rednecktech Posted October 10, 2007 Share Posted October 10, 2007 I bought a 89 750 Virago with 28500 miles.The rear cyl. runs about 125 psi The front is 95psi one teaspoon of oil brings it up to about115 psi The fool that had this bike before me adjusted the only valve he could. that was the exhaust valve on the front cyl, he set it so tight that the valve was not closing completely, so it will back fire a lot I reset the valve and it runs better but still backfires after it gets hot. I am wondering if the carbon is so much that it is trying to ignite? The plugs are showing a very rich mixture, but I have rebuilt the carbs and put new plugs . My plan is to place fans in front of the engine,plull everything from carbs,run the engine and shoot marvel mystery oil into the carbs to break up the carbon,trying to clear the cyl. Has anyone done this and made it work. How good will the rings clean up? There is a lot of work on it if this dose not fix the problem. Any ideas ? Thanks for the help. Link to comment Share on other sites More sharing options...
Andyco11 Posted October 10, 2007 Share Posted October 10, 2007 Personally i would whip the heads of and re seat the valves by re-griding them in. also sounds like you have a piston ring problem could just need re honing Link to comment Share on other sites More sharing options...
yoda Posted October 10, 2007 Share Posted October 10, 2007 I think that you might have a burnt valve. If the magic oil fails to clear the problem, it's heads off time. Link to comment Share on other sites More sharing options...
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