So I've been struggling to get the injector bores sparkly clean. There is some kind of build up that you can see in the picture (sorry for the mediocre quality, its hard to get the camera in there). The only way I am able to remove it is when I just tried scratching it with a flathead and it seemed to scrape up into a dusty white-ish powder. I don't really want to be scraping the inside of the bore with metal to scratch the bore itself.

I have tried: brake cleaner, carb cleaner, rust remover, straight acetone, and even a wire bottle brush made for injectors attached to a drill. Nothing removes it other than scraping it. I'm guessing its not carbon as one of the previous should have removed it, I assume...

Any ideas? The injectors do seem to fit in regardless, so since the main seal is the tip and not this wider part, do I even bother?

 

You could gently use brass tube brushes or gun barrel cleaning brushes of the required diameter/caliber. If you put grease on them the stuff that comes off will stick to the grease and not fall in the cylinder. The grease and other schmoo that comes off could be removed with a clean shop towel.

 

Thanks for the detailed pictures. I wonder if you can measure the exact inside diameter and find a fluted reamer that would clean that up. But in the end I'd guess that red scotchbrite on a Dremel or Die Grinder would do the job better than anything. That stuff is horribly abrasive and it is imperative to keep any it's debris out of the cylinder. It is possible to use shop air down the sparkplug hole to provide positive airflow up the injector hole. Or simply use some form of plug that cannot go down the injector hole and seals well. If that is a form of corrosion, it is best to remove it and prevent it from spreading or causing future removal problems.

From my engine porting days, I have all sorts of tools for cleaning up aluminum bores. I would be tempted to very carefully use a scotchbrite wheel or even a small sandpaper flap wheel.

 

My first thought was something like a flex-hone. They're available in many sizes, but sSince you've already tried a brush on a drill, I expect you'll either need to get creative or settle for less than spotlessly shiny. It's aluminum oxide, so might soften up with distilled white vinegar. Maybe wet a piece of cloth with it (but not enough that it will drip into the cylinder and let it sit in there for a few hours? The rotating brush might work then.

 

Be very careful if you use vinegar to clean the bores. If you don't rinse it out/neutralize it thoroughly when you are done you may cause the injectors to seize in the future because of aluminum acetate formation. I like the ball hone idea but that might be too aggressive.

 

I was assuming some kind of cleanup and anti-corrosion drill before reinstallation, but thanks for calling it out specifically.

Ball hones can be had in many grits. I've only used them in iron cylinders but when I did a quick check earlier I saw that they were available in multiple materials and grits, and in sizes down to 4mm:

https://goodson.com/blogs/goodson-ga...ight-flex-hone

 

No.

 

I think that's the winning answer.

 

Aluminium (Allooominum) Oxide.

Have you tried a Dremmel with a flexi extension and fine wire wheel?

Alternatively, and I think a safer bet as you don't want any fine wires disappearing down the abyss, is to use an acid cleaner.
There's plenty off the shelf engine cleaners for motorcycle that would turn that to a fizz in no time.

 

Update:

I tried distilled vinegar (let is sit for several hours) and the softer brass wire brush. No luck. Thanks for all the suggestions, but I think after spending MANY hours on this I'm gonna just move forward. If I have a leak I'll try that acid and I guess buy a dremel as a final resort.

Thanks!

 

You may have already done this, but I found when doing my injectors that the safest way is to use an injector seat cleaner kit. It will come with a cap that seals the injector hole (will not go past the opening into the engine). You will have to screw it into place. Then you will attach several different wires to your drill and use a vacuum to pull out the debris. Some kits are designed for you to use the wire brush in a clockwise manner and then a separate brush going counter clockwise to lift the debris out of the injector seat. The debris will be corroded metal from the seizing of the injector to the engine (if you had a coolant leak), debris from the heat and sound shielding material under the supercharger (it just crumbles apart), and any dirt from the road. It's important to go slow and purposeful to keep anything from falling into the piston chamber. Fortunately, the design of the inlet has a little lip on it which actually keeps the debris collected towards the bottom of the seat, before the opening. So it is possible to clean them without an injector seat cleaner kit. However, I was worried about scoring of the cylinder/pistons/rings should a piece of debris find its way in there. When done right the injector seats will be nearly spotless. Hope this helps. Here is a of how it's done.