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XR600R, Carbs or electrical?

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First, let me apologize for asking some of the same questions again... :thumbsup: I'm at a loss here, it's got me stumped.

As some of you know, I just rebuilt my '86 XR600R. All went well with that, though I've now got an issue that I just can't figure out.

The bike runs really good at times, and is very strong. Other times it will loose power, spit, and pop, backfiring out of the exhaust, etc. It's not predictable when this will occur, and it will do it hot or cold, but always at around 1/3 throttle or more.

The obvious thing would be to go through the carbs, which I have done multiple times, both before and after the rebuild. They are spotless, no leaks, stock jets, etc. (45 pilot, 122 mains both carbs) Everything is free moving, no sticking, no vents or passages clogged, no worn out parts, etc. I've flushed the tank out, cleaned the petcock, and put new fuel line on it.

The airbox is clean, filter is a Uni filter, side panel isn't opened up, it's all stock.

The fuel and air system *should* be near perfect right now, I've gone over everything multiple times.

The problem still remains, and is still not predictable. The only thing you can count on is that even when the bike starts acting up, it'll still idle all day long and run just fine just above idle, both sitting and riding.

So that leads me to believe that the problem may indeed be electrical. I've had coils fail, but they were more predictable. When they get hot, they stop working, they cool off and start working again sometimes. I've never had a stator go out, but have worked on bikes with a bad one, and it was just dead, no spark at all.

Is there somewhere I can find the tolerance on the stator and coil so I can start checking them with a meter?

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I had a similar problem when I got my 600. It would break up around midrange and above regardless of throttle input(clue #1) and no amount of screwing with the carb would get it to change(clue #2). You know what the problem was? A loose connector on the coil would vibrate and break connection intermittently above a certain rpm. I pinched the connector down for a tight contact and the problem immediately went away.

I don't have an '85-87 XR600 manual, but my '88-90 says this:

5a8f5ed5.gif

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Hmmm... Maybe I'll take the time to go over all the electrical real close and check connectors and such... :thumbsup:

I found the same manual, wasn't sure if the specs would be the same for the older bikes though. I'll check it tomorrow and let you know what I come up with!

Thanks for the tip!

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Ok, double checked everything this morning... Here's my findings:

Stator (Ignition) - 271 Ohms

Stator (lighting) - 0.58 Ohms

Coil (Primary) - 0.7 Ohms

Coil (secondary) - 4.14K Ohms (no cap)

Pulse Generator - 392 Ohms

These were all done cold, hadn't started the bike since yesterday. All the wiring and connectors look fine. The connector for the pulse generator was questionable, but I checked it and it wasn't shorted or open anywhere. I did clean up up and double check it again though, it's still fine.

Going by the specs from the manual, and what I've found on the bike, I think I'm going to change the coil and see what that does, since it's pretty low in the secondary winding.

Anyone else agree, disagree? :ride:

Now if I could just find a good coil to try... Gotta go check the old parts bikes out back... :thumbsup:

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If you can do a check when hot. The numbers should go up on the stator due to heat. If they go down it is reason for concern.

Doing what HeadTrauma suggests is a good idea when any electrical issue is a possibility. I have had the same bad connection problems with several bikes. It's a generic issue with older motorcycles.

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Ok, update... I found another coil on a little four wheeler in the pile of junked bikes, checked it, and it too checked low on the secondary coil. A little lower in fact. Maybe it's not the same, who knows. I tried it anyway, and it started and idled fine, let it warm up and took it down the road, it ran great! A few miles later it started the same old popping, cutting out, etc. Came home, started pulling it apart again, then took a break and checked for replies here. I went back out and checked the stator with it hot, and it's up to 330 ohms now, was 271 cold. I guess that's a good thing right?

I pulled the plug out again, double checked the gap, it's right in the middle of specs. It's a nice brown/tan color, a little black around the outside. Definitely not lean, looks ok to me.

Should I assume that the coil is indeed bad, and the one I tried was either not the same, too weak, also bad, or something else to that effect?

I'll try to buy a coil if I have to, but it'll be a little while before I can. (broke again... :thumbsup:) I was hoping to nail it down in the meantime, even if I can't fix it, I'd like to have a good idea of what's wrong and a plan of action... :ride:

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After replacing my stator and pulse generator on my 87 I found my CDI was the culprit , my bike was not showing quite the symptoms your is though, mine was hard starting , would run , idle , and seemed to be week all throughout the power,and after a short time 4-5 minutes it would just quit. now it starts 2 kicks and rocks !!!!!!. Great power !!! what a 600/630 should be. Hope this helps.

