Hows it, from new zealand here!
Im normally pretty good at fixing bike issues but this quad has me a bit puzzled.

My previous bike which was a 02 trx350 finally died at 93000kms & 9600hrs! On the original engine with no rebuild!!!

So i purchased an 05 model, has been great for the last 3 months until recently.

Went to go up a bumpy hill & bike started coughing & spluttering until it died half way up then wouldn't start again, had to tow it home with tractor.
i pulled carb which was a bit cruddy & thoroughly cleaned, took for a ride was great for about 15mins then same thing happend on a hill again. Got it back home pulled carb again & fuel tank found tank & filter was full of **** so cleaned out tank, filter & carb again. Well i had tank off i adjusted valves then also added an in-line filter.
Put it back together, bike was even worse wouldnt start at all unless i put my hand over air intake inside box to force fuel into carb, so i pulled carb out again & cleaned it, put in a new plug & checked all the vent hoses.
put it back in & it starts but has a very rough idle, then well reving up it coughs & splutters & back fires badly. When u try ride it will intermittently feel like its guna die then kick in again & take off etc. I pulled plug & its sooted like its running rich. Fuel mixture screw is at 2 turns out which i where iv always had them.

Im totally stumped, could it be electrical? Tested battery its at 12.7v with ignition off & 14.2 when running.

Needing advice from the real experts out there before i yield & take it to a shop!

Thanks in advance



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Firstly, be sure you put the carb back together properly. I would also fit another plug, new doesn't always equal good. It is also possible the carb has been blocking slowly for a while and the previous owner may have richened it up to compensate (main jet needle position). Also check the diaphragm for holes. The choke can stick on that carb too. After that, a failing coil or other electrical problem can throw these symptoms but it would be a matter of substitution to find out just what.

 

Got it running better, put new o ring on choke. It does occasionally pop & give small back fires under load not too sure why iv got air/fuel screw at 1 3/4 turns out as any higher it really plays up.