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ViragoTechForum.com XV750 Starter circuit issue? (SOLVED)

#1:  Starter circuit issue? (SOLVED) Author: scrow Post Posted: Sat Jun 26, 2010 10:25 pm

My bike which was able to start but no longer may have a starter issue. I remember reading in the yamaha service manual that the tach contol unit will cut off the starter motor once the rpms reach a certain amount also that another circuit will cut of the starter if the cam shaft isn't moving after a few seconds of cranking. So what I am seeing on my bike is sometimes when I crank it will automatically stop cranking after a few seconds and most of the time the headlights will turn on after it stops cranking. In order to get the starter circuit to work again I have to turn the key switch off then on again. I know the engine is turning over since I can feel air out of the exhaust and I think the headlights only turn on due to the engine running. Is this normal operation for the starter circuit? Is this the cause of my bike not starting?

Last edited by scrow on Sun Jul 04, 2010 1:56 pm; edited 1 time in total

#2:   Author: totallyredvirago Post Posted: Sat Jun 26, 2010 10:35 pm

there is a rev limiter.. but that does not shut off the starter..
there is nothing watching the cams or the chains that will shut off your starter.
the headlight will come on after you let off the starter button.. this happens so the headlight is not on while cranking..
have you checked for spark?
it is possible that the side stand switch maybe at fault. first check for spark and then we can go from there....dan

#3:  Re: Starter circuit issue? Author: scrow Post Posted: Sat Jun 26, 2010 10:59 pm

I do have spark sometimes I am able to crank indefinitely but sometimes it cuts out after a few seconds and only works after a key switch toggle. I just checked the manual again and it says that the tachometer control unit will trip the starter cut out relay after the engine starts. It seems that this may be happening even though the engine does not start.

#4:   Author: 1986 XV700 Post Posted: Sun Jun 27, 2010 1:21 am

It took me a while to find out what the the purpose of the cut-out relay was and why the tach controlled it. Finally found what you were talking about in the Clymer manual.

"The starter cutout relay prevents damage to the
starter motor and gears by disabling the starting
circuit after the engine starts. After the engine starts,
a signal from the tachometer control unit causes the
starter cutout relay to switch OFF, preventing current
flow to the starter motor."

I doubt that the tach is kicking the cut-out relay out too quick, but the cutout relay could be going out. TRV probably has you on the right track with the side stand switch or its relay. They perform a similar function to the cut-out relay. The part that I find confusing is that you have to cycle the key switch. When the starter quits without cycling the key switch does:
The headlight still shine after you release the Start button?
Turn signals flash?

The reason I ask is the contact in the key switch that delivers power to the ignition (same for starter relays) also delivers power to the headlight and turn signals. That contact inside the switch could be dirty or corroded and building up resistance as it heats up and quits conducting until you wipe it again by cycling the switch.

#5:  Re: Starter circuit issue? Author: scrow Post Posted: Sun Jun 27, 2010 10:07 pm

regarding the side stand switch, in the closed circuit position i get about 1.5 ohms resistance at the switch connector (under the seat) which seems a little high. But the side stand switch is only necessary for starter operation if the neutral switch is not closed (plus you have to have the clutch pulled in). The side stand relay is essential for the ignition circuit but not for the starter circuit. As far as '86 is asking, the headlight does stay on when I let go of the starter button (as it should). I will have to check the flashing of the lights, but i have a feeling they don't flash. Looking at the circuit it seems the only thing that would cause this exact issue is that the tachometer control unit w/y wire is going high and staying high (causing the starter cut-out relay to open) until the power is removed from the brown wire on the tach control unit. Perhaps my tach control unit is simply broken. Does anyone know how the tach control unit works? thanks in advance...

#6:   Author: totallyredvirago Post Posted: Sun Jun 27, 2010 10:28 pm

side stand controls the TCI for spark.. the relays have to be satisfied and sends a signal to the TCI to allow spark.. i feel this is what is going on with your bike.. its turning over but spark shuts off.. you can jump the side stand switch on the harness side and see if the bike runs..dan

#7:  Re: Starter circuit issue? Author: scrow Post Posted: Sun Jul 04, 2010 1:55 pm

1986 XV700, your suggestion about the key switch was right on. Thanks... Now my bike is starting, not running correctly yet, but starting.

This is what I did, I repeated my issue where the starter stops working and then the headlight stays on. Then i checked the starter relay to see if there was still voltage (R/W wire) at the coil. It measured about 10 Volts which is low. And when i pressed the starter button the voltage dropped some but the relay did not close causing the starter to run. So i took a look at the key switch jumped the connector (headlight area) and the starter did not cut out. So i took apart the key switch cleaned the connections with scotch brite and some electrical contact cleaner. Then it worked as supposed to. Now I am able to get it to consistently start. So thank you all for your help.

#8:   Author: 1986 XV700 Post Posted: Sun Jul 04, 2010 7:54 pm

Glad to hear it. Are you starting to smile again? These issues can rob you of all your joy.

#9:  Re: Starter circuit issue? (SOLVED) Author: scrow Post Posted: Sun Jul 04, 2010 10:54 pm

'86 thanks for your concern. I was relieved that i got it to run again and did celebrate for a few minutes but if my joy were found in this bike I would be in big trouble. Fortunatly I find joy in my Savior. thanks again for your help.

#10:  Re: Starter circuit issue? (SOLVED) Author: scrow Post Posted: Tue Jul 06, 2010 9:57 am

Last night had the engine running (barely) then all of a sudden the electric shut down on the bike (as if the main fuse was blown). I found no fuses blown but did find a bad connection in the fuse box connector. This connector looks like it has aluminum contacts and both the male and female contacts on one position were rusted badly. I know the pros on this site keep saying check "all" electrical connection thoroughly, but I didn't. I checked only some of them and who knows how many hours I've wasted. My guess is that this bad connection which supplies power to about 85% of the bike (including the ignition system) is causing weak spark and thus mimics a fuel problem. Tonight I will jumper this connection and see if the bike runs better and more consistently.

#11:  Re: Starter circuit issue? (SOLVED) Author: scrow Post Posted: Tue Jul 06, 2010 9:19 pm

Okay that one connection from the fuse box was really bad amber brown from rust and probably sparking too. So now the bike starts up pretty good. The test will be if tomorrow it starts up again, and then again the next day. Still need to do the carb sync and mixture & idle adjustments, then hopefully it will run well and consistently. Thanks again all...
ViragoTechForum.com XV750 Starter circuit issue? (SOLVED)


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