Kmx 125 wont start, please help

[sam_w]

i tried to start it this morning and i couldnt even get it to tick over. i tried it on the choke and everything. it was quite hard to start when i used it last saturday but it was at least ticking over and then cutting out, now it wont even tick over. Anyone any suggestions to what the problem is? before sarurday it would fire up on the first kick

Edit: one more thing i forgot to mention. i heard a pop/backfire in the exhaust on a couple of kicks this morning but this didnt happen on every kick

[Keir]

new spark plug required possibly.
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Current : '08 Yamaha FZ1s
Previous: '99 Honda CBR 600FX, 03 ZX636 B1H, 99 Fazer 600 (red), 02 GSX-R 600 K2, 00 SV650s (red), 2008 ZX10R, 97 Bandit 1200N, 04 ZX6RR K1H, 04 GSX-R 1000, 98 Fazer 600 (gold), 05 Madness 110 Pit bike, 04 CR125R, 00 SV650s (black), 06 KTM 625 SMC, 99 SRAD 600 track bike, 03 SV650, 98 Bandit 1200N, Bandit 600SY, 03 GSX-R 600 K3, 01 GSX-R 600, 01 Fazer 600 (black), VFR 400 NC30 x3, 78 Honda Dream, 00 Speedfight 50

[sam_w]

yer i was thinkin it might be spark plug related as it was startin up fine up until a few days ago. thanks for the quick reply mate

[Keir]

when was the last rebuild? If its not the plug being fouled then a compression test would be the next thing i would do.
____________________
Current : '08 Yamaha FZ1s
Previous: '99 Honda CBR 600FX, 03 ZX636 B1H, 99 Fazer 600 (red), 02 GSX-R 600 K2, 00 SV650s (red), 2008 ZX10R, 97 Bandit 1200N, 04 ZX6RR K1H, 04 GSX-R 1000, 98 Fazer 600 (gold), 05 Madness 110 Pit bike, 04 CR125R, 00 SV650s (black), 06 KTM 625 SMC, 99 SRAD 600 track bike, 03 SV650, 98 Bandit 1200N, Bandit 600SY, 03 GSX-R 600 K3, 01 GSX-R 600, 01 Fazer 600 (black), VFR 400 NC30 x3, 78 Honda Dream, 00 Speedfight 50

[sam_w]

it hasnt had a re-bulid yet. its only done 9000 miles. Wouldnt there be other signs of needing a re-build like loss of power etc? the bike has been runing great up until the last two times ive used it so i dont think its that. i think its plug related. il take the plug out and check its condition and replace. thanks

[sam_w]

if my plug is fouled does that just mean my mixture just needs a bit tuning?

[Jello]

Not necessarily.

Try a new plug and see what happens. What condition was the plug in when you took it out?
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Honda MTX 125

[chillpill]

combination of cold conditions , bad plug and needing new rings

fit new piston rings as soon as you can mate before it starts marking the barrel

[Keir]

i wouldnt start messing with the mixture if its been fine for 9k. just stick in a new plug. As chill says, after 9k you could do with new rings and might aswell do the piston while you're there - they are maintenance items on a 2t.
____________________
Current : '08 Yamaha FZ1s
Previous: '99 Honda CBR 600FX, 03 ZX636 B1H, 99 Fazer 600 (red), 02 GSX-R 600 K2, 00 SV650s (red), 2008 ZX10R, 97 Bandit 1200N, 04 ZX6RR K1H, 04 GSX-R 1000, 98 Fazer 600 (gold), 05 Madness 110 Pit bike, 04 CR125R, 00 SV650s (black), 06 KTM 625 SMC, 99 SRAD 600 track bike, 03 SV650, 98 Bandit 1200N, Bandit 600SY, 03 GSX-R 600 K3, 01 GSX-R 600, 01 Fazer 600 (black), VFR 400 NC30 x3, 78 Honda Dream, 00 Speedfight 50

[sam_w]

ok thanks for your help guys. just an update i took the plug out and it was a little black but not oil fouled. i put the plug back in and the bike started 1st kick but was bogging down when i tried to give it a bit of throttle then just cut out. so any idea what problem this might indicate? i will also replace the piston and rings like suggested

[chillpill]

indicates low compression , wich would be fixed by piston and rings dont forget a new gaskets to go with your piston

[stevo as b4]

my 200 just poped and backfired a couple of times when i tried kicking it over, after the engine made some nasty noises and ground to a halt. The reason for this was that the piston crown and rings had come away from the skirt, and i had a bottom end and exhaust full of bits of metal, and sod all compression.

I doubt that is your bike's problem, but it's certainely worth checking the compression pressure which should for the 125 be between 120-178psi.