bog down at top speed

well it seems lately that im having a small issue with my top speed..everytime it gets to the top speed the motor will bog down a bit then resume. it will repeat the process over again..what could be causing this? im not even maxing out the throttle. thanks for any help its driving me nuts!

timeing off a little???
Check yur magneto (little black box that generates the spark) make sure its close but not touching the flywheel
could be a cloged jet but that is rare
what was it oh ya the keyway might be bent a small bit
try replaceing the little soft metal peice with another one (NEW ONLY don't use a used one) see if anything helps

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maybe it wants more air and gas.

Check you motor mounts to be sure they are not loose, it can cause a small vibration that will cause a fuel delivery problem.

Be sure your fuel valve on the tank is flowing properly, could be the valve or the gas cap not venting properly. I'd start there and keep us posted.

At times, I've got the same issue. Aggravating to say the least.

Sometimes, she runs GREAT! But at other times, she'll hit 22 MPH, Bog down to 19, and then run back up to 22 again. What gives?

I have a newer build, with 120 some miles on it. At it's best, she's done a good 29 MPH. So what keeps changing here to give me different results on each ride?

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Cowboy Rider's Bike Pics at Webshots

The float bowl is not filling fast enough to keep up with the engines demand for fuel. fairracing31 has suggested several reasons this could be happening.

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I was having the same problem as you guys are describing and the filter in the tank was clogged. I cleaned both the in tank and the in line filter and cut 1 1/2 inches off my fuel line and that really helped my motor scream. keep the fuel line as short as possible.

340 lbs at 33 mph / 80cc raw - 44 tooth

I had my bike acting up the other day and found the base gasket leaking just a little bit it would do strange things idle, them idle high, then idle back down.
bogging can be the main jet drilled too big. when its bogging try the choke start putting it on if it runs better then you know its not getting enough fuel.
Starving for fuel will also make it bog. Fuel filter? yea there is one on some, in the tank clogging off with crud. If your bike is like mine fill it up a little too much and you get fuel tracks on the tank then its not the cap not venting.
Float sticking or set so the level is too low and running out of fuel or sticking shut.
My guess is measure your main jet and see just what size it is and if it is a nice round hole or like some drilled with a hammer and a nail (hole oval shaped). You can fix that with the proper drill and solder. check out my link on the carb.
Motorized Bicycle Carburetor install and rebuild
Norman

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I totally Removed the in tank screen/filter. Replaced it with an in line fuel filter that I can see fill up as I ride. This seems to have helped a bit, but I haven't been on a 5 to 10 mile road cruise yet after this change.

In the neighborhood, So far so good. I'm still not getting what I expected, but while I'm here more, I think I have the wrong gear on the rear wheel for the Ultimate Speed.

I have a 50 Sprocket. For Speed, I think I need a 44 or less sprocket. But for Torque and Power, I think I want the 50 Sprocket.
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Somewhat of a decision point here on my end, huh?

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Before: <}----------{> After:
~Scott.
Cowboy Rider's Bike Pics at Webshots

If you are still having problems on a longer ride, check the gas cap to make sure it is venting properly.

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If it ain't broke, and you mess with it long enough, it will be.