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After fiddling with the carb for a few days and trying to figure out why the bike wasn't running right, I've fixed my high RPM stumble by going back to a smaller jet. I've also confirmed what I knew all along... that all carbs/motors/bikes are different and jetting can vary wildly.



I'm located in NY by the water, I bought the bike with the original 114 jet, stock intake, stock exhaust and the bike ran well. I've since changed the intake to a UNI pod and the exhaust to the DG Oval. Based on other's experience on the board, I knew it was likely that I'd have to rejet. Based on the information on this board, I found that most people had to put the 130 jet and a few are running the 132.5 jet with good results. I bought a 120, 130 and 132.5 aftermarket jet from JetsRUs.



I started with the 132.5 jet and rode around with a friend following me where the bike stumbled heavily at 3/4 throttle. My friend mentioned that he could easily smell that I was running rich, so I swapped in the 130 jet that evening. I went for a second test ride the morning after finding a similar high rpm stumble at WOT. The bike would not go over 65. Finally, I swapped in the 120 main. The bike is happy and can hit 70 with my 15/47 sprocket setup.



Without my friend telling me what he smelled and without checking the plugs carefully (it only showed minor signs of soot and was not wet) the symptoms did not seem typical of running too rich. The stumble felt like I was not getting enough spark (like a CDI issue), a plugged fuel filter, a clogged main jet or even an improperly set float. The stumble almost felt like bouncing off a rev-limiter. The bike would rev up to 60mph in top gear without much issue, it was only showing as a problem at WOT under load in top gear.



Just wanted to share my experience with running too rich. Also, if someone has similar mods in NY by sea level, you may not need to run the 130/132.5 jet afterall
 

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Sounds like you have an older carb. Newer carbs have 126 mains as stock and thats why we use 130s generally. Sounds like you could either use a 116 or 118. That 120 you have would be the equivalent of a 132 in my bike which would be a little too rich where I live at under 500' above sea level. A 130 for you would be way too rich.
 

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Thanks, that's very useful information which kind of confirms a hunch I had about my TW.



Because of the symptoms I had previously thought my high speed miss was an electrical issue, but now I'm leaning toward jetting.



On a recent trip I fought the miss until I neared home. Like an old mare headed for the barn my TW ran better the closer I got to home. As I neared home I made a significant drop in elevation. The other day I rode up on nearby Kolob Mountain. The miss returned. So, I guess I need to spend some quality time with my carburetor.



Thanks for sharing your observation.
 
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