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Makotosun

71 RT1 360 spark issue (Water damage?)

  • Lucas de los Rios
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71 RT1 360 spark issue (Water damage?) was created by Lucas de los Rios

Hello,

I'm working with my 71 RT1 360. I just got the cylinder back from a bore job. Got everything buttoned up and running. Decided to give the bike a bath and set it up for the night. Fired it up in the morning(rough start that seemed weird since it fired right up the day before.) Warmed it up for a minute and went to putt from the garage to the house(30yards) and it died. Kicked it til my foot was bruised. Figured out I had no spark. Opened the side case and water poured out. Must have run in the hole where the wire pass through. Tried my spare coil with no response. Changed the condensor to no avail. I'm reading 3.2 ohms from my black wire to ground with the points open. Any advise or is my magneto fryed?
14 Aug 2025 18:30 #1

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Replied by MarkT on topic 71 RT1 360 spark issue (Water damage?)

I've drowned out many times, never fried anything.  Most likely just needs to dry out real good.  
 
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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14 Aug 2025 21:56 #2

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Replied by alnarv on topic 71 RT1 360 spark issue (Water damage?)

I agree with Mark. Leave the mag open for a couple days, or hit it with a hair dryer on warm for an hour, then clean the points (drag a business card thru closed points). It should then have spark.
15 Aug 2025 06:12 #3

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Replied by RT325 on topic 71 RT1 360 spark issue (Water damage?)

Compressor & wd40 sprayed in & around. I use crc56 but not sure what you guys have.
15 Aug 2025 16:09 #4

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  • Lucas de los Rios
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Replied by Lucas de los Rios on topic 71 RT1 360 spark issue (Water damage?)

I've been working on this problem for weeks now. The entire magneto assembly is out on my work bench. It is all definitely dry. Today i retested the ohms and I got 4.5 from black wire to housing ground. Closed the points and it stayed the same. Shouldn't it go to infinity if I close the points? And why would my ohms go up overnight? Weird things going on.
15 Aug 2025 19:31 #5

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Replied by pabdt on topic 71 RT1 360 spark issue (Water damage?)

Ok, you used that wet stuff (water) on the whole bike for a bath? check the on/off switches and make they are not wet. You may be activating the kill switch, by grounding the coil out.
1974 Yamaha DT125A
1974 Yamaha DT360A with SP96 Exhaust
Next…196x-197x Yamaha something.
15 Aug 2025 20:46 #6

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Replied by alnarv on topic 71 RT1 360 spark issue (Water damage?)

You have it backwards. If the points were actually in contact you would read 0 ohms, and when open, you are reading the resistance of the source coil copper wire plus any leakage thru the condenser (there shouldn't be any leakage) Since you see no change, your points are not contacting.
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16 Aug 2025 05:13 #7

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Replied by RT325 on topic 71 RT1 360 spark issue (Water damage?)

So we're back to the old "Clean the points trick". Just draw some light emery through them while the stator is on the bench & see if reading shows contact--O ohms.
16 Aug 2025 14:43 #8

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Replied by MarkT on topic 71 RT1 360 spark issue (Water damage?)

Yes, agreed, clean your points.  

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1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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16 Aug 2025 17:53 #9

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Replied by RT325 on topic 71 RT1 360 spark issue (Water damage?)

I knew Mark was thinking that so got in first haha.
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16 Aug 2025 19:27 #10

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