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We can omly guess at the cause not knowing whether your checks have been good enough. Only real way to eliminate the Coil is by replacement with a good working one. Have you had the Stator off the bike and checked the wires that run from it to the point of connection on the wiring loom. You really should have a good look at them to make sure theirs no half break somewhere in that circuit that may be vibrating and giving you a bad connection at certain times. They do have a habit of getting pretty weak and flimsy after a while of being bathed in all the oil and heat of the actual engine..So in essence,,It's all guesswork on our part..My move would be to get the Stator off the bike and check it's wiring ..ie..unwrap or slice the plastic type covering which covers the Stator wires between the Stator windings and where they exit the motor .That does not mean you slice the actual covering over the copper/metal..just the outer covering so you can get a look at the wires themselves..otherwise they are hidden from view. .So go from the Stator to about 6 inches up from the point where that rubber oil sealing type grommet sits in the motor and make sure they are all solid and not hanging together by a thread..I've sort of said it before but an ohm meter may give you a correct reading but thats no good if the bikes vibrating and carrying on and your wires are half poked,,Ohm will say good at engine stop..but vibration changes things..The eyeometer on those wires is a more thorough check imho..

Edited by Horri

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I will certainly pull the cover off and stator out to check it better. I haven't yet.

Can I lay the bike over far enough so it doesn't loose all the oil? I literally just changed it yesterday since the rings are breaking in. I thought it couldn't hurt to put some fresh one in... :banana:

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Yep...Just lean it over..needs to go a fair way to avoid spillage..Your choice on the change..I wouldn't bother if you've just done it,,.And as scotty2fast says,,Don't rule out that CDI..XL600,,,.250(XRXL) or an 82 XL/XR 500 one does as a replacement,,,In fact just about any XR/XL CDI will do from 79 up.,,their's .minor differences in the wiring plugins but thats not a major to an onto it person.....650 ones are no good though..they are different electrically..also wouldn't go for anything in the 400 department,,not later models anyway.

Edited by Horri

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I just went to a buddie's house and took two more coils off some old Honda 3-wheelers, that look identical the the one on the 600. They both measure close the the same as the one on the bike now. (4.9k and 4.7k ohms) Is it time I start checking my meter? :banana: What are the odds I've got 4 bad coils here?

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I just replaced my Pulse Generator...it was measuring O/C. The old Pulse Generator now reads okay on the bench...so obviously it is intermittant. However...this is weird...the bike still will not start. Weak spark...just a brief sign of life when cranking is all. I did notice that the Pulse Generator gap was fairly large...possibly ~1mm instead of specified 0.7mm.

However I didnt think it significant for the purpose of triggering the CDI. It would be a coincidence but could I have CDI failure? Or exciter winding?(measures correctly at 90 Ohm)

Interested in any comments...Roger

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I just replaced my Pulse Generator...it was measuring O/C. The old Pulse Generator now reads okay on the bench...so obviously it is intermittant. However...this is weird...the bike still will not start. Weak spark...just a brief sign of life when cranking is all. I did notice that the Pulse Generator gap was fairly large...possibly ~1mm instead of specified 0.7mm.

However I didnt think it significant for the purpose of triggering the CDI. It would be a coincidence but could I have CDI failure? Or exciter winding?(measures correctly at 90 Ohm)

Interested in any comments...Roger

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Yes your CDI could be your only problem, it was for my 87. But theres no way to test the CDI, through process of elimination is how I figured it out. The CDI gets heat soaked and fails to do its job. And if its weak to begin with like mine the power output suffers as well.

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In doing a little more research, the shop manual for the old 200 three wheelers that the coils I got today came from specify that the secondary winding should read close to what all three coils I have hear are showing. That, and the fact that they look identical to the coil that was on my 600, along with the fact that it was put together by a guy that does a lot of work on 3-wheelers before I got it, leads me to believe that my problem is in fact the coil. Not that its bad, but that's it's the WRONG ONE! :banana:

I'm going to buy a new coil later on and see how it works out. It'll be a little while (couple weeks probably) before I've got the cash to buy it though. I'll update once I do!

