Kelum Posted August 17, 2012 Share Posted August 17, 2012 Hi fellas, As I mentioned here I bought a new virago for 350USD a month ago and its front piston rod was seized as the oil pump wheel had been worn. I got the engine fixed and it cost me around 100USD for replacing rods, piston rings and for the mechanic. The bike came back to life and wonderful acceleration and pickup. It ran fine for few days. Now it runs fine but sometimes tend to slow down and stop as if it doesnt get fuel. You feel it when u ride as it stalls, slowers and revs when u squeeze the clutch..and finally stops. Plugs are fine, both are white, no carbon soot at all. Once stopped it sometimes tries to start when cranking with starter, but doesnt hold on. sometimes no firing at all. But after around 5-10 mins, when you crank with the starter, hey suddenly she starts as if nothing happened. My mech tried starting her in petcock's ON and RES positions, but it worked only at PRI. So we left it that way...I read somewhere not to use PRI too long, is this harmful? Today when bike stopped on the way, some guy came up and removed the front top hose of the petcock, which comes from the inlet manifold for vacuum, it is so lose that it comes off so easily. He removed it thinking its the petrol line. Knowing its not he fit it back. Then I pressed start button and she started. So I figured out I need to fit the vacuum tube tightly on manifold, petcock and fuel pump. I would use some claps or tight fitting new hoses for this. And there is no carb air inlet? hose that goes to air cleaner fitted, I read here someone had said it should be connected to give necessary pressure...I would address that too. May be ON, RES settings do not supply fuel to carb because vacuum is weak as the hose is loose. But when petcock at PRI petrol is fed directly, does pump still pumps fuel at PRI position? Then could this be a faulty pump issue? Since its getting a hose from inlet manifold, does it also operate through vacuum? So could there be a vacuum issue? The same problem came with my other bike still under repair. Please help me guys.. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 17, 2012 Moderator Share Posted August 17, 2012 yeah kelum, naturally the vacuum pipe ends should be a good tight fit or you will lose vac, sort tthis out and see where that gets you Link to comment Share on other sites More sharing options...
Kelum Posted August 18, 2012 Author Share Posted August 18, 2012 yeah kelum, naturally the vacuum pipe ends should be a good tight fit or you will lose vac, sort tthis out and see where that gets you Thanks buddy...ur awesome! Link to comment Share on other sites More sharing options...
Kelum Posted August 20, 2012 Author Share Posted August 20, 2012 I sealed all the vacuum hoses with gum and new tubes. And rode it, earlier bike didnt run in ON position of petcock, now it does, but after 4 km run it sputtered and stopped, then I put petcock to PRI position it started fine. Later put back to ON position and bike was running up to now. Another thing, when I remove the petrol line to carb from fuel pump when petcock is in ON position, petrol fairly rapidly drips. This cant be right? I mean at ON position there cant be a petrol flow to carb when engine not running as no vacuum is created by piston. ???? So am guessing my petcock is not sealing the free flow of gas? Petcock is faulty? I think bike running fine at PRI as it is not affected by vacuum valve in petcock...I feel like petcock is faulty...what do you think.... Link to comment Share on other sites More sharing options...
Kelum Posted August 20, 2012 Author Share Posted August 20, 2012 I fitted a long hose to the vacuum line of the fuel pump and blew air in and out, petrol pumps out easily through carb line...so pump is ok...am suspecting petcock, or whtelse should I look for... Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 20, 2012 Moderator Share Posted August 20, 2012 yeah perhaps the petcock has debris in it, it may also have a filter screen that is blocked up! i would carefully strip it and examine / clean it Link to comment Share on other sites More sharing options...
Kelum Posted August 20, 2012 Author Share Posted August 20, 2012 yeah perhaps the petcock has debris in it, it may also have a filter screen that is blocked up! i would carefully strip it and examine / clean it Actually i did strip it. Didnt see any debris inside, its not that complex inside, the rubber washer that seals the petrol line was ok. Holes were not blocked, no oxide even...the spring was rusty but it was working fine..the washer under the ON-PRI-RES tap was ok...screws seal the petcock perfectly...what the hell is wrong with it I wonder... Link to comment Share on other sites More sharing options...
Kelum Posted August 21, 2012 Author Share Posted August 21, 2012 Are there alternative vacuum petcocks I could use instead? Am pretty sure any with the same settings would work...the exact one not available for buying here.And I saw somwhere else that u should not leave petcock setting in PRI as it could fill bores with petrol and then petrol can get to the oil sump. They say the ON position makes sure that you dont forget to off gas flow when bike not driven as it automatically shuts supply when engine isnt running. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 21, 2012 Moderator Share Posted August 21, 2012 ...........And I saw somwhere else that u should not leave petcock setting in PRI as it could fill bores with petrol and then petrol can get to the oil sump. They say the ON position makes sure that you dont forget to off gas flow when bike not driven as it automatically shuts supply when engine isnt running. That is correct kelum They developed this method to stop engines self destructing when the starter was pressed with an engine full of fuel! Link to comment Share on other sites More sharing options...
Kelum Posted August 22, 2012 Author Share Posted August 22, 2012 That is correct kelum They developed this method to stop engines self destructing when the starter was pressed with an engine full of fuel! Am wondering what to do....it runs fine at ON position now, but on and off the prob seems to be coming. I think I should order a petcock from ebay, or I should use a vacuum operated tap from some other bike .,.. Link to comment Share on other sites More sharing options...
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