Possible electrical problem...high rpm's?

buckroseau

Hi,

New guy here, but have been lurking and reading for a several weeks now. Have a question that maybe electrical related, at least I think?

I have a 1980 Yamaha xs650 that I bought this winter to cut up and make a chopper out of it, which I did. The bike hadn't been started since 2001, guy said it ran, but needed carb work.. I bought the bike in January when it was 20 below and not hearing it run for $200 bucks. Once home this winter I cut it apart (still not even attempting to start it), fabbed up a new frame, seat and other misc. stuff. I emailed the wiring schematic to a buddy of mine who is an electrical engineer for Polaris ind. Told him to eliminate everything in the wiring harness, except the headlight, tail, brake and start switch. He email back the revised version, which I followed to the letter. I re-built the carbs prior to attempting to start it. Once I was done with the bike, I turned the key and it pretty much started right up.....everything seemed fine.

Anyway. Once out on the highway the bike seemed fine the first few days, no problems to speak of. Then after a few days it seemed to start to spit and pop and high RPM's....and that's where I'm at now. No matter what gear, when it tacks up on the top end of each gear it seems to start to miss? I don't think it is fuel, almost positive of it. The bike has and occasionally has run decent, but if it starts to get into this problem I have pulled the choke and it doesn't change a thing. It may also be occuring when the ambient air temp has been warmer, or when the bike warms up...but can't 100% confirm that.

I've thought of something in the stator? Timing? Ignition box? Coil? I'm at a loss here?

Just wondering if anyone else has had this problem? Also included a pic of what I built this winter and what I did with the wiring.

Thanks in advance, Matt

xsjohn

What do the plugs look like......

John

INXS650 · 650Rider Supporter Joined: Mar 22, 2007 Posts: 645

Does the bike still miss at higher RPMs if you sustain them? Not trying to full throttle accelerate, but say you get to 7K, can you hold it there and have it smooth out? What tank did you use for your bike. Love the look.

buckroseau

xsjohn wrote:

What do the plugs look like......

John

Just pulled them.

Left is a very solid dark brown on the ceramic, slightly sooty around the edge of the plug.

Right is a very light brown on the ceramic, slightly sooty around the edge of the plug.

Thanks, Matt

buckroseau

INXS650 wrote:

Does the bike still miss at higher RPMs if you sustain them? Not trying to full throttle accelerate, but say you get to 7K, can you hold it there and have it smooth out? What tank did you use for your bike. Love the look.

Yes, the bike miss's at higher RPM's if you try to sustain them...I would say very hard to hold 55 to 60 mph because the bike is back firing and popping the whole time. If you back off the throttle and back the speed down to 40 or 45 ish, it runs fine.

Tanks is off a victory vegas. I welded up all the vent, emission and fuel injection junk on the bottom, welded in a 1/4" pipe coupler on the lower rear and threaded a versitile swather sediment bowl. I like it also.

Thanks, Matt

xsjohn · Last edited by xsjohn on January 2, 2008, 9:37 am; edited 1 time in total

Right cylinder runs a lot hotter ......working up some kits to fix this problem......

What kind of filters do you have.....

John

buckroseau

xsjohn wrote:

Matt--Right carb is lean just like my 80.....The right carb on mine requires a larger MJ.....I use the stock air boxes 135MJ left carb---140mj right carb---sounds wacco but that's the way it is......

What kind of filters do you have.....

John

Hi John,

I will check the MJ's, but I think I am above 140 on both, can't remember? When I re-built the carbs I sized up on the mains and pilots because I knew I was going to be increasing the air flow.

Air filters are some fairly cheap ones I got from BW choppers. Nothing special, just a metal screen..no paper. So the air flow I think is moving pretty good.

Thanks, Matt

buckroseau

xsjohn wrote:

Matt--Right carb is lean just like my 80.....The right carb on mine requires a larger MJ.....I use the stock air boxes 135MJ left carb---140mj right carb---sounds wacco but that's the way it is......

What kind of filters do you have.....

John

Not to argue to much, but when it starts having the problem I have pulled the choke several times...with no change. So that is why I was ruling out the fuel delivery issue a bit??

Thanks, Matt

xsjohn

What I was getting at that maybe the right carb is lean and jetting would be different for that one....That is the way Mine is.....Not sure about the missing problem.....Ignition module or pickup coil or a weak magnet in the rotor or poor wiring connection.

I think everyone with an 80 should check the righ plug and make sure it is not lean...Thats why when you mentioned 80 I asked about the plugs.....

To big of MJ's would make it break up at higher rpms..........

John

buckroseau

Ok, not sure if we've moved passed electrical, but I think we still might be there?

I was working on the bike today, still same problem. I took the rotor off, cleaned it up and sprayed everything down with QC electronic cleaner....everything looked fine. I then was looking at the wiring harness and I may have had a bad connection between the coil and my new harness. I used a 2 wire trailer connector, cut, butt spliced, soldered a shrink wrapped everything back up. Took the bike out for a spin....where I live I have about 800 ft before I have to turn, so I tacked it up high in 2nd gear..only there for several seconds, but no popping or banging, which it had done earlier that day......I'm thinking problem solved.

