Member Contributer SamW Posted June 19, 2014 Member Contributer Share Posted June 19, 2014 Hmmm... Any chance you got the plug wires going to the wrong cylinders? I know that is hard to do, but maybe the PO screwed up with wire/coil combo. Not sure if you can pull this off, but pull all the plugs to keep it from starting, put the plug in the wire for the non-working cylinder and ground it against the engine where you can see it spark, use a finger/hand to cover the spark plug hole on the non -working cylinder, then hit the starter to see if the spark and compression stroke are at the same time. Could possibly be a mixed up wire or a sensor for the crank is going bad, but I would expect that to result in no spark, not miss timed spark. Link to comment Share on other sites More sharing options...
Member Contributer Rice Posted June 19, 2014 Author Member Contributer Share Posted June 19, 2014 You said spark was solid, but how did you check it? Did you leave the spark plug in the wire and ground it to the block to check spark or use a screwdriver in the wire and ground it? With good compression and dumping fuel in the carbs, it is hard to believe it wouldn't fire that cylinder. I have this spark tester - One end into the boot, the other onto the plug and you can see the spark in the clear plastic case. I also checked with the plugs out and grounded on the frame. I can't believe this either. Will re-check compression. Link to comment Share on other sites More sharing options...
Member Contributer BCmcrider Posted June 19, 2014 Member Contributer Share Posted June 19, 2014 Put metal object in plug wire and hold in right hand. Pull plug and put left middle thumb over open spark plug hole. (must have really long thumb) Crank engine over with chin on starter button. Verify spark arrives at same time as compression by verifying pain in right hand coincides with compression pulse on left thumb. Don't do any of the above but do do what sam says above assuming spark arrives at both front cylinders simultaneously or something else to verify spark (or valve) timing is not ie 180 deg out. Link to comment Share on other sites More sharing options...
Member Contributer Rice Posted June 19, 2014 Author Member Contributer Share Posted June 19, 2014 Hmmm... Any chance you got the plug wires going to the wrong cylinders? I know that is hard to do, but maybe the PO screwed up with wire/coil combo. Not sure if you can pull this off, but pull all the plugs to keep it from starting, put the plug in the wire for the non-working cylinder and ground it against the engine where you can see it spark, use a finger/hand to cover the spark plug hole on the non -working cylinder, then hit the starter to see if the spark and compression stroke are at the same time. Could possibly be a mixed up wire or a sensor for the crank is going bad, but I would expect that to result in no spark, not miss timed spark. I will check that. I don't think that there is a way to screw up the plug wires, but there might be a chance to mismatch the wires going to the coils. Put metal object in plug wire and hold in right hand. Pull plug and put left middle thumb over open spark plug hole. (must have really long thumb) Crank engine over with chin on starter button. Verify spark arrives at same time as compression by verifying pain in right hand coincides with compression pulse on left thumb. Don't do any of the above but do do what sam says above assuming spark arrives at both front cylinders simultaneously or something else to verify spark (or valve) timing is not ie 180 deg out. This sounds like fun. It actually reminds me of a time when I was trying to get the outboard motor of my ex-powerboat going in the middle of the NY bay in November. I cleaned the plugs, put the boots on and yelled to my friend CRANK! All the while standing in the bilge full of salt water and holding on to one of the plug wires for purchase. It's the sort of thing I will only do once. Maybe twice Link to comment Share on other sites More sharing options...
mcrwt644 Posted June 20, 2014 Share Posted June 20, 2014 are the wires on the coil packs? what does it look like inside the spark plug boots? I know on my xj700's too much corrosion would build in the boots and even though you would have spark, not enough of it. You said you have spark...is there any way the timing could be off? Did you pull the plugs, clean them and re gap? are the spark plug boots really on the plugs well? When the bike is running on just 2 cylinders, can you rev the bike to have the other cylinders kick in? That is how I brought my 91's number 3 back on line after 3 weeks. Link to comment Share on other sites More sharing options...
Member Contributer Rice Posted June 20, 2014 Author Member Contributer Share Posted June 20, 2014 Plugs are clean and have correct gap. Boots are on good. I'll need to check for corrosion inside. Didn't think of it before. Regarding the strength of the spark, all i can do is a visual comparison with known good coil. Will do that as well. Thanks! Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted June 20, 2014 Member Contributer Share Posted June 20, 2014 Do you think someone install a new cam on one of the heads and the cam timing is off ? Link to comment Share on other sites More sharing options...
