Virago 700 in the shop

pontiac428 said:
Mixture control valve. You want that! It's in the intake cover or dummy cover because it needs the intake air temperature to modulate vacuum.

VALVE, MIXTURE CONTROL​

product number: 4X71354100
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Thanks John! Knowing that is a big help in getting this back together correctly.:encourage: It looks to me like it hooks on to the
intake block on the rear cylinder. The Haynes manual covers too many models with not enough detail on the 700, still handy though.
 
cathead said:
Thanks John! Knowing that is a big help in getting this back together correctly.:encourage: It looks to me like it hooks on to the
intake block on the rear cylinder. The Haynes manual covers too many models with not enough detail on the 700, still handy though.
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Haynes manuals are very basic and omit details applicable to a specific model. I learned this the hard way; get a specific factory manual. They are available on line.
Also, a factory parts manual is usually very helpful as they usually show exploded views that help in assembly. Not to mention the cool factor of walking into a Yamaha dealer and knowing exactly what you need and not sounding like a newbie.
 
Today was a short session with the Virago XV700. I cleaned up the disc brake assemblies so they are ready to install
when the new pads arrive. Also, I machined some metric adapters for the brand new mirrors that came with the bike
and got them installed. And finally I added a red plastic handle to the ignition key. It worked to a fashion but was only
3/8 inch wide so inconvenient to use. I milled out two pieces of red plastic to fit the remains of the key and sandwiched
it together. After a bit of grinding on the disc sander and some heat with a propane torch, it turned out quite usable.

The other thing I did was to remove the 7000 ohm resistors that are in the connector that attaches to the spark plug
and installed some copper rods to bridge the gap. The plugs are resistor plugs so don't need two resistances in series
to cob up the works. Just for fun I shot a little gas in the carburetor and it ran better for a few revolutions. So now I
need to be patient till the carburetor kits show up, maybe find some other stuff to work on in the meantime...







The black key fits the little compartment way in the back on the sissy bar and the red key fits the ignition. Sometimes
a little improvising turns out better than anticipated.


P1030777.JPG
 
great white said:
I’d be careful removing resistors from the HT leads without figuring out what they’re actually for. I’ve seen guys burn up their ignitor boxes that way before….
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Thank you. It has resistor plugs too so will have to look and see if it has the right plugs. I think it has BPR7ES plugs if i remember correctly.
 
cathead said:
Thank you. It has resistor plugs too so will have to look and see if it has the right plugs. I think it has BPR7ES plugs if i remember correctly.
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The thing is; if the ignitor box is expecting to see the combined resistance of the plug and the resistor “pill” and you’ve removed one of them, it will put out too much voltage and burn itself out.

Personally, I’d just leave the ht leads alone. Eveeything runs a resistor plug these days, so it was probably designed the way it is for a reason….
 
great white said:
The thing is; if the ignitor box is expecting to see the combined resistance of the plug and the resistor “pill” and you’ve removed one of them, it will put out too much voltage and burn itself out.

Personally, I’d just leave the ht leads alone. Eveything runs a resistor plug these days, so it was probably designed the way it is for a reason….
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The manual I looked at indicated the plug to be a BP7ES. I put the resistors back in and will buy the right plugs when I go to town.
 
cathead said:
The manual I looked at indicated the plug to be a BP7ES. I put the resistors back in and will buy the right plugs when I go to town.
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This morning I did a little reading on spark plugs and resistors. The purpose of the resistor is to reduce radio interference.
The resistance can be incorporated into the plug, the wire itself or in the plug that attaches to the plug. That could add up
to a lot of resistance. Using a resistor requires more voltage for the plug to fire and this affects timing of the spark. I found
that an interesting point. Theoretically then a resistor retards the timing of an engine although probably not much and
likely not too significant. In testing the distance the spark will jump on this Virago, I find it will span at least 1/4 inch. A spark
jumping a millimeter requires about 3000 volts so my coils are generating at least 20,000 volts.
 
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