Electrical Problem.

Pighuntingpuppy · May 26, 2019

Ok...So I got my bike back from the dealer after they did a valve adjust and carb sync. Bike runs phenomenal. So today....Decided to give it a run to my buddys place. 60 miles away. There is a hill that crests 7500 foot. This hill is on the interstate which is 75 mph. I was doing between 80-85 mph.Seemed like someone hit a power reduce switch going up this hill. I never lost speed. I had to give more throttle to keep speed. 3/4 the way up, the bike returned back to normal. For 12 more miles, there was no indication of a problem till I got off the interstate. Then the bike started bucking and jerking at lower RPM and speeds. The tach appeared to be dropping in relation to the bucking and jerking. Like someone quickly killing and restarting the bikes ignition switch. In town, I had to keep the RPMs raised so that the bike wouldnt stall. The bike did stall and wouldnt restart with the starter no matter where the throttle was. Since I was still rolling, I could pop start it. 1 block away, traffic came to a stand still, bike stalled and I had to push it off the road. Would not restart. So, I turned off the bike including the handlebar mounted kill switch. For kicks, I tried one more time to re-start. It kicked on and ran like nothing was wrong. At my buddys place, first thought I had was the kill switch. So I quickly took it apart and didnt really find anything that jumped out. I cleaned the contacts shiny to eliminate the kill switch as a possibility.

I started it again, filled up with gas and after a few hours went back home. The bike drove like nothing was wrong all throughout the 60 mile return trip. I get home, shut the bike off, open my garage and then start the bike up again. It started normally, idled normally....but no tach.

Since I happen to know this isnt coincidental, I am wondering if anyone has run into this and what would be the things to check? Would a tach prevent the bike from running right? Can something else take the tach out and cause the problems I described?

With the exception of the kill switch, where would be the starting point?

lonfu · May 27, 2019

Had something similar happen to me. Got half way home from the dealer and the electrical system started acting up. Had to pull over. Pulled the seat off and found that a connector had dropped down near the battery just out of sight so the mechanic missed it and the battery was not charging. Forget which wire it was but it was a single pole connector. Had to pull the batt, right there by the side of the road, to get to the connector. Look it over real carefully, it is hard to see it. It was running off the alt. when I had high rpm's then when idling tried to run of the batt which after a bit went dead. When I let it set for a while the new batt would recover enough and it would start again and run until I had to idle in traffic. That was the last time I allowed a shop to work on "The Beast"..... 1992

El Canadiense · May 27, 2019

Been a mechanic almost all of my adult life and this happens a lot. If a vehicle has been in the shop and then has problems shortly after; then look for the most obvious things right away in the area that the last person was working; like a loose battery cable, connection, carb intake boot or hose/cable not installed properly.

Pighuntingpuppy · May 27, 2019

roy saxton said:
Had something similar happen to me. Got half way home from the dealer and the electrical system started acting up. Had to pull over. Pulled the seat off and found that a connector had dropped down near the battery just out of sight so the mechanic missed it and the battery was not charging. Forget which wire it was but it was a single pole connector. Had to pull the batt, right there by the side of the road, to get to the connector. Look it over real carefully, it is hard to see it. It was running off the alt. when I had high rpm's then when idling tried to run of the batt which after a bit went dead. When I let it set for a while the new batt would recover enough and it would start again and run until I had to idle in traffic. That was the last time I allowed a shop to work on "The Beast"..... 1992

Thanks, I will look into that. Since this is a new to me bike, I dont know what the "issues" were before getting the bike. I put about 500 miles on the bike before heading it off to the dealer for the work. I put another 300 on it before this issue cropped up.

I did start it earlier today. Feels like it has a misfire. I have yet to pin it down to see which(if any) cylinder is misfiring. The dead tach though leads me to believe I do have something more serious than a loose connection due to studying the wire schematic and the tack also shares power with the coolant gauge. Since the coolant gauge still worked....I can eliminate that aspect of the circuit.

According to the wire schematic, the tach gets its reference from the #3 cylinder coil which is sent out from the igniter unit. I am presuming that since the bike will start and run right now, the pickup coil should be good. As a mechanic myself, I have never seen a pickup coil fail where it took just one cylinder out. Usually its a I'm working or not type part.

Another thing...I can hear the fuel pump operate with the key on. There is a wire from the #3 coil that goes to the fuel pump relay then to the tach. So...Unless the wire schematic is wrong, It is leading me to believe I have a dead tach. I will need to check the ground for the tach though since its the only part of the circuit I havent checked.

Pighuntingpuppy · Jun 1, 2019

Since this happened just a few days after, I just sent it back to the dealer to see what they left loose. Things happen so I am not upset. Afterall, I wrenched for a living myself and none of us are perfect. With that, I didnt do anything to make them think I was in there fiddling around. Let them look for their mistake and secure it better.

One weird thing....when I was loading the bike up, Figured I would see if the tach was still dead....It worked. So....I am betting a heat issue with a connector is the problem. I will post what they found when I get the bike back.

Pighuntingpuppy · Jun 7, 2019

One of my biggest pet peeves is when someone has a problem, asks for help, gets it then never replies what the fix was.

Well....here is what was going on.....When I bought the bike, the Vboost didnt cycle. Was told that the controller was dead. I did confirm that by cycling the ignition and never getting movement out of the servo. So....as some may recall, I asked about switches for the Vboost. I installed a 3 way on off on switch for the Vboost. When I did that, I left the controller disconnected for fear of a back feed. Well, the dealer, when they did the carbs and valve adjust hooked all the wires back up that they disconnected for the job. As I was right to leave the controller disconnected, the controller connected caused a back feed through the switch and into the CDI causing it to internally short momentarily.

So....There is a bonus to this....They disconnected my switch and hooked up the Vboost controller. The servo cycles and kicks in when it should now. Despite the dealer kinda pooching me on this one aspect, I can kinda forgive them for that since this bike runs soooooo well right now.

The dealership I went to for reference is Bobby Js Yamaha in Albuquerque. It is the oldest Yamaha dealer in the country being here since 1956. Overall reviews of the dealer are positive and I can attest to that. They filled my bike back up before giving it back to me. The initial repair for carb rebuilds and sync with valve adjust and LOF was under $1000. And they hacked off over $300 of the quoted price. They didnt charge me for the second visit.

Well, I hope this fix may help someone somewhere sometime if they took the path I did.

user 16790 · Jun 7, 2019

happy to hear you got it sorted

El Canadiense · Jun 8, 2019

I have seen people who are not mechanically inclined; find out there problem was a loose battery cable or they had the shut off switch on or were using their choke backwards and once they find out, feel a bit stupid so don't want to respond. When I bought my bike for $500, the guy told me he had hit something and it had a bad wobble. I took it for a ride and it did indeed have a wobble. The tires were finished so I bought new ones and after installing them, no more wobble. The bead in the tire had broke when he hit whatever he hit and that had caused all of his problems. Bad for him but lucky for me. The bike had $4,000 of hard to find accessories on it and has been one of the most reliable bikes I have ever owned and been as far as Guatemala.