Mast doesn't tilt on these, the fork carriage does.

BT state forks parallel to the floor & 10 to 15mm clearance.

Simple. If the threaded rod has some adjustment left, tighten chains with mast tilted back, until forks just clear the floor

As lifter01 says, 3% anywhere on the chain and that's the limit for leaf chain.
There are a number of chain gauges available (here the UK the FB chains gauge is most popular).
It can also be measured with a 300mm vernier caliper across 10 links.

Note all chain pitches are imperial and best to convert values to mm if its easier.

1) Establish chain pitch (measure from center to center of 2 pins on an outer plate) The pitches will be 5/8, 3/4, 1" ect... Note if the chains worn you can't take this measurement for exact, you just want to know the basic pitch.

2) Multiply this value by 10 for your base reading of a new chain over 10 links.

3) Measure your existing chain over 10 links with calipers on the outside of the teo end pins of these 10 links - record the value.

4) Subtract 1 x pin diameter from the measured reading - this is your actual length of the chain being tested across 10 links.

5) Take the 'base' reading (from step 2) for a new chain and calculate the percentage difference from the value (from step 4) we've just measured from the tested chain.

Most importantly when you measure a chain always measure the FIRST section of chain that wraps around/runs over the chain pulleys as usually this shows the most extreme wear as the pin/rollers pivot here more then any other section of the chain.
If the truck works in a bumpy area its also sensible to measure close to the fork carriage too due to the forks bouncing up and down when empty on rough ground - wear can accelerate rapidly under these conditions due to shock loading.

5

3 percent wear over 10 links no matter what the chain type. Also don't go adjusting the chains until you check if there is a carriage stop on the machine. If there is the clear neck should be around 10mm I've known engineers shorten the chains on a hyster and tear a stop off the back of the carriage on an H2.00xm

yes their are various gauges & ways to measure chain link wear. Check with the lift manufacturer or their authorized dealer for specific wear limits. These limits may differ based on link design (rtype or leaf type), load capacity rating etc.

It would be well worth measuring the chain wear limit percentage before you adjust the lift chains.

Mr.johnr,
thank you so much for your response.

adjust the mast chains at the carriage connecting point follow manufacturers recommended procedure.
Mast chains tend to lengthen over time due to wear on the pins of the connecting pins of the chain links. Some people call it "chain stretch".
Wear on the pins happens quicker when oil or grease is applied to the chains as it traps dirt. There is a specific lubricant for mast chains.