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yankee-flyer

Well Known Member
We're supposed to check the trigger coil clearance on the engine but the single B&W photo on the plans doesn't show much. The plans say that the procedure is in Section 15.1 of the Line maintennance manual, but none of the manuals supplied on the DVD that came with the engine have such a section. If we're supposed to stick a feeler gauge between the black rear housing (says "ROTAX") and the silver nipple, then I've got more than .016 clearance. But I'm not sure that's where to put the feeler-- you can change the clearance by changing the angle you stick it in at. But does that clearance change as the prop shaft is rotated?? The plans say to change the clearance by rotating the prop shaft but don't say what to look for/measure and when. Looks like this will be impossible once the engine is hung, so if I have a problem I have to fix it now. Suggestions from those who've been there??

Thanks!!!
Wayne 120241
Still workin' on the engine
 
OK-- I searched the forum

and see that others have run into the same thing. But I still don't know exactly what I'm mesuring between and if that clearance changes as the prop shaft is rotated??

Still confused

Wayne
 
New Section 46 Posted on Vanaircraft

Wayne,

A revised Section 46: Engine Installation, was posted on Vansaircraft (along with a lot of other plans updates) today.

On page 46-03, Figure 2 may be of some help.

-Dave
 
trigger coil clearance 46-03

In order to check the clearance, the cams need to be adjacent to the coils (one at a time). It is pretty hard to tell where the cams are with the black plastic Rotax cover in place. I took it off. Use Loctite on the screws when you put it back on. Each coil of wire is wound on a metal core. The measurement in question is between the core and the cam. I measured mine at 0.010". If the gap is not very far off, I would not fool with it. I assume that the mounting screws have thread-locker on them and have been properly torqued at the factory. In my opinion (someone will correct me if wrong), the danger of too small of a clearance is mechanical damage if parts collide. The pickup coil will function fine with less clearance. If the gap is too big, the voltage generated by the pickup coil might not be enough to function as designed.
Joe
 
Wayne,

It took me a while to figure out that one has to rotate the crankshaft (with sparkplugs removed) to get the magnets on the flywheel lined up with the pickup coils. That in itself is not easy as there is a lot of resistance to turning the crank. Use the large screw driver as instructed.

Once I was able to measure the gaps, I found that 4 out of 5 were OK - just barely at about .012". However the fifth one was really tight at .010, so I called Van's. They told me to adjust it so I loosened up the mounting screws and moved the sensor. Pretty easy to do once I worked up my nerve to start loosening things up.

Since there are screws common to two or more sensors, make sure you recheck ALL the gaps after you tighten the mounting screws back up.

John
 
New Info

The revised pages for the powerplant instructions are MUCH better!! Photos showed what I needed and also the text now references the HEAVY maintennanace manual though the recommended search didn't work. Easy to check clearance with that black cover off and all mine were apparently OK. You can check one pair at a time when you get the fluwheel lined up correctly and it's obvious which magnet should line up with the 5th one.

Hanging engine tomorrow!

Wayne 120241
 
Remeber that the trigger coils are magnetic and they will pick metallic debris, so be extra careful about dropping washers and cotter pins around the trigger coil cover. A new trigger coil harness is $700, and requires an engine pull to change.
 
trigger coil check

I could use a little help here. I checked the trigger coil gaps using a .012 feeler gage. Each of the 5 accepted the feeler gage at .012, but some were really tight. Is this okay?
Slane
 
Wayne, there are some good posts above which should help you. If you are still in question call Dean Vogel at Lockwood Aviation .He is outstanding regarding customer service on Rotax. He walked me thru miine after some bad advice resulted in my having to pull the engine to correct the gaps. Better to be sure before you hang it.
Dick Seiders 120093
 
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