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Discussion Starter · #1 ·
Hello,

this is my first step into the sumo world so I don’t really know what I’m doing here and need some advice.
I converted my 2012 300xc with 17” wheels and run 15/40 gearing, there’s a lot 55mph roads and even with this gearing it still feels like I’m pushing the bike to average those speeds. I read somewhere else someone was running If I remember correctly 14/45 and did a 20 mile 70mph trip comfortably, how is that possible? only power mods on my bike is a fmf gnarly header.

so my question is how can I make it run 55 a little more comfortably?

any and all advice is appreciated
 

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Do you have any idea what rpm the motor is running at? I know my 2012 250xc falls flat in the upper rpm past the bulk of the power. Any chance your jetting is off? Maybe raising the needle up one clip will give you more fuel up there any maybe make it feel better.

I cant recall the final ratio but i would have guessed in 6th gear your sprocket choices would be good.
 

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Discussion Starter · #4 ·
Do you have any idea what rpm the motor is running at? I know my 2012 250xc falls flat in the upper rpm past the bulk of the power. Any chance your jetting is off? Maybe raising the needle up one clip will give you more fuel up there any maybe make it feel better.

I cant recall the final ratio but i would have guessed in 6th gear your sprocket choices would be good.
I think u might be right, I stole a fmf fatty from another bike an it runs way better, I thought I had it right but I suck at jettting 😅, unfortunately I don’t have an rpm meter.
 

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I think u might be right, I stole a fmf fatty from another bike an it runs way better, I thought I had it right but I suck at jettting 😅, unfortunately I don’t have an rpm meter.
2 strokes are real temperamental. I went riding once where it was 30f in the am but 55f by the afternoon and my jetting was off.

There are jetting charts. Years ago i had a mikuni one and it had elevation and temp on it. Was helpful. I tend to ride the same elevation and temps so i dont fiddle with much jetting changes anymore but i did get extended adjuster screws for those afternoon tweaks.
 

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Discussion Starter · #6 ·
2 strokes are real temperamental. I went riding once where it was 30f in the am but 55f by the afternoon and my jetting was off.

There are jetting charts. Years ago i had a mikuni one and it had elevation and temp on it. Was helpful. I tend to ride the same elevation and temps so i dont fiddle with much jetting changes anymore but i did get extended adjuster screws for those afternoon tweaks.
thanks for the info, I’ll try jetting again

first 2 stroke was an 05 kx100, never changed jetting since I got it, still Runs flawlessly. i have 2 ktms a 300 and 380 and they constantly needing adjusted!

Little off topic but I have a trail tech striker on the bike now, will a trail tech vapor plug into the wires for the striker or will I need to run new wires?
 
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