Have two bathrooms back -to-back of each other. The toilets are less than 6 ft apart from each other.
The toilet in one flushes strong and has no problems.
The toilet in the other one flushes very week and will not flush completely unless I pour water into it as I flush it. If I flush the handle and then quickly pour about 16oz water it flushes fine.
I have already ran a 6 foot snake down this bowl , no change.
I have already inspected all the tank guts and everything seems to be working fine , the tank is filling up to the same level as the water ring and the same level as the other toilet.
I have replaced the flapper and timed it compared to the other toilet , it stays open the same amount of time.
I have adjusted the handle chain ,  no change.
Have not replaced the complete tank kit yet because all seems to be working as should.
Help!!

In one of my toilets, only one, I got a mineral build up in the holes thru which the water has to flow to flush out the bowl.  

It wasn't the holes around the underside of the rim.  It was in the holes that are at the bottom of the bowl, the ones that continuously submerged.   There were three or four of them.

With these holes clogged, the flushing action was very weak.  Even repeated flushing would not clear the bowl.


To clear the build up, I had to use metal tools to open the passages.  At first, I used screwdrivers to gouge out the material.  Because I had to go to the bottom of the bowl and poke back up, it occurred to me to use my tie wire twister because of its shape.  I was done in a few seconds.


It's inexpensive, too.


I have no explanation why this one bowl clogs up and the one on the other side of the wall does not.



P.S. - Do I have to mention, start with a clean, empty bowl and turn off the water supply, then flush the tank to empty it.

I have often found large (say, the size of a marble) pieces of chlorine tab, or other debris, that blocks the siphon jet, and slows the water coming into the bowl enough that it cannot start the siphon without help.

As was said before, make sure the rim holes are clear, and that the siphon jet  is too.

Has there been any repairs to the toilet (other than parts in the tank)?  Recently replaced a toilet that was having no-luck-flushing because there was some repairs at the bottom (near the siphon jet) that I believe changed the dynamics of the flush.

clean the holes and pour some muriatic acid down the fill tube and let it sit about 5-10 and then flush. should get some gunk out of it. same thing happened to mine.

No repairs or work done.

Thanks fro all replys , will check out the noted items.