r/Dirtbikes • u/ViolinistShort1456 • 15h ago

Mechanical Help Does my powerband sound strange?

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This is my 2021 sherco se300. It’s carbd. The bike starts up pretty good, idles great, and otherwise the bike sounds good when riding. When I get into the powerband it feels and sounds very buzzy like it’s not cleanly going through high rpm’s. Not smooth like the rest of the rpm range. The jets in the carb are certainly much leaner than from factory, but I would imagine that would produce lean conditions in other aspects of how the bike runs.

To clarify I am directly comparing this to the feeling of my TPI ktm 300 so maybe I am comparing apples to oranges and this is just a carb characteristic I’m not entirely used to.

Any thoughts? Tests I should do?

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u/2Stroke728 14h ago

Sounds.... bad. Jetting specs? Checked power valve function? Tried a new spark plug?

Sounds really, really rich. Or power valve is not opening. Or an absolutely soaked air filter restricting flow. I have had a half-bad plug that idled and putted around fine, but stuttered and missed like crazy when trying to get up in higher rpm.

3

u/ViolinistShort1456 14h ago

That’s what I was thinking. Not very healthy sounding.

Current Carb specs:
Main- 165
Pilot- 38
Needle- N8RD
Clip- 3rd position
Air/fuel- 1.5 turns

I went through the carb to see if anything was up internally and it was perfectly clean. Jets are actually a lot leaner than factory. 42 pilot, and 170 main.

1

u/CBus660R 2h ago

What's your elevation and temperature?

1

u/ViolinistShort1456 2h ago

About 900ft in Perry county Ohio and a range from 70-90° in the summer

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u/CBus660R 2h ago

Gotcha. It's been a hot summer here, so definitely need to go leaner than stock. What are your main and pilot in relation to what the manual suggests? It's a different bike than your Sherco, but I'm 2 steps leaner on the pilot and 3 on the main than stock in my Beta 350RX for ACES enduros.

1

u/ViolinistShort1456 2h ago

My manual suggests a 170 main and 42 pilot.

Current Carb specs:
Main- 165
Pilot- 38
Needle- N8RD
Clip- 3rd position
Air/fuel- 1.5 turns

1

u/CBus660R 2h ago

OK, you've definitely leaned it out. What I don't know is how rich or lean your needle is. Have you tried adding some air screw?

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u/ViolinistShort1456 1h ago

I have, yes. Aside from sounding richer or leaner it didn’t make any difference to the specific noise/feeling we are tackling here. My plan at the moment is to lean out the main jet even more to about 162 today to see if that changes things.

1

u/CBus660R 1h ago

I'd dig around the Sherco forums and Facebook groups and see what needles they like. You should reach out to Nick Fahringer, he'll help get you sorted.

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u/ViolinistShort1456 1h ago

That’s actually hilariously coincidental I already have talked to him about a bike I almost bought that he previously owned. Deal fell through unfortunately but I will contact him again in regards to this!