582 high engine temp
in 2 Stroke Technical Questions
13 years ago
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by bill martin » 13 years ago
Mike,
Those cylinders and pistons look great. You can still see the hatchmarks in the cylinder walls. Very little wear evident. Did you check to see if the rings would move up and down in the grooves? Since your compression was within specs, I doubt any of your rings are stuck but while the exhaust is off, you might see if you can wiggle them up and down. You'll have to look close, they don't move far. Use that oil trick I mentioned. It makes the movement more obvious.
150 is ideal but you haven't done any damage at all at 120 warmup. Dennis is right. With too much pitch, you will never reach top rpm and the engine can overheat. Serious problems can result if it is only one blade that is off pitch. all you need is an adjustable bubble protractor which you can usually find at your local building supply house. If you want to go first class, get one of the digital cubes or pitch gauges made for props. They are around thirty bucks.
Adjusting the pitch is a piece of cake. The engine doesn't have to be level. You can do it right where it sits. You don't have to remove the prop. You can do a perfect adjustment in less than an hour. When you decide to do it, anyone on this thread can walk you through the process.
Bill.
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by Nick Axworthy » 13 years ago
Its odd though Bill that Mikes RPM should drop all of a sudden...thats what puzzles me,
I know Mike had a new stator fitted a while back...and I just cant remember if the ignition timing has to be re-set during this process....if it does I thought maybe the timing could have ended up to far advanced...it would loose power and overheat at the same time if this where the case.
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by bill martin » 13 years ago
You could be right Nick. I didn't know the stator had been changed. The pickup modules have to be removed to change the stator and the timing has to be reset. If the spark is advanced or retarded too far, you will definitely lose RPMs. Timing does weird things to a two cycle engine. A retarded spark makes the engine extremely easy to start and the idle is very smooth but you will never develop the RPMs or horsepower you need. Advance the spark too far and it makes for hard starts, rough idle, and loss of RPM on the top end. Both situations lead to overheating beause you are trying to swing a prop which is set up for 80hp and the engine is struggling to run with less hp. Kind of like running a straight drive car in high gear at low speeds.
Checking the timing is not a big deal but you do have to be able to get to the flywheel and that is sometimes difficult in a tractor installation where the flywheel cover is often very close to the firewall. You also need a dial indicator with an adaptor to screw into the spark plug hole. The timing has to be exact. The good news is that with the Ducati solid state ignition, you set it and forget it. Nothing to burn, wear, or get out of adjustment except the plugs. Even the older point ignition system requires only little extra maintenance.
Unlike some two cycles I have worked on, once the Rotax is set up properly, it is a great engine. Very dependable.
Bill.
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by Dennis Richardson » 13 years ago
Hi Michael - I was out of town so I am sorry that I did not reply immediately. I like to see the t-stat open during warm up before I apply take off power. That should be visible on your temp guage as a slight drop in temperature. Mine will open at about 145F indicated and drop to about 140F before it continues to climb during the run up. My enviroment is a little different than yours, during the winter I normally pick days that are warmer than -20 but have flown in -40 conditions. By controling the volume of air through my single radiator I am able to maintain 170 - 180F, summer and winter, without changing any cooling system components. A normal summer day for me would be 70F but I have flown when it is in the 80's, I have no cooling issues with the plane but my old body suffers at that temperature.
Dennis
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by Michael Regan » 13 years ago
Nick, all these symptoms began about 2 weeks BEFORE I replaced the stator. I know this to be sure because I was hoping the new stator plate would fix the low rpm problem. I can only suspect the high temps began at the same time but cannot be sure.
Have included more pics of left and right piston and cylinders. On one or two pics there appears some brown/orange horizontal curved marks, but they are camera related and not in real life.Left_Cylinder.JPG (You do not have access to download this file.)Left_Piston.JPG (You do not have access to download this file.)Right_Cylinder.JPG (You do not have access to download this file.)Right_Piston.JPG (You do not have access to download this file.)
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