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Ok now I'm thoroughly confused... Further into the manual where it talks about the coil, it says that I should measure 7.4K - 11K WITH the cap, and 3.7K - 4.5K WITHOUT the cap. Obviously this is because of the resistor in the cap. However, it contradicts what the manual says at the beginning of the chapter about the electrical, which was posted previously in this thread. A typo in the manual perhaps?

I've been testing these coils without the cap like the first part of the manual says, and looking for 7.4K - 11K Ohms which is what they spec there. However, taking this new info from the other page which I'll post here, all the coils I have, including the one on the bike, test fine. Now I'm really stumped.... :banana:

coil.jpg

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Scotty...I definitely had a faulty Pulse Generator(it measured O/C) and hence paid A$73 for a replacement...This bike is super reliable and I assumed this would fix it...however still won't start (wimpy intermittant spark). Will post back here when I find the problem..but it may take some time as I may have to psych-up for a CDI.

Sorry to hijack the thread but I did think my problem is relevant...

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Convinced that the coil is good going by the other specs I posted, I turned my attention to the stator. I pulled the cover off, pulled the stator out of the cover, and checked the wiring from it, all the way to the CDI. Everything looks great, no weak spots in it, measures good, even with wiggling/pulling the wires. I put it back together, and just for fun, pulled the carbs apart again. I found a big piece of trash in the main jet on the secondary carb. Great! Found it! Right? Put it back together, and it ran great for about a half mile, came home, pulled the carbs yet again, they are clean. Back to the old mysterious problems that I just can't seem to find...

I'm really at a loss here. I've checked everything... Carbs, airbox, filter, stator, pulse generator, coil, etc. The only thing that's left to try is a CDI... I really hate to spend the cash on one though, just to see if that's it. I've got a buddy with two XR250Rs, an '82 and a '94. Will one of those work long enough to test? I'd rather it be something a little cheaper than the CDI, but I would be so very happy to find out that it was the problem, 'cause then I could change it and go riding! :banana: At this point I'm out of ideas and options...

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Convinced that the coil is good going by the other specs I posted, I turned my attention to the stator. I pulled the cover off, pulled the stator out of the cover, and checked the wiring from it, all the way to the CDI. Everything looks great, no weak spots in it, measures good, even with wiggling/pulling the wires. I put it back together, and just for fun, pulled the carbs apart again. I found a big piece of trash in the main jet on the secondary carb. Great! Found it! Right? Put it back together, and it ran great for about a half mile, came home, pulled the carbs yet again, they are clean. Back to the old mysterious problems that I just can't seem to find...

I'm really at a loss here. I've checked everything... Carbs, airbox, filter, stator, pulse generator, coil, etc. The only thing that's left to try is a CDI... I really hate to spend the cash on one though, just to see if that's it. I've got a buddy with two XR250Rs, an '82 and a '94. Will one of those work long enough to test? I'd rather it be something a little cheaper than the CDI, but I would be so very happy to find out that it was the problem, 'cause then I could change it and go riding! :banana: At this point I'm out of ideas and options...

Keith,the XR600R is nortorious for bad OE stators,,almost every time i`ve seen people on this forum with weak spark,or quiting when hot it`s the stator...doesn`t mean it`s that for sure,,but if it runs fine cold and like shit after warming up i`d be checking that stator really close..

Brian

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keithluneau wrote"""

I've got a buddy with two XR250Rs, an '82 and a '94. Will one of those work long enough to test?

The 82 one should work..As I said previously just about any of them will work. The difference is in the pin arrangement of the plug on the wiring loom and the pins on the body of the CDI,,Some of them lie this way ---- some this way |. Take yours to your mates and check,,It's all just for ease of connection as to why you want the right one..I mean who wants to frig around with wiring if you don't need to. If the pins match just plug it in...if not you will have to get a new plug for the loom and wire it in ..Thats why you need one with the same pin layout as your original..ease of connection,,Nothing else..

The real difference between them is the 250 CDI's allow you to rev the bike higher,,thats why some people use them..They will not blow your bike up or anything..If the pin layout matches it'll be just the same as your original but you will be able to rev the bike higher,,No danger whatsoever of anything untoward happening..I use them on a couple of my 600's and have never blown anything up through over revving them,..No need,,just ease off on the revs if you get concerned about possible explosions..or simply change gear upwards..If you can't tell when a bikes screaming change up or ease off then you shouldn't be riding one..

and "you" doesn't mean you Keith..refers to people in general..

Edited by Horri

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