We install a Big Bore cylinder kit: size matters ...

The Big Bore Kits of direct installation for the increase in displacement are acquiring more and more prominence when improving the performance of motorcycle engines. The main reasons are the simplicity of installation, the ratio improvement of the motor/economic investment and the reliability, since we are not "squeezing" the engine, but changing it for a larger one.
Another advantage is that this modification is not appreciated externally, since at aesthetic level the components are identical to the originals.

The Screamin 'Eagle Kit
For this occasion we are going to proceed to assembly a kit from the Motor Company high performance components, specifically the Big Bore Stage II Kit of 103 ”(1700cc).

This kit is made up of pistons and cylinders, more “cheerful” camshaft, a high -performance air filter kit capable feed the greatest demand due to the increase in displacement and a reinforced clutch spring to handle the largest motor torque. We have also added an oil radiator kit to maintain the stable temperature in moments of maximum effort or in high environmental temperatures and a collector without catalyst or active exhaust valve with the aim of allowing a greater flow of exhaust gases.

Disassembly
Our test motorcycle is going to be an electra glide of 2010, with which we will begin by disassembling the lateral lid and disconnecting the maxi-fusable to leave the system without electric current (safety is first).
We then proceed to remove the original escape and collector.

If we observe the back of the collector we can see the active exhaust valve and the catalyst.

We continue with the disassembly of the top of the engine until we reach the pistons, which we will extract with the specific tool for this task.

We can at this time compare the original cylinders and pistons with those of the kit, appreciating the difference in size that will result in a much higher motor torque.

With the “top end” or upper upper part we continue with the replacement of camshafts, which we will strictly following all the steps and procedures of the workshop manual.

Assembly and adjustment
With the lower part of the finished engine we continue installing the new pistons and cylinders using a segment compressor.

We will continue with the original cylinder heads, since this kit has been designed so as not to have to make any modification on any component of the original engine, hence the simplicity of installation.

One of the recurring problems on high performance Twin Cam engines is excess oil coming out in the form of steam through motor vents, which condenses in drops and comes out of the air filter. With the Big Bore kit, the new vents that HD has designed to minimize this problem is included.

With the tightening of the cylinder heads (remember, following the manual ...) we will mount the balance sheet boxes and the new vents.

The next step is to re -install the admission body in its location,

followed by the new air filter system with the highest flow.

At this step we can install the escape, starting with the new collector without restrictions (catalyst).

With the finished exhaust system we only have to open the primary chain crankcase to replace the clutch spring with the one included in the kit, a little stronger and according to the new features and performance.

The oil radiator
Once the Installation of the Big Bore kit will be completed, we will continue with the radiator assembly, for which we will disassemble the oil filter and install the proportioned adapter.

Next we will locate the radiator at the bottom of the chassis and connect the feeding and return tubes.

Final operations
As always before trying the engine we have to reprogram the switchboard to indicate the new parameters and volumetric efficiency data, we will make several passes recording data and updating the tables. Incidentally, we can adjust the electronic accelerator response to obtain a more immediate behavior when turning the gas fist.

As a final climax we will place the air filter embellis that warns the unsuspecting that this motorcycle no longer belongs to the flock and has become a asphalt predator.

Frank Burguera

#mecanicaharley