Virago 700 in the shop

[Nesse1]

From one motorcycle guy to another, my advice is to KEEP GOING!

Rebuilding motorcycle carbs is one of my main hobbies these days. I haven't done any Virago carbs, though. The q-tip business throws a red flag; I can't tell you how many times I've read about someone "rebuilding" their carbs...two or three times before they get it right.

This tutorial isn't specific to the carbs in question, but the methodology is pertinent. It shows a complete teardown, soaking in carb dip, then reassembly with new O-rings. I can't tell you how many old carbs I've rebuilt where the O-rings crumbled as soon as I touched them. It's best to bite the bullet, do the teardown, then build back up with 100% certainty they are clean and ready to run.

https://gsarchive.bwringer.com/mtsac/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf

 

[lordbeezer]

Spray lightly is the key phrase there. Done it for many years without a problem. Gotta use little caution where you spray. Most vacuum leaks not around exhaust or spark plugs. Have used propane testers without problems as well.

 

[Nesse1]

A quick check of the parts fishe on Partzilla shows that the rubber boots that attach to the head have large O-rings in them. I'd remove the boots, inspect them closely for cracks, and replace the O-rings straight away. Spraying junk on the engine will find gross leaks, but not smaller fine ones, the type that lead to an inconsistent and creeping idle when warm.

 

[cathead]

I'm still working on the carburetor but now I'm having difficulty with the starter as these Vir-hog-os
are noted for. I see there is supposed to be a washer of some kind to keep the reduction gears
from jamming up. I made up a test washer out of cardboard and it seems to work so decided to do it
right and make something out of metal. My first thought was to get out the rotary table and try to make
a washer out of aluminum but while in the shop I found a piece of DOM close to the right diameter.
From there it was a simple matter to chuck the pipe up in the Monarch lathe and machine the ID and OD
to the needed size. Then it was just a matter of using a cutoff tool to slice off a couple of rounds
of a thickness that I think would be appropriate. I made two, a thin one about .020 and a thicker one about .035
so will use one or the other or gang them up for .045 inch spacing.

The idle screws are untouched so may need to drill out the brass plugs as I am still having problems
getting the engine to rev up properly. Anyway, that will be next after I install the steel washers in the
starter. Thanks for reading along on my quest.Here is a photo after cutting off a round shim.




This is my setup to bore out the DOM a little so the washer fits in the starter assembly. This was way easier
than trying to make the washers using a rotary table. It could be done but this was better!

 

[great white]

I'm still working on the carburetor but now I'm having difficulty with the starter as these Vir-hog-os
are noted for. I see there is supposed to be a washer of some kind to keep the reduction gears
from jamming up. I made up a test washer out of cardboard and it seems to work so decided to do it
right and make something out of metal. My first thought was to get out the rotary table and try to make
a washer out of aluminum but while in the shop I found a piece of DOM close to the right diameter.
From there it was a simple matter to chuck the pipe up in the Monarch lathe and machine the ID and OD
to the needed size. Then it was just a matter of using a cutoff tool to slice off a couple of rounds
of a thickness that I think would be appropriate. I made two, a thin one about .020 and a thicker one about .035
so will use one or the other or gang them up for .045 inch spacing.

The idle screws are untouched so may need to drill out the brass plugs as I am still having problems
getting the engine to rev up properly. Anyway, that will be next after I install the steel washers in the
starter. Thanks for reading along on my quest.View attachment 437941Here is a photo after cutting off a round shim.




View attachment 437942This is my setup to bore out the DOM a little so the washer fits in the starter assembly. This was way easier
than trying to make the washers using a rotary table. It could be done but this was better!

Although it's difficult to diagnose carb issues on the internet, I can at least give you a couple things to look at.

Problems with increasing rpm is not typically associated with the idle setting. It's usually transfer ports, needle settings or ignition.

If you didn't remove the idle mixture screws when you cleaned the carbs, it's entirely possible the passages are gummed up. Carbs need to be stripped bare and then either dipped or given a round or two in the ultrasonic to get them actually clean. Anything less is a band aid at best....