In our last issue I told you how to dismantle your TC88 engine to convert it to a 95. Now I'll tell you how to put it all back together! We used a lot of editorial pages to explain and illustrate a fairly simple process-sometimes it takes longer to explain how to do something correctly than to actually do it.
By now your cylinders have been bored to 95 inches, the new cams have been in-stalled, and you've gathered the piston assemblies, pushrods and gaskets. Maybe you have a geared cam drive, something that will add a few horsepower but isn't really necessary for street use. Now it's time to build your 95 engine.
Preparation
Inspect all the engine parts. Check the pistons for nicks, and remove any you might find with a fine file. Never use sandpaper, which leaves hard particles embedded in whatever you have sanded. Those embedded particles will wear your engine out. Clean all gasket surfaces. Rick used Scotch brand plastic scrub pads to remove all the old gasket material from the surfaces of the heads, cases and cylinders. He then cleaned the surfaces with either denatured or isopropyl alcohol-either will do (Photo 2). While you're scrubbing and cleaning, check for nicks and bumps on the gasket seating surfaces. Flatten any you find. I use a small, fine single-cut "mill" file for this.
Clean the Cylinders
Your newly-bored cylinders will appear to be clean; they're not. Oil from the honing procedure leaves some honing-stone particles (carborundum) in the surface of the cylinders. Those particles are harder than any part of your engine and they'll wear anything they rub against. They're held in place by the surface tension of the honing oil. Scrub the cylinder bores with an SOS, Brillo or a similar soapy pad made of steel wool. Use hot water to rinse, and immediately apply a thin coat of oil to the bores to prevent rusting. Note: Carefully deburr the top and bottom corners of the bores so you won't cut yourself while scrubbing them.
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American Rider
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End Gaps
Check the end gap of the piston rings. Chances are very good that the piston rings will have the correct end gaps; however, you must check and adjust the gaps if needed. If a piston-ring end gap is too small, the ring will jam as it nears running temperature. This, in turn, can damage the bore, break the ring, and completely ruin your new engine. Use a piston to push the ring you're checking down the bore. This will assure that the ring is "square" with the bore. Use a feeler gauge to determine the end gap.
If needed, gently clamp the ring in a smooth-jawed vise and remove a small amount from one end. Use a fine file or similar tool. The ring material files very easily, so go slowly.
Assembly
Install a piston-pin clip in one side of each piston. Now, with the piston on the bench, it's a good time to practice clip installation. Remember, you must not deform the corners formed by the pin holes and the sides of the pistons. Install the rings on the pistons. Use a piston-ring installation tool if you have one. They can be installed with your fingers, but it takes practice and tough skin to do it that way. Be sure to get the rings oriented correctly.
The top and second compression rings are different, and they have an "up" and a "down" side. Marks (dimples, dots, etc.) near the ends of the rings indicate the up side. The oil control rails have no top or bottom. The top compression ring has a shiny edge; it's chrome plated. Its working edges are slightly rounded when compared to the second ring's edges. The second ring is black and has sharp edges.
When you install the oil-control rails, place the end gaps on opposite sides of the piston. This is not critical; just don't line the gaps up with one another. The top and second rings should be installed so that their end gaps are not lined up. A quarter-turn apart is good enough. Remember, the compression rings rotate and are constantly changing their relative position, so exact positioning is not important.
Piston Pins
Smear some engine oil in the bores of the piston-pin holes and on the pins themselves. Install each pin into the end of the piston's pin bore. They should be a close fit with some drag, and they might even stick a little in their bores. At operating temperatures, the pins loosen slightly. Remember to have the crankcase cylinder holes covered. Now, install a piston pin onto a connecting rod. We started with the rear cylinder. Install the second piston-pin clip into the piston carefully so as not to damage that pin- hole corner I warned you about. You are now ready to install the cylinder
Cylinders
You are now ready to install the cylinder, but first install the O-ring seals onto the cylinder spigots. Check again that the ring gaps are not aligned with one another. Place the piston-ring compression tool over the rings and squeeze the rings into their grooves. Leave a little of the piston sticking up as a guide into the cylinder. Place the cylinder over the piston and push or tap it down over the piston using a soft-faced mallet. Continue until all the rings are started in the cylinder, then remove the ring clamp. Remove the material you used to cover the case hole and ensure that the seating surface is clean and free of any debris. Push the cylinder down until it is seated on the case. Rotate the engine using the rear wheel to raise the other piston. It's a good idea to fit a spacer and one of the head bolts over the first cylinder so that it won't lift as you rotate the engine for the second cylinder installation. Now install the second piston and cylinder just as you did the first.
