Kelum Posted July 30, 2012 Share Posted July 30, 2012 As I mentioned earlier my bike had a bad lubrication as the oil pump wheel was worn out. It stopped and didnt start for sometime. I fitted a new wheel and flushed the engine. Now bike running but the front cylinder plug gets some oil splash and it misfires. Eventually plug stops sparking Once a new plug is fitted it fires well until it begins to misfire...once oil hits spark gap u need to wipe it away with carbon soot and put it back in. Mech says the rings seems to have abraded during the oil pump issue. So of course we will have to replace the worn with new. Am hoping to disassemble the whole engine, clean and if necessary, install new bearings and piston rods of the crank shaft. However, there seems to have some carb issue too. at PRI position of the petcock the engine should receive gas even when the engine not running. But at PRI position when I loosen the float screw on carb, the bowl gas comes out and once it ran out, the drip stops. There is a problem I guess. This starting issue and sudden stop while running all seems to be a problem associated with this and plug oiled case. So am wondering if I could place two separate valves across two gas lines from gas tank and direct them directly to the carb's supply line..has anyone ever done this? This way I will be able to check either petcock or gas pump faulty? I have noticed many Indian bikes here have no gas pumps and too many hoses, they have a simple design and are easier to diagnose. They rock on the road. Please advise! Thanx! P.S. I recently bought a red xv125 whose worn plastic wheel of oil pump had screwed up piston rods. I bought it for 350 USD roughly. It cost me around 90 USD to repair rods and rings. Still its being refitted. Link to comment Share on other sites More sharing options...
Kelum Posted July 30, 2012 Author Share Posted July 30, 2012 What are the pros and cons of fuel pump and petcock (well petcock is advantageous of course, but the rubber washer like thing inside gets broken over the time, so its not reliable) over direct feeding through filters. This is the means most of the Honda and Indian bikes have in common, and it assures trouble-free riding. Uploaded with ImageShack.us Link to comment Share on other sites More sharing options...
Paulwhite Posted July 30, 2012 Share Posted July 30, 2012 the way the carb works is petrol flows into the carb till the float rises, once the float is at the top a needle valve stops the flow of petrol, if you open the bottom of the carb (or the drain), then the float will never reach the top, your best bet would be to take the carb off the bike, place over a bowl and take the float bowl cover off, attach a fuel line to the carb and see if the valve is working properly, when u push the float up the fuel should stop going into the carb. if this works then i cant see why you cant run a direct setup. im not sure if you can run petrol straight through as the bike runs on a vacuum setup (but i think its mainly the petrol tank) as to oil on your spark plug defiantly sounds like your piston rings have gone as far as i know the original rings are expensive so if you find an alternative then please tell us, and to let you know the piston rods are connected to the crank in a way that you will need to replace the whole crank, you cant just replace the rods Link to comment Share on other sites More sharing options...
Paulwhite Posted July 30, 2012 Share Posted July 30, 2012 and just to say the picture is what you have now, but the 1st 2 filters are in the tank attached to the petcock Link to comment Share on other sites More sharing options...
Kelum Posted July 31, 2012 Author Share Posted July 31, 2012 Hey Paul..thanks for the reply mate. I will check the way you say with carb. Yes I know filters are there in petcock n fuel pump. Am telling here since they seem to be making probs over the time, as the illustration shows, we can have filters in a totally separate and new setup of gas lines as shown in the figure. We need to place simpler taps and filters as shown. So that's my idea here buddy. I will see how ur suggestions would help when I put my idea into work. The other thing is, mechs here are good at reusing. U take ur bike or any other vehicle to a mech here, he will try his best to do that at the minimum cost and superb quality. Like I said earlier you can get a sprocket chain repaired so reliably. The same way, when the piston rod was stuck so u cannot rotate the crank shaft there is a machine ( I couldnt see it) they use to remove both rods and put in the new. Its not a new thing it has been around for ages now. I have attached here the pics of old rods removed and the new ones installed. New rods were just 70 USD both and the cost for fitting was 7.5USD. So since Yamaha shipping genuine piston rods, I dont see why u have to put a new crankshaft with rods at a higher cost. There was a free-play in one rod while the other was stuck u couldnt even move. It took seconds for the guy to remove them and put the new in, just like new. In the clutch housing also we made a repair. By kelumpj at 2012-07-31 By kelumpj at 2012-07-31 By kelumpj at 2012-07-31 By kelumpj at 2012-07-31 By kelumpj at 2012-07-31 By kelumpj at 2012-07-31 See the installed new ones and removed old ones on the floor. Link to comment Share on other sites More sharing options...
