air leaks?

generallee

New Member
Oct 15, 2008
25
0
0
Pennsylvania
i've been through 3 or 4 gallons of gas on my bike and i guess it's supposably broke in. it tops out at around twenty- from wat i hear these things can go faster than that? im thinking that i mite have some air leaks . i sealed everything before but i guess could still be gettin extra air? how should i go about checking for air leaks?
 

Dave31

Active Member
Mar 1, 2008
11,204
29
38
Aztlán, Arizona
You could use some wd-40 or carb clean, spray around the intake and carb/intake connection with the engine running. If the engine RPM changes you know you have a leak.

Also looking at the plug will also give you a good indication of the air/fuel ratio. If the plug is whitish in color then it's running lean.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
237
63
up north now
There are several reasons the bike may only be going 20 mph.

Intake restriction (unmatched port to intake manifold).
Exhaust restriction (same thing, and also check the baffle and outlet, one bike I built had a hole the size of a pencil at the outklet where they welded the tip on and almost closed).
Incorrect fuel mix (24:1 fresh gas)
Incorrect fuel to air ratio (does the engine four cycle all the time, or just at a cruise?)
Bad plug.

Or, a combination of any of the above.
 

Norman

LORD VADER Moderator
Jan 16, 2008
2,605
2
38
68
pampa texas
one thing no one said anything about if you find no air leaks and your engine is running fine etc. The number of teeth on your rear sprocket the smaller dia sprocket will get you faster speeds some kits come with a 50 tooth rear sprocket and it will climb trees but not very fast a lot come with 44 tooth rear sprocket and that is a fairly nice one I have one bike with a 36 tooth rear sprocket and it will haul the mule and going almost 40 mph scares me on a bicycle. look here on the side of the forum at the adds got some nice sprockets for sale from Kings.
Norman
 

generallee

New Member
Oct 15, 2008
25
0
0
Pennsylvania
one thing no one said anything about if you find no air leaks and your engine is running fine etc. The number of teeth on your rear sprocket the smaller dia sprocket will get you faster speeds some kits come with a 50 tooth rear sprocket and it will climb trees but not very fast a lot come with 44 tooth rear sprocket and that is a fairly nice one I have one bike with a 36 tooth rear sprocket and it will haul the mule and going almost 40 mph scares me on a bicycle. look here on the side of the forum at the adds got some nice sprockets for sale from Kings.
Norman
Right now I'm pretty sure there's a 44 tooth spocket on my bike, so if I would get a smaller one, would that make much of a difference in my power. Where I ride there's hills everywhere so I'm wonderin if it would be a good idea to get a smaller rear spocket.
 

Norman

LORD VADER Moderator
Jan 16, 2008
2,605
2
38
68
pampa texas
If you have a lot of hills 44 tooth would be a good choise. If you weigh under 150 lbs you might get away with a 40 or a 36 tooth. My bikes top out around 34 mph with the 44 tooth and I weigh in at around 204 lbs.
 

deacon

minor bike philosopher
Jan 15, 2008
8,117
3
0
north carolina
one thing no one said anything about if you find no air leaks and your engine is running fine etc. The number of teeth on your rear sprocket the smaller dia sprocket will get you faster speeds some kits come with a 50 tooth rear sprocket and it will climb trees but not very fast a lot come with 44 tooth rear sprocket and that is a fairly nice one I have one bike with a 36 tooth rear sprocket and it will haul the mule and going almost 40 mph scares me on a bicycle. look here on the side of the forum at the adds got some nice sprockets for sale from Kings.
Norman
The other thing not mentioned in my case is the weight of the rider. Some of these thirty mile an hour riders most likely don't weight 220 lbs like me. My bike ran well and topped out at around 25 on the flat and it was stock all the way. That was plenty fast for an old nervous guy like me.