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Discussion Starter #1
Howdy. I bought a long term storage Bonneville. It was stumbling when I bought it, but no major wierd engine noises, so I thought I'd give it a go. I cleaned the carbs and fuel system, and replaced the jets with what it came with, 42 pilots and 118 mains. The mufflers are aftermarket and louder than I like, but they have no markings and look old style. The bike still was hard to start, and would run well after warming up, then start missing upon taking off. The miss was eratic, like it was a coil problem. I took the coil and wires and fuel tank off my good running 2005 and put it on the '01. It idles well, but still has the erratic miss on open throttle. Pulls hard when it is not stumbling. My next trick is swapping the ignition control unit from the 05. I am wondering how to get it off without breaking the black plug opposite the end with the bushing and nut.

Any more clues about this? Thank you, gentlemen.
 

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My next trick is swapping the ignition control unit from the 05. I am wondering how to get it off without breaking the black plug opposite the end with the bushing and nut. Any more clues about this? Thank you, gentlemen.
Mr. guzzi,

Just cut off the plastic "plug" with a knife or sharp chisel. Then upon reassembly use a self locking nut and a bolt to replace it.

Don't forget to service the entire petcock system and check the filter that lives in the fuel Tee at the carburetors.

Namaste,
Charles
 

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Discussion Starter #3
Mr. guzzi,

Just cut off the plastic "plug" with a knife or sharp chisel. Then upon reassembly use a self locking nut and a bolt to replace it.

Don't forget to service the entire petcock system and check the filter that lives in the fuel Tee at the carburetors.

Namaste,
Charles
Thank you! The ignition control unit swap did nothing . Bike has new (stock) spark plugs BTW. It did the same with the old plugs. (iridium). Can I get to that "T" filter without carb removal? I guess the next thing is look in the alternator cavity and pickup coil gap? I tried seperating the nuetral light connection;bike will not run without that being plugged in.
 

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One thing at a time.

Can I get to that "T" filter without carb removal? I guess the next thing is look in the alternator cavity and pickup coil gap?
Hold on now. The thing is, when several attempts to remedy an issue are made at the same time, you might end up not knowing what the issue was.

Yes, the filter can be accessed without carb removal. With the tank off it's not to bad to access the clamp and line.
If you have serviced the petcock and it's filters and feel good about that, the fuel line filter can be left out, at least until your issue is sorted. Since I put a Pingel on my bike I have been without mine, without fault.

Make sure the fuel delivery is adequate at speed and that the carburation is doing as it should. Then go to the next thing, which may be electrical.
Yes the pick up gap should be checked at some point. As well as other ignition values.
Don't forget to make sure your battery is up to snuff and the connections are clean and tight.

Charles
 

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Discussion Starter #5
So far, I have swapped for a known working coil and wires. No difference. Then I swapped for a known working ignition control unit. Niope. Then I put the fuel tank on from my running Bonneville, with fresh gas. No difference. Then looked at the fuse block and checked the 30 amp fuses.They are not blown. Battery is fully charged; terminals are tight.
1) Could not find the main ground connection to check it.
2) Did not yet look inside headlamp shell or at the main key switch.
3) Bike will start up and idle with choke, and it seems to warm up normally.
4) When I pull it out on the road, it will studder and run intermittently when given the gas.
 

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Also check to make sure that tip over valve is in the correct position and not stuck closed or remove it altogether. Also check and or replace all of the vacuum caps on the carb and intake manifolds.
 

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Discussion Starter #9
Today I checked the hidden "T" filter. It has a tiny piece of crud in it. I removed it entirely. I then checked the tip over valve. it will suck but not blow so the check valve is working. The bike will start and idle ok. It will even rev up some until it gets good and warm. Then it starts cutting out and seems to be missing on one side. I still have not found the main ground wire where the negative cable goes to. It made no difference when I removed the gas cap. The rubber boots/plugs on the carbs are not leaking; spraying with starter fluid causes no difference in RPM. I jiggled the kickstand, it made no difference. Looked inside headlight shell, all wired connected and no obvious burnt components. Still stumped.
 

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Remove the stupid side stand sensor. Its an intermittent fault so jiggling it might not make it fail. Other thing to check is the crank sensor clearance, this was changed on the earlier models from 1mm to 0.8 or something for this same issue. Might be worth replacing it but its costly, I have a spare but I'm in the UK? Another issue that I have myself was the fuse wires had come loose in the fuse box. Try pushing them back up into the housing and make sure they both pinch the fuse.

Chris.
 

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Below the airbox I think.
 

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Discussion Starter #15
Today I ran the ohm meter on the ignition pickup coil. Got about 550 ohm, within range. Took the alternator cover off, found the air gap to be set at about 6mm, a little tight but some guys are running at 6mm with good results. I ordered a new pickup coil and alt cover gaskets. Will change out the pick up just to be safe. If the new one acts like the old one, I have a spare...
 

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Let us know if that fixes it. Also did you replace the vacuum caps on the carb and intake manifold. They are cheap. They dry out and crack over time and you may sucking air in through a leak in one or more of them.
 

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I'm curious about this too guzzi, as I get the same thing on my 08 Bonnie. At first it always happened on wet or even damp roads. And that is after it had stopped raining.
It would start to splutter under load, then cut in and out on one side and eventually cut out altogether.
After it cuts out it will still start and idle, but do the same thing again when I give it some revs.
I assumed it was water mist getting in somewhere until it happened on a dry sunny day.
Every time it has eventually come good again while limping home on the side of the road.
I've checked everything you have apart from the sidestand switch, and I'm still baffled. Although the switch is worth a look due to it being close to the road.
 

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Discussion Starter #18
Today I installed a new ignition pick up coil and gasket. Gapped it @ .031. Put back together. It does the same thing. I tried the kickstand bypass trick, same results. Still cannot find the main ground. They hid it real good.... :( I'm slap outta ideas.
 

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Well this does seem to be an electrical issue... but just in case...
When you had the carbs apart, did you do a manual check on the float heights? There is also a check you can do on the bike using clear silicone tubing to see if the fuel level is correct - it's in the manual can't remember what page at the moment. Could also be a torn or leaky diaphragm in the top of the carbs

As you have a good running spare pair of carbs, how about swapping those in to see if it makes any difference???
 
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