Learn Hardcore Indonesian: Kami ke bengkel lagi karena ban kempis untuk kedua kalinya. - We go to the workshop again because the tire is flat for the second time.

In Indonesian you can omit a motion verb when the destination is clear. Kami ke bengkel is perfectly natural and means “we went/are going to the workshop.” You can add a verb if you like: Kami pergi/berangkat/menuju ke bengkel.

Isn’t lagi redundant with untuk kedua kalinya since both imply repetition?

They refer to different things:

lagi marks the main action as repeated: we went again.
untuk kedua kalinya counts the occurrence of the reason: the tire went flat for the second time. Using both is natural and a bit emphatic. You can drop one:
Focus on repeated trip: Kami ke bengkel lagi karena ban kempis.
Focus on count of the flat: Kami ke bengkel karena ban kempis untuk kedua kalinya.

Where does lagi go? Can I say Kami lagi ke bengkel?

Place lagi right after the phrase it modifies. Kami ke bengkel lagi = “We went again.”
Kami lagi ke bengkel is not idiomatic for “going again.” Colloquially, lagi can mean “currently,” but then you’d say Kami lagi di bengkel (“We’re at the workshop right now”), not with ke.

What’s the difference between kami and kita?

kami = “we” excluding the listener.
kita = “we” including the listener. Choose based on whether the person you’re talking to is part of the “we.”

What exactly does bengkel mean? Is it specifically an auto shop?

Bengkel is a workshop/repair shop, most commonly for vehicles. You can be more specific:

bengkel mobil = car repair shop
bengkel motor = motorcycle repair shop
bengkel ban / tukang tambal ban = tire (puncture) repair

Is ban kempis correct? What about kempes or bocor?

kempes is the most common word for a flat/deflated tire.
kempis is also correct, but sounds a bit less common for tires in everyday speech.
bocor = leaking/punctured (the cause). A tire can be bocor and therefore kempes. Example: Ban bocor, jadi kempes.

Why is it just ban and not ban-nya or ban itu for “the tire”?

Indonesian doesn’t require articles. ban can mean “the tire” if context is clear.

ban-nya adds definiteness or possession (“the/its tire”).
ban itu explicitly marks “that/the tire.”
All are possible; the bare noun is very common.

Is untuk required in untuk kedua kalinya? What are the alternatives?

untuk is optional. Common variants:

untuk kedua kalinya (very idiomatic)
untuk yang kedua kalinya (a bit more emphatic)
kedua kalinya (also fine)
kali kedua / kedua kali (both mean “the second time”) You’ll also hear: Sudah dua kali ban kempes (“It’s happened twice already.”)

What does the suffix -nya do in kalinya?

It makes it definite, like “the.” kedua kali = “second time” (general), kedua kalinya = “the second time” (specific/definite). Here it reads naturally as “for the second time.”

Does untuk kedua kalinya modify only ban kempis, or the whole sentence? Can I move it?

It modifies the reason clause (ban kempis). You can move it earlier, but it’s most natural after the predicate:

Natural: karena ban kempis untuk kedua kalinya
Also possible: karena, untuk kedua kalinya, ban kempis (more marked/emphatic) Another smooth option: karena ini sudah kedua kalinya ban kempis

Can I start with the reason clause using karena?

Yes: Karena ban kempis untuk kedua kalinya, kami ke bengkel lagi.
When the karena-clause comes first, use a comma before the main clause.

Why ke bengkel and not di bengkel?

ke marks motion to a place (to).
di marks location (at/in).
So Kami ke bengkel = “We went to the workshop,” while Kami di bengkel = “We are at the workshop.”

Should I add sudah to show past/completed action?

Not required. Indonesian often leaves tense implicit. You can add it for clarity:

Kami sudah ke bengkel dua kali.
Ban sudah kempes (“the tire was already flat”).
Use baru for “just/only recently”: Ban baru kempes.

Are there colloquial alternatives for “flat tire”?

Yes:

ban gembos/gembes (colloquial for deflated)
ban pecah (blown/burst tire) Choose based on severity and register. kempes is the safest general term.

Is kali the same as waktu when talking about “time”?

No. kali counts occurrences (once, twice, third time), e.g., dua kali. waktu refers to time in the sense of time/when, e.g., waktu itu (“at that time”).

Could I rephrase the whole sentence in other natural ways?

Some options with similar meaning/nuance:

Ban kempes untuk kedua kalinya, jadi kami ke bengkel lagi.
Kami kembali ke bengkel karena ban kempes untuk kedua kalinya.
Kami ke bengkel lagi; ban kami kempes untuk kedua kalinya.
More emphatic: Karena untuk yang kedua kalinya ban kempes, kami ke bengkel lagi. Avoid overly formal double conjunctions like karena … maka … in everyday speech.