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http://www.flickr.com/photos/[email protected]/8072006227/in/photostream

Apologies for the vertical video. I've scoured this board several times while owning this bike and having some issues with it, but I've never seen this issue described. It will misfire and eventually drop a cylinder causing the motor to bog and die. That issue seems common. But this strange blowback is something that I haven't read anywhere else. The puff/mist actually knocks the carb back a bit and then comes out of that boot downstream of the carb.

So far I've torn down the carbs and made sure they were clean and jetted properly. Then I ordered a Procom CDI and a Nology coil. The coil is, of course, on backorder until December (I ordered it in June!). The Procom box hasn't improved the situation at all.

Since I've had time to think I'm wondering if this is even an ignition issue at all, though I don't know what else it could be. Maybe some stuck valves (it does this on both cylinders)? But the bike only has 5900 miles so that seems wrong. Would a bad ignition sensor cause this?

Anyone have any thoughts as to what could be causing this? I tried searching several times over and never found anything that seemed like an issue matching my video. Thanks for the help!
 

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Check all 4 (if your AI has been removed) black vacuum covers. They maybe dry rotted or cracked. If they appear dry get new covers.
 

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This sounds exactly like what mine does right now although I am not getting the blowback I see in the video. I'll give you some background which may or may not help you.

My bike starts but sounds like it is running on one cylinder, when I try to give a little gas it runs worse and then dies. Both cylinders get hot so I know they are both firing. I checked for spark on both and it is good, (I changed the plugs just in case anyway). Both spark plug wires measure fine with the multi-meter. Dumped the old fuel out and replaced with fresh fuel, no better. Changed the coil, no better. Cleaned the inline fuel filter, no better. Started the bike and sprayed starter fluid onto the carb filters (which by the way I cleaned and are as new) and no difference. Checked the carb floats, slides ect., all look in good working condition. No rodents in my exhaust. At this point I would assume it is NOT a fuel issue or the starter fluid would have made her run proper.

So, i think I have two options remaining; the pickup coil or the ignitor. I dont really want to get into the alternator to check the pickup coil so I figure plugging in a known good ignitor would quickly tell me if mine has gone bad. If the new ignitor does not fix it, I will take it to the dealer.

Don't know if this helps at all but thought I'd mention it.
 

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This is interesting as I was just about to start a very similar thread.

Here's my story:

Details: 2008 Bonneville T100, stock carbs, ARK with K&N pods (freshly oiled), AI removed, 150 mains 42 pilots

First a little background of what’s gotten me to this point. I’ve been running 150 mains with 42 pilots since I did the ARK about 3 years ago. The bike ran fine, but I thought I would play around with the jetting to see where it would take me. I’ve read where most folks don’t change out the pilots from stock, so I decided to switch from the 42s that came with my ARK back to 40s. With 40s, the bike would run like crap from idle up thru the low end of the RPM range. Similar to what it’s doing in the video, only more predominantly. So I switch back to the 42s on the pilot and started futzing with the mains, going from 150 to 145 to 140 back to 145 and back to 150 with shim and no shim on each of the different combinations. I finally decided the best set up was the one I originally started with… 150 main / 42 pilot with no shim. However, now that I’ve got the jetting set back to where I started, it’s developed the issue you can hear in the video. At 00:36 and towards the end of the video, you can hear what to me sounds like the engine missing (when RPMs drop, that’s just me releasing the throttle). It seems to clear up once the bikes really and I mean REALLY warmed up. But it still doesn’t feel like it’s running 100%. Now I’m trying to determine what’s causing it and how to remedy it.

Note: The K&N pods were freshly oiled and I’m wondering if perhaps I coated the filters with too much oil. I’ve cleaned the filters, but I haven’t recoated/installed them yet. Going to do that this evening when I get home from work. Also, I’ve cleaned the fuel filter at the “T” connect going into the carbs, but not the fuel filter in the tank.

http://s73.photobucket.com/albums/i...-85CA-E19C7FD82C87-11400-0000120BB06DCD7D.mp4
 

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Blues...Go out and run her around to get her up to operating temp, come back and remove pods and go for short trip to see if problem went away.

