i installed a trinity stage 4 head pipe and silencer on a friends 05 ltz 250. it had a 125 main stock, i put in a 130..ran and checked the plug..still looks new, put a 135, same 140 same 145 same but now lurches from 1/2 to full throttle, is the plug supposed to change color as fast as a 2 stroke? how long should it take to change the plug to a tan color? we are going on a ride tomorrow and need to get this dialed in before we drive 2 hours to ride and possibly toast his engine. i'm lost, this is my first 4 stroke jetting experiance, i also moved his needle up with the original washers all placed underneath the needle. PLEASE PLEASE help???!!!!

 

i dont think the plug should change colors that fast if its the stock one you might want to try and get a more high performance one my 250 has different jets in it too and at sea level it ran fine but at higher elevation we had to change to a smaller jet we also adjusted the idle so it idled faster and it would jump a little when i shifted into gear from nuetral so i would suggest lowerin the idle and if it still lurches take the jet back down to a 135 or 140

 

i think its lurching because its running too rich now...it idles perfect....i'm just worried about the plug and if its runnin lean, i put a new plug in it when i put the exhaust on it..so i had something new to look at. what jets are you running with what mods?

 

i have a white bros e2 exhaust its just the slip on tho no aftermarket head pipe yet (mines an 04)
my main jets a 135 i dont really know much about carberators but if its lean that means too much air not enough gas so maybe go with a bigger jet

 

Ya I was going to say you are probably just running too rich I mean if it ran fine with the smaller jets then all you should have to worry about is getting the jet changed by tomorrow!!

 

i know alot about jetting...i have a 2 stroke that built up...i just havent messed with any 4 strokes. and how do you know if its lean or rich...if the plug dont change color like a 2 stroke, when i jet my quad i put a new plug in it, run it wide open in 6th, shut it down and check it, and its already changed color...in a matter of minute, we rode this 250 for 5 hours so far...but some people told me that it takes a few days to change color...any ideas?