HS 142F idle

Joined
Jun 8, 2017
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#1
Hello everyone! Back into the build! I recently rebuilt my 4 stroke and properly adjusted the valves
(0.08mm intake and 0.10mm exhaust) I'm also using an exhaust pipe similar to that of Phantom bikes and an NT carb. So far this is how it idles..



however i want it to idle like this..


how do i do this?
 


Joined
Apr 14, 2015
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#2
I would think it is in your valve adjustment. Try
.004 thousandths .102 mm
.006 .152mm
And turn idle down a bit.
 
Joined
Jul 2, 2018
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#4
Your idle sounds pretty good to me.

The red bike you want it to sound like has a different carb on it. The stock carb wants to idle at 1200 rpm or so.
 
Joined
Jul 2, 2018
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#5
Thought about it a little bit more. The real reason the red bike can idle so slow is that there's no clutch. He's using the rear wheel as a flywheel. If you took the chain off, the engine would die.

In the video you can see the chain pulling both ways. It pulls the wheel on the power stroke and pulls the engine thru the other 3 strokes, that's why it's got that funky wave action.

You might be able to rig a flywheel on the recoil side of the engine. The bigger and heavier the flywheel, the slower your idle can be. But your acceleration will be a lot slower.
 
Joined
Jun 8, 2017
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#6
And here she is..
after much tuning (setting needle clip at middle and turning idle screw clockwise.. yes! clockwise I found out that the idle screw was way out i had to turn it clockwise at first the idle came up then a few more turns the idle was stable just like in this video and when i turn it more the idle goes faster. I guess she was running pretty lean at idle because of the loose idle screw. But at these settings she runs great! crisp acceleration, pulls hard, btw im using a 5:1 tranny with a 36T rear sprocket

 

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