Just rebuilt most of a 2 stroke jet boat. ( if you need want any boat details, see: this thread )

When I purchased the boat, the thickest negative battery terminal wire was not connected to anything. This is literally the last connection I have to make before trying to turn over the new engine I just installed.

Can anyone tell me what this wire is supposed to be connected too?

  • 2
    I take it the other end is connected to the battery? If so, I'd almost bet it connects directly to the engine some how. Commented May 22, 2016 at 21:43
  • Yes, its the thickest wire connected to the battery.
    – Calvin
    Commented May 22, 2016 at 22:03
  • 1
    What type of alternator do you have? If its a one wire alternator (with built in regulator), the one wire goes from the alternator to the positive battery terminal. That means you will need a large wire to go from battery negative to the engine block. (Depending on if your metal boat requires negative chassis ground. I'm no expert on boat electrical including, anode and cathode related issues.) You are going to solder that cable to a nice copper ground terminal Then bolt that terminal securely to the engine block.
    – zipzit
    Commented May 23, 2016 at 0:53
  • @Calvin, so you got the boat running? That's awesome!
    – JPhi1618
    Commented May 23, 2016 at 14:16
  • @JPhi, yes I did and I bought the engine from the link you gave me. So Thanks for finding me that great deal!
    – Calvin
    Commented May 23, 2016 at 23:43

2 Answers 2


Connect it to the engine block:

A bolt on the engine end of one of the engine mounts, or one of the bolts that hold the starter, but not a hot spot like one of the exhaust manifold bolts.

Anywhere on the engine block is pretty-much equivalent so connect it to the most convenient place.

  • 1
    Attached to the engine block.. She fired right up :) Thanks for the help Paul & Jasen!
    – Calvin
    Commented May 23, 2016 at 12:12
  • As mentioned, when I attached this wire to the block she fired right up and worked... Unfortunately, the next day I came out and found the CDI box fuse had blown, after replacing the fuse, she worked for a day and then stopped getting any power to the Starter, I believe the starter relay is now fried. After consulting the owners manual, I found the black wire was supposed to be connected to a bolt that mounted the starter. Think the placement of this black wire caused these problems?
    – Calvin
    Commented May 31, 2016 at 17:15
  • the starter mounting bolt is electrically the ideal place to connect it but the starter flange is often aluminium and getting a reliable connection there can be tricky. Often it's not connected there and works fine under some other engine or transmission bolt. starter relays are pretty hard to destroy
    – Jasen
    Commented Jun 2, 2016 at 2:50

After referring to page 26 of the owners manual here, I have confirmed that the large black wire coming from the negative black terminal should be grounded to one of the bolts that mount the starter motor to the block.

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