Jetting Question

Joined
Jul 12, 2000
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#1
I have a 83' XR200R. The stock main jet is a 138. I have removed the snorkel, baffle, and cylinder was bored out .20 over. I changed the main jet to a 145, but I can put the choke on half and still hold it wide open for about 10 seconds until it starts slightly missing(thats why I think it very lean, also engine runs very hot). I compared the 138 to the 145 and the owner before my must have drilled it out because the whole is bigger then the 145. If I go up to a 158 would I be getting closer to where it is jetted just about right? Also why would I have to go up this far on the main jet?

PS: The pilot is stock and the needle set to stock position.
 
Joined
Dec 10, 2000
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#2
The easiest way to find the correct main jet if you are nowhere close is to go up in sizes, one at a time, until you reach the size that causes the bike to start to blubber and sputter from being too rich at WOT, then go back down one size. This will get you close, then you can fine tune it from there.
 
Joined
Jul 12, 2000
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#3
Wouldnt I have to go up a few sizes to start off with since I can run it on half choke with hardly any sputtering? I already went from a 138 to a 145 and didnt seem like it helped any. Also I still have some of the air box taped up.