As neil_cb125t posted. I have been using simple green. I spray down the inside very well you have to remove the top Y section to show the open section.
I spray down the intake making sure to get the back section where the linkage gets bound up and make sure to really get the flap mounts really good. From there don’t spray water in the intake. I use a template I made with an air hose extension on it that I bolt to where the Y pipe would go and I intraduce air to blow out the access simple green. I cover one entire side of the intake ports to create pressure to force out the simple green out the other side and then repeat with the other side.
Obviously you guys won’t have a template that you can bolt down unless you want to make one so you can just use a towel and a air line you just need to make sure you have lots of pressure.
I found that this works incredibly well. Simple green won’t dry out the intake and it leaves behind no adverse residue. It helps break down grease and cought dirt if there is any. You might want to rotate the intake manifold a few times after you spray in the simple green.
I will say this. While I always see a nice collection of dirt and grime come out when I clean the inside. We need to remember that these intakes even the original ones didni’t brake until they had like 80k on them and that’s with no carbon clean and obviously no maintenance all together. So don’t get too hung up on spending all day cleaning the intake.
