Which carb jet to change after Accel coil install?


Information and questions on GL1100 Goldwings (1980-1983)
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macd
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Which carb jet to change after Accel coil install?

Postby macd » Fri Nov 01, 2013 8:02 am



I pulled my motor recently because there are things I need to address that are just easier this way. One of these issues was rust in the fuel tank (Metal Rescue works wonders, try home depot), the other is clutch plates and springs.

So, I swapped original coils, which were cracked, with Accels #140404 (amazon $160) on my 81 GL1100 and the instructions say to up-size the carb jets to #135 and possibly modify the air filter.

My question, being a novice where it pertains to carburetors, is......which jet? The main, the secondary main, the idle jet.

Can someone throw me a bone here....PLEASE!

Forgive my ignorance.
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Dave
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SteveB123
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Re: Which carb jet to change after Accel coil install?

Postby SteveB123 » Fri Nov 01, 2013 3:34 pm

macd wrote:I pulled my motor recently because there are things I need to address that are just easier this way. One of these issues was rust in the fuel tank (Metal Rescue works wonders, try home depot), the other is clutch plates and springs.

So, I swapped original coils, which were cracked, with Accels #140404 (amazon $160) on my 81 GL1100 and the instructions say to up-size the carb jets to #135 and possibly modify the air filter.


Whose instructions say that? These are universal 4 cylinder coils from Accel.
http://accel-motorcycle.com/media/instructions/accelmotorcycle/ACCEL_Motorcycle_Instructions_SuperCoils_140403_140403S_140404_140404S_0001.pdf
Current:82 GL1100 Interstate, 60 Amp Poorboy, MSD coil
Previous: 93 GSX1100F Katana
82 GL500 Silverwing

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macd
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Re: Which carb jet to change after Accel coil install?

Postby macd » Fri Nov 01, 2013 9:44 pm

Steve B, Accel includes instructions with their coils recommending changing the jet sizes, but it's unclear to me which ones.
Dave
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Fatwing Chris
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Re: Which carb jet to change after Accel coil install?

Postby Fatwing Chris » Sat Nov 02, 2013 6:08 am

Just a guess,but if these are a higher output coil I'd say hi-speed(main jet).I do have some thoughts to back up the guess,but I'll keep them to myself for now.
If I'da known it would last this long,I'da taken better care of it.
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dingdong
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Re: Which carb jet to change after Accel coil install?

Postby dingdong » Sat Nov 02, 2013 6:58 am

If memory serves I think you have the wrong coils. I think you need the 140403 because of the voltage that is fed directly to the coils and not through the ignition. I could be wrong though.
Tom

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macd
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Re: Which carb jet to change after Accel coil install?

Postby macd » Sat Nov 02, 2013 7:52 am

Thanks FC, if I had to guess this would be my choice also.
Dave
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macd
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Re: Which carb jet to change after Accel coil install?

Postby macd » Sat Nov 02, 2013 7:55 am

Ding Dong,

I originally bought the 403's then read the Clymber manual which states the '81 is CDI. The 403's are listed for points only due to ohms rating.

So i exchanged them for the 404's, however, you are not the only one i have heard say this...

Guess i should call Accel directly before i mess something up.
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eklimek
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Re: Which carb jet to change after Accel coil install?

Postby eklimek » Sat Nov 02, 2013 9:19 am

Any chance you can post these recommendations to change the jet size?

It strokes me as odd that combustion ignition should be so dramatically altered that this should be needed. This would be more likely useful if you alter the intake air flow as seems suggested. In which case the jetting would change.

The most likely effect of coil change would be to reduce plug fouling at idle with less effect at peak power demands in anything short of a full out performance motor. In light load ordinary conditions off idle carbs tend to run slghtly lean (1 to 14 -16) to preserve fuel economy. Its only in heavy load that a slightly rich mixture (1 to 12 - 14) is used to maintain power and temperature. That would be potentially altered by opening up intake air flow and warrant jet increase.

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macd
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Re: Which carb jet to change after Accel coil install?

Postby macd » Sat Nov 02, 2013 12:48 pm

Eklimek,

Here are the instructions. (having a time trying to upload them today)

Perhaps the stock ones jets are adequate.
Dave
Middleburg, Fl

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SteveB123
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Re: Which carb jet to change after Accel coil install?

Postby SteveB123 » Sat Nov 02, 2013 4:04 pm

eklimek wrote:Any chance you can post these recommendations to change the jet size?

It strokes me as odd that combustion ignition should be so dramatically altered that this should be needed.


Indeed.
How on earth does Accel know what bike these coils are installed on? They fit virtually any four cylinder bike with a CD ignition!
Ignition's are reactive....they only put out the voltage required to jump the gap, and not a volt more.

Perchance, was there a gap increase specified as well? That MIGHT explain a richening of mixture.

SteveB
MSD coil, coil relay mod, new wires and caps. Factory jetting.
Current:82 GL1100 Interstate, 60 Amp Poorboy, MSD coil
Previous: 93 GSX1100F Katana
82 GL500 Silverwing

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macd
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Re: Which carb jet to change after Accel coil install?

Postby macd » Sat Nov 02, 2013 10:58 pm

for some reason I can't get the picture of the directions to upload. the directions say as excels motorcycle coils are quite powerful and delivery much stronger spark in the original equipment coils, considerable care should be taken after the installation to be sure the carburetor jets on your model are adequate. it also says a hotter spark normally requires larger jet sizes in order to maximize power output and prevent a possible lean fuel condition that could result in an overheated or possibly damaged engine.
Dave
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macd
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Re: Which carb jet to change after Accel coil install?

Postby macd » Sat Nov 02, 2013 10:59 pm

the instructions also say for optimum performance be sure to open spark plug gap to a minimum of .0 35
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eklimek
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Re: Which carb jet to change after Accel coil install?

Postby eklimek » Sun Nov 03, 2013 8:04 am

If the coil can carry the burden they all call for increased plug gap because the consumer will note the improved idle and low speed performance where plug fouling is common.

The width of the gap depends on coil saturation time, engine speed and compression pressure of the air/fuel mixture. As the two latter increase a smaller gap ensures ignition.

The coil which saturates faster at higher rpm allows for a wider gap.

But, going back to the original post, adjustment of the air-fuel mixture is not warranted unless it was initially suboptimal to accomodate inadquate ignition.

Not sure if you are interested but some of this is discussed in
Chapter 7
A Graham Bell
Performance Tuning in theory and practice Four strokes

It can be found on the web if you are motivated to find it.

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macd
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Re: Which carb jet to change after Accel coil install?

Postby macd » Tue Nov 05, 2013 10:34 pm

Thanks for the reply Eklimek. Doesn't sound like i need to do much other than sync the carbs.

I think the literature you quoted is a bit over my head, but I'll look for it. Maybe I'll learn a thing or two.


Dave
Middleburg, Fl


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