Stator Testing
Posted: Thu Apr 16, 2020 8:52 pm
Copied from Dix's site
Testing a stator involves two steps... resistance test & cranking output voltage test.
Resistance test of a stator calls for a good ohmmeter (digital) that can read down to tenths of an ohm at least, and up to 200 megohms or better... specs are in the service manual if you have one.... under: electrical / testing procedure
494 = Nippondenso CDI system
494 220w:
10-15 ohms between the red & red/blk wires... 0.0-0.5 between the black & ground (the iron core or engine case)... infinity between either red or red/blk & ground.
0.05-0.6 ohm between the two yellow wires... infinity between either & ground... even if you don't use the charging system don't ignore the ground resistance check on this circuit.
290w:
11.6-21.6 ohms between the red & red/blk.
0.1-0.4 ohm between the two yellow.
Other values same as 220w above.
360w: (3 phase)
0.0-0.5 ohm between any pair of the 3 wires (yellow, yellow, green)
infinity between any wire & ground (except the gray or black of the tach output pair if present)
NOTE: AC voltage (yellow & red, red/blk wires) must be isolated from the DC ground!!!
This is often the cause of a weak DC system... if there's any reading other than infinity between the stator output wires & ground (black wire and/or the iron core/engine case) get a new stator or get it rebuilt. (make sure the megohm reading you are getting isn't your body's resistance reading :> )
This can also be the cause of weak/mystery ignition issues, batteries that don't last, etc... while you may not be using the charging system, the 494 CDIs & early MPEMs have a regulator/rectifier circuit in them that changes the AC to DC for the ignition system's use... which is grounded to the engine via that black wire coming out of the stator.
Once it passes the resistance test, you should also perform a cranking test... as was noted in the other topic, shorted/weak coils can sometimes not be obvious via resistance test... measure the voltage at the stator output wires at engine cranking speed (remember, AC voltage... not DC)
220w:
red, red/blk: 10.0-13.5 V
yellow, yellow (if used): 3-7 V
290w:
red, red/blk: 15-30 V
yellow, yellow (if used): 0.5-2.0 V
360w: 3.5-5.5 between any pair.
Response to the above information:
This information was extremely helpful! 3 weeks ago I purchased a used F500 with blown engine, but it came with a new engine. Performed the engine swap, checked out a few things and then tried to start it. Won't start, no fire unless the engine is rotating backwards! Did all of the above tests and was happy to see everything was good from a static standpoint. Took the plugs out last night and set them on the cylinder head, turned out the lights in the garage while I pulled on the starter cord, no spark! Grabbed the driveline and spun the engine backwards and we have all kinds of spark? Any help here would be greatly appreciated!!!
It is a rotary valved 494 engine. I see only one pickup on the top of the engine case.
Dix said: I'm having a funny feeling someone may have accidentally put a 583 flywheel in there... that would explain it.
Sunday April 27th Sit Rep. She RUNS!!!! Fired right up once we swapped out the flywheels!!! Dix you were right, it had a 583 flywheel in it. I noticed 2 different part numbers when I finally got them both out. Then I googled the one the came out of the new engine all the result said Rotax 583. I did go into town and found a beefier harmonic puller but I must say that sitting overnight with PB Blaster on it seemed to do the trick. It ran pretty good but was so loud we didn't run it long. Time for a silencer so we can run it around the neighborhood and make sure it is jetted good and everything is nice and tight. Next up is how to get the clutch to engage a little sooner for auto crossing. Thanks Dix for the help! My son was all smiles today!
Just for general future info.... the 583 flywheel is the only part of the ignition system that can't be swapped amongst the older RV engines 440/500/583/670 from 1996-2000.
Testing a stator involves two steps... resistance test & cranking output voltage test.
Resistance test of a stator calls for a good ohmmeter (digital) that can read down to tenths of an ohm at least, and up to 200 megohms or better... specs are in the service manual if you have one.... under: electrical / testing procedure
494 = Nippondenso CDI system
494 220w:
10-15 ohms between the red & red/blk wires... 0.0-0.5 between the black & ground (the iron core or engine case)... infinity between either red or red/blk & ground.
0.05-0.6 ohm between the two yellow wires... infinity between either & ground... even if you don't use the charging system don't ignore the ground resistance check on this circuit.
290w:
11.6-21.6 ohms between the red & red/blk.
0.1-0.4 ohm between the two yellow.
Other values same as 220w above.
360w: (3 phase)
0.0-0.5 ohm between any pair of the 3 wires (yellow, yellow, green)
infinity between any wire & ground (except the gray or black of the tach output pair if present)
NOTE: AC voltage (yellow & red, red/blk wires) must be isolated from the DC ground!!!
This is often the cause of a weak DC system... if there's any reading other than infinity between the stator output wires & ground (black wire and/or the iron core/engine case) get a new stator or get it rebuilt. (make sure the megohm reading you are getting isn't your body's resistance reading :> )
This can also be the cause of weak/mystery ignition issues, batteries that don't last, etc... while you may not be using the charging system, the 494 CDIs & early MPEMs have a regulator/rectifier circuit in them that changes the AC to DC for the ignition system's use... which is grounded to the engine via that black wire coming out of the stator.
Once it passes the resistance test, you should also perform a cranking test... as was noted in the other topic, shorted/weak coils can sometimes not be obvious via resistance test... measure the voltage at the stator output wires at engine cranking speed (remember, AC voltage... not DC)
220w:
red, red/blk: 10.0-13.5 V
yellow, yellow (if used): 3-7 V
290w:
red, red/blk: 15-30 V
yellow, yellow (if used): 0.5-2.0 V
360w: 3.5-5.5 between any pair.
Response to the above information:
This information was extremely helpful! 3 weeks ago I purchased a used F500 with blown engine, but it came with a new engine. Performed the engine swap, checked out a few things and then tried to start it. Won't start, no fire unless the engine is rotating backwards! Did all of the above tests and was happy to see everything was good from a static standpoint. Took the plugs out last night and set them on the cylinder head, turned out the lights in the garage while I pulled on the starter cord, no spark! Grabbed the driveline and spun the engine backwards and we have all kinds of spark? Any help here would be greatly appreciated!!!
It is a rotary valved 494 engine. I see only one pickup on the top of the engine case.
Dix said: I'm having a funny feeling someone may have accidentally put a 583 flywheel in there... that would explain it.
Sunday April 27th Sit Rep. She RUNS!!!! Fired right up once we swapped out the flywheels!!! Dix you were right, it had a 583 flywheel in it. I noticed 2 different part numbers when I finally got them both out. Then I googled the one the came out of the new engine all the result said Rotax 583. I did go into town and found a beefier harmonic puller but I must say that sitting overnight with PB Blaster on it seemed to do the trick. It ran pretty good but was so loud we didn't run it long. Time for a silencer so we can run it around the neighborhood and make sure it is jetted good and everything is nice and tight. Next up is how to get the clutch to engage a little sooner for auto crossing. Thanks Dix for the help! My son was all smiles today!
Just for general future info.... the 583 flywheel is the only part of the ignition system that can't be swapped amongst the older RV engines 440/500/583/670 from 1996-2000.