Power loss

[highhobo]

Hello!Could someone give me some advice on my engine?It runs well for about a mile,then it starts to bog down then cuts out.I can restart it if i let it rest for a min or two.Then the same thing again.I've cleaned my carb,checked the wireing,an nothing.The next step is changeing out the gas.The bike is pass the brake in time.It will restart after it bogs down i just have too wait for a min to get it to going right.Please help!Thank you!

 

[CrazyDan]

You might be running too lean, either from too small jetting, or a possible air leak. Both of those can make the engine run hot from a lean condition, requiring a cool down.
Do a plug check. If you want us to help, run full throttle for a block or 2, and keep it at WOT (wide open throttle) the entire time, and throw the killswitch while still pegging the engine. Take multiple pictures at different angles showing us your plug, bonus points if you actually chop the plug with a hacksaw or at least shine a blindingly bright light showing us colors down the electrode ceramic down to the bottom.
I advise not doing it like me. I use one plug, and risk massive failure by cooking my new plug to the new settings .
Most pros will use multiple new plugs to tune their jets.
I just test a mod about a quarter mile, and only finish it if it didn't feel wrong. I then pull the plug and see what color change it gained. Even though it is a used plug, I can see if the engine ran richer or leaner during that run. I know my plug like my third leg. I have a micro drill bit set and a solder gun with solder. Never had a single issue with jetting.
The 3 biggest things I see almost everyone have the biggest issues with on kit or custom motorized bikes: jetting, gearing and alignment.

 

[FNTPuck]

It could be overheating, which if you havent messed with compression or put a super restrictive exhaust on would mean it is running lean.

Another possibility though, I had a customers bike only run for a few seconds at a time and it ended up being a small rock/grain blocking the main fuel inlet on the carb. It was only partially blocked so it still turned on, but it made it take ages to fill the carb bowl. Once the bike was running, it would use up the fuel in the bowl then quickly shut off. Sitting would allow the bowl to slowly fill, which would make it run again for a brief time.

 

[CrazyDan]

A clogged tank filter, petcock, gas cap vent or an incorrectly set float valve can also prevent the bowl from refilling fast enough to keep up with fuel demand.

 

[Karl Snarl]

my first experiance with these symptoms ended up being a short in my stator ( magneto)coil. swaped all of them stock ones out for super magnetos and i've not had a problem with tht since. it would run fine till the engine heated up, then chug out and die. once it cooled for a few minutes, it would fire right back up and do it again a mile or so down the road.

 

[darwin]

WOW, I'm impressed of the above advice. Carry on!