After idle screw mod best air bypass setting 2021 GasGas

[Burger72]

Hi 

Ok I’ve read some many conflicting posts on this now , Jeff Slaven saying 20-21 bikes needs to be set around 4 turns out as there rich but 18-19 only half a turn out as there lean....

Ive got a GasGas 21 EC300 and have just competed the idle adjustment mod. I’ve tried both half-1 turn from fully closed and 3-4 turns out, both still give me a slight off idle stutter..... they idle tho can be set low enough that pipe bang is eliminated.

I’m in the U.K. and guessing our maps will be different to the US .... any U.K. riders on a 20/21 Tpi found the sweet spot yet ? .....

 

[jrodicus100]

Don't listen to slavens. Test it for yourself. Try slightly higher idle as well. 

I found that 1/2 turn out (from fully closed) gives the best immediate off-idle response. I also have the idle screw mod. 

I also found that a faulty CCPS (or one starting to go out) can also cause an off-idle stutter - a new sensor cured it.

Edited April 29, 2021 by jrodicus100

[Stubs]

I’m running one turn out on my 21 and it feels pretty good, honestly I didn’t feel much difference between 3 out down to closed. 2-3 out felt maybe a hair lean but nothing drastic. On my carbed bikes I noticed a difference messing with mixture screw but on my TPI not so much. 

[HSV-DirtRider]

On 4/29/2021 at 7:40 AM, Burger72 said:

Hi 

Ok I’ve read some many conflicting posts on this now , Jeff Slaven saying 20-21 bikes needs to be set around 4 turns out as there rich but 18-19 only half a turn out as there lean....

Ive got a GasGas 21 EC300 and have just competed the idle adjustment mod. I’ve tried both half-1 turn from fully closed and 3-4 turns out, both still give me a slight off idle stutter..... they idle tho can be set low enough that pipe bang is eliminated.

I’m in the U.K. and guessing our maps will be different to the US .... any U.K. riders on a 20/21 Tpi found the sweet spot yet ? .....

 

Check this thread for possible solutions to the off idle stutter. The CCPS may not be bad but rather the seal of the tray and sensor could be bad. Going with a direct connection to the crankcase to the sensor is a cheap (free) way to test it out. I would try this before replacing the sensor itself.

 

 

[Clydee2000]

On 4/29/2021 at 10:40 PM, Burger72 said:

Hi 

Ok I’ve read some many conflicting posts on this now , Jeff Slaven saying 20-21 bikes needs to be set around 4 turns out as there rich but 18-19 only half a turn out as there lean....

Ive got a GasGas 21 EC300 and have just competed the idle adjustment mod. I’ve tried both half-1 turn from fully closed and 3-4 turns out, both still give me a slight off idle stutter..... they idle tho can be set low enough that pipe bang is eliminated.

I’m in the U.K. and guessing our maps will be different to the US .... any U.K. riders on a 20/21 Tpi found the sweet spot yet ? .....

 

Per other comments, test, test and test. You'll find what works best for you. Someone else posted this insight but I'll repeat it as it is quite valuable and what I also found in finding the ideal setting for my bike. The air screw setting does not behave like your typical carb when testing different settings. A carb will generally get worse as you move away from the ideal setting (blubbery=too rich, bog=too lean) and this will tell you which way to go with your tuning, but you don't really find that with the air screw and you will generally only notice when you are within 0.5 turns of ideal, most other settings will be indistinguishable.

So best way is to find a small test loop and start at 0.5 turns, then repeat at 4 turns, next 1 turn, then 3.5 turns, then 1.5 and 3 and finally 2 and 2.5 turns. You'll then know when you have the right setting as it will stand out.    

[Burger72]

I’m with @Stubs on this I tried from

0.5 to 4.5 turns and felt barely anything, I’ve settled at 1 turn out from fully closed, my bike pulls clean it just has a minor stuttery  feel just of Idle 

[Geoffit]

I put the idle screw in my GG at the stock setting with the air screw std (4t) and the off idle and idle speed seems perfect. I plan on looking at some other settings down the road . The fueling and running is so clean it’s hard to imagine it being better?

Edited May 17, 2021 by Geoffit

[Burger72]

On 5/17/2021 at 2:29 PM, Geoffit said:

I put the idle screw in my GG at the stock setting with the air screw std (4t) and the off idle and idle speed seems perfect. I plan on looking at some other settings down the road . The fueling and running is so clean it’s hard to imagine it being better?

So you’ve done the idle screw mod ? I think the air bypass screw setting must be different from bike to bike as mine was factory set at 2.5 turns out and now I have it set at 1 turn out.

 

[Burger72]

Something worth looking at is an excess of oil in the Reed block ...

My local dealer told me that they have had some tpi’s running rich off idle etc due to being over primed at the factory, I thought it was worth a look as mine is definitely rich just at the first small twist of the gas .... this is what I found ! My reeds were soaked in two stroke oil as was the Reed block and the housing. I’ve removed and cleaned them up so will report back after I’ve ridden it next but one would think that must have been having an effect on how the bike was running .....