Just in case any of you snowbirds are missing Wisconsin we have been having a winter weather event all day long. They’re predicting 18” by tomorrow here And I already have 3’ high drifts in the driveway.
Today I began work on the engine. There are a couple of things that needed to be done to make the 1200 engine work in the 76 frame. The 1200 engine doesn’t have a groove for the snap ring that holds the u-joint on like the 76 engine dose. And the pulse generator on this 84 1200 will interfere with the frame and the swingarm on the 76 frame. The 86/87 engines don’t have this problem because the pulse generator is mounted on the front of the engine.
The first step was to remove the pulse generator and rear cover from the 1200 engine. My system for keeping track of the bolts on a cover like this is to make a drawing like the one pictured below in the build log. The “1” at the top on the drawing indicates the first bolt. The arrow indicates the order the bolts were taken out. I lay each bolt along the edge of the paper and mark the end of the bolt. Under each mark is a list of the bolts that are that length. When I get to a bolt that is a different length a new mark is made and the numbers of the bolts that are that length are listed below it.
With the cover off you can see the pulse generator shaft coming out of the end of the crankshaft.
When I remove it you can see the o-ring on the crankshaft end of the shaft and the shoulder on the rear cover end of the shaft. The shaft has to stay in place because it's restricting the oil flow out of the end of the crankshaft. Without it the oil will gush out and the oil pressure to the rod bearings will be low. But we don't want it just sticking out of the rear case cover ether. The shoulder rides against the bearing in the rear case cover to hold the shaft in place.
So I cut the shaft on a chop saw at the outboard and of the bearing journal and then chanffeured the cut to get rid of any burrs. This solves clearance problem caused by the pulse generator but I'll have to make a plate to cover the exposed bearing.
The final drive shaft just pulls out. I also removed the final drive shaft from the 1000 engine. As you can see they are identical except for the o-ring grove. I mike’d the bearing journals on both ends of bolt shafts and they match to within about .0005. The shafts are also the same length and the springs have the same number of coils. So that solves the snap ring problem all I have to do is swap out the shafts.
I reinstalled the rear cover and bolted down with two bolts. Because I will be painting this and I don't want all of the bolt heads painted I will wait until after the painting is done to install the rest of bolts.
Now I needed to make an aluminum plate to cover the pulse generator shaft. To start with I took a 1/4” thick scrap aluminum and using the plastic pulse generator spacer as a pattern I center punched the bolt holes. Next I drilled pilot holes using an eighth inch bit. I screwed the plastic spacer, the aluminum and a piece of gasket paper to a piece of three-quarter inch plywood. With everything screwed together I clamped the whole works, plywood up, to the drill press table. Then I used the router with a tracer bit to cut out the aluminum part.
Now I have a nice cover for the pulse generator bearing and a perfectly matching gasket. All I need to do now is to polish it.
The back of the engine is all set and should bolt in without any problems. Tomorrow after I dig out the driveway I will start on the heads. It’s going to take a lot of work to to figure out which head will give the best performance. I’m convinced that some of the information that has been put out on the net is wrong and I’m suspicious of some of the performance claims around using the 1000 heads on a 1200 motor.