Good tip, thanks Karl!

I got the passage cleared.  I gave up on trying to unclog it, and drilled it open with a 3/32 bit.  It punched thru some kind of obstruction and now flows fine.  I definitely opened it up a little more than the other three.  So I drilled all four chambers to balance them out.  I hope I didn't create a problem with my choke circuit.  I don't think it would, since all I'm doing is providing plenty of gas for the choke pickup pipe to circulate. 

This is such a common problem on every carb I work on, that I wonder if I shouldn't just make this part of every carb rebuild. Even when I get the passages cleared, barely any fluid trickles thru on every chamber. If the choke circuit works fine on these carbs, I think I'll start doing this from now on. I'll use the next smallest drill bit though, I just used the smallest one I had on hand.   

Dang a turbo 1380cc

I have been following the journey of a British couple as they travel across the US on a pair of Royal Enfields. In this video chapter. They are in El Paso, Texas, and stop into a local bike shop. Watch the video..... If you know about historic or legendary FJ's. You are in for a treat.

https://youtu.be/0Ms1yJc38wg?si=ZHTEMthzSSzAdQ9B

I am glad to see this special FJ is still around.


Fred

I gave up and got new carb bodies!  That's a hard passage to clear.

I've got my carbs back together with no problems except one. The choke pickup tube passage hole at the bottom in one of the float chambers is clogged. These are always stubborn to clear, but I simply can't get one flowing.  I've used penetrating fluid, sonic bath several times now, air pressure, and a bristle brush wire, but haven't had any luck. It's the very last think keeping me from putting these carbs back on the bike tonight!

Can I drill the passage open wider to get it cleared without causing problems?  It seems that all the passage does is supply the pickup tube with fuel for the choke circuit. 

Suggestions?           

Quote from: red on February 18, 2026, 03:25:02 PM

Quote from: MarioR on February 18, 2026, 01:27:32 PM

Quote from: Warp84 on February 16, 2026, 08:49:53 PMSimple Green is what burned the coating off my carb bodies. I'll have to see about that Tillbrook Cleaner you mention.

10% simple Green + 10% vinegar + 15 min in 50-60 degree process = decent results but still no original effect.

MarioR,

EEK! The regular Simple Green is NOT suitable for any use with aluminum. There have been problems, described by the maker as "hydrogen embrittlement," causing cracks in the aluminum over time.
The maker now offers an "aluminum safe" version of Simple Green, but the container has a very different label. So you know, there really was a problem there.

Correct, aluminum safe version, not old formula.

Red is right.
Just checked the SDS for the Simple Green Pro HD, purple colour. It states the pH is 10-11.5.
Never allow pH greater than 8.5 anywhere near aluminium.

Aluminium is stable in pH ranges from about 4-8.5. Greater than 8.5 and aluminium is susceptible to alkaline attack.

Essentially the outer passive aluminium oxide layer, or anodic (anodised) aluminium oxide layer is stripped.

As aluminium is highly reactive (conductive), it tries to re-grow the oxide layer immediately, thus accelerating surface pitting.

If, as in the very warm ultrasonic cleaning environment, there is a lack of oxygen in the solution near the aluminium it becomes self sustaining (autocatalytic), a process known as hydrolysing (possibly where the maker mentions hydrogen embrittlement).

Overall, aluminium is tough, but incredibly reactive to alkaline attack. If there is any salt/chlorides/chlorines etc, and free oxygen is taken up by other processes, in a solution that has pH higher than 8.5 the cleaning solution will be very aggressive and damage the surface.

Troyskie

Quote from: MarioR on February 18, 2026, 01:27:32 PM

Quote from: Warp84 on February 16, 2026, 08:49:53 PMSimple Green is what burned the coating off my carb bodies. I'll have to see about that Tillbrook Cleaner you mention.

10% simple Green + 10% vinegar + 15 min in 50-60 degree process = decent results but still no original effect.

MarioR,

EEK! The regular Simple Green is NOT suitable for any use with aluminum. There have been problems, described by the maker as "hydrogen embrittlement," causing cracks in the aluminum over time.
The maker now offers an "aluminum safe" version of Simple Green, but the container has a very different label. So you know, there really was a problem there.

Quote from: Warp84 on February 16, 2026, 08:49:53 PMSimple Green is what burned the coating off my carb bodies. I'll have to see about that Tillbrook Cleaner you mention.

10% simple Green + 10% vinegar + 15 min in 50-60 degree process = decent results but still no original effect.

Anyone tried Omega Clean solution yet? Pics?

https://www.omegasonics.com/product/omegaclean/

Thanks