1997 Virago xv1100 - Runs poorly

Hello All,

I recently purchased a 1997 Virago xv1100 that needs some TLC. My xj700n is very fun and fast but it does not lend itself to saddle bags or 2 up riding so I though the Virago would be a good addition to my stable.

I took it for a brief test drive before I bought it and rode 35 km to get it home. These are some of the features of the bike when I bought it:

• 22000 km on the odometer
• engine serial does not match the frame
• starts up easily
• pulls really strongly
• suffers from excessive vibration
• won't idle without the choke
• idle jumps between 1000 to 3000 rpm

I have a Clymer manual for the bike so I started working my way through the maintenance\troubleshooting.

First I replaced the air filter with a OEM Yamaha filter which appears to have resolved the idling problem. The bike will now idle without the choke and sits at around 1050 rpms.

Second I adjusted the value clearances to spec. (This was much easier than adjusting the valves on the XJ. No shims!) The valves were very tight with no clearance at all. Adjusting the valve clearances made no noticeable difference to the running of the engine except that now I can hear the valves tapping as they should.

Third I tested the compression and both cylinders tested at 130 psi which I think is good.

Fourth I attempted to sync the two carbs by connecting the vacuum gauge set that I purchased off Amazon. The valve needles bounced around erratically and I was unable to accurately measure the vacuum. The adjustment on each of the gauges effectively allowed me to set the reading of the gauge so there is not way I could be sure if the carbs were balanced or if I had just adjusted them to look that way. I will try again with a homemade manometer.

In the meantime I "tested" the engine by removing the front spark plug lead from the plug while the engine was running. This made no appreciable difference to the running of the engine. I reconnected the front lead and then tried removing the rear and the engine died right away. It appears that the engine is only running on the rear cylinder, at least while it is idling.

I have ordered a couple K&L carb kits so I can rebuild the cards and get them in working order.

Next I tested the primary and secondary resistance of the coils. My Clymer manual indicates:

"
Ignition coil resistance
1984-on
Primary windings 4.2 ohms
Secondary windings 13,200 ohms
Spark plug cap resistance 5,000 ohms
All resistance specifications are ±15% at 68° F (20° C).
"

Both plug caps tested at 5,000 ohms.
Both my front and rear coils tested 4.3 ohms for the primary and 17,000 ohms for the secondary with the plug caps on.

If my reading are correct then both the coils are out of spec on the secondary winding by almost the exact amount. I suppose this is possible but it seems unlikely to me. Another possibility is that I should be taking into account the 5k added by the plug caps which would bring the reading to 12k which is within 15% of the 13,200. The manual seems to indicate that the 13,200 includes the plug caps though. This is exactly what the manual says:

"
If checking secondary winding resistance
with the sparkplug lead removed,
be sure to factor in the sparkplug cap
resistance Sparkplug cap resistance is
5000 ohms on all models and is added
into coil secondary resistance specifications
"
Maybe I am reading this wrong, or maybe the manual is wrong. Wouldn't be the first time.

Has anybody had any experience with the Virago coils and can help give me some clarity on how I should be factoring in the plug caps? Maybe somebody has the Haynes or Yamaha manual.

Thanks
Paul

 

Virago Tech Forum

 

Doesn't the virago have independent idle screws ? And most vacuum gauges have a small plastic plug with a very small hole in the lines to dampen the air flow?

 

There one "throttle screw" which is used to adjust the minimum throttle which is used to set the idle. Each carb also has its own pilot screw but I have not adjusted those.

My vacuum gauges do have a knob on each gauge to dampen the airflow but there is nothing on the lines themselves. Part of my problem might have been that I did not plug the vacuum hose I took off of the front cylinder to attach the vacuum gauge. I will try again after I have rebuilt the carbs and replace the vacuum hoses.

 

There is an idle speed screw-and-locknut on the other carb, but it's not normally used to adjust the idle speed (though it is a good idea to replace the screw on that carb with an idle adjustment knob).
One open vacuum port will really cause trouble on a twin. I'd bet that's the whole issue.

The coil resistances given in the manual are just for the coil, and the cap ressitances are measured seperately. Given what you're seeing, I'd be more inclined to think that the meter is off by a tad than that both coils are out of spec.

 

I'm getting mixed info on the viragotechforum. I have a Virago moderator with one million posts telling me that the coils should be tested with the plug caps and mine are out of spec. Others are saying they are fine as they are.

I ordered an aftermarket set of coils off eBay so I will test those when they come and presumably they will be in spec.

I am in the middle of taking the carbs off. One of those impossible Chinese puzzles you get in Christmas crackers. The forums say it is possible to remove them without dropping the engine so I will figure it out eventually.

 

That poses a question... why the hell did you buy a Virago?
Worse carbs than a maxim and terrible starters to boot.
82,83 xj750k would have been a great choice.

 

I got a good price on the Virago and I haven't seen any XJs within reach. I do live on an island which limits my selection. I made a couple trips to the mainland only to have the bike be a piece of crap or sold before I arrived.

The Virago is a 97 so it doesn't have the starter problem that the pre 85 years did. This is the first time I am attempting to rebuild a carb so I figured these two would be simpler than the XJs four.

Also the XJs are happy when you have the rpms up so there is always a feeling of urgency. I have that little 250 Virago and I though it would scale well into a nice chill ride at 1100 for a longer ride with a passanger.

My XJ is still my daily though. I actually got a 'Hey, nice bike man!' from a hipster on the street yesterday. That was my first and I liked it. Maybe I'll give it a bath and polish the rust off of the headers.