Taking it to the Street


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Taking It To The Street

What happens to your bike while it’s under the knife?

Haphazard doesn’t cut it when building power; rather it’s a proven process that will provide the reward of an exceptional final product. When you hand over your bike for precision performance work you want to know that the shop will take the proper time and care required to produce top quality work. You want them to treat your bike like it’s their own. At T-Man Performance, a strict process is followed from the moment the customer drops off their motorcycle until it’s delivered.

The first step is to establish a baseline horsepower and torque number with a few dyno runs. This allows the customer to know exactly where they started before the build and allows them to see the improvement after the engine build is completed. It is also informative to the staff, as the baseline can provide crucial clues about potential issues to be checked during teardown.

The second step is the teardown process, which starts by removing the exhaust in order to get to the cam chest. The cam plate assembly is removed in order to check the pinion shaft for runout.

This occurs first so that if the crankshaft is out of spec the customer can be made aware before the entire top end is disassembled. Once everything checks out, the camshaft relief is completed and the cam chest is cleaned.

At this point the heads and cylinders are removed.

The assembly of the engine also begins in the cam chest, with new Torrington cam bearings, T-Man’s 3-Stage oil pump and billet cam plate assembly installed.

This is done with the cylinders removed so that the crank can be spun by hand while tightening the oil pump bolts to ensure everything rotates freely. Once the cam drive sprockets are installed they are checked for proper alignment.

Lifters are then reinstalled, followed by the tappet covers and the cam cover being torqued to complete the cam chest installation. Fresh oil is added to the bottom end for easier priming on initial start-up.

The pistons and cylinders are the next components installed. This includes piston ring gaps being checked and filed to specifications and all parts thoroughly cleaned before assembly. Cleanliness should never be overlooked as dirt and grit will cause engine damage on start-up. Once the rings are properly oriented on the pistons, the pistons are installed in the cylinders on the work bench. This method makes it easier to use the ring compressor off the bike and has less chance of damaging rings during placement.

When the cylinders are positioned, they are secured to the cases and the deck height is checked at top-dead center.

This is important as there is no guarantee that the piston will come up perfectly at the top of the cylinder. If there is any change here, it can have an effect on the compression ratio. If necessary, deck heights can be adjusted by shortening the cylinders or using different gaskets.

Before the new heads are secured, they are checked with a leakdown test on a custom fixture to ensure a perfect seal at the valves.

Once torqued down on the cylinders, the engine is leakdown tested again, this time checking the sealing of the piston rings.

The pushrods and tubes are next in line. The inner pushrod tubes are drilled on a lathe with a 39⁄64” drill to remove material on the inside that the pushrod could rub against when using a higher lift cam.

Initially, these components are put together loosely so that the lower rocker boxes and rocker arms can be installed.

When the lower rocker boxes are in place they are checked for clearance around the valve springs and are then torqued, followed by the rocker arm support block. Then the rocker arm supports are torqued and the pushrods are adjusted. Once all pushrods are properly set, attention is turned to the top rocker covers, which need to be clearanced above the valve springs and the pushrods when using higher lift cams.

If this is not done, contact with the rocker arms can occur, causing excess noise or a low compression reading.

Proper fitting of the intake manifold is the next step and is frequently overlooked. When using aftermarket cylinders, it is important to be aware that some cylinders are different in length and when doing performance head work where material is removed from the heads, the length of the manifold will need to change. If this is not addressed it can result in an air leak which makes tuning the engine difficult and could cause a potentially destructive lean condition. The head and manifold may also be damaged during installation. The manifold should line up seamlessly with the opening of the intake ports to ensure the best performance and to achieve this, boring the intake openings may be necessary.

The engine is nearly ready for initial start-up. With the spark plugs out and the oil filter off, the engine is rotated to get oil flowing freely. Next, spark plugs are gapped, the oil filter is replaced and the motor is ready to begin the firing process. T-Man Performance goes through a start procedure that consists of starting the engine (this does not mean revving the motor) and letting it idle until the cylinders get warm to the touch. It is then shut off and allowed to cool. This is repeated multiple times. While the engine is still warm, a cranking pressure check is done in both cylinders before the motorcycle gets a brief run on the dyno. Again, the engine is not run hard; it is only done to check the tune in the lower RPM ranges where the bike will be ridden during its break-in miles. This ensures that the engine doesn’t run too lean or too rich during those first few hundred miles, which are the most crucial miles in the new engine’s life.

The motorcycle is now ready for pickup. The owner is instructed on break-in procedure and asked to put between 300 and 500 miles on the engine. The next time the bike returns to the shop it will be for final dyno tuning. IW

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