KZ1000-J / KZ1100 OEM Mitsuba Starter Motors

Between two and four brush early 1980's OEM Kawasaki starter motors, is one considered better than the other?

A four brush give you more cranking power due to the higher ampere flow on the two extra field coils, just a thought.

Four brushes in opposing pairs (180 degrees apart) should produce more torque as it is utilising more winding loops simultaneously

Agree that the 4 brush starter has the potential to produce more than the 2 brush starter, but it also has the potential to put more of a load on the battery/electrical system. Keep in mind that a starter is seeking a certain amount of watts (volts x amps) and does not care how it gets it. If there are not enough amps then it will attempt to pull more volts, or if not enough volts it will attempt to pull more amps.in an attempt to find the wanted/needed amount of watts.  The starter is the biggest draw on the electrical system than any other component in the system.

Four brush is the one to have, especially for higher comp and tuned motors.

Great information guy's!

Can a factory installed two brush starter be replaced with a four brush unit without making modifications or upgrades to an original (properly functioning) KZ electrical system?

And, when it comes to replacing the starter motor, which is better...OEM or aftermarket?

The four brush starter found on all the J/GPZ based 998/1089cc fours is a direct fit to the earlier engines with no other alterations needed or detriment to the original electrical system.
The only difference is that the positive pole on the main body is in a slightly different position which puts it close to the crankcase casting so you have to watch out for that.
Personally i'd go for OEM if in good condition and have never used a pattern one although Ricks Motorsport sells a stronger Z starter which had good reviews but i don't know if they are 2 or 4 brush or just have more windings.

daveo wrote:

Great information guy's!

Can a factory installed two brush starter be replaced with a four brush unit without making modifications or upgrades to an original (properly functioning) KZ electrical system?

And, when it comes to replacing the starter motor, which is better...OEM or aftermarket?

Check the "wattage" spec for both in regards your electrics. Personally I don't believe there will be a significant difference in the current draw, using two pairs of brushes simply employs more windings simultaneously to increase torque

Wookie58 wrote:

daveo wrote:

Great information guy's!

Can a factory installed two brush starter be replaced with a four brush unit without making modifications or upgrades to an original (properly functioning) KZ electrical system?

And, when it comes to replacing the starter motor, which is better...OEM or aftermarket?

Check the "wattage" spec for both in regards your electrics. Personally I don't believe there will be a significant difference in the current draw, using two pairs of brushes simply employs more windings simultaneously to increase torque

 

Both have 0.6 KW noted on the rear housing cover.  But the two-brush starter weighs 30% more (4.55 vs. 3.5 pounds), and it's brushes and commutator are larger.
Another choice factor may be the cost of OEM brush kits.  Partzilla has two-brush 21039-003 kits currently priced about $40, and four-brush 21039-1053 kits around $90

When used in a stock motor, is the performance (torque) difference between the two starter types significant enough to matter?

If you are running stock compression and have had no cold starting issues to date then it's a matter of choice (IMHO)

YMHO is greatly appreciated.