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American Rider
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Since your engine is probably fairly new and since Twin Cam valves and their seats wear so little, there is little need to remove the valves for inspection. Unless you have a good reason, like low compression, I wouldn't bother with removing the valves from the heads.
Head Gaskets
Double-check all mating surfaces for burrs, bumps and foreign material. Remove any you find with a fine file. Clean the heads with rubbing alcohol or spray contact cleaner. Lightly oil all threaded fasteners. A light film of engine oil is fine. You don't need special greases, moly paste, etc.; light oil is enough. The steel head gaskets recommended for this upgrade don't crush and it isn't necessary to re-torque the heads. Simply follow the shop manual's procedure for head-bolt torque sequencing and torque values. Don't increase the torque values over those specified in the manual.
Setting the Squish Height First, check the deck height of both cylinders. As used here, deck height refers to the difference in position of the tops of the pistons and cylinders when the pistons are at TDC. Chances are the pistons (Wiseco) are going to be slightly lower than the cylinder tops by a few thousandths of an inch. If so, fit the 0.030-inch Cometic head gaskets. If the pistons are more than 0.005-inch above the cylinders, fit the 0.040 gasket that's part of the Wiseco piston kit. I normally use a set of feeler gauges to check deck height. The cylinder, of course, must be clamped down with a couple of spacers and head bolts while making this measurement.
Wiseco does it a different way. Dave Fussner at Wiseco recommends the following: Place a small length of thick (0.060-inch) solder on top of each piston. Install and fully torque the heads, with the gaskets in place. Turn the engine over several times to flatten the solder. Now, remove the heads and measure the thickness of the solder. You are looking for 0.030- to about 0.045-inch in thickness. Adjust the gasket thickness to get within this range. This is a lot of trouble but is the surest way to properly measure squish height.
Heads
Finally, install the cylinder heads and rocker boxes. This is simply a matter of carefully sliding them into place and tightening all the fasteners in order according to the manual. Take your time and enjoy the experience of buttoning up your own performance motor.
Valve Gear This is the most complicated part of building your engine. It isn't that it's more difficult, but it's more complicated. There are more parts to fit and the rocker gaskets can be installed incorrectly, causing a monumental oil leak. Take your time, follow the manual, and you'll get it right. The one assembly difference from the manual involves adjusting the pushrods. The correct lengths of the pushrods depend on the total height of the cylinders, heads, and head gaskets. Since the new head gaskets are about 0.015-inch thinner than the originals, the correct pushrod length is now slightly less. Since the change in overall length of the cylinder/head assembly is so small, chances are that the original pushrods would work just fine. However, rather than take that chance, most mechanics fit adjustable pushrods.
I would take the chance on the original pushrods to get the greater reliability of their one-piece construction. If they happened to be too long, a valve might be held slightly open and I would have to replace the pushrod with an adjustable. If too short, a valve might get noisy as the engine reached operating temperature and, again, I would have to fit an adjustable. Being a mechanic, I would take the chance; however, most professionals will not. It could take additional time they might not get paid for and, if the customer doesn't understand, might make them look bad. The choice is yours.
Screw the pushrods together to make them as short as possible before installation. Leave the valve covers off and the spark plugs out until you have adjusted all the pushrods. We used Andrews pushrods. We also selected the aluminum version because they're lighter and I believe they run a bit quieter than steel pushrods. After installing the pushrods (see below), install the spark plugs to seal and complete the engine.
