Greetings from North of Lake Tahoe, CA

[kenlani]

Just finished my 49cc in my Mtn bike--started right away and had me laughing, it was such fun---
however now I want to start tuning, and my first problem is the carburetor--I idle way too fast and it wont adjust and it seems rich at speed
I'm at 5700 feet so I'm sure thats the problem, does anyone have any tips on what I can do to lean out this thing? thanks

 

[NunyaBidness]

hey kenlani, welcome aboard
I'm sure one of the more experienced members will be along shortly to help you with your problem
good luck and happy motoring

 

[Dave31]

Welcome to the forum, glad you joined us

Be sure you do not have any kink's in your throttle cable. Your cable might be too tight...adjust on the top of the carb...

To change the fuel mixture...move the clip on the carb.
Check post #5 the "e clip"

http://motorbicycling.com/f4/carburetor-pictures-how-install-rebuild-195.html

 

[Dave31]

Sorry I forgot to mention to lean the carb move the clip up...to go richer you would move it down.

 

[stude13]

hi; it could be a vac leak at carb. mount.

 

[paul]

welcome to the site. the idle screw is the only screw on the carb. i had to mess with mine alot to get it where i wanted it. also check both on the throttle and where joe put the picture of the cable coming into the carburator and make sure it is not kinded or to tight, glad to have you with us

 

[Ilikeabikea]

Welcome to the forum. Lots of motorized bicycle enthusiasts here. Glad you joined us..........................

 

[kenlani]

I moved the clip up, runs a bit better, can adjust the idle faster, but I'm already idling way fast---my cables are not kinked and the adjusters at the throttle and on top of the carb are all the way in--so I have to be rich and need to jet for the altitude--
how do I get to "Classic Posts" to find where to buy some---anyone have an idea of what size down I should try? again I'm at 5700 feet----thanks

 

[Dave31]

I'd check for a vacuum leak first...use some wd-40, carb clean, brake clean, and spray around the manifold & carb. If the engine changes RPM you know you have leak and use some RTV to seal it up.

 

[Bikeguy Joe]

If you are too rich it won't cause it to idle high. You may be too rich because of altitude, but have an air leak so you are idling high.

What does your plug look like?

 

[Bikeguy Joe]

Classic Instructions for Building and Repairing Motorized Bicycle Engine Kits - Bicycle Engine Kit Classic Posts at Motorized Bicycle Forum

 

[kenlani]

Thank you all for the help---Ive checked the carb for air leaks and found none so I rechecked for kinks in the cable and discovered that even with my cable straight and all adjusters bottomed I still have a big gap at the bottom of my throttle slide- 5/32"- so it seems the throttle is part open at idle----what if any gap should there be? do I trim down the plastic stop thingee at the hand throttle to close the gap?

oh and the spark plug is wet and black ---thanks again