you pull the plug again. if you remove it on a hot motor, you could take the threads out of the head with the plug. then check the color.

if the tip of the plug was white to begin with, then move the clip down a notch, and check it again.

it could still be an airleak, though. with the engine idling, spray a few light bursts of carb cleaner around the manifold where it attaches to the jug and where the carb attaches to the manifold. if it revs up, there's a leak.
 

cnodie1

New Member
Jan 27, 2010
60
0
0
Baton Rouge, Louisiana
after i tightened up the nut on the choke, i crushed the threads with a punch and a hammer. you gotta take the carb off and support it well so you don't smash anything else. basically, i made a ding in the threads where it contacts the nut. so far it's holding.
(loc-tite may work, but i'm anti loc-tite. just personal preference...)

as for your needle setting, you need to check your plug and see what color it is. black and oily is bad, tan is good, white is deadly. you want a nice cocoa color.

if it's black, it's too rich, and you need to move the clip on the needle up. ride the bike, hit top speed, then shut it down and turn the gas off.

WAIT TILL IT COOLS before you pull the plug again. if you remove it on a hot motor, you could take the threads out of the head with the plug. then check the color.

if the tip of the plug was white to begin with, then move the clip down a notch, and check it again.

it could still be an airleak, though. with the engine idling, spray a few light bursts of carb cleaner around the manifold where it attaches to the jug and where the carb attaches to the manifold. if it revs up, there's a leak.
Ill give all that a try. ill have to find that complete carb breakdown thread because I have no idea where the clip for the needle actually is :D lol
 

bairdco

a guy who makes cool bikes
Aug 18, 2009
6,537
264
63
living the dream in southern california
it's at the end of the throttle cable. you just need to unscrew the cap off the top of the carb and the whole assemble should pull right out. just make sure it all goes back in the same way. there's a tiny stud in the carb that needs to line up with a slot on the slide.

the whole assembly should drop in without any force. if you have to force it, you're doing it wrong.
 

cnodie1

New Member
Jan 27, 2010
60
0
0
Baton Rouge, Louisiana
status report: I fixed the needle and it seems to be running well but i havent had a chance to go all out on it yet. however i have found one of the teeth where the carb mounts to the manifold is broken. and i have a feeling vibration is my main problem. Im not sure what to do about it though :(
 

cnodie1

New Member
Jan 27, 2010
60
0
0
Baton Rouge, Louisiana
it's at the end of the throttle cable. you just need to unscrew the cap off the top of the carb and the whole assemble should pull right out. just make sure it all goes back in the same way. there's a tiny stud in the carb that needs to line up with a slot on the slide.

the whole assembly should drop in without any force. if you have to force it, you're doing it wrong.
ok so after messing with the needle and going all out it seems as though my motor is performing worse. i could only get up to about 28mph and i used to be able to do 35mph so thats no good. and it still seems like when i am approaching max speed my engine is bogging and surging and making odd noises. could this be four stroking? i have no idea what it of what it sounds like so im not sure. I just wish the motor was back to like it was a few weeks ago :(

I know i have to order a new NT carb because one of the tabs is broken on the one im using now and im afraid once i get a new one the problem will start all over again
 

Brent436

New Member
Feb 14, 2010
55
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0
Massachusetts
i had a problem with the choke nut coming loose. i screwed it on to how tight i wanted it and then i put clear silicone rtv over the nut and stud to hold it in place. so far its done the job and its been ridden about 400 miles since i did that