Throttle Adjustment

brown bull

New Member
Nov 16, 2008
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pittsburgh
Hi, I just got a motorized bicycle, which was assembled by someone else, and the the bike bogs down at full throttle, but runs great at part throttle. What kind of adjustment do you think this requires: adjust the throttle so it only goes so far, or adjust the carb so it responds better to full throttle?
 

Saddletramp1200

Custom MB Buiilder
May 7, 2008
1,439
40
48
Houston, Texas
Welcome Bull, like that. Check the slide in the carb. There is a cpin on the needle. Pointy thing. Move it down one slot. re-asymble and try that. Don't cross the threads when you put the top back on the carb.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
235
63
up north now
I'd check the plug so you know where your air/fuel miture is and go from there.

Move the clip up to lean the mix, down to richen.

Start with it at the second from the top.

Are you done with break-in?
Running the stock plug and wire?

Welcome to the forum!
 

brown bull

New Member
Nov 16, 2008
17
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pittsburgh
Thanks for the replies. I'll check out that carb in a couple of days.

The motor is a couple of years old, I'm told. I just replaced the plug and wire with parts from Pablo at sickbikeparts. I'm waiting on parts to replace the fuel line, fuel filter, and chain tensioner pulley. I took a look down the spark plug hole and it looks pretty carbonized in there. Also, the inside of the gas tank has some rust. Should I be concerned about those issues? There's a distinct rattle, like a marble moving around, coming from my gas tank (I think) when I rock the bike forward and backwards. I haven't figured out the source yet.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
235
63
up north now
You'll want a filter at the very least. Remove the tank, and dump it out. rinse with K-1 or diesel until it's clean, then rinse once lightly with gasoline and re-install. I wouldn't worry too much about the carbon, but you could remove the head and scrape it with a wooden stick or other non-metal item.
 

brown bull

New Member
Nov 16, 2008
17
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0
pittsburgh
Thanks for all the great feedback. I've only run the bike around the block several times and it rides and runs great. I removed the 'stock' plug and wire and installed the recommended plug and plug wire from sickbikeparts.

What's the function of the spring-loaded button type mechanism next to the idle adjustment screw on the carb?

It took me a few minutes to start the engine today during a brief test drive in 35 deg. F weather. Is that normal?
 

Motormac

New Member
Sep 23, 2008
108
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Ontario Canada
That little button is called a "tickler" its a primer button you push it a couple of times to get some gas in the carb. what it does is push down the float to allow gas to get in. Up here in Canada its way below freezing and I have my engine running within 10 seconds of pedaling, try starting with the choke all the way up and as it starts to sputter move the lever down so its running somewhat smooth, after 5minutes of warmup put the throttle in full down position.