Carolina Spur Posted January 30, 2015 Share Posted January 30, 2015 Hello guys, I have a XVS 125 thaty I'm trying to get cranked up after sitting 3 years with a bent valve. I replaced the valves and lapped the new ones in and put the head on. I have an original Service manual the previous owner gave me which as per usual seems a bit misleading to the unlearned. I am a certified car mechanic but metric bikes are new to me so I'm rookie in a way. My problem is that the "T" and "I" timing marks are not exactly TDC but the 3rd "timing mark" that is a line just so happens to be TDC for the rear cylinder. Although I will admit I got this totally wrong and timed the beast to the stroke of TDC. Now that I have found my error and after many spins of almost cranking as long as you hold the starter button down... I am trying to get the cam chain to stay on after installing the gear and tensioner... It's doing my head in.. Is there a way to make sure the chain is in the bottom teeth before turning it over? It keeps trying to roll of like a bicycle chain out of alignment. And to clarify I have taken the carburetor apart and cleaned it, checked the joint for cracks, I made sure the accelerator pump was spraying and the fuel was filling the bowl and what not. While I was spinning her over I checked the spark plugs to see what colour the spark was and it was red. So I figured the voltage regulator was breaking down and/or the coils so I replaced them just to be sure. Link to comment Share on other sites More sharing options...
blackhat250 Posted January 30, 2015 Share Posted January 30, 2015 Am thinkn thers a fault with the timing chain line up too , that's maybe why it had a bent valve ,[ pervious owner] I hope you havna bent a valve again , when the chain slipped, the bottom sprocket has to be right - as its on the crank,,the top sprocket ? cam shaft ? is it located correctly, what state is the tensioner in,, are the prone to fk up ... 1 Link to comment Share on other sites More sharing options...
Carolina Spur Posted January 31, 2015 Author Share Posted January 31, 2015 The tensioner seems to work properly and keeps the chain snug as best I can tell before it actually runs. This chain not being on the crankshaft just happened last night and I turned it over by hand just in case (previous experience of timing engines) to make sure there was clearance. Another thing that bugs me, there are 3 marks on the crank. A "T" a capital"I" and a line. Granted I don't have a disc to measure 300 degrees counter clockwise but the book says the I is the mark for the rear cylinder but the pictures only show the line? My best assumption is the plain line with no letter is the mark used for a timing light. Link to comment Share on other sites More sharing options...
KevtheRev Posted January 31, 2015 Share Posted January 31, 2015 Hi there , is that a new camchain ? I can't understand why it's not running straight for you . Is the camchain kinked ? 1 Link to comment Share on other sites More sharing options...
Carolina Spur Posted January 31, 2015 Author Share Posted January 31, 2015 Just checked the valves, still holding pressure and no other issues in the head as I can see at the moment. I have another xvs 125 that is a rebuild by the previous owner who was a mechanic. Damn if its not timed to the plain line? Engine has never been run and is sitting in the frame so am I looking at a mistake or is that TDC for the rear cylinder? Link to comment Share on other sites More sharing options...
Carolina Spur Posted January 31, 2015 Author Share Posted January 31, 2015 Cam chain looks fine think I wasn't getting it on the bottom as I let it slip and used a telescoping magnet to retrieve it Link to comment Share on other sites More sharing options...
Carolina Spur Posted January 31, 2015 Author Share Posted January 31, 2015 Here's the rebuilt engine and how the rear cylinder is timed. I turned the crank to the "T" and made sure the front cylinder was showing it was lined up then turned the crank counter clockwise 300 degrees (as best I can tell) and put it on the plain mark and it shows the rear cylinder is timed to it. Link to comment Share on other sites More sharing options...
KevtheRev Posted January 31, 2015 Share Posted January 31, 2015 Good photos , if she'll turn over by hand without binding you should be ok . 1 Link to comment Share on other sites More sharing options...
Carolina Spur Posted January 31, 2015 Author Share Posted January 31, 2015 Juyst got finished putting a new head on used the timing mark "I" and it appears I have very low compression on the rear cylinder. I dont have the compression gauge I borrowed before but placing my thumb over the spark plug hole of the front and the rear whilst spinning there is a huge difference. and nothing out of the tail pipe of that cylinder. The front plug is carboned up and the rear is clean. when trying to start it it spits and pops but only if you really twist the throttle a few times. nearly starts but the starter has to stay engaged which I think is the front cylinder being as it seems to be firing due to the blackened plug. I'm probably missing something but in my opinion even a low compression cylinder should allow the good one to fire up or no? Link to comment Share on other sites More sharing options...
Carolina Spur Posted January 31, 2015 Author Share Posted January 31, 2015 Good photos , if she'll turn over by hand without binding you should be ok . Hrey thanks, Yeah I usually try that first just to make sure I don't screw up and end the show before really starts Link to comment Share on other sites More sharing options...
Carolina Spur Posted January 31, 2015 Author Share Posted January 31, 2015 Well there it is... The piston rings were knackered either broken by the valve smacking the top or just sat too long. I will rebuild this engine but decided to put the other one in for now. Old engine out... New engine in Link to comment Share on other sites More sharing options...
Carolina Spur Posted February 3, 2015 Author Share Posted February 3, 2015 New motor installed all hooked up and .......... a singing starter........ well, I pull the starter off and replace it with the old starter. and the same thing. like it's running backwards. So I stick my finger in the hole and turn the gear. it locks one direction and free spins in the other. Check the old engine and it is locking in the opposite direction. What are the chances of getting a backwards sprague as it will only go in one way? Is the Virago similar but with a reverse mounted starter? Link to comment Share on other sites More sharing options...
Carolina Spur Posted February 5, 2015 Author Share Posted February 5, 2015 the timing mark is in fact the straight line for the rear cylinder. Just to clear things up for anyone looking at timing their XVS 125 properly. Link to comment Share on other sites More sharing options...
blackhat250 Posted February 5, 2015 Share Posted February 5, 2015 Am amazed at the amount of metal [ fins] surrounding the piston , am refurbing a Dt400 engine the now, its 85.25 mm bore , And just took me by surprize lokkin at your XVS, Glad your getting there,, 1 Link to comment Share on other sites More sharing options...
Carolina Spur Posted February 5, 2015 Author Share Posted February 5, 2015 Am amazed at the amount of metal [ fins] surrounding the piston , am refurbing a Dt400 engine the now, its 85.25 mm bore , And just took me by surprize lokkin at your XVS, Glad your getting there,, Yeah buddy, I think it displaces around 60mm? just a tad bigger than a shot glass hahaha 1 Link to comment Share on other sites More sharing options...
Williamdon Posted September 6, 2020 Share Posted September 6, 2020 Hi lads / ladies I have a yamaha viragoxv125 and I cant seem to find a workshop manual anywhere on the internet to re time her can anyone give me help please Liam Link to comment Share on other sites More sharing options...
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