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Bought my first dirtbike!

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Yesterday I bought a 04 flywing mx 100 for 200 off craigslist.wouldnt start at first but after cleaning the carb and push starting it fired up.rode it around a bunch today had lots of fun I mean this thing is little and isnt super fast but for 200$ it is great and to make it fit me better I drilled a hole a lower than the original one on the top shock mount wich raised the back about 4 inches.theres one problem though when i first start it it bogs until i rev it for a while and it bogs for awhile when i first shift into a new gear until i pick up some speed in that gear this goes away after riding for about 15 minutes any idea what it could be?

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Both of my ttn 125 bog down when you start them till it warms up, which is normal, but 15 min is too long.

You probably need to remove carb, take it apart, clean all passages and jets with carb cleaner.

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I have this exact bike I use to run around my property with. I actually cut the subframe and welded in extensions to lift the seat as it was really low.

Pull the carb and clean it out real good. Mine seems to get a piece of dirt lodged in the pilot jet about every two weeks no matter how careful I am with cleanliness.

It seems real touchy with how warm it is as well. Messing with the air screw can make a big difference. Also watch the sprocket bolts. Mine loosen up every ride even with Loctite and will fall out if they aren't constantly tightened.

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Alright thanks I will try cleaning it again.Thats a good idea im actaully pretty good at welding so I could do that i havent tried messing the airscrew but i will experiment a bit today.yeah i noticed that i just put loctite on them yesterday guess i will have to keep watching it.

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For the sprocket, Get some spring washers or lock washers... whatever they're called and use some loctite. They should stay in.

My 250f had the same problem, took the carb apart, cleaned all the sand out of the throttle body and cleaned up the jets. Runs awesome now. The float was also sticking in my carb till i used seafoam, its a great carb cleaner!

Keep in mind that this bike was a race bike and i bought it second hand. Thing was dirtier than hell

Edited by jp-lightning

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Well the part the sprocket is attached to came loose and broke so replaced it the new one that is three teeth smaller than the other one and the bolt heads are locked in and the nuts are locked in so it cant come loose.it ran good after i replaced it i road around for a while and it ran good then parked it at my friends house came back out later started it up and warmed it up it didnt want to rev up unless i was full throttle then i took off and it wouldnt come out of the bog i would rev it up in first a bit(once i could get it to rev up) and then shift and it would bog very bad.so i took it back up to my friends cleaned the carb good put it back in same deal.dropped the needle clip a couple times until it would run a bit better.then we messed with the airscrew a bunch until we found the best position after that i could get it to go through the gears but it was still bogging bad pulled the plug and it was black :/ im kind of at a loss with this thing seems like no matter what i do to it bogs bad.could the plug being bad do this?cause before the first time i started it wasnt sparking between the gap so i pulled it and put it back and it sparked good maybe the spark plug is worn and the cap isnt getting good connection with the top of the spark plug?not sure just a thought,

.

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Ok  I finnaly figured out the problem, the kill switch was messed up so it was making my spark weak.unplugged it and it ran perfect no bog at all but now theres another problem,the bike wont start unless push started once it warms up it starts up no problem but once it cools all the way down you can forget about kick starting it.... any ideas?

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Next place id go is a compression test. It most likely has low compression. When its hot, the rings expand creating more, and when your pull starting it it creates more compression when the motors spinning so fast. Hope I could help good luck!

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