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Old 08-16-2009, 08:55 AM   #1
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Default what is a lean bog???

I think i might have one. I mean no matter how much i lean it, the engine still runs fat or like it wants to bog when it idles. I mean i can lean the low end really high til it just wants to rev constantly, any lower and it just bogs.


air leak?
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Old 08-16-2009, 09:10 AM   #2
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Or idle setting. Go back to original setting and reset the idle screw to show a .6 to .9 gap and then chase the lsn setting. Many people (including myself) ignore or dont know about it and it can cause much grief and totally goof the rest of your settings. Try that first. And seal the carb. (Deja Vu, I just got done posting same thing on another thread....)
But to answer your question, lean bog is generally associated with the top end, where the hsn is set too lean and makes it fall on its face running out of fuel, also having real high temps.
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Old 08-16-2009, 09:14 AM   #3
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First- yes- check for air leaks. Small cracks in your fuel hose. If you have been battling a idle tune the usually cause is a airleak.

A lean bog is the point that you have leaned the engine out so far for performance that you have now lost performance.

* Cool the engine completly

* Check for airleaks: head and carb screws, fuel line, and around the glow plug.

* Install a new glow plug

* Take the lsn, hsn, and idle screws back to stock settings.

* Do the same final tuning steps as you did when breaking in the engine.

Good smoke and fat and adjust from there.

The leaner the engine the hotter and less oil is going thru.
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Old 08-16-2009, 12:55 PM   #4
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it takes fuel to make ponies. whenever your trying to figure out the tune on a motor always error to the safe side, richen the high speed needle. make a pass down the straight and you'll know right away which way you need to go. most motor guys will tell you to tune the top end and then get the bottom done. but with the fuel coming in thru the high speed needle, a big adjustment will effect the low speed some. at the top of the offroad forum theres some really good info on breaking in and tuning motors.
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Old 08-16-2009, 01:02 PM   #5
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i would also check your clucth if it is worn it will have bog on the bottum are if the bearings also.
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Old 08-16-2009, 09:36 PM   #6
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fuel makes power not air
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