# Adjust GX390 high speed screw?



## oscaryu1 (Mar 25, 2007)

Just wondering where I should "start off" from. The place I bought it from doesn't adjust it before shipping it out 



^ It runs!


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## 30yearTech (Sep 14, 2006)

Your carburetor has a High Speed adjustment screw on it??

I have not seen this on any of the newer engines that are emission compliant that are adjustable.


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## oscaryu1 (Mar 25, 2007)

Eh, actually, you can bypass that by buying another carburetor... the one I bought was a GX160, and it had a bigger bore than the GX200 confused... If you look really closely, you can see the screws on the Clone. Took it for a spin around the neighborhood today.

Movie with random title:

http://tinypic.com/player.php?v=20qnsch&s=4


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## 30yearTech (Sep 14, 2006)

Engine sounds good, looks like it was getting along pretty good. 

What kind of drive setup are you using?


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## oscaryu1 (Mar 25, 2007)

Chain drive currently, #41 chain (wirecutted and grinded to perfect length ), 10 teeth on clutch, and 54 teeth on sprocket. At 8,000RPM, I should be doing around 51MPH.

With my soon-to-be-setup (#35 chain), 60 tooth sprocket, and 17 tooth clutch, at 8,000 I'll be doing around 81.

12" Slicks on all 4 wheels.


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## 30yearTech (Sep 14, 2006)

oscaryu1 said:


> Chain drive currently, #41 chain (wirecutted and grinded to perfect length ), 10 teeth on clutch, and 54 teeth on sprocket. At 8,000RPM, I should be doing around 51MPH.
> 
> With my soon-to-be-setup (#35 chain), 60 tooth sprocket, and 17 tooth clutch, at 8,000 I'll be doing around 81.
> 
> 12" Slicks on all 4 wheels.


Be careful! Are your tires designed for those speeds??


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## oscaryu1 (Mar 25, 2007)

No idea. Only 3 of them say "not for highway use" 

I doubt the bearings were designed for that high either. Either way, I properly (if not slightly overfilled) aired the tires, and lubed the bearings with 80W-90 and high temperature SuperTech grease. They should hold up slightly longer.


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