Stutter on acceleration

[EZdriver]

When I accelerate slowly, the engine runs fine. If I swiftly accelerate, the engine stutters between 2000-2500 then smooths out. I removed all the California emissions crap, capped the vacuum ports on the center two carbs. Picked off of #4 carb for the vacuum advance line with the backfire filter. There is a tiny metal line off of #1 carb coming from the throat. I don't know what this is. Can't find it anywhere. I just capped it.
Any help?

[debron]

I had a problem last summer exactly as you describe. Started in Logan, Ohio at the Rally. I could only accelerate very slowly and carefully and had to keep the rpm's up. I rode all the way home to Oregon by way of the Dragon (not fun with an engine running rough that you can't accelerate quickly) with the engine running like that. Turned out to be a broken spark plug cap. New plugs and new caps and it runs better than ever!

[EZdriver]

I posted before that I pulled the ends of the wires out of #2 and #3 caps trying to revive a 20 year old bike that sat in a barn for at least 12 years. My solution was to buy two of the NGK wire splices and add a 8 inch pigtail on those two. I may have not gotten good contact on a plug wire. It was hard to get to the short wire (why they didn't give you more wire to service the plugs I'll never know). So I may have not gotten good contact. I'm dreading having to pull the whole front cowl off to get to the coils and install new wires. Anyone done that?

[JHD]

I posted before that I pulled the ends of the wires out of #2 and #3 caps trying to revive a 20 year old bike that sat in a barn for at least 12 years. My solution was to buy two of the NGK wire splices and add a 8 inch pigtail on those two. I may have not gotten good contact on a plug wire. It was hard to get to the short wire (why they didn't give you more wire to service the plugs I'll never know). So I may have not gotten good contact. I'm dreading having to pull the whole front cowl off to get to the coils and install new wires. Anyone done that?

EZdriver, I have and most other owners have taken there fairings apart to service something. It is a very easy process. The best way to go about it is each piece that is removed screw the fasteners for that section back into the frame or fairing section so you don't lose them or forget which fastener goes where. Since my XII was used I had found that the POV had a few of the screws in the wrong place but have it all sorted out now.

The coils aren't the easiest to get at. I have new wires that I have installed on my coils but have the motor out of the bike for servicing and everything out of the way. I used 7mm copper core wire that sold at O'reilly Auto Parts (less than $4 for a 5' piece). It is a Borg Warner brand and is really nice. I would say it is comparable to Packard 440 wire which is a top tier wire. Now the stock wires have protective jackets on them that are most likely to protect the wires from heat and abrasion. I was able to remove mine and install them on the new wire set. I wouldn't do it again, you can purchase spark plug wire sleeving material online or at some auto parts stores. I also bought a set of Taylor heat shrink number labels that you put on the cap ends of your wires to identify the order. There are two sets of numbers in the kit so you can put them at both ends of the wire or save the extra set for a another project.

The NGK splicers might come in handy for you. When I took my wires out of my coils a couple of the rubber and plastic feral pieces that wedge the wire in place when you tighten the cap where complete toast thanks to either the POV or someone else working on the bike. Well you can't find replacement parts for those coils short of buying a new one so I bought two of the NGK splicers and used them to replace the feral's parts on my coil caps. Just like new again.

I would also do a continuity check on your plug caps, should read 5kohms. I had bought 4 new aftermarket NGK caps SD05F a few years back at a Kawi dealer and when testing them recently I found that 3 out of the 4 where not good. That is crazy, only a few years old and had checked out fine when new. I have purchased a new set through NGK Wholesale online (great pricing for plugs and caps). The new ones are a waterproof version SD05FP. Hopefully they last much longer. Carl Leo states that the factory caps are NGK also but are much better than the aftermarket NGK's. But at $30 something a pop it just seems like a ripoff.

To finish it off I bought a new set of Denso iridium IX24B plugs from NGK Wholesale (under $9). After reading some comparisons online between NGK and Denso iridium's I decided to try the Denso's out.

Hopefully you get everything running smooth.

Brad

[gery]

First, check the fuel filter and air filter.

gery

[EZdriver]

Replaced fuel filter, Air filter OK>

[gery]

Motorcycle does not ridden for a long time. I think, carburetors for removal, cleaning and synchronization.

I had similar symptoms, so that my bike is not ridden for 3 years. Do not clean the carburetor manually - use ultrasonic cleaners, definitely synchronize carburetors.

I have one suggestion - may be incorrectly set fuel level in the float chamber.

gery

[EZdriver]

Removed, inspected, cleaned, synchronized. Replaced one float that was bad. Re-set float levels I/A/W the maintenance manual. Engine runs great except for one RPM band and only intermittent. If a float was off or jet plugged, it would run badly 100% of the time.
Thanks for the note.
Ken

[JimK]

You mentioned a small metal pipe coming from the #1 carb. I believe that should be connected via a small hose to ignition control module on top of the air box. I think it is for vacuum advance. Good luck sorting it out.

[EZdriver]

I disconnected the vacuum hoses from all but #4, capping 1-3. I used #4 to provide vacuum for the advance. I wonder if that's too much vacuum and could cause the stumble (if the tiny pipe on #1 is supposed to provide vacuum for the advance?

[Brealytren]

Another thought....what air filter do you have installed? After cleaning my carbs I test ran it with no filter and had a significant hesitation/stumble. Put in a new filter and it runs fine. Per Carl....the carbs need just a bit of restriction to get the vacuum actuated pistons to perform correctly. Just a thought.

Chuck

[EZdriver]

I have the stock paper filter, but it's 20 years old. Clean but I'm buying a K&N replacement (on order).
I found something interesting. The small vacuum source from th #1 carb, when measured with a gauge, is metered, meaning with no restriction, it doesn't wobble the vacuum gauge like the larger vacuum ports. This could be the source of my problem, as I used the large vacuum port on the #4 cylinder for vacuum advance. Film at 11... Thanks for all your help. I'll report when I do my test ride.

[Kevin B in Illinois]

If the tiny rubber hose has come loose on the carbs it will cause a stumble upon acceleration. I have dealt with that before, also replaced a coil before on one of the Voyagers. In time you will find the culprit and be back to good times.

Kevin Braddy
in Southern Illinois

[EZdriver]

Does the hose for vacuum advance hook up to the small pipe on #1?

[triton28]

Yes, it does.
Dave

[EZdriver]

Thanks.

[Lance McCaw]

I have the stock paper filter, but it's 20 years old. Clean but I'm buying a K&N replacement (on order).
I found something interesting. The small vacuum source from th #1 carb, when measured with a gauge, is metered, meaning with no restriction, it doesn't wobble the vacuum gauge like the larger vacuum ports. This could be the source of my problem, as I used the large vacuum port on the #4 cylinder for vacuum advance. Film at 11... Thanks for all your help. I'll report when I do my test ride.

What K&N filter did you order ? Let me know how it fits please. I just put in a new napa one but I prefer a K&N.

[EZdriver]

http://www.partspros.com/3010015.html
A little trimming on the edges...

[voyager55]

I use the stock air filter, If ever needed, it's washable. Mine never gets that dirty thou.

[Mr Jensee]

Personally I would buy replacement rubber hosing for the carbs and vacuum advance because a 20 year old bike will develop cracks from the rubber drying out. Also check your carb boots for cracks. Air getting in there under acceleration will cause a stumble.