Pushrod Adjustment
The following method is the easiest I know. It's simple, accurate and the least trouble. First you must get one of the pistons at top dead center (TDC) on the compression stroke. Pick a cylinder to adjust-front or rear-with the rocker box cover removed. Turn the engine in the normal direction using the rear wheel (from the right side of the bike you will turn the wheel clockwise) while you watch the valves of the chosen cylinder. Continue rotating the engine until the piston reaches TDC. To sense when the piston reaches TDC, I recommend using something like a soda straw inserted into the spark-plug hole to avoid possible damage. You can turn the motor backwards a bit if required to get the piston near TDC. With the piston at or near TDC (it is not all that critical) and with both valves closed, you are ready to adjust both pushrods for that cylinder.
To adjust a pushrod, first lengthen it until all vertical free-play is removed. The pushrod will be snug and begin to feel difficult to turn because you are beginning to force the valve open against the valve-spring pressure. Now the idea is to move the sub-piston inside the hydraulic tappet half-way through its total travel, which is 0.200 inch (a little more than 3/8-inch), so you want to extend the pushrod half that, or 0.100 inch. A simple way to do this, after you've taken the play out, is to run the pushrod nut upward until it almost touches the pushrod body. Then extend the pushrod until the gap between the pushrod body and the locknut is 0.100 inch. You can use a feeler gauge for this. I bent a piece of 0.097-inch music wire I found in a hobby shop to make a handy gauge.
In the case of the recommended Andrews pushrods, simply extend the pushrods four full turns (24 flats) to get 0.100 inch of sub-piston compression. The 0.100-inch is not critical; it can be .080 or 0.110. All that matters is that the sub-piston be in the approximate middle of its total travel to allow for cylinder and head growth from heating. Before adjusting the pushrods on the other cylinder, it's important to not rotate the engine until the pushrods can be turned with your fingers. The tappets need between five and 15 minutes (typically) to bleed down. If they can be turned with finger pressure then the valves are closed and it is safe to turn over the engine. Repeat this same technique to adjust the remaining pushrods.
Final Assembly
Now that you have an engine, it's time to reassemble the remainder of your Harley. I see no need to give you a blow-by-blow description of this part of the conversion. Besides, you may be working on an FLHT instead of a Softail and the details will be different. If you have packaged all the fasteners and kept them with the parts they attach to your bike, and, if you've taken some pictures to guide you in moments of self-doubt, you'll do just fine.
Follow the procedures and torque specifications of your shop manual. Take your time and double-check everything you do. Better yet, get a friend to do the double-checking. Earlier in this article I mentioned working with my friend Dave Allee on his road racers. Racing bikes get worked on a lot and the chances of incorrect assembly are increased. We used a final inspection technique that proved to be very effective:Each of us would thoroughly inspect one complete side of the bike and then switch sides and check again. On occasion one would find something the other had missed. It's a good technique and I recommend it to you.
Break-In The only parts of your new 95-inch Twin Cam engine that need break-in are the piston rings and the cylinder walls they run on. This can and should be done in a very short time and over a short distance; a few minutes and a few miles, in fact.
The precision of the Wiseco bore job, their pistons, and the rings are such that only small initial wear is required to properly seat the rings. The proven best way to accomplish this is to load the rings against the walls of the cylinders by accelerating at full throttle. Here is how you go about seating your new piston rings:
1) Do not start the engine until you are ready to ride the bike.
2) After starting, quickly get out on the road and into third gear.
3) Accelerate at full throttle from 30 to 60 mph in third gear.
4) Close the throttle and coast back to 30 mph.
5) Repeat this full throttle/coast procedure a total of 10 times.
6) The rings are now seated and you can ride normally.
I would, however, avoid constant speeds over 85 mph for about 50 miles.
Summary
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American Rider
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You are in for a treat! This simple conversion delivers performance far beyond its low cost and the moderate effort required to complete it. You now have an engine with about 40 percent greater useful power than before. Equally important is where and how that power gets delivered. The quality of engine performance just might startle you; it will run crisply and cleanly at all useful rpm, and this engine is much more responsive to the throttle than most other modification packages, especially in the low-to-mid rpm range. Your friends, especially those who have fitted "high performance" cams, will need to downshift once or even twice to stay with you in a top-gear roll-on. All the while, you'll have a well-behaved, smooth, mechanically quiet, and reliable engine.
I'm sure you'll enjoy this!
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