SuperHawk Forum - Better hurry up, mikstr!

I had a bit of a mishap, my last time out. The coolant bypass tube decided to separate from the water pump body and dump avery last bit of my coolant out on the track and into the bottom of my lower fairing - good thing I was running Water Wetter. Anyway, my first indication was when I happened to look at my temp gauge and it was at about 210, when it had been running at 180. Two laps before, I had the ass end slide going into turn 3. I thought it was strange, but it seemed ok after that. I decided to pull in and saw the coolant everywhere.

As the engine was cooliing, it made that sharp tink, tink sound. I knew I had overheated it and the heads were moving around on the block. I got the water pump fixed at the track - the guy installed a setscrew through the pump body and pipe and sealed it up with red loctite. He told me it happens pretty often with Honda water pumps.

I ran a couple sessions that afternoon, then had a really good, full day the following day - the best in a long time. But my coolant reservoir was losing water, so I knew I had blown head gaskets and possibly warped my heads - not to mention that the cylinders would be out of round. Great. I got it home and the coolant resorvoir smelled like exhaust, confirming the head gasket problem.

So I tore it down. In the meantime, I found a REALLY good engine, with very low miles that a guy had bought for a kart project that never happened. He sold it to me for $250, because he was tired of having it in the garage. The cylinder walls and everything I have inspected still look new.

When I got the heads off my motor, I found out that the heads didn't warp! The cylinders were about .0025-.003 out of round, which is not too terrible, for a 4" bore. I put new head gaskets in and it will run like a champ. It might burn a bit of oil, where it never did before. At least I'm back up and running. I'm happy about that.

so in the meantime, I've been planning a custom piston design. I measured the installed height of the stock pistons, from the donor engine and the shelf-stock JE pistons in my engine. The JE pistons averaged .020" below the block deck and the stock pistons were .024" below. The head gaskets are .027" thick installed. So the squish clearance is tighter with JE pistons, but I would like to be in the .035-.040" range. I also want to end up with a true 12.5:1 compression ratio. JEs and Wisecos are about 11.3:1.

I found a guy that had some custom CP pistons made, that produce 12.5:1 compression ratio, with stock combustion chambers. They are designed with a higher compression height, for tighter squish and a ~.002-.0025" skirt clearance, in stock bores. I have a set of stock RC51 pistons to measure. I know the specified compression height for the CP pistons. I'm measuring the stock piston height - from the wrist pin center, to the squish face. If the squish sounds right, I'll probably buy a set of those.

Once I know the piston weights, I'll send my spare crank out to be lightened and balanced for the pistons and Carillo rods.

I may have a winter project brewing...