Suzuki 2.5 Idle issues/hang despite new gaskets and uktrasonic clean

[westcoastgrind]

Engine is a 2023 suzuki 2.5 with less than 20 hours on it. The idle is hanging pretty bad. It takes about a minute to come down from only a little bit of throttle.

I have cleaned the carb twice now; the second time with an ultrasonic cleaner. Carb never looked dirty, and jets looked clear. I also replaced all the carb gaskets, all the way to the cylinder block. Everything is torqued to spec.

I am confident the carb is clean, the idle speed is correct, and that there's no leaks from air intake to the block.

I have also played around with idle mixture screw. Richer makes idle hang worse, and leaner helps. I have heard that typically idle hang is due to air leak or lean condition, so this is confusing to me.

A suzuki tech briefly looked at it and was the one to tell me he suspected it was an air leak.

I'm really hoping to avoid spending hundreds of dollars to fix an engine that is brand new and should be warrantied. dealer is not being agreable and wont rouch it under warranty because messed with idle screw

What else could be causing my idle hang?

 

[westcoastgrind]

Only thing I can think of is something is defective with the carb itself. Or somehow my rigorous cleaning did not work.

Could valve clearances, or leaks from another area of the engine cause this? I am considering taking the lower cover off and checking the torque on all bolts

 

[westcoastgrind]

Here is a video of the problem

 

[Rappey]

Spray easy start around the carb. You will hear if there is an air leak
Is the butterfly valve in the carb returning to tickover position when throttle lever is released ?

 

[westcoastgrind]

Spray easy start around the carb. You will hear if there is an air leak
Is the butterfly valve in the carb returning to tickover position when throttle lever is released ?

Will try forsure. Anyway to diagnose if it's leak coming from elsewhere such as cylinder block cover ect?

Butterfly is returning.

 

[VicS]

Check that when the twist grip is returned to the idle position the throttle butterfly closes to the idle position.

If the cable is disconnected from the lever on the carb does the butterfly snap shut if pushed open by hand then released ? If that's Ok look at the cable and the twist grip assembly.

 

[westcoastgrind]

Check that when the twist grip is returned to the idle position the throttle butterfly closes to the idle position.

If the cable is disconnected from the lever on the carb does the butterfly snap shut if pushed open by hand then released ? If that's Ok look at the cable and the twist grip assembly.

Hi thanks for the advice. Maybe you did not see the video I posted. I check all of that in the video.

 

[Bluefin21]

Hi, you have gaskets on the Inlet manifold to isolator block and also from isolator to cylinder head, remove the gaskets both side of the isolator block and replace with silicone. Honda 2.3s suffer badly from this. The difference in materials expanding and contracting often cause vacuum leaks on the inlet side.
Hope this sorts it.

 

[westcoastgrind]

Hi, you have gaskets on the Inlet manifold to isolator block and also from isolator to cylinder head, remove the gaskets both side of the isolator block and replace with silicone. Honda 2.3s suffer badly from this. The difference in materials expanding and contracting often cause vacuum leaks on the inlet side.
Hope this sorts it.

Ok good advice. I did take the isolator/intake pipe off. The oem gaskets where stuck on pretty good. They looked like fiber rubber, but also has a ring of pre applied sealant. I was wondering why they had that and the gasket for the carb did not.

I replaced them with a diy felpro rubber gasket and no sealant. I don't think it's leaking there. But I will definitely try using some Sealant.

One thing I noticed is thwhen I torqued them to spec (8lbs ft). I had to go back and forth a few times before they settled at 8. Obviously the gasket was being crushed. Was that right right thing to do? I read elsewhere that overtifhtening can warp the plastic block and lead to leaks.

What about using a rtv coated gasket?

Lastly to you recommended any specific type of rtv?