Originally Posted by
jwm2
Ok i've got a question. I just noticed the lsn on the 3 port engine i have is a short needle (it does not stay in the throttle body when opened) and the previous owner had the lsn completely tight. It seemed to run just fine but i decided to richen it up abit and it still runs fine, in fact it doesn't appear to have changed anything or very little even with 1 1/2 - 2 full turns out from where it was. It creates smoke but only when past half throttle. Also richening the lsn doesn't seem to have any effect on the idle. Is this normal? I didn't have much of a chance to play around with it this morning i only ran about 1 tank through it. But it seems to have plenty of horsepower and runs very well. I'm just worried about long term damage as i'd like to be able to use this engine for at least a year or 2. Any help is greatly appreciated. Also a link to a guide or post where there is instruction on tuning the short needle carb would be great, unless of course its the same as tuning any other short needle carb. Thanks
That LSN is definitly lean if you are not getting any smoke until half throttle.
Check the idle gap is correct (.7 to 1mm) this may be why you are not seeing a difference when you turn the needles.
The short needle carb will tune just like any other motor. It's only the long needle version that is a little different.
The HSN settings on all the GO carbs is pretty sensitive, so very small adjustments only.
Set the idle gap. Set HSN to 1/2 turn in and LSN to 1 turn in. That should get you ball park with the short needle, then fine tune from there.
If it won't idle at the .7 - 1mm idle gap, lean the bottom end until it will idle - do not adjust the idle screw until you have the motor tuned.