Clarification on coil test with ohmmeter

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sgracer5072
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Clarification on coil test with ohmmeter

Post by sgracer5072 »

Gentlemen,
New to the Spree world, new to the board. I recently acquired a really clean white 84 NQ50 Spree in non running form, and I have a lot of needed parts ordered (the carb had been "tuned" by a relatively clueless person resulting in stripped mounting stud holes and the needle broken off the bystarter, and silicone on the fuel bowl to supplement the flattened o ring gasket among other things. So it goes. While I wait for parts began checking out the electrical system and was pleased to see no butchery there. Horn works, starter works, front turn signals come on but don't flash (thinking it's a ground problem with the rear ones as they appear to ground through the rack), fuel gauge and low oil light are operational (I checked the fuel sender out of the tank first with an ohmmeter to verify that it should work). It even has the original Owners Manual and a registration from Niles, Michigan from 1985 tucked under the seat.

So since all was looking so good, I checked the spark and had none. So I consulted the service manual I downloaded from this most wonderful and informational site and started following the checklist on P. 14-9 and started with the coil. So after all that explanation, here's my question: following the procedure outlined in the service manual on P. 14-8 I came up with this: reading resistance across the green and black spades on the coil I get .4 ohms which is very close to the prescribed .1-.3. But when I check across either the black or green spade and the end of the spark plug wire with the boot removed, I get infinity.

So I'm thinking I have a bad coil, but I'm hoping some of the knowledgeable folk here will drop in and either confirm my diagnosis or tell me to move on down the checklist.

Love the site. Started reading all the tech stuff long before I went hunting for a Spree to mess with. Thanks to all and I hope someone has a little time to read my diatribe!
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ss800
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Re: Clarification on coil test with ohmmeter

Post by ss800 »

your .4 primary likely ok (your meter possibly "off"?)
but secondary should read 3.7 to 4.5 ohm (cap removed) according to book

the book doesn't lie (nor does the meter, provided its operational and calibrated)...coil FAIL, IMHO

Replaced a set of 15 year old Dyna performance coils on my older Ducati this summer....secondary readings were double book Ohm value. The cylinder involved was missing at a certain RPM on acceleration and burbling on deceleration.

Problem solved...@ $140 per PAIR (only way they are sold) ...ouch.

And welcome from another newbee here.....i'll yield to others to opine as well.
Last edited by ss800 on Sun Dec 17, 2017 9:51 pm, edited 1 time in total.
**Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba.... Hunter S. Thompson**

'95 Ducati 900SS/SP
'98 Honda VFR800
'07 Ducati SS800

www.customcarbservices.com
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sgracer5072
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Re: Clarification on coil test with ohmmeter

Post by sgracer5072 »

Thanks for the reply. Glad to see we came to the same conclusion. I had a similar situation to your Ducati. I have a 1977 Kawasaki KZ650 I am restoring and it had a habit of dropping a cylinder or two after taking off on a ride. It would eventually pick it back up but it was frustrating. Checked the coil and saw high secondary readings also, so replaced it and the random cylinder drop went away. Gonna get a coil for the little old Spree and see if it fixes it!
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ss800
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Re: Clarification on coil test with ohmmeter

Post by ss800 »

Just for yuks, i browsed ebay for Spree coils, quite affordable, readily available.

Quite a contrast to my recent Dyna coil sticker shock! I've been quite fortunate with my '86 Spree....other than tires , fresh fuel purges and occasional carb cleans..its been issue free since purchase used in the mid-90's. It does do its fair share of sitting, though. I've got another Honda I can ride, too : )
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Last edited by ss800 on Sun Dec 17, 2017 9:53 pm, edited 1 time in total.
**Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba.... Hunter S. Thompson**

'95 Ducati 900SS/SP
'98 Honda VFR800
'07 Ducati SS800

www.customcarbservices.com
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sgracer5072
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Re: Clarification on coil test with ohmmeter

Post by sgracer5072 »

As a matter of fact, I just ordered one....very reasonable. I got the Spree for $200 and have spent about $90 on ordering things so far and when it all gets here I should have most everything I need to get it up and running. The Ducati is beautiful.
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ss800
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Re: Clarification on coil test with ohmmeter

Post by ss800 »

^ a very reasonable "buy-in" on your scoot.

Not my Duc... thats my 5th Generation '98 Honda VFR800 pictured (very special gear driven camshafts)
**Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba.... Hunter S. Thompson**

'95 Ducati 900SS/SP
'98 Honda VFR800
'07 Ducati SS800

www.customcarbservices.com
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