1981 Virago 750

Found a common issues with the heads so far. There seems to be a weak spot.
DSCN0096 by Tim Brown, on Flickr
DSCN0095 by Tim Brown, on Flickr
Two different engines both 750s and the rear head. Almost the same place for the deterioration of the head. This is what the head gasket does.
DSCN0090 by Tim Brown, on Flickr
I have one good head that has a valve issue. Will have to sort that out and then see if I can get it to work.
DSCN0094 by Tim Brown, on Flickr
I will take some 100 grip sand paper to it and see if I can get it a little better.

 

Can you o-ring the head with a piece of copper wire as the old hot rodders used to do?

 

If a person wanted to put the time and money into one of these bikes you can. Here is a good vid of what some folks are doing to save these bikes. I guess the gen 1 head gaskets were just nasty. When they failed the engine eat the top end.

When you buy a new head gasket it is made of different material. Once I get the other bikes I have for sale out of the shed, I will try to save at least one of the blown engines. Yesterday I put in the good donor engine in the bike. 150 psi on both cylinders. Today I hope to get it running. I moved the bike without the engine in it, that shifted the frame a little and I had a heck of a time getting the new motor in the titled frame.

 

All is going well with the motor swap. The engine is a beast 150 psi both cylinders. The starter is a 4 brush cleaned and working great. Starter clutch gear has been re-shaped and engages very well. Now the issues, this motor has so much compression that even with a 800 cca battery and 2 gauge jumper cables, there is no starting this bike. The starter just can't spin motor fast enough to get it to fire and run. She hit compression stroke and stops, throws off some smoke from firing and that is it.

If I wanted to keep the bike I would take the heads off and put some compression relieve valves in them. I think that would be the best option for these old Gen 1's. I think it is time to find a new home. I have a title with it and I would guess I can at least break even. I have asked for help with what I might be doing wrong, I guess it is just the way these bikes were.

 

Don't know much about the Virago but I've have had high compression engine starting issues before.
Just a thought...
Have you done a voltage drop test?...perhaps the ground wire (from engine to chassis) should be a larger gauge wire, or maybe there's corrosion along the path.

 

I did a newbie thing and am just laughing at myself. I had the coil wires swapped....yes that was it. Changed the coil wires hit the starter button and it fired right up. I felt so stupid...just looking too hard and not sticking with the basics.

As for the starting, from what I have read the starter on all the Virago's need to be gone through and cleaned up. Most of the OEM/2 starters are 4 brush and really help with turning the engine over. Making sure the valves are set and all the rest (coil wires for 1 and 2 in correct plug) and the engine should fire right up.

The marble sound can be fixed if you take it on. Easy it is not, until you get used to it. I have done three now and it gets easy. The face of the starter clutch gear get "rounded". Taking a dremel with the cut off disk you can "sharpen" them back up to look better. That will really help the "marble" sound and basically eliminate it. Will it go away for ever, no, it is a bad engineering issue that was not fixed until the 2nd Gen bikes.

The donor bikes all nice parts have been changed over to the bike with a title now. It is starting to look good. The new starter relay came in the mail today and I need to get a good battery for it. Will be time to get that $164.oo new title and go from there.

 

Out of nowhere I now have a electric gremlin. It is in the headlight bucket and it is a lose wire. I have a new Probe III that I picked up, time to use it to see what is up with the lose wire. The bike starts and runs well now, as you drive it the vibration from the road or revs will cause a open to one of the relays in the rear of the bike. This new Probe III tool should make it easy to trace. I am so used to the old school multi meter, but a friend of mine that owns a shop showed me the Probe. I hope it makes things easy to find.