Member Contributer Rice Posted June 21, 2014 Author Member Contributer Share Posted June 21, 2014 A small update. I have temporarily given up on trying to get all cylinders to fire. It's a case of walking away to clear your head. In the meantime, I have decided to tackle the starter clutch slippage. Engine cover off And the clutch inner is cracked as expected. I put everything back together temporarily and whadayaknow.. The starter no longer slips. Cranks that bad boy w/o a single stumble. Another minor mystery, but I'll take it. As for the non-firing, I have confirmed that compression is good on all cylinders. I have also confirmed that there is spark and fuel. AS next steps, I will test all the coils as per the manual to make sure that they produce the right amount of spark. BTW, there is no way to mix up the coils and wires going to them and to the plugs. It is very neatly controlled by the position and length of all the wires. Link to comment Share on other sites More sharing options...
mcrwt644 Posted June 21, 2014 Share Posted June 21, 2014 ah, the starter clutch...such an easy fix but such an ugly noise Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted June 21, 2014 Member Contributer Share Posted June 21, 2014 But a clear sign that someone has abused it .. Link to comment Share on other sites More sharing options...
mcrwt644 Posted June 21, 2014 Share Posted June 21, 2014 not always, every vfr I have had has had this issue, every one Link to comment Share on other sites More sharing options...
timmythecop Posted June 22, 2014 Share Posted June 22, 2014 every single Virago made in the 80's had a bad starter clutch from new. EVERY ONE. Link to comment Share on other sites More sharing options...
Guest Posted June 23, 2014 Share Posted June 23, 2014 You can let the old gaskets set in a PB Blaster bath for an hour or so. It well soften them up and bring the back to life. Link to comment Share on other sites More sharing options...
timmythecop Posted June 23, 2014 Share Posted June 23, 2014 PB blaster is like witchcraft. It can do anything !!!!! Love that stuff. Link to comment Share on other sites More sharing options...
Guest Posted June 23, 2014 Share Posted June 23, 2014 If they are way out of sync it can cause it not to run. Link to comment Share on other sites More sharing options...
Member Contributer Rice Posted June 23, 2014 Author Member Contributer Share Posted June 23, 2014 You can let the old gaskets set in a PB Blaster bath for an hour or so. It well soften them up and bring the back to life. OH! This is good stuff! I'll do this ASAP - Not crazy about having silicone in there. If they are way out of sync it can cause it not to run. I'll take the chance that they are in sync enough to get running at least poorly at first. I'll also be checking the timing. By method of deduction, it is the only remaining ingredient to running that is yet unchecked. Also, judging by the fact that I was hearing popping back through the carb, it just might be the ticket. Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted June 23, 2014 Member Contributer Share Posted June 23, 2014 Do you think someone install a new cam on one of the heads and the cam timing is off ? Yep ... Link to comment Share on other sites More sharing options...
Member Contributer Rice Posted June 23, 2014 Author Member Contributer Share Posted June 23, 2014 Do you think someone install a new cam on one of the heads and the cam timing is off ? Yep ... Yeahhhh... I know... I've never touched timing and I was trying to exhaust all other possibilities before delving in to it. I guess you were right I I'll have to add a new skill to the vast amount of useless knowledge sloshing around in my head. Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted June 23, 2014 Member Contributer Share Posted June 23, 2014 Do you think someone install a new cam on one of the heads and the cam timing is off ? Yep ... Yeahhhh... I know... I've never touched timing and I was trying to exhaust all other possibilities before delving in to it. I guess you were right I I'll have to add a new skill to the vast amount of useless knowledge sloshing around in my head. I hope its not but you wrote the cams look brand new . I know mine at 3000 miles look like crap . Link to comment Share on other sites More sharing options...
Member Contributer Rice Posted June 23, 2014 Author Member Contributer Share Posted June 23, 2014 Update on the timing. To my dismay, it appears to be correct. As per the service manual: And that's exactly what it is. T2 mark is aligned and all the arrows are pointed as specified. Back to being stumped Link to comment Share on other sites More sharing options...
Member Contributer BCmcrider Posted June 23, 2014 Member Contributer Share Posted June 23, 2014 Spark not sparking under compression? Can you test the coils with a megger? Run the bike in a dark garage and look for sparks where they shouldn't be? Link to comment Share on other sites More sharing options...
Member Contributer dalesvfr Posted June 23, 2014 Member Contributer Share Posted June 23, 2014 Forgive me if this has been mentioned, but how about a bad ECU? Only test I would know of is a swap with a known good one. Or maybe it's the connections or ground for it are questionable. Link to comment Share on other sites More sharing options...
SEBSPEED Posted June 23, 2014 Share Posted June 23, 2014 Doesn't the fuel pump and or pump relay need to be plugged in for the spark circuit to complete on the 3rd and 4th gen? Link to comment Share on other sites More sharing options...
Member Contributer YoshiHNS Posted June 23, 2014 Member Contributer Share Posted June 23, 2014 Doesn't the fuel pump and or pump relay need to be plugged in for the spark circuit to complete on the 3rd and 4th gen? I remember that happening on my previous VFR. The wiring schematic seems to say yes. You can jump the wires out and it should still work. I think I jumped my relay out until I fixed the issue. Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted June 23, 2014 Member Contributer Share Posted June 23, 2014 Update on the timing. To my dismay, it appears to be correct. As per the service manual: And that's exactly what it is. T2 mark is aligned and all the arrows are pointed as specified. Back to being stumped Doesn't the fuel pump and or pump relay need to be plugged in for the spark circuit to complete on the 3rd and 4th gen? Yep thats right, thats where it gets it trigger voltage .. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.