YZ125 Jetting

Hey guys, just did a new top end and it runs pretty good. Fires up but idles high and if I give it throttle, it takes a long time to come back down to idle. Idle is great right when it fires up but after any revving it doesn't want to idle back down. Even when warm I get a little smoke and after riding, theres a trail of spooge running down the silencer. As far as I know the jetting is stock but i'm unsure. I'm curious as to what size jets I should be running and anything else to help this idle problem. Air screw is 1 turn out but i played with it from 1/4 turn to 2 1/2 turns and same problem. I'm new to these 2 strokes so I have no idea what jetting I should be running with this exhaust. I trail ride in the lower rpm's but I get on it whenever I have the chance and she rips. So if anyone can recommend jets I'll give it a shot. Thanks

Bike is a 1999 YZ125

Pro Circuit Platinum Pipe

FMF Turbine Core 2

New top end, Wossner Piston

I also checked the reeds and they looked new (i think). Nice and flat

91 Octane fuel at 32:1

Edited by biebs53

At best go back to stock jetting,your manual has that data.

The jettimg is stock right now

Edit: I failed at reading your post

Edited by kan3

If the idle is hanging after throttle on and does not return to normal it may indicate an air leak causing a lean condition. One of the places air can leak is the left side crank seal.

If there is excessive smoke and spooge this can sometimes be caused by a worn crank seal on the right side (engine pulling trany oil in)

So, you could just need crank seals all around.

EDIT: I forgot the most important question. Did it act like this before you did the top end, or only after?

Edited by rjpjnk

Only after. Before the top end it wouldn't kick start but ran perfect. New top end and had good compression but still wouldn't kick start. The air screw was in a bad spot (I forget but I think it was like 2 turns out. I moved it and she fires right up but has a high idle and takes forever to idle back down after revving. She sits anywhere from 1900-2200 for 30 seconds to a minute after a quick throttle blip. Wasn't losing any tranny oil but I haven't checked recently

Bump

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