XLH 883 to 1200 Upgrade
At this point I have torn down the engine, determined what my mechanical compression ratio will be by setting the squish and am ready to put things back together. Its Sunday April 12th now.
Writing this with hindsight I'll begin by saying, this part is easier that I expected it would be. There are different schools of thought on how to install the pistons into the cylinders; you can either mount them on the connecting rods first, or; you can insert them into the cylinders BEFORE mounting them to the connecting rods. In the first case you'll probably need a ring compressor. In the second, you absolutely do not need one.
I had the benefit of getting advice from a couple of people locally on how to install the rings, pistons and cylinders. One guy, Keenan Tatro, a long time racer at Bonneville and engine builder and from Al Mativi who has rebuilt at least twenty or more big twins and Sportsters in his garage over the past eight years. They both recommended the latter option of installing the pistons into the cylinders BEFORE installing the cylinders onto the cases. Having no prior experience with this myself, I decided I'd give it a shot. I can tell you, by the time I bolted my heads down, I had inserted and pulled my pistons with new rings etc. out of the cylinders six times. Believe me, this method is VERY easy to do.
How is it done?
Your first step should be to insert one cir-clip into each piston's groove that locks the wrist pin into place. I inserted the clip that would eventually be on the left side of the engine as I wanted to do my re assembly from the right side. After completing the entire re assembly I now think it would be easier if I had put the cir-clip into the right side groove instead. Less chance of the other one falling into the tappet bores.
Before installing the rings you must check their end gap. For this step you'll need a feeler gauge. Wiseco says that the general rule to follow in checking the end gap is to insert each ring into the top of the cylinder by carefully, using the top of the piston, push it down into the cylinder about 1/2 inch insuring that it is level, or parallel with the circumference of the bore. Then insert your feeler gauge into the gap. They say the safe range should be "the min. ring end gap is .004 for every inch of bore , so in the case of installing 1200 pistons having a 3.498" bore, the ring end gap should be between .012 to .020." That's .004x3.498 or .014". When I measured mine they were all .015 and within Wiseco's specifications. If the gap is narrower than .014, you'll need to file them, BUT VERY CAREFULLY. Read the service manual first before attempting to file them.
Once your gaps are verified correct, you can install the rings onto your pistons. Your ring set will be comprised of 5 individual rings. Having only three grooves around your piston means you'll be inserting three rings into one groove and one ring into each other groove. If I've got this right, The rings are called from top to bottom; the compression ring, the middle ring, and into the third groove goes, in this order, a very thin retainer ring, and oil spring ring (looks corrugated), and another retainer ring. That means the oil spring ring has a retainer ring above and below it.
You start putting your rings on by installing the oil spring ring into the third (lowest) groove first. Then carefully, spread a retainer ring and install it in the same groove just below the oil spring ring. Next install the other retainer ring just above the oil spring ring, also into the lowest piston groove.
Next, insuring the middle ring is facing in the proper direction (i.e. dot up), with your thumbs you can carefully separate the space wide enough to put the ring over the piston head and into the 2nd groove. Once again, you repeat this for the compression ring as you allow it to fit into the top groove.
With all your rings in place, you now insure their gaps don't overlap, nor do they lay within 10 degrees of the piston skirt thrust faces. That is they should be offset from the center line of the piston as its installed in the scoot. That center line being an imaginary line drawn from the front to rear of your scoot. This is explained quite well in the service manual.
The service manual also gives H-D's recommended spacing of ring gaps as your rings lay in their grooves. I chose to use its recommendations. Basically it says space each gap 90 degrees from the next. When done the lowest retainer ring gap will be directly below the gap of the highest ring, the compression ring. So yes, as you imagined, there is one overlap of gaps, but neither will affect the other.
With the rings in place you can surprisingly, very easily slip your pistons into their cylinders. Here orientation is again important. Your piston manufacturer. will have indicated which thrust edge should face your exhaust port. Make sure, this is how the piston's end up in the cylinders.
Now, turn the cylinders so that the head of them is on your counter top (protected) and wipe some assembly lube around the lower 2" of the cylinder bore. You should be looking into the base of the cylinders now. Carefully insert the piston head into the bore so everything is resting on the compression ring. Now, with your thumbs pressing on each side of the ring and 90 degrees away from the gap compress the gap and tilt that part of the piston into the cylinder so the gap is below the edge of the they cylinder (inside the cylinder). Once you've got the gap inserted, its VERY EASY to continue compressing the ring as you slowly tilt the piston back to level. Follow this same procedure with the middle ring, then the oil rings. I found at times I had to lightly tap the piston to push it further into the cylinder as I moved to each succeeding ring.
Once you've got all rings inside the cylinder, make sure you don't push the piston in so far that you can't insert the wrist pin. This is critical so be very gentle when inserting the oil rings into the cylinders.
Now after wiping some assembly lube on your wrist pin and the groove the locking cir-clip will go into, insert the wrist pin far enough so that it won't interfere with the connecting rod when you lay this whole assembly over the studs and lower it to the connecting rod. At this point you can to install the cylinder/piston as one assembly.
First, remember to clean the top of your cases around the case bores and INSTALL YOUR BASE GASKET over the studs. Now, carefully lower the cylinder and piston over the studs until the piston wrist pin aligns with the connecting rod bushing. When aligned, using your fingers, just push the wrist pin through the connecting rod bushing until it is stopped by that cir-clip you installed at the beginning of these instructions.
