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Discussion Starter #1
So I opened up the airbox on my '00 Thunderbird. Dismantled and rejetted my carbs. Put in 42 pilots and 140 main jets, set my slow screws to 2-1/2 turns out, put in new float needles and left the height at about 19mm. Now the bike won't start. Turns over but sounds like no gas. FRACK!
 

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s km

Time to backtrack. "Where did I go wrong?" First time I did one of these [16-17 yrs. back], I got it a block down the street [downhill of course] and it quit. Had a neighbor help me get it back in my shop and found I kinked the fuel line putting the tank back on. Just have to go back over it carefully. ...J.D.
 

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Discussion Starter #4
Yeah, pretty bummed to not have it run after all that work. (For me it was all a new experience) There is fuel in bowls. It sounds as though it's sparking. I'd be surprised if it isn't.
I did change the plugs but the rest of the ignition ran before I did the carbs and air filter mod. I will pull one plug to make sure it's sparking. I guess Backtracking is my plan. Take the cabs off again and make sure everything is clear. Thanks.
 

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Do you smell gas as you're cranking with no sputtering/sparking?
42 mains may be a little rich for startup at 2.5 turns, even with air intake mods. You may want to back down to 2 turns.
Mine are happy at 1 7/8 turns.
Also, since the carbs were off, hopefully you didn't disturb the balance screws...that will also add problems at cold starts.

One problem with these motors is that they can be very picky at startup.
Make sure your battery is nicely juiced up, and then go after confirming your spark if nothing fires.

Good Luck!

Dan
 

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Discussion Starter #6
Do you smell gas as you're cranking with no sputtering/sparking?
42 mains may be a little rich for startup at 2.5 turns, even with air intake mods. You may want to back down to 2 turns.
Mine are happy at 1 7/8 turns.
Also, since the carbs were off, hopefully you didn't disturb the balance screws...that will also add problems at cold starts.

One problem with these motors is that they can be very picky at startup.
Make sure your battery is nicely juiced up, and then go after confirming your spark if nothing fires.

Good Luck!

Dan
I did try charging the battery with my car. Didn't think it would help but figured it was worth a try.
The bike definitely cranked better but still no start. There is gas in the float bowls but I do not smell any near the engine or exhaust. Ballance Screws? Not sure. I looked at bench syncing the carbs but the the butterfly valves all seemed pretty tight in line with each other. I'll go over it all again this weekend.
 

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Don't really think your pilot jet or mixture adjustment would be the problem. If it is a little rich it would probably start easier. I am wondering what your bench settings are on your throttle butterflys. Should be a spec. for that somewhere [I don't have it at hand]. You would measure the distance between the butterfly and the throttle bore and set all three the same. Then after you get it running you can balance the carbs. ...J.D.
 

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Maybe be sure the float needles are correct. If there is fuel in the bowls , not sure why it wouldn't run, even if it ran poorly still should start .
 

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Real dumb thought but I did it when I rebuild something on my bike. Did you hook the spark plug wires up to the right cylinder? I spent 4 days fighting my own stupidity.
 

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Discussion Starter #11
Do you smell gas as you're cranking with no sputtering/sparking?
42 mains may be a little rich for startup at 2.5 turns, even with air intake mods. You may want to back down to 2 turns.
Mine are happy at 1 7/8 turns.
Also, since the carbs were off, hopefully you didn't disturb the balance screws...that will also add problems at cold starts.

One problem with these motors is that they can be very picky at startup.
Make sure your battery is nicely juiced up, and then go after confirming your spark if nothing fires.

Good Luck!

Dan
Upon further examination it might not be the carbs. Apparently I'm not getting a spark anymore. I pulled the plug wires off #1 and #3 cylinders, one at a time, put a plug in the wire, and cranked the engine while holding the plug to the frame. There was no spark. That was a good call to check that. And yes, I did smell a bit of gas at the exhaust.
 

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Discussion Starter #12
Maybe be sure the float needles are correct. If there is fuel in the bowls , not sure why it wouldn't run, even if it ran poorly still should start .
Hard to know where to set my float needles with the air intake and needle changes I made. I thought I would have to run it first to know if they were too high or low. They are set about 19mm now.
 

