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Recenty rejetted my DR350

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I live near cleveland ohio, purchased a 1990 dr350 a year ago, it came with an aftermarket pipe horrible installed, and i have yet to fix its leaks or replace it, its a straight through, no muffling, no spark arrestor. I just did the kientech airbox mod and installed a 140 main jet,it had a 137.5 in it before, i assume thats not stock. I also installed a 40 pilot, becouse the previous 37.5 couldnt hold a predictable idle, cold was nice and idle, when the engine warmed it raced.

Heres my question, The engine has a different tone behind it now, its more rumble than the snap it used to have, it appears to have the same/better power down low, but high end is appearing to be maxed out earlier, and I think i had more high end power before the rejet.

But the thing i do like is the engine is running extremly cooler than previously, i realise the climate is changing, but a week or so ago it was colder than what i rode yesterday, and the engine case would scald me, now its just hot, but tolerable. This makes me believe i did have a really lean condition previously, and perhaps that would explain the different sound from the exhaust. From what i believe leaner mixtures burn hotter but longer, so it could have still been burning previously at the start of the exhaust stroke ( Right before rejetting i was riding at dusk and saw flames from exaust at a high rpm.)

So is this how my bike is supposed to sound/act/heat up? Im not too upset that the highend isnt as it was before, becouse i dont race, and use most of my power in the low end. Which seems about the same to slightly improved, i can still easily wheelie in 2nd by just a roll of the throttle.

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You will need to test different main jets to find the best peak power. The bike was probably running lean before, as you suggested. Try increasing the main jet 2 steps at a time to compare and then refine the setting.

James

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