So, as I turn the corner my neighbor is out for a walk. I stop and talk to him for about a minute, start the bike back up and lay on the throttle hard.....gravel road by the way. Rear tire spins as I am leaving, rpms went very high for a few seconds and then all of a sudden in a nano second it starts to pop and sputter right down to nothing. Took me about 60 seconds to get it to start again, but now it only seems to run on idle and when you try to give it gas....evening standing still...it just pops, sputters and backfires to beat hell.

Thought it may have got out of time some how, but I looked at this link
www.650motorcycles.com...iming.html and I think I am fine on timing?

I am clueless at this point where to go...you can barely get it to start let alone drive it now..even while at extremely low rpms.

Thanks, Matt

jayel

that's lined up at the top dead center mark if it's timed there is running retarded, it's supposed to be between the two hash marks at idle on both cylinders

buckroseau · Last edited by buckroseau on June 3, 2007, 11:55 pm; edited 1 time in total

Update:

Went out in the shop just now to take a quick audio/video clip so you guys could hear it....started up right away...rev'd if up standing still...popped, sputtered for 2 seconds and died. Won't start...pulled the plugs....

No spark now???

att

ttmaniac · Full Member Joined: Dec 22, 2006 Posts: 468

Don't use butt connectors. That is failure waiting to happen. Eliminate all butt connectors. Hard wire every connection with the exception of the stock connectors (I hope you have separated and inspected those already).

Did you use a "chopper" wiring setup? If so, is it properly grounded with a sturdy ground cable? A proper ground is key to electrical systems.

The other thing is carbs. I've ranted plenty about 20 year old stock carbs and their lack of virtue in my eyes. I've personally experienced this funky type of behavior with my bike and stock carbs. One minute, burning. The next minute sweating while trying to push a hot bike home on a hot day. Most guys don't want to spend the 300 bucks on the carbs, but lemme tell you, it is worth the money and takes some of the guesswork outta de-cludding and de-shadetreeing these old machines. Good luck.

buckroseau

ttmaniac wrote:

Don't use butt connectors. That is failure waiting to happen. Eliminate all butt connectors. Hard wire every connection with the exception of the stock connectors (I hope you have separated and inspected those already).

Did you use a "chopper" wiring setup? If so, is it properly grounded with a sturdy ground cable? A proper ground is key to electrical systems.

The other thing is carbs. I've ranted plenty about 20 year old stock carbs and their lack of virtue in my eyes. I've personally experienced this funky type of behavior with my bike and stock carbs. One minute, burning. The next minute sweating while trying to push a hot bike home on a hot day. Most guys don't want to spend the 300 bucks on the carbs, but lemme tell you, it is worth the money and takes some of the guesswork outta de-cludding and de-shadetreeing these old machines. Good luck.

Hi,

I do have butt splice connectors, but they are not the cheap plastic coated ones just crimped on. I have butt splices in areas where I had no choice but to add wire. They are bare metal, crimped, electrical soldered and shrink wrapped, should be an extremely solid connection.

Ground wire is same gauge as original, directly from the negative post to frame. And I have seperated the remaining stock connections and looked them over...they seem to be fine?

I will take the carbs into consideration, but I need to get my plugs sparking again. Just not sure where to start now, before I had something...now I have nothing?

Thanks, Matt

Xumi

buckroseau wrote:

ttmaniac wrote:

Don't use butt connectors. That is failure waiting to happen. Eliminate all butt connectors. Hard wire every connection with the exception of the stock connectors (I hope you have separated and inspected those already).

Did you use a "chopper" wiring setup? If so, is it properly grounded with a sturdy ground cable? A proper ground is key to electrical systems.

The other thing is carbs. I've ranted plenty about 20 year old stock carbs and their lack of virtue in my eyes. I've personally experienced this funky type of behavior with my bike and stock carbs. One minute, burning. The next minute sweating while trying to push a hot bike home on a hot day. Most guys don't want to spend the 300 bucks on the carbs, but lemme tell you, it is worth the money and takes some of the guesswork outta de-cludding and de-shadetreeing these old machines. Good luck.

Hi,

I do have butt splice connectors, but they are not the cheap plastic coated ones just crimped on. I have butt splices in areas where I had no choice but to add wire. They are bare metal, crimped, electrical soldered and shrink wrapped, should be an extremely solid connection.

Ground wire is same gauge as original, directly from the negative post to frame. And I have seperated the remaining stock connections and looked them over...they seem to be fine?

I will take the carbs into consideration, but I need to get my plugs sparking again. Just not sure where to start now, before I had something...now I have nothing?

Thanks, Matt

Take a quick look at your carb diaphragms through light.. Make sure you don't have any holes. I've seen the same symptom caused by this... and make sure your slides are moving freely.

buckroseau

Ok, this is where I'm at....took a little more extreme measures. I had my friend the electrical engineer from Polaris ind. swing out to my house this evening, same guy who revised my stock wiring diagram.