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I was just saying to be sure they were the correct type but it seem as though you've identified a different issue. Good luck with that
 

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You may want to back-track and check everything you touched as you removed/reworked your carbs.

Also, all of the wires that attach to your coils, are the connections clean & tight? I like to use a nice light smear of di-electric grease on freshly cleaned connections....just good insurance!
Don't forget the coil mount bolts, they are a frame ground connection.
If you still get no spark, you should check for ground at your igniter plug (black wire to igniter -> frame (or negative battery terminal)
I've found problems in the past with a missing ground signal at the igniter.

Finally, your clutch switch, neutral switch (shifter) and kickstand switch also provide a ground signal to the igniter, and the signal is necessary for the igniter to fire. You can check each switch, or "feather" all of them while trying to crank - maybe one of them is intermittent.

Good Luck

Dan

P.S Did check your magnetic pickup for the correct resistance at the plug?
 

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Discussion Starter #15
You may want to back-track and check everything you touched as you removed/reworked your carbs.

Also, all of the wires that attach to your coils, are the connections clean & tight? I like to use a nice light smear of di-electric grease on freshly cleaned connections....just good insurance!
Don't forget the coil mount bolts, they are a frame ground connection.
If you still get no spark, you should check for ground at your igniter plug (black wire to igniter -> frame (or negative battery terminal)
I've found problems in the past with a missing ground signal at the igniter.

Finally, your clutch switch, neutral switch (shifter) and kickstand switch also provide a ground signal to the igniter, and the signal is necessary for the igniter to fire. You can check each switch, or "feather" all of them while trying to crank - maybe one of them is intermittent.

Good Luck

Dan

P.S Did check your magnetic pickup for the correct resistance at the plug?
Brother, I really appreciate the advice but after checking to be sure the plug wires are tight that is all way above my pay grade. I don't have a clue as to how to check for a ground signal on any of that. I'm going to have to dig into my Haynes book to figure all that out.
 

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Avid,
Sorry if it was info overload.
So you have a Haynes, that is good!
Just start by checking out your magnetic pickup resistance ... the two wire plug coming out of the right side cover if you have an ohm meter. If you don’t have an ohm meter, just locate the clutch switch on the left handgrip, the neutral switch below the shifter lever, and kickstand switch....just check the connectors. Then next time you try to crank it, shift in, and out of gear, put the stand up and down, then while cranking, pull the clutch in and out.
See if she at least coughs for you.
 

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Discussion Starter #17
Avid,
Sorry if it was info overload.
So you have a Haynes, that is good!
Just start by checking out your magnetic pickup resistance ... the two wire plug coming out of the right side cover if you have an ohm meter. If you don’t have an ohm meter, just locate the clutch switch on the left handgrip, the neutral switch below the shifter lever, and kickstand switch....just check the connectors. Then next time you try to crank it, shift in, and out of gear, put the stand up and down, then while cranking, pull the clutch in and out.
See if she at least coughs for you.
Will do! Thank you much!
 

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All good advice so far. If there's fuel in the bowls and you are sure you have a spark then your close. Wind in the idle hand screw a couple of turns. You will have Keihins on a 2000 so 2 1/2 turns on ilde air screw is a good starting position as long as the butterlys are just open. Be sure you have spark though, check the kill switch circuit - taking the tank on and off it's easy to disturb a cable.
My jets are 38/140 and float height at 19mm is OK with airbox mod btw
Good luck
 

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Upon further examination it might not be the carbs. Apparently I'm not getting a spark anymore. I pulled the plug wires off #1 and #3 cylinders, one at a time, put a plug in the wire, and cranked the engine while holding the plug to the frame. There was no spark. That was a good call to check that. And yes, I did smell a bit of gas at the exhaust.
It takes four things to make an engine run. (1) Spark, (2) Fuel, (3) Air, (4) Proper timing. What is missing ? In my too many years of working on engines, this lesson was taught me back in Vocational Training in the early 1960's. It never fails. Supply these four things and it will run. This, of course is assuming the engine is in otherwise good condition. It may not run well until you dial those things in a bit, but it will run. ...J.D.
 
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