Over oiled K&N's will throw CV carbs to the wonky side. Don't ask how long I had chased what I thought to have been a for sure spark issue only to find out the CV's were pissed that I choked them with a over-oiled K&N. I didn't think the K&N was even close to being over oiled but apparently it was just a touch too much.
 

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Thanks for the response, Wheelie . I really welcome and appreciate any help or opinions at this point. I've already cleaned the K&Ns using K&N cleaner, rinsed them and they've been drying overnight and today. When I get home, I'll put them on before coating them and see if there's a noticable difference.

@yeha22, sorry for jacking your thread, I just didn't see a reason to start another thread on what may be the same issue. :cool:
 

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Discussion Starter #9 (Edited)
Thanks for taking the time to help, everyone. I still haven't been able to narrow this down much.

Check all 4 (if your AI has been removed) black vacuum covers. They maybe dry rotted or cracked. If they appear dry get new covers.
I've got three vacuum covers and the one that's visible in my video with some kind of lead away from it. I bought the bike as-is, so I don't know if that's the stock setup or not. Some of the rubber isn't brand new, but none are dry and can move freely. I also tried loosening the gas cap as I've seen recommended in some other AI threads, but the issue persists.

Plugged air filter?
If this were the case, it wouldn't run normally in between this misses. Right? I also don't know how a plugged filter would cause the blowback in my video. Then again, maybe the stock airbox is more convoluted than I know.

You mention that it does this on both cylinders, is it at the same time or sometimes one, sometimes the other?
As far as I can tell it's sometimes one, sometimes the other.

@yeha22, sorry for jacking your thread, I just didn't see a reason to start another thread on what may be the same issue. :cool:
No problem at all. I hope you got the answer you needed! It seems that there's no shortage of similar issues, all with different solutions.
 

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Looking carefully at your video it appears the puff of smoke is coming from the joint in the AI pipe where it fits into the rubber. Could be there's a crack in the pipe itself or the joint's loose ?
It's a while since I removed my A1 but if I remember rightly the take off wasn't on the same as yours, it was on the back one next to the carb.
 

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Nope, I still wasn't able to sort my issue. It only happens when the engines cold and up around 2500-3000 RPMs. I let off the throttle and it idles fine. I'm assuming if it were a vacuum leak, the bike would have trouble idling and want to die on me. Because this started happening when I went back to the 150 main jets, I'm going to pull the bowls off, pull the needle jets, reinstall and see if I can get some resolution.
 

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My issue appears to go away when warm as well. I've ordered new boots, clamps and vacuum caps. Once those come in, I'll give them a go.
 

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I haven't removed the manifolds on my Bonnie to date so I'm not intimately familiar with the gasket design, but I did just repair a leaking intake manifold gasket on my truck - to me 'white puff' in the video looks like it might be coming from the manifold-engine gasket.

Might also explain why it goes away when warm, as the metal expands to fill the gaps.

Just another thing you might want to check. And while you're changing the gaskets, since its all apart anyways, might as well just go ahead and upgrade the carbs ;-)

Cheers.
 

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How come no one has suggested checking the compression?
By this I mean checking to see if the valves have tightened up.
Seems like too low mileage for that but still needs to be checked.
But back firing sounds like that.
 

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I'm hoping I've found my problem. I've got parts on order from BikeBandit.com. Hopefully I'll know soon enough.



 

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just looking at your video, it could be pre-ignition. (cold motor oily/carboned plugs)
else the ignition timing is too far advanced @ idle. thus backfires through the inlet valve just as it's closing. over advanced ignition generally shows up as lack of power at low revs (coughs, splutters) wont go until you hit higher revs!
 

