smitty74 Posted August 7, 2011 Share Posted August 7, 2011 Ok, so I have a 1990 xv535, that I bought used a week ago. Here is the issue, it seems to run rich, and I am only getting about 100mi out of a tank of gas. I ran seafoam through it, and changed the spark plugs, and it accelerates smoother now. One thing I did noticed when I changed the plugs is there was oil on the threads, and the end of the plugs was charred black. I know that the black on the plugs is from the bike running rich, but not sure why there would be oil on the thread of the plugs. I need help with both issues. I am worried that there is a major problem, and that's why there is oil on the plugs. Thanks for the help! Link to comment Share on other sites More sharing options...
Ttaskmaster Posted August 8, 2011 Share Posted August 8, 2011 The air/fuel mixture can usually be adjusted via a small screw on the carb somewhere. Your Owners Manual should show where that is (unfortunately I don't know the Virago that well). Oil on plugs - First check you don't have too much oil in the sump. If you do, just drain some out and re-level the oil in your sight glass. Try those and then go for another test ride. Let us know how it's going. Link to comment Share on other sites More sharing options...
tinybiker Posted August 8, 2011 Share Posted August 8, 2011 I have owned a 1990 535 for +15 years in the UK, but there will be subtle differences between your machine and mine. For example, we don't have the plumbing for the air injection system that may be on the Californian model from 1990 on. First - the miles per tankful of petrol(gas?). I assume you have the under-seat and top tanks model with 13.5 litre capacity. At legal speeds, riding solo (up to 75 m.p.h) I used to get c120 miles before having to switch to reserve. I modified the fuel system because the electric reserve was unreliable and now run without a reserve. I get c180 miles from fill-up to running on fumes. At speeds higher than 75 m.p.h the fuel consumption rises dramatically. I have 80,000 miles on the clock and these fuel figure are very consistent. Dry black plug surround may not be rich mixture. With unleaded petrol this is a less reliable indicator than with old-fashioned leaded petrol. The central electrodes are more indicative of the mixture. If you don't need choke to start-up on cool days you are running too rich. High ethanol content may also impair burn efficiency (and eventually wreck your engine). Also, is the end of the exhaust pipe black rather than brown? The most likely common causes of rich running are in no particular order: 1. Wrong grade of spark plug. 2. Air filter needs changing. 3. Choke does not completely free off. 4. Valve clearances are incorrect. 5. Carburettor jets blocked or obstructed. 6. Carburettor diaphragms/needles are worn/damaged. Note 5 & 6 above are difficult to check or fix because removing and replacing the carbs on a 535 is a very painful experience. I did mine with help from a friend at 75,000 miles. Next time I will take the bike to a dealer. Also if the needle/diaphragm assembly needs replacing it will cost lots of money for the Yamaha part. Try to to find an alternative after market source. The oil on the threads maybe because the previous owner grease the threads. Oily black plugs or dark smoke when starting up or cruising at normal speeds, you may have worn valve guides or piston rings. Ask your dealer. As tTaskmaster says, take care not to overfill the sump, which is more difficult than it should be with no centre stand. Hope this helps. Link to comment Share on other sites More sharing options...
tinybiker Posted August 8, 2011 Share Posted August 8, 2011 Further to my earlier reply: I recommend you buy or borrow a copy of the Yamaha Workshop Manual if you are going to do your own maintenance. Now read on. If the spark plug type/gaps, valve clearances and air filters are all o.k., you may want to check the air mixture settings. Only dismantle the carbs as the last resort. The air mixture screws face outward on the right-hand side of each carb, at their lowest mid-points. If you must fiddle with the factory settings, or because you suspect the previous owner already has, then do the following for each carb: Remove any blanking plug, the mixture screw is at the end of a short horizontal tunnel. Note the current angle of the slot on the screw. Noting the number of turns, including partial turns, VERY CAREFULLY and VERY GENTLY screw in the slotted screw until resistance is felt. DO NOT SCREW IN UNTIL TIGHT because you will damage the mixture assembly. It is very important to note precisely what you do, because if you make changes and they make the mixture even richer or too lean, you can at least get back to the current settings. Backout the slotted screw for 1.5 turns, this is approximately the factory setting. Note - some manuals say 1.5 turns, others 2 turns. Start with 1.5, do test ride, re-check mixture and if necessary back out the mixture screw a little more. Make any adjustments in small increments. My bike prefers nearly 2 turns, but it is high mileage and maybe this is why. The above procedure should only affect the slow and lower speed mixture, before the main jets take over. Link to comment Share on other sites More sharing options...
Ttaskmaster Posted August 8, 2011 Share Posted August 8, 2011 I think Tiny just became the official YOC Virago God!! Link to comment Share on other sites More sharing options...
neversaydie Posted August 8, 2011 Share Posted August 8, 2011 Ok, so I have a 1990 xv535, that I bought used a week ago. Here is the issue, it seems to run rich, and I am only getting about 100mi out of a tank of gas. I ran seafoam through it, and changed the spark plugs, and it accelerates smoother now. One thing I did noticed when I changed the plugs is there was oil on the threads, and the end of the plugs was charred black. I know that the black on the plugs is from the bike running rich, but not sure why there would be oil on the thread of the plugs. I need help with both issues. I am worried that there is a major problem, and that's why there is oil on the plugs. Thanks for the help! Tank capacity up to 1989 was only 1.9 gallons, whuich would only get you approx 102 miles 1989 0n, tank capacity was increased to 3 gallons, enough to take you approx 160 miles Even if you are runing rich, I doubt that youd run a 3 gallon tnak dry after just 100 miles or so on a 535 You sure about the year? You should be getting around 50 - 55 mpg Is the engine smoking, are you having to top up the oil, whats the mileage? Link to comment Share on other sites More sharing options...
Themightyblues2000 Posted September 25, 2011 Share Posted September 25, 2011 On my wife's 535 it has the 13.5 ltr fuel tanks. However, I think the fuel tap is knackered, as after about 110 miles the engine started spluttering so I switched to reserve. After another couple of miles it started spluttering again and then cut out. :-( Link to comment Share on other sites More sharing options...
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