Take a good look at this lead shot, then compare it with the finished engine at the end of the article. You’ll find no difference, and there lies the slick work by the magicians at JIMS. They’ve managed to stuff one hundred and six cubic inches into a stock case, using the stock bore, and we’re going to tell you how they did it!
To give you all a good look at what composes this kit JIMS R&D department laid out to the whole package for us to take a shot of.
Pay special attention to the oilers at the bottom of the picture, we’ll talk about them more later. These flywheels are completely redesigned and utilize aerospace quality 4140 forged steel. The pistons are also JIMS design and are also aerospace quality 4032 high silicon aluminum alloy. All assemblies come pre-balanced and ready for installation.
We gotta figure that if you’re gonna try this at home you already know how to get your engine out of the frame, so we’re going to focus on the bench work. We started breaking down the stock engine by pulling apart the cam case.
(You’ll find complete instructions on twin cam installation elsewhere on Bikernet’s JIMS site.) Then the cases can be split without removing the alternator.
JIMS tool number 1047TP makes this a snap.
While we encourage you to use new bearings, if you’re going to keep your old ones you’ve got to pull them off your old flywheels.
Now is a good time to take a look at JIMS oilers.
You can easily see the difference in the clearance necessary to miss the pistons on their downstroke. These oilers must be installed properly, the screws and there holes must be cleaned with Locktite primer before being assembled.
We took this shot of one of JIMS oilers, on the left, installed next to a stock oiler to really give you a clear look at the difference.
OK, now we’re getting to the good stuff.
We heat the bearings to facilitate their installation on the sprocket shaft, using JIMS tool number 97225-55 shown below.
The flywheel assembly is then placed in a holding fixture and the primary side case is mounted and the bearing clearance checked.
At this time we took a second to check the piston skirt downstroke clearance.
The other case half is prepared with sealer…
….and, using a seal protector….
….it is fitted to its other half. The case bolts are now installed and torqued.
The oil pump is reinstalled….
….and the twin cam assembly put in place.