So, he whips out the multimeter and starts testing from 1 end to the other. He believes with a fair amount of certainty that my ignition box took a sh-t. He did look at that link of the TIP120 connector, and I was able to get one at radio shack today, but he said that part tested out fine and he believes that it is something else in the ignition module. At that point....new ignition module.

This is where I'm taking a different path in the road. When I bought the bike I didn't mention that I got a parts rig with it. Nothing fancy, in fact junk, but still parts... 1975 I believe. I rolled the chassis up to the garage, pulled the covers for the points and fly weights...looked great underneath there. At that point I decided that I am going to switch everything over to points. Maybe a stupid move on my part, but they operate independently of the everything else, so I won't have to worry about the iginition module. And, by installing the bushings in the end of the cam, I can switch over to a boyer ignition system if I want to I think. The price is right on parts for the points...the only thing I had to order from Mikesxs was the outer needle bearings in the cam shaft. I would have ordered the brass bushings, but he is out of stock Sad

That comes to my next question...anyone else have any of these bushings for sale? And if not, does anyone have any they can bust out a micrometer and measure the i.d. x o.d. and length. I have a lathe and could turn them down, but I want them to be accurate. I would prefer to just buy them though for $4 bucks.

Few pics of what I ripped out of the parts rig, and had a little time to cut and weld up a bracket for the new coils. Didn't have to cut anything on the frame, just the new bracket. I should be able to wire everything by tomorrow.....then I'm just waiting on those bearings.

P.S. Does anyone have a link to a stock wiring schematic for a 75....can't seem to find one. Not sure if I need that little black diode??

Thanks, Matt

buckroseau

last 2 pics

buckroseau

black diode??

jayel

check my album "jayels album" 74TX wiring should be same as 75 wiring

buckroseau

jayel wrote:

check my album "jayels album" 74TX wiring should be same as 75 wiring

Took a look at it...Thanks!

Quick question for you. I see on the 74 and the 79 diagrams you just posted they both have gray wires coming out of the coils. I have orange and brown.

Forgive the cheeziness of the diagram I made, but I think it gets the msg. across. I am running both my orange wires coming off the coils to the hot 12v coming from the key ignition. I am running the 2 browns to the condesors and then onto the points. The condesor wires are both black, so I'm guessing it doesn't matter there. The points have 1 gray wire and 1 orange wire. I assume if I have everything right it will spark, but if it doesn't run after putting the plugs in...switch the point wires around??

And of course..the coils are grounded by the mounting studs to the frame and points are grounded to the motor by the mounting screws.

Thanks, just want to make sure I have it right...

jayel

yes, and the condensers are also frame ground the wire color doesn't matter, difference between year or manufacturer, top set of points gray wire or orange goes to right side coil and cylinder if your cam is in right you won't be 180 out, your diagram is fine connections are correct

buckroseau

Otay....this is where I'm at. I picked up my cam shaft parts this weekend and got home this afternoon. Took about 3 minutes to install that brass bushing and outer bushing. Got the weights, rod and points bolted back in. Had the plugs out, turned the key....we have spark!!!!

Put the plugs back in, turned the key.....nothing. Swapped the grey and the orange wire coming out of the points.....started right up!! Did a little tweaking with the plate where it was running pretty decent and idled nice. Took it out on the highway tonight and wicked it up to about 70 mph...no misses or sputtering. So I am atributing that problem to the iginition box that eventually failed, because right now it runs pretty nice.

I do have a question though. I was reading the manual I have and it says to line the mark up with the "F" mark on the stator. I don't have an F mark on mine, only T mark. Wondering how I should handle this, for timing? Only reason I ask is because I think it could be a little more reponsive at the throttle.

And one other thing. Got a guy at work telling me that there is supposed to be a resistor of some sorts in the 12v line to the points to knock the voltage down. He's telling me that the points aren't designed to handle 12v and should be about 3 or 4v. I didn't see any resistor in the factory schmetatics? Should I tell him where to shove his advice?

Thanks, Matt

jayel

don't know how a resister would help coils are weak anyway, dropping the voltage won't help them, as far as timing goes the line on the rotor should line up between these two with a strobe at idle

buckroseau

Came home after riding the bike to work tonight, actually ran pretty good.

Hooked up the timing light and figured it must be pretty close since it was running so good. In the photo I marked where it was when I started timing tonight and where it seems to run the best. The plate with the points on it is pretty much all the way it can go clockwise. If I turn the plate all the way counter clockwise, the timing marks come into line, but it pretty much runs like sh-t on 1 cylinder? I played around with it a little tonight, but it seems to run the best all the way clockwise and then the mark is where I put the red mark. It actually started running worse after I changed it back where it was, kinda missing a bit and running on one cylinder, but seems to run the best when it's there.

Wondering what you guys are thinking now?

Thanks, Matt

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