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Well, I replaced the carb boots, clamps and vacuum caps (haven't done the 'O' rings on the intake yet [still waiting on those from bikebandit]) and the problem is still there. The more I listen, the more I'm thinking it sounds more like a clicking noise. Like it's more electrical than a vacuum leak. Also the reason I'm thinking it's electrical due to the fact that after I got the carbs back on the bike and fired it up, not only was the issue still there, but I also noticed a small amount of smoke forming around the headlight bucket. At first, I thought it was something burning off of the engine or pipes, but then it occurred to me, I hadn't gone anywhere to cause anything to have to burn off. I think I'll have a look in the headlight bucket to make sure I didn't burn any spaghetti.

So starts the process of elimination... R/R, Coil/HT leads & Pick-Up Coil. I know it's not the ignitor as I had similar results with a spare I had on hand.

I found this here on the TRAT site. Hopefully I’ll be able to apply some of this.

"Quick charge test. set voltmeter to the 20 volt scale and connect it across battery terminals, with the engine running at around 2000 RPM measure battery voltage at the battery; battery voltage should be 14.5 volts/+ or - 0.5 volts .....above 15 volts faulty rectifier/regulator but first check the battery terminals are clean and tight, check frame and engine earth connections are clean and tight...battery fully charged, check that any fuse in the circuit is not blown or of the correct rating..(fuse#2ignition switch main feed )[30A]..(fuse#5 instruments , ignitor unit, starter relay)[15A]..(Main fuse #11)[30A].If it's below 14 volts two more series of tests will be needed then it could be the rectifier /regulator or the alternator if this is the problem. That will check those. As far as the Electronic Ignition: It's not the transistor type which uses the battery. Ours is the Digital electronic type CDI (Most of which do not require a battery. Uses a microcomputer to calculate perfect ignition timing. Most of these systems incorporate some kind of fail safe mechanism that kills the engine when timing ,engine speed, or fuel delivery goes off scale. If things are a little off the computer advances or retards the timing to suit the engine requirements.......... System Description: a)Pick-up coil...b)throttle position sensor...c)Igniter unit....d)Ignition HT coil. a) As each projection passes the coil a signal of low electricity is sent to the c)igniter unit [brain] evaluates the signals from a) pick-up coil which tells it engine speed, piston position, b)TPS sensor, which informs it of throttle valve position. From these signals the c) ignitor unit calculates the correct ignition timing ,and supplies the proper voltage to the d)HT coil . The basis for the calculations come from the pre-programmed ignition parameters within the igniter unit.[Brain] d)Ignition HT coil (Black box) is a low resistance primary winding is fitted to allow amore rapid coil action; this allows the coil to function at low and high engine speeds superbly. It functions on the 'wasted-spark' principle both plugs being fired twice for each engine cycle once on the compression stroke{ignition coil#1} and once on the exhaust stroke.{ignition coil#2}Good Luck. Fair well."
 

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Again, sorry yeha22, I feel like I've commandeered this thread.

So I went out into the garage tonight and started poking and probing around. Started with the Regulator / Rectifier, moved onto the coil and ended with testing the Pick-Up coil. Good news... I opened up the headlight bucket to test the R/R and found there was NO burned spaghetti. :D

Here are the results. Any thoughts or opinions would be appreciated.

Regulator / Rectifier:
Positive test lead on black wire with white stripe:

1) 9.19
2) 9.03
3) 9.85

Negative test lead on black with red stripe:

1) 12.20
2) 12.47
3) 14.56



Spark plug wires with probes in each end: 4.82 & 4.62 (my understanding is as long as they're both close in proximity, they should both be good)

Here are the results of testing the coil: Do the spark plug leads on the left seem low at 2.814K?



And finally I found the plug where the Pick-Up coil plugs into the wiring harness. With the positive test lead on the red wire and the negative test lead on the black wire, results were 0.613. Until I get an extra gasket, I didn't feel like pulling the cover to test the gap of the PU. But if I'm going to crack it open, I might as well replace it. ;)

 
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