1989 Banshee 370 cc Long Rod Engine Build




Part 1 - Part 2 - Part 3 - Part 4

The torquey 370 cc Long Rod Banshee engine is a very capable performer. Take a look as I re-assemble this one.


To make a 370 Long Rod Banshee engine it's necessary to start with one of these. It's a rebuilt crank that's been fitted with Pro-X RD 400 Connecting Rods (1A1) part # 04965, all new bearings and rebuildable crank webs. It's been trued and welded as well.


A couple more of the parts needed for this combination. There's a stock Banshee piston on the left and a stock forged Blaster piston on the right. They are joined by a wrist pin. In this photo it's easy to see the Banshee piston is shorter. They are resting on a surface plate.


The difference in height looks about like this. I'll measure it more carefully to find out the actual difference. Notice how the Banshee piston has more of a crown to its top.


The Banshee piston is 5.6 mm taller from the top of the wrist pin to the edge of the piston crown than the Blaster piston. This makes the Banshee piston flush with the deck.


I always weigh parts to determine changes that are difficult to see. In this case I was pleasantly surprised.

The Banshee piston is 70.7 mm tall. It measures 27.6 mm from the top of the wrist pin to the edge of the piston crown.

The Blaster piston is 65.7 mm tall. It measures 22 mm from the top of the wrist pin to the edge of the piston crown.

The stock bore (66 mm) Blaster piston weighs 173.6 grams. That's a considerable amount lighter than they were just a couple of years ago. The pistons I'm replacing had modified crowns and oil retention grooves cut into their surfaces and they were still over 20 grams heavier than these newly designed pieces.


1989 Banshee 370 cc Long Rod Engine Build

Part 1 - Part 2 - Part 3 - Part 4






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