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Makotosun

79' yz400 hard start

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Replied by MarkT on topic 79' yz400 hard start

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Thank you Tinkicker.  Now everything in the world makes sense! 

Here's an instructional video on repairing CDI's to guide folks that have "exceptional" knowledge of ignitions and repairs...  (I found it on the Internet so it must be accurate)

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 Sep 2023 08:09 #21

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Replied by Yamfan on topic 79' yz400 hard start

Whatever is in ethanol fuel, seems to earth out the centre electrode, and prevents start, until either a new plug is fitted, or the plug is heated with a blowlamp?

This I would guess is one of the reasons why the majority of people running businesses, that use 2T powered equipment, dont use ethanol type fuels?
16 Sep 2023 09:45 #22

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Replied by MarkT on topic 79' yz400 hard start

Ethanol is corrosive to metals like aluminum, hard on rubber parts like the critical little diaphragms in most 2T lawn equipment "pumper carbs".  It also doesn't store well and can absorb a lot of water.  Lots of reasons not to use it in lawn equipment or older machines if you have a choice. 

(On a side note, ethanol absolutely annihilates old gasoline deposits....  I've had a couple of old tanks with a thick layer of rock hard sludge in the bottom...  filling the tank with E85 dissolves the crud in a few days and both tanks came out spotless.) 

I don't know that I've fouled a plug in one of my two strokes in 15 years and ethanol mix gasoline is pretty much all I can get without buying expensive specialty fuels.  Been on many group rides and I don't remember anyone fouling a plug.  I can't say that was true before ethanol fuels...  plug fouling was a much more common occurrence back then.

Significantly increased plug fouling from ethanol fuel?  That might be more folklore than fact. 

 
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
16 Sep 2023 10:43 #23

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Replied by dwyson on topic 79' yz400 hard start

The coil had some tape around the plug boot, and it was a little loose where the wire goes into the coil, I think it was a mix of the wire and plug, but atleast I got it to start easily
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16 Sep 2023 13:19 #24

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Replied by MarkT on topic 79' yz400 hard start

Congratulations!

That kind of problem can be tricky and maddening to figure out. Good job.
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
16 Sep 2023 14:09 #25

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