Now insuring that there is NO POSSIBILITY that anything can fall into your cases by stuffing lots of rags or paper towels all around the connecting rods, insert the second cir-clip into its groove which ultimately locks the wrist pin into place. Make sure this cir-clip is seated properly into its groove, then sit back and imagine the damage that will be done if it isn't and the wrist pin comes (slides) out towards the cylinder wall during operation. After that scares ya' to death, check it again!
Putting your thumb over it during installation helps keeping it from flying across the garage in case it springs out before you have it totally locked into place. I found by inserting the edge of the clip at the gap all the way into the groove, and grabbing the other edge near the gap that was still sticking out with a needle nose pliers, I could easily force it into the hole. Then using a small flat blade screw drive I was able to push it from the teeth of the needle nose right into the groove. Make sure the clip gap is opposite the space that is molded for use during cir-clip removal. With the piston and wrist pin clipped in you can now gently lower the cylinder down to the base gasket by gently rocking it back and forth.
I did the rear cylinder first as its a little harder because of the room allowed by the frame. With the jug installed, I continued with that cylinder until I had the head installed and torqued to specifications. In my case, Bartel's recommended torquing the head bolts in three increments leading up to the last tightening being 35 ft-lbs. After torquing the rear head into place I repeated everything above for the front cylinder.
The next article, which is my next to last post on this project, I'll review how I decided to reassemble the rest of the engine and bike. I didn't exactly reassemble everything in the reverse order as my disassembly steps and in that post I'll tell ya' why.
OK, its time put the scoot back together. At this point we've got the base gasket in place, the piston on the rod with cir-clip securely in place and the cylinder slid over the piston, resting on the base gasket.
Next I took the tappets (sometimes called lifters) that had been soaking in a coffee cup full of 20-50 wt. oil and dropped them back into their respective locations in the case. There is only one way they'll fit properly. First the roller rides on the cam, and secondly, they need to be rotated in their bores so you can reinsert the tiny chrome guide pins. Don't forget to install new rubber guide pin o-ring seals. Most assuredly, yours are compressed. Once the pins and o-rings are in place, replace the triangular guide pin retainer plate and torque it to manual specs.
Next the chrome down tubes are re installed. This is one of the more trying steps of the rebuild. You'll need new down-tube base seals. I used Harley's at $2 each. I was told that James makes them also for about double the price. One difference being, they install easier. I slid them into place on the down-tube, then slid the metal down-tube base holder into place over the seals, then placed the whole assembly onto the case over its respective the tappet hole and tightened the allen screw to specification. Some people will experience difficulty getting the base of the rubber seal that touches the case to align itself within the down-tube base holder.
At this point you'll lay the new head gasket onto the cylinder top and install the heads. Bartels does NOT recommend using any gasket sealer on their copper head gaskets.
Now place the upper down-tube o-ring seals into the head and soap them a little (I wet my finger and rubbed it on a bar of soap, then around the o-rings). That allows the top of the down-tubes to slip into their o-ring seals much easier as you place the head on the cylinder.
Now I'm about ready to replace the head. With the Gasgacinch setup on the gasket and the head, I lower it over the studs and carefully align it onto the dowels that are protruding from the cylinder. I replace the head bolts and follow the torque sequence recommended by Bartel's since I was using their gasket. Basically it said to torque the bolts in three increments to 35 ft.-lbs. So I did, 12, 24, 35.
With the head bolted into place I followed the same steps on the front cylinder and heads. Once they were both in place I completely finished up the rear cylinder assembly. The procedure here is a little different than on the front cylinder. You'd think the next step would be to insert the push rods into their tubes but its not. Because of clearance problems you'll need to lay your rear lower rocker box in place then insert your push rods, then readjust the position of the rocker box arms over the tops of the push rods. I should have mentioned earlier, before you do this, the crank should be rotated so that both tappets are at their lowest point (i.e. valves closed).
Now you tighten the lower box to specs. using the method mentioned in the service manual. Basically that means in a crossing pattern and not too quickly as the tappets will have to bleed out some of the oil in them as the rocker arms force the push rods down upon them while you tighten the rocker box to the head.
The last steps for this cylinder are to lay the middle rocker box cover into place, then the top one torquing it to spec. (11-14 ft-lbs).
Here's where I deviated from the tear down process. Instead of finishing the front cylinder I re installed the intake manifold. There is a lot more elbow room at this point, with the front cylinder's rocker boxes still not installed. After the intake manifold was in place I installed the front motor mount, then the left side motor mount, then the V.O.E.S. and the ignition switch. This was all easier to do with the front rocker boxes still sitting on the side.
Now I finished the front cylinder's rocker boxes. With them done, I re attached the carburetor, but before I did that, I pulled the bowl and filled it with gas so I wouldnt have to crank the engine for a long while before it would start.
After installing the carburetor and its associated throttle and idle cables I installed the horn, the coil and its associated wiring, then the gas tank, the fuel line going to the carburetor, the gas tank vent hose. Once everything was in place and torqued properly I re installed the exhaust system and re attached the brake pedal's arm to the master brake cylinder plunger completing the job, or was it? Nope, I still had the battery to install but once it was in place, the scoot was ready to be turned over.
|Copyright 1997-2006 Stephen Mullen, Oldsmar, FL -+-|