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ViragoTechForum.com Tech Help Runs great - then dies. (SOLVED)

#1:  Runs great - then dies. (SOLVED) Author: webales Post Posted: Fri Aug 20, 2010 11:01 pm

After reading most of the "one cylinder dropping out" posts, I'm thoroughly intimidated by the troubleshooting challenge I'm facing. My 1990 XV1100 idles great and runs like a scalded dog up to 75. Cruising at 75 I can snap the throttle open and climb to 100 smooth and quick with no stumble or hesitation. After about 10 minutes of running, one cylinder drops out and after a bit more the other one goes and it won't start. I've sprayed starting fluid around the hot carb boots after one cylinder dies with no effect. After the bike cools, the cycle repeats - it is very consistent. My question is: with the way this bike runs, do you think I can focus on the ignition to find the source of the problem? If so, I'd rather just replace the whole ignition than try to fix it piece by piece. I've read threads where all sorts of ignitions are discussed, but I'd like to know if there is a reasonably priced and easy to install replacement aftermarket ignition for the virago. Thanks for any input on this.

#2:   Author: grazingazer Post Posted: Sat Aug 21, 2010 8:32 am

does your problem occur at all rpms after ten minutes riding or just at high speed...will it restart immediately if you use starter fluid...are you getting spark when you try and restart?

#3:   Author: 48vintage Post Posted: Sat Aug 21, 2010 10:40 am

The carb or tank vent could be faulty also?

Gary

#4:   Author: pofarm Post Posted: Sat Aug 21, 2010 2:37 pm

On your next ride take a spare known good spark plug with you. When it dies pull a plug wire and insert the spare plug in the boot and ground the threads against the motor. Turn the motor over and see if you have spark. If not, I would suspect the coils, pick ups or TCI. Most likely the TCI is breaking down with heat. There are many threads on here about test procedures for these components. If you don't have a manual, you can download one HERE.
If you have fire, check to make sure the tank is venting properly. Open the tank cap and try to start it. If it starts the cap is probably not venting. You will need to disassemble the cap and clean it.
Not much available for the ignition aftermarket. The coils can be replaced with a harley single fire coil with 3 ohm primary windings. There are several brands available, including Crane, Accel, Daytona.
The TCI can be rebuilt. http://xvfinishes.com/tci.html You could also replace it with an Ignitech module.

#5:   Author: grazingazer Post Posted: Sat Aug 21, 2010 3:48 pm

3.0 ohm coils will not work...the 90s viragos require 4.2 ohms

#6:  Re: Runs great - then dies. Author: webales Post Posted: Sat Aug 21, 2010 6:03 pm

Yes, I am getting spark - should have checked that first thing doh . Also, it doesn't seem to matter how I ride, as soon as it heats up, one cyl. goes, then the other. So it has to be a vacuum leak that is openning up with heat? I guess it has to be two vacuum leaks! I cleaned the carbs, then cleaned them again, drilling out the idle screw caps and cleaning the screws and passages the second time - they were grungy. So the carbs were in and out twice. I noticed that the holders had cracks that would appear when I stretched them, but I figured that once the clamps were on tight the rubber would compress and seal. I replaced the o-rings under the holders and replaced the hex head bolts with socket heads that I can torque down with a long ball driver socket. That made getting the carbs in and out a LOT easier. I looked up new carb holders and it looks like they're going to set me back about $80 just for the rubber part. Is that the next thing to try? Thanks for the assistance.

#7:   Author: grazingazer Post Posted: Sat Aug 21, 2010 6:09 pm

what about the electric fuel pump sometimes when they go bad they'll quit when they get hot but start working again when they cool off...are you getting fuel pressure...vacuum leaks will usually speed up the idle

#8:   Author: webales Post Posted: Sat Aug 21, 2010 6:55 pm

I forgot to mention that the tank cap is venting properly. I'll check the fuel pump when it is hot - sounds like fun! I tested it again, and now I'm getting backfiring while I'm riding and the heat-up period is shorter, so it's getting worse. I have good spark when I try to restart.

#9:   Author: bstig60 Post Posted: Sat Aug 21, 2010 7:07 pm

Backfiring could be an indication of a lean condition. Have you checked your fuel filter? Check your fuel/float levels.

#10:   Author: webales Post Posted: Sat Aug 21, 2010 9:21 pm

I had just filled up before the problem started - pulled the fuel line and only getting a trickle.

#11:   Author: grazingazer Post Posted: Sat Aug 21, 2010 10:22 pm

check the fuel filter...does the pump click when you try to restart

#12:   Author: webales Post Posted: Sat Aug 21, 2010 11:37 pm

I put a new fuel filter in when I cleaned the carbs the first time - a couple of weeks ago - so I didn't suspect it at all, but it was clogged! New filter fixed the problem. I guess it was letting enough fuel through to keep it running but the fuel level in the bowl was slowly dropping until it leaned out so much it wouldn't run. Now I wonder if running lean like that burned the valves. The other question is how can a fuel filter clog in 2 weeks? My tank is clean inside, no rust or anything. One thing is for sure though, you guys are a great help. Thanks a million!

#13:   Author: bstig60 Post Posted: Sun Aug 22, 2010 11:52 am

It is possible it was just a bad filter from the factory. Glad you got it running. Your valves will probably be OK although it wouldn't hurt to check the clearance.

#14:   Author: webales Post Posted: Tue Aug 24, 2010 5:59 pm

Yeah

#15:   Author: webales Post Posted: Tue Aug 24, 2010 6:03 pm

The "Yeah" actually sort of self-posted - maybe there is something wrong with my computer. Sorry about that. I was just going to say, "Yeah, I considered cutting the filter open but it had been thrown away."
ViragoTechForum.com Tech Help Runs great - then dies. (SOLVED)


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