renegade master Posted June 26, 2015 Author Report Share Posted June 26, 2015 Ok very early days yet! but might have solved it? Ok we took out the carb again to check the jetting size! and after another inpection of carb we found a broken component! one of the jetts! the one that goes all the way into the bowl ( jet choke i think ) I have post a picture of it below, so we just used another carb that I got and put everything back together and tested it out! 20min spin and its still going! switched the bike of and frist kick it starts again! I will probably bring it to the hill at the week end for a real test, but does this broken jet make sence to you guys as to the plug blown problem? Cheers guys Quote Link to comment Share on other sites More sharing options...
tony27 Posted June 26, 2015 Report Share Posted June 26, 2015 Broken choke jet could very well be the problem, when the o-ring on it gets damaged it affects the jetting due to fuel bypassing it Out of interest how different was the jetting numbers in the 2 carbs? Quote Link to comment Share on other sites More sharing options...
crazybond700 Posted June 26, 2015 Report Share Posted June 26, 2015 Might definitly cause problems Quote Link to comment Share on other sites More sharing options...
pschrauber Posted June 28, 2015 Report Share Posted June 28, 2015 (edited) Yep problem solved, as the broken choke het together with the damaged o-ring will let in too much fuel even when the choke is off. Small things can have very big effects. especially in carburetion. Edited June 28, 2015 by pschrauber 1 Quote Link to comment Share on other sites More sharing options...
johnf2711 Posted July 3, 2015 Report Share Posted July 3, 2015 Hi just been reading your tread with interest am currently building a Jtx 200 and need a sa barrel and piston assembly. I run lots of small two stroke tool and had a sthil chainsaw that was blowing plugs all the time.This turned out to be debris in the case not allowing cool air to the head, and them getting far to hot.Have you checked that you have coolant in the cylinder head? On my sons gasgas there is a bleed nut on the top to vent the air. John Quote Link to comment Share on other sites More sharing options...
renegade master Posted July 6, 2015 Author Report Share Posted July 6, 2015 Broken choke jet could very well be the problem, when the o-ring on it gets damaged it affects the jetting due to fuel bypassing it Out of interest how different was the jetting numbers in the 2 carbs? There a slight difference between jet size, I will check tomorrow on the old carb for sizes Quote Link to comment Share on other sites More sharing options...
renegade master Posted July 7, 2015 Author Report Share Posted July 7, 2015 Ok sorry for late reply on update, took a spill off my gasser pro last week that put me out of action, ok so finiely got to test out the jtx 270 o the hill yesterday, and yep problem solved! on another note tho, something i havent come accross before!!! as the bike was running great when i got up the hill halfway (hight of hill 671meters) the bike felt like there was a hard spot in the chain! a sort of hold back feeling, abrupt tug! so got to the top and on the way down i was in frist gear and having a 9t/40t setup makes it nice for steep down hills, but bike kept cutting out and wouldnt start only on full choke! I had my suspicions tho! as my mate was on his 97 315r and complaining of the same problems! we came to conclusion it was altitude sickness! of the bikes that is!, both bikes are 1997 so are similar, once we got back down again bikes were fine! funny thing is we have been up there before on newer bikes but hasent effected them! mabe the older bikes dont like altitude! also something to point out, te weather was damp foggy kind of stuff! just thought id mention it! Quote Link to comment Share on other sites More sharing options...
crazybond700 Posted July 7, 2015 Report Share Posted July 7, 2015 (edited) THat weather (moisture) and altitude can make a great difference yes! Really needs rejeting to work propperly. (smaller because of the richer mixture). But offcoarse this is quite a hassle since you need to change it back to normal when going down. 671 is not that high, but it could (and will) make a difference than sea level). But seeing from that picture the humidity was very high and that could be a problem. Edited July 7, 2015 by crazybond700 Quote Link to comment Share on other sites More sharing options...
renegade master Posted July 7, 2015 Author Report Share Posted July 7, 2015 So best to stay away from them poor/damp weather conditions when trailing on the hill, im guessing this wouldnt happen to the newer bikes? Quote Link to comment Share on other sites More sharing options...
crazybond700 Posted July 7, 2015 Report Share Posted July 7, 2015 (edited) Could also happen with newer bikes, its one of the disadvantages of carburators, they dont adjust themselves. Also it could have been something else, maybe too long on a certain angle, water getting in somewhere? But putting the choke on it to solve could explain it that its due to the weather and altitude. Edited July 7, 2015 by crazybond700 Quote Link to comment Share on other sites More sharing options...
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