Kelum Posted July 31, 2012 Author Share Posted July 31, 2012 Hey Paul, abt the piston rings...seems the engine had been bored in singapore (most of the viragos here seems to have imported from Singapore). The piston ring number was 25. I could buy the same genuine yamaha set from a local japanese part dealer for around 10.3 USD. Wait - the new rod install has cost 48.5 USD roughly If you want I can send u pics of the machine they use to install rods on the crank.. Link to comment Share on other sites More sharing options...
Paulwhite Posted July 31, 2012 Share Posted July 31, 2012 booo im so jealous! there are only a handful of people here in the uk who have the tools to take the piston rods off the crank and they charge anywhere between £100 and £300 to do it! the machine heats it up so the parts expand and can be removed not sure what its called....but anyway if the float needle valve is working properly then i cant see why your idea wont work but i would recommend either modifying the old petcock or use a different petcock with just an on off and res setting i would go with the simplest idea which would be a new petcock with no filter attached, 1 pipe with an in-line filter attached to the carb, oh and block off the pipe coming from the rubber bit that holds the carb to the cylinders, that should sort it out. glad to hear that you managed to get piston rings as there hard to find here in the uk!! iv seen people be quoted over £50 for 1 set ! ....i might have to look into moving and here is an idea if your interested it comes from modifying little honda engines ......try and see if you can get bearings put on the crankshaft to hold your piston rods so it gives a more free movement, you might not be able too but it would give the crank more life span plus will help with friction, so should in theory let the engine rev up faster and allow you to use the hp more efficiently. Link to comment Share on other sites More sharing options...
Kelum Posted August 1, 2012 Author Share Posted August 1, 2012 Yes Paul when flywheel was so hard to remove we had to heat it up to remove. I think the machine may be using the same technique. Will try to get a pic of it. I think it will be worth it for you to send me the old crank when you want a piston rod install, that amount of money will cover the postage and any other duty and still you will have a balance for some ice cream. The last time I checked the petcock, the rubber washer/valve had some broken areas where it had touch the metal projections on petcock housing. It does collect water and the spring and aluminum body tends to corrode. Fuel pump too can be faulty. So if the direct line to carb fixes issues I know where the problem is. Part replacements are not that easy here, they are unique to the particular model and importers do not seem to maintain stocks of them. For such they always ask to find a place where people rip down old bikes, which is not likely to find anyway. Thats why am considering a setup without both. I thought it is easier to find anything for the virago in UK...piston rings not available...its one of the most necessary for a biker..whats wrong with them, and when available so much pricey? The rings, both 5-piece sets has cost me 1300 SL rupees, which is around 11 USD. They are genuine Yamaha. Next time u want them jst tell me I can post you any amount Yes I get your point on placing bearings on rod-crank contacts, you shouldve told tht earlier buddy now that the mech has fitted the engine almost. He will eat me if I say something like that. Only rear head to go today. But placing a bearing would cause more issues as the rod must hv a larger hole right... the rod and piston ring thing regarding the new bike I bought. Its being resurrecting and hopefully today or tomorrow we can mount the engine n crank. .................................................... My earlier one having oily plugs and missfire, pug pug sound in front cylinder. So we knw its requesting new rings. That we will be addressing next. Old bike likely having petrol line probs too thats why I proposed direct feeding of carb to figure it out. And there is a problem with starting. Motor is so sluggish. It drains battery power a lot and battery goes dead in seconds. so we gonna disassemble motor today. may be the solenoid. may be the motor. It should probably be having a high friction inside, but checking wire, solenoid and then the motor. (I installed a new battery yesterday, so its not a bad battery). Starting is difficult as engine is not turned strongly. Pushing instantly starts. Link to comment Share on other sites More sharing options...
Kelum Posted August 3, 2012 Author Share Posted August 3, 2012 I found the brushes of the starter motor were worn out, bought new and they were not fitting to brush bay so had to trim out for perfect fitting. A magnet was loose put some super glue and it was fixed. then I accidentally had changed the polarity of the magnets and the motor was cranking the engine reversely , snapped to other way and motor was ok. Old bike however having some petrol starvation issue. so planing to totally overhaul the engine next week. ........................................ The new bike too had petrol starvation-like issue, we fixed it. Now she's in perfect condition. I still expect someone's direct petroling technique. I think the petcock and the pump ruining my time with bad operation. Thanks people! Link to comment Share on other sites More sharing options...
Recommended Posts