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My Firebird always started and ran well but it has been off the road since 2019.

I am going to sell it this year so I wanted to make sure it would start well before i sold it.

I started it once after blowing out the pilot jet through the screw with carb cleaner and flushing the float bowls. It had wet-sumped so I waited until all the oil was returned to the tank then I took it around the block.

I decided to do a video to show how well it started but of course now it won't!

Today I drained and replaced the fuel, blew out the pilot circuit again, tickled both carbs and it still would not start.

I borrowed an inline spark tester which shows a good spark.

Compression seems good and the only obvious problem is the plugs which seem very oily - presumably from the wet sumping.

I'll sell it as a non-runner if i have to but i feel like i caused this problem so i should fix it.

Any suggestions gratefully accepted.

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You have to clean your carbs, not only fuel pilot jet, but small orifices under the slide, they could give you exactly the problem you are describing. After cleaning and starting its worth to take it 10 times around the block, not once, to make sure everything is in order on a hot engine and you won't have any more surprises later.

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Spark plugs are funny things. They look to be solid steel and ceramic, and if you try to take one apart with a hammer you'll find out just how tough they are.

But if you gas-foul or (sometimes) oil-foul one, it may never work properly again. The in-line spark checker will confirm there's high-voltage on the line, but it doesn't guarantee that there's a spark jumping the gap in the fuel mixture.

In addition, my Firebird HATES NGK spark plugs. It'll run about 500 miles on a set, then start popping and barfing and getting hard to start until I replaced them with Champion N3 plugs, and never any more problem.

I'd try new plugs on the Check Compression Then Ignition Then Fuel in that order principle. Compression first - you may have a little chip of carbon that got knocked loose holding a valve open - it's happened to me.

Lannis


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I would put a $ on battery condition...

. try running a "hot wire" from your car battery (disconnect the bike one) and see if that works ... ease diagnostic that doesnt cost anything to do


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Originally Posted by Lannis
Spark plugs are funny things. They look to be solid steel and ceramic, and if you try to take one apart with a hammer you'll find out just how tough they are.

Never thought of you as being the barbaric type Lannis 😅 lol!


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68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (now rebuilt)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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Quote
Today I drained and replaced the fuel, blew out the pilot circuit again, tickled both carbs and it still would not start

Cleaning the carburetor idle circuit can take a number of tries .
With carburetor cleaner and compressed air often being among the less effective methods .
buy or make an " AMAL pilot cleaning tool "
with a #78 drill bit .
Most retailers have a version of this
[Linked Image from cdn.shopify.com]
Or you can make your own with the drill bit glued into a piece of WD-40 straw .
( the plastic straw add a bit of flexibility , which is a useful touch )
the drill bit on a stick is Twisted , as it is allowed to push Inward and find its way .
the drill flutes pick up gummy swarf that otherwise might just gets pushed back further inside the idle circuit , with other methods
Make sure the bit is well crimped/glued
Because if you pull the straw out
without the drill-bit it's a guarantee that the pilot jet is clogged
.

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Thanks for the help so far.

I did not take the carb bodies off the bike but i pulled off the float bowls and took out the jets cleaning everything with carb cleaner. There was no sign of debris or gunk anywhere. these carbs were new a few years ago and i guess i must have drained the float bowls when i put it away - everything looked pristine.

After reassembly (no leaks so yay) it showed no sign of starting. The air cleaners were off so i put the tiniest spritz of ether in the right hand side and it started but only on that cylinder. I cleaned the other spark plug and it started on both cylinders. After a while it settled to a normal idle.

Tomorrow i'll try to source new spark plugs and borrow a compression tester but i think starting with ether maybe says it's still a carb issue.

A question: Before i started cleaning the carbs I closed up the idle air screw and it only took 3/4 of a turn to close it vs the 1.5 turns i've seend described elsewhere. I've left them at 3/4 turns but it seems odd.

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Originally Posted by Allan G
Originally Posted by Lannis
Spark plugs are funny things. They look to be solid steel and ceramic, and if you try to take one apart with a hammer you'll find out just how tough they are.

Never thought of you as being the barbaric type Lannis 😅 lol!

Well, I wasn't doing it just for a sadistic high, torturing a spark plug.

I was making a home-made compression test fitting from a plan in a cycle magazine 50 years ago when I couldn't buy a factory made compression tester. You had to beat the center out of the plug, and just leave the part that screwed into the cylinder. You had to use a way bigger hammer than you thought you would.

I'm still betting on Bill's issue being spark plugs .... !!

Lannis


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cleaning everything with carb cleaner

Pilot jets cannot be cleaned properly by either compressed air or carb cleaner, the 25 jet is a 17 thou hole which gets encrusted with deposits that will only be cleaned by a 16 thou drill. Only this will correctly clean the jet back to 17 thou without resizing it.

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I mention the drill bit method to a lot of people, the amount of people that say “I’m not putting a drill bit in there, it will resize it” yet they would be happy to use a .016” guitar string which might scratch/resize the jet.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (now rebuilt)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)


Moderated by  Allan G, Jon W. Whitley 

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