Carb and idle issues

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vtm822

New Member
Nov 16, 2009
4
0
0
Alabama
I finished installing it yesterday, started up fine and rode it for 20 mins or so. After riding for a couple minutes i noticed a lot of gas dripping from under the air filter so i turned off the gas and tried to run the engine to get all the excess out. Then turned the gas back on and it started dripping again. So i took off the air filter to see where the leak was and its coming out of a little hole to the bottom right of the hole that the air goes through(the hole the choke covers). Is this normal? As soon as i turned the gas line on it would start pouring out of that hole. I put it back together and rode some more turning the gas line on and off so that it wouldnt leak. Also i am using the choke almost exclusively for throttle because the throttle doesnt make much difference. When i pull in the clutch to stop the engine races and i have to close the clutch all the way for the engine to shut off then i can peddle to start again and use the choke to accelerate. So baisically i have a few questions:
1. Is fuel supposed to come in next to the air filter through a small hole?
2. How do i adjust the throttle so that it works?
3. Why is the engine racing when clutch is engaged?
4. If something wrong with the float and how would i check that?

Thanks, i know its a lot but all help is greatly appreciated
 
Last edited:

BarelyAWake

New Member
Jul 21, 2009
7,194
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Maine
Sounds like yer float isn't doing it's job and yer idle isn't set properly. The float is easy enough, just drain and remove the carb and pull the float bowl off (2 screws). Inside you'll find the float and the tabs it presses up against to shut off the fuel when the bowl is full. Check to make sure the float isn't cracked and filled with gas and that the tabs are bent enough so the float can close the inlet.

The idle is adjusted with the one big screw on the outside of the carb (has a spring behind it). Turn it in all the way (by hand, don't force it) and then back it out 3 1/2 turns. This will get you close to the correct idle speed and you can fine tune it from there (tighten to raise idle speed, loosen to lower).

Better and more detailed instructions can be found here: http://motorbicycling.com/f4/carburetor-pictures-how-install-rebuild-195.html
 

vtm822

New Member
Nov 16, 2009
4
0
0
Alabama
Thanks barelyawake, the float seems to be working fine now, i havent noticed any leaks, but the choke and throttle are still having problems. When i start it i turn full choke after a few minutes the engine steadily increases rpms without me even touching the throttle until its maxed out. If i use the throttle it revs even faster. After its warm, however, if i move the choke all the way closed, the engine will not increase rpms even if i turn the throttle. So the only way to control the throttle is to constantly adjust the choke. And if i pull in the clutch when choke is open at all, the engine races. I'm not sure whats going on. Thanks for the help!
 
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Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
252
63
up north now
It could be the throttle cable being too tight, check where it goes into the top of the carb, there should be a tiny bit of freeplay there. Also check for an air leak. Take the carb off and remove the manifold. Coat both sides of the gasket with some RTV and re-install it. Make sure the carb is all the way on the manifold.
 

vtm822

New Member
Nov 16, 2009
4
0
0
Alabama
Thanks so much guys. I will definitely try to seal the gasket better with rtv. Are there any other ways to check for an air leak? Also, I know most all my questions are answered somewhere on the site but it takes years to search through all this stuff. Are there any good sites that have a broad overview of how things should work with pictures? Because i'm not sure if the slide in the carb is going high enough, but i don't know what to compare it with. Thanks
 

bairdco

a guy who makes cool bikes
Aug 18, 2009
6,537
264
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living the dream in southern california
http://motorbicycling.com/f39/motorized-bicycle-carburetor-install-rebuild-302.html

there's a link to norman's carb rebuild.

for airleaks, buy some Gummout carb cleaner from any auto parts place and spray it around your intake and carb mounting surfaces. an airleak will either rev it up or kill it. either way, you'll notice a change in idle.

don't go crazy spraying it, if it sucks into your carb throat, it'll kill it. just a few short bursts will find a leak.

it also cleans all the dirt off, hence the name, "carb cleaner."
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
7,266
1,797
113
Los Angeles, CA.
Just so that we're clear here... The metal choke lever "up" is to start it, the choke lever "down" is to ride!
Is that how you're doing it?

Also, if you screw the large top cap on the carb on too tight, it will warp the carb body & cause the slider to stick!! (only screw it on 'hand tight'!!!)
 

vtm822

New Member
Nov 16, 2009
4
0
0
Alabama
yes, to start it the choke is all the way up, but then after it is started, the handle bar throttle doesn't do anything, the only way to control speed is by pushing the choke down to go faster and up to slow down and idle. Hopefully today i can get something to seal the gasket and intake better and adjust the throttle cable and that might solve the problem. It may just be a combination of adjusting the cable and fixing an air leak. I'll keep ya posted, thanks for the help fellas
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
7,266
1,797
113
Los Angeles, CA.
There's something wrong with the way you have your throttle set up if theres nothing happening at all when you turn it!!!
Check out the link Bairdco posted for you, & look at your cable & top cap too!!