Re: 88 and 89 XR4 the same? - Service Manual?
I got curious so I looked it up. The evolution of the XR4 goes something like this.
All are a vertical reed front 2.4l V6 conservatively rated at 150HP with a 1.78:1 small prop diameter LU. There are a couple of versions of the LU, the later one being a bit stronger in the driveshaft bearing department.
At first, they had a 16 amp rectifier on the starboard side and a shunt regulator on top. They had a combination idle stabilizer/advance module on them. The cowl is a clamshell that won't go over a 40 amp flywheel cover, but it will clear a 40 amp flywheel. (ask me how I know)
Then they went to a bucket type cowl.
Then they switched electrical to 40 amp with the wetback regulator.
Then they dropped the advance part of the timing module, leaving only the idle stabilizer. (That was a very good thing)
Most of us immediately ditched the idle stabilizer/advance module, mostly because when they fail, they advance timing about 30 degrees, which at WOT will throw rod caps at the driver and put wrist pin inspection ports in the pistons.
The 40 amp wetback worked fine when it worked, often burned out the regulator, and the regulator is very expensive. It's easy to convert to 16 amp with flywheel, stator, stator screws (shorter) and rectifier. The shunt regulator/fire starter is not needed.
I put a 40 amp dual regulator system on mine. A mounting plate for the regulators goes where the advance module and shunt regulator were. I split my system with 20 amps for the engine battery, and 20 amps for the trolling motor batteries. A power relay connects the trolling batteries in series for use, and with ignition 12V energizing it, puts them in parallel for charging.
Key mods from stock. If you ditch the advance module, set WOT timing at 23 degrees. If it balks or loads up at fast idle, set the throttle pickup adjustment a bit later in the throttle arm travel. (timing advances a bit more first)
They go like a scalded dog. Enjoy it.
John
