XV1100 Virago

[BA80]

OK...... it's popping and farting above 4.5 - 5K under a load. Runs perfect in the garage revving.

Also, the clutch is slipping pretty bad. I think it might be an oil problem but if not, how difficult are the clutch springs to change?

[Bonz]

Running in the garage vs. under a load on the road is very different, so it's to be expected when starting from the ground up like you are. Slide lift is totally different, fuel draw is different, etc. Redline looks to be 7000 rpm, so the stuff you describe is in the heart of the power band I speculate.

Can you share a few more details?

-I assume it starts up ok

-Does the bike cruise pretty well? What does the bike do when you whack the throttle open at cruise, if it is able to "cruise"?

-When accelerating from a stop, will it pull smoothly then get the stumbles above 4.5k rpm?

-Does the bike pull through the popping and farting, or just keep doing it as you accelerate more?

-Does the bike pop on decel when you roll out of the gas?

I am fresh in the middle of adapting ZX11 carbs onto my ZRX1200, and have them running really well after CZ helped me sync them yesterday.

Let me know, we'll get them going strong!

[BA80]

I've been posting and asking questions on the Virago Tech Forums.

The thing runs great except for at WOT under load. If I don't WOT it cruises fine.

It starts fine (other than an occasional backfire through the carbs) and idles great. Synced up fine and the decal valves are working. No pop on decal.

It's gotta be something simple. If it was an XS I'd be looking at the pick up coils. Not clear on how that works on this bike though.

[3Phase]

Pressure Sensor

Greg,

Maybe the new slide springs you bought aren't the right springs?

The Virago has pick-up coils but I'm pretty sure they're on a fixed timing plate. Is the Boost Pressure Sensor hooked up and working? It's like the one on the XJs and tells the TCI what timing curve to use.

1TA-82380-20-00 -- no longer available


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[BA80]

Slide springs I got were from a 750. Same part # in the parts fiche. The slides seem to be working as they should.

Just now tested the boost sensor according to Clymer. It tests good.

Where are the pick ups on this shake pile? (when I rev it on the center stand it bounces across the garage floor)

[Bonz]

I am assuming it has stock jetting, stock needles now? You are well aware of the stuff below, but I'll say it anyway.

Do you have enough main jet? Can you shim a needle?

OK, you have the right springs sounds like...

If floats are too high, it's not getting the fuel it needs when it tries to pull in the fuel. Or you have something plugging up a main jet orifice, which comes into play at WOT more than any other time.

Then again, I did not stay at a Holiday Inn Express last night...

[BA80]

122 in #1, 128 in #2 for mains, 40's for pilots. needles stock too as far as I know.

Float height check first thing this morning.




A little high but not flooding, certainly not starving.

Plug check, this is just from around the block a few times.



I don't think it's a carb issue personally. I could be wrong (again) though.

[3Phase]

Bad Wiring Harness?

Slide springs I got were from a 750. Same part # in the parts fiche. The slides seem to be working as they should.

Just asking because Yamaha changed from Hitachis to Mikunis in (some freakin' year in the '80s, I don't remember) so the part number's not always correct. The wrong springs might fit but I think it'd it'd be ugly enough you'd have noticed before you laced up the carbs.

Just now tested the boost sensor according to Clymer. It tests good.

Right on, at least it's working for the basic test! You'd have to check the timing curve under load to know if it's working as-designed but that'd be totally annoying even if you don't mind trying to use and watch a timing light while you're riding.

Where are the pick ups on this shake pile? (when I rev it on the center stand it bounces across the garage floor)

I have no idea, the parts fiche doesn't even list them. Follow the wires from the TCI? They have to be on there somewhere or the bike wouldn't work!

While I was trying to find the pick-up coils I found this little tidbit while I was jumping through part lists. It's for a '95 XV1100 but the bike had a bad wiring harness and the '86 might have a similar weak spot:-

Probable Solution to the "Firing on One Cylinder" Issue...50MPH at WOT No More!

"... WOT and only 50MPH...WTF (starting to sound familiar?!?)

<...>

Finally, when turning the steering head back and forth, the bike sprung to life and then as I turned it back the other way, one cylinder. BINGO, I had stumbled upon something interesting. I then grabbed the wiring harness at the point where the single harness comes up on the left side of the tank and splits into three bundles, pressed my thumb into the harness and ROAR, the bike immediately responded with both cylinders. Release and one cylinder...press and WOW! I found the problem!! So I started cutting open the wiring harness to find that bad boy and as I was going one wire at a time, a red wire w/white stripe pulled loose from one of the upper bundles of wiring. I tracked down the only point in the harness (the upper bundle of the three) where there was a splice and sure enough, as soon as I touched the loose wire to that point (two other red/white stripe wires)...ROAR, both cylinders come to life and stay alive...something new! Remove the wire and BINGO, one cylinder again so I find a point farther down the wire to splice into and VOILA, the bike runs better than when we bought her new!!"

.

[BA80]

You might have something there Scott. There are 2 part numbers listed for the 82 Virago springs. 1 number off from each other. One the same as this bike and the other not. Could be the difference from Mikuni to Hitachi. These fit fine but now that I think about it one was slightly longer than the other too.

I messaged the ebay seller. I'll see what happens.

[3Phase]

I hope it's just a bad wire or something, I hate taking apart carbs when they're full of fuel.

.

[Bonz]

Scotty, drain the float bowls?

What float height measurement does that fuel level translate into?

[BA80]

This is what I went by for the dry setting and the pics I posted are where the clear tube check ended up. Pretty damn close.

http://viragotechforum.com/viewtopic.php?f=75&t=2126

[Bonz]

I have not thrown in the towel on the springs being incorrect. You guys and your electrical diagnosis... Meh...

Sounds too much like a fuel issue, going lean up top. Diaphragms are hole-free?

Springs don't matter so much at lower speeds when you have nominal slide lift. It's the pilot circuit and needle just coming off the seat, along with fuel level in the bowl. At WOT and such, slides want to come up as high as their little selves can go and at a certain rate, by the laws of physics, and the wrong springs put the whammy on that.

Aftermarket jet kits change the spring strength/length, but do it in concert with other changes to make the kit work.

To me, it's doubtful the carbs in an 1100 Virago application would have different springs over the model years if the same carbs were used.

What could happen, is the spring will be different if the same carbs are used on a different model, such as a 750 vs 1100. The spring has to work with a different vacuum signature on a 750 vs 1100, so I would guess springs would vary, no?

[BA80]

I hope it's just a bad wire or something, I hate taking apart carbs when they're full of fuel.

.

Now that you brought that up and I looked back at the part numbers I think I just skimmed and saw the one that was the same as the 1100 and went with it. I don't remember seeing the other number.

These springs might be a bit to strong if they are the wrong ones (Mikuni) and not letting the slides come all the way up on WOT.

[BA80]

What could happen, is the spring will be different if the same carbs are used on a different model, such as a 750 vs 1100. The spring has to work with a different vacuum signature on a 750 vs 1100, so I would guess springs would vary, no?

If you look a 82 750 up in the parts fiche you'll see that the part # for the springs has 2 numbers listed. 4X7 14933 00 00 and a 4X7 14933 10 00, then you look up an 86 1100 and the spring # is 4X7 14933 10 00. The same as the second number listed for the 750. They changed from Mikuni to Hitachi sometime in 1982 I think.