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Discussion Starter #1
My 99 ST4 has left me sitting. :(

Seems like rear cylinder may not be firing. Bike starts and idles fine, but does not accelerate well. Tested spark in hotel parking lot. Rear seemed a bit week, and rear header not quite as warm to touch as front.swapped plugs. No help. Checked grounds and/or negative terminal. Any other ideas? About to rent truck, trailer, etc., to get this thing back home from Cape Breton, Nova Scotia to Pennsylvania
 

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Is it worth a call to these guys?

Atlantic Motoplex
950 Champlain St.
Dieppe, New Brunswick, Canada, E1A1P8
Tel.: +1 506 383-1022
Fax: +1 506 383-8540
[email protected]

They appear to be the closest Ducati dealer even if they are 4 hours away.
 

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Any chance this is fuel delivery related? Sounds like what mine was doing when the in tank hoses finally crumbled and split.
 

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Good guess on the fuel lines. My ST2 would idle, but bog when you twisted the grip.
Best way to check is in a quiet area--LISTEN to the tank when you first turn the key to the RUN position (see WHOOSH). Then, if you're brave, open the fuel cap, remove key, place it in the ignition. With cap open, watch the activity in the tank as you turn the key on. Small amount of bubbling is OK. A loud WHOOSH and fuel shooting around in there is a popped line.

Double- check the plug wire routing--look for chaffing.

There's a few bike shops in the Halifax/Dartmouth area. I "got real lucky" and found a no-name shop that had a Dyna III ignition unit from a 4 cyl. Jap bike that restored the spark on my old R100S (that was altered with dual plugs...). I think this was in 1981 !
 

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Discussion Starter #6
The comments re: fuel lines do remind me that the bike has always "leaked" fuel from the gas cap - that is, whenever I lift my tank bag, its bottom pad is soaked with gas, and I have many times heard the cap "singing" at the conclusion of a ride. It has been this way, though, for the 2+ years that I have owned the bike.

I rode the bike, in its current condition, from the U-Haul drop-off in Yarmouth, NS, to the Ferry (about 3 miles). Bike seemed to struggle most when pulling out from stopped. Had to rev to maybe 7K RPM or so to get it to take off at all. At times, when moving at > 15-20 MPH, it ran perfectly fine...

Wayne Beaver
99 ST4
 

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Discussion Starter #7
Posting an update because I often see that people don't post the solutions to their problems. I replaced fuel lines and fuel filter. The lines showed some external surface crumbling - no blatant breaks/splits/holes, but they had seen better days. I also reconnected the hose between the fuel pressure regulator and the air separator, which I found disconnected when I removed the fuel-delivery bits from the inside of the tank (http://www.flickr.com/photos/[email protected]/3697554981/in/set-72157621009832299/).

A 10-15 mile test ride has given me reason to believe the problem may be fixed. Plan to go for an extended test ride later today...
 
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