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Jetting size, Weird question
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Posted by: ringoesroadking

Yesterday i let my buddy ride my 250r. I just put a 38mm a/s carb with a 170 main and a 50 pilot jet. My other mods are as follows
v-force reed cage
trinity pipe
K&n filter (no airbox lid)
RRP race ported cylinder

My question is, he rode the quad for half a tank of gas smoked me on his worked LT250r(damn right there's only one R) many times around the track and in a drag race. I got back on it and it was pulling really hard and seemed to be running fine. I decided to check the plug anyway. When i went to take the plug out I noticed that the choke Had been on the entire time! I took the plug out and it looked good. What does this mean? Do I need to put a larger main jet in? I didn't run it with the choke off because i was afraid of leaning it out and blowing it up. What do you guys think? Thanks

Posted by: 86 Quad R

do a plug chop with the choke off and go from there.

Posted by: GOTFEAR

was that on race gas

Posted by: wilkin250r

That depends.

Your spark plug can only tell you the LAST thing that happened inside your cylinder. Many people go ride around at WOT, then idle back to their garage or camp and pull the plug, and believe it tells them their WOT jetting. Wrong.

Go through the whole process. Imagine that your jetting is lean at WOT, but rich at idle (certainly a possible scenario). So you ride at WOT, your plug turns white, then you idle back to camp. Because your jetting is rich at idle, your spark plug gets covered in black soot. When you pull it, it's black. It's not telling you ANYTHING about what was happening at WOT, does it?

Forget what your plug looks like now. Most likely, it's not telling you anything about WOT and your main jet, it's only telling you idle. Do the proper plug chops at all throttle ranges.

Posted by: GOTFEAR

YEP run it like a drag bike full throtle to shut down