help with bogging just past idle

triprop · Today, 02:30 PM

pentora 250 with nibbi PE30 that has always run perfect stock. went out and was running great for over 30 minutes and then started to bog real bad just past idle. turned it off waited a couple minutes and started it back up and was running fine, just as i got back to the house it started bogging again. do you think that is more likely a pilot jet or a air/fuel screw thing?

TominMO · Today, 04:30 PM

If it ran fine at first, then later on started bogging, I'm thinking you need to do a valve adjustment. Exhaust valve stem heats up and lengthens, valve doesn't close completely, loss of power. It may be something else, but this would be the first thing to check. Also check the intake valve clearance too of course.

triprop · Today, 05:33 PM

thanks for the reply. i did adjust valves and all seemed fine. did .003" and .004".
i thought maybe i forgot to turn off choke, but no.
i checked plug and its super lean. trying to download pic but not letting me. but very tan tip and white insulator. that needs to be fixed but i dont think that would make it act up or would it? too much air not enough fuel?
whats the first adjustment you think i should do? air screw first then pilot jet then needle, to adjust a lean condition?

triprop · Today, 05:36 PM

a lean condition can be caused by carb not adjusted properly or is it caused mostly by the valves, particularly the exhaust side?

Today, 02:30 PM	#1
triprop Join Date: Mar 2024 Posts: 17	help with bogging just past idle pentora 250 with nibbi PE30 that has always run perfect stock. went out and was running great for over 30 minutes and then started to bog real bad just past idle. turned it off waited a couple minutes and started it back up and was running fine, just as i got back to the house it started bogging again. do you think that is more likely a pilot jet or a air/fuel screw thing?
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Today, 04:30 PM	#2
TominMO Join Date: Sep 2021 Location: De Soto, MO Posts: 1,937	If it ran fine at first, then later on started bogging, I'm thinking you need to do a valve adjustment. Exhaust valve stem heats up and lengthens, valve doesn't close completely, loss of power. It may be something else, but this would be the first thing to check. Also check the intake valve clearance too of course. __________________ 2021 Lifan Xpect--sold 2022 Lifan KPX 1972 Honda CT90--The Carrot 1969 Honda CT90--The Tomahto Cheesy is the WDK (workplace drama king). Now retired. Nope, back in the saddle. Climate: The Movie https://www.youtube.com/watch?v=A24fWmNA6lM How our government really works https://www.youtube.com/watch?v=QjadCd0VRBw Question all authority.....think for yourself
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Today, 05:33 PM	#3
triprop Join Date: Mar 2024 Posts: 17	thanks for the reply. i did adjust valves and all seemed fine. did .003" and .004". i thought maybe i forgot to turn off choke, but no. i checked plug and its super lean. trying to download pic but not letting me. but very tan tip and white insulator. that needs to be fixed but i dont think that would make it act up or would it? too much air not enough fuel? whats the first adjustment you think i should do? air screw first then pilot jet then needle, to adjust a lean condition?
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Today, 05:36 PM	#4
triprop Join Date: Mar 2024 Posts: 17	a lean condition can be caused by carb not adjusted properly or is it caused mostly by the valves, particularly the exhaust side?
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