Breaking up @ 4500rpm

[NorazDad]

Thanks for helping me on this hunt. Yep Griz, I took the switch off yesterday and re soldered the the brown(it looked pinched) and the red white. But I didn't check voltage. The crazy thing is that the hiccup occurs at exactly the same point in warm up and run. I was able to set the idle and set the timing for five or so minutes and then took it for a test ride. The bike ran strong for about a half mile and then break started and then quit. What would it be that it happens at the exact same point in the run? I'm going to dig into the Reg/Rec today and look into a Mosfet.
I need to check AC out of the PMA, etc. I am going to try running battery only and see if there is some conflict coming from the charging system...but it is charging, maybe it is spiking somehow when it gets hot and setting the whole thing off. I hate to take the PMA out, but I may have to to check the windings and the routing of the wiring. It's crazy because this came up all of a sudden.
Thanks for your input and 2Many, fuel does not seem to be a problem, but I will check again. I did a flow test from the tank and through the carb bowls and fuel flowed fine. I've also had the carbs off and on and cleaned them numerous times as my previous posts indicate.
What would interrupt ignition at the same point in a run?

 

[peanut]

The part that mystifies me is that is surges like it really wants to take off and then stumbles. I'll get three r fur seconds of surge and then it stumbles and then surges and stumbles.
I believe I am goin to test the Pamco next.

surging is commonly caused by a lean mixture which could be due to insufficient fuel or excessive air ie a leak.
Try applying a little choke whilst the engine is surging and see if that corrects . The choke supplies an separate independant supply of fuel and air and is a useful diagnostic tool for tuning

With all that on and off of the carbs you might have damaged the seal at the inlet rubber to cylinder gaskets or at the carb clamps .
If your revs are slow to return to idle when the engine is hot, an air leak is likely I would think

 

[NorazDad]

Yes indeed I will try that test...if I ever get it running again. I installed new boots within the last year or so. I don't think there is any air leak. But if I get it to idle today, I will try the spray test as well.

 

[grizld1]

ND, a lot of things can act as you describe. The last time I went on a protracted gremlin hunt it involved fine behavior anywhere below 6500 rpm, at which point a misfire occurred. The misfire seemed worse at full throttle, so I violated my own Rule #1, which is IFF(Ignition First, Fool!) and played with the carbies. Then checked power delivery and coil resistance, installed new plugs, caps, and cables, installed some fresh wiring--on and on and on. For weeks. Finally decided to try a different Boyer ignition from my parts stash. The Boyer design is interesting, to say the least. The Hall effect trigger mounts in the camshaft, and the timing plate mounts on the edge of the ignition housing and covers it so that you can't see what's going on. The timing plate had warped concave, to the point that several solder pads on the back were worn where the rotor was making contact.

 

[NorazDad]

That's interesting. This I my second pamco. The first shorted out from my futzing trying to get it to work. I eventually had to cut the plate to make it advance. However, it eventually failed and I knew it because I blew the fuse over and over trying to find it, I found it and tried to fix it but couldn't. Ordered another one and it all worked perfectly. I am going to look at the PMA and the Reg/rec today. I may consider ordering another pamco and or a new mosfet. I'll find it. Thanks

 

[grizld1]

Before you spend more on the charging system, you might try removing the PMA stator and taking a ride on the battery only. A fully charged OE-type battery will give you a good 40 to 50 mile ride with no alternator.

 

[NorazDad]

That was my intent. I kicked and kicked, checked the kill switch and the brown and r/w, all fine. Decided to disconnect the reg/rec and it kicked over and idled for three minutes. Puteringear and rode off to die a half a block away. This time, I knew it wasn't fuel, carbs or charging system. I gotta say "Ignition". Don't know where. Cut and re soldered the connection to coil and to the sensor from the E-Adv. Inspected both sensor and blue unit for any signs of shorts or weak solder. None. Put all back. Kicked it and got a smokey two cycle rev puff and nothing. Something is not connecting right with the ignition. I have new wires and boots coming. Will change out and give it a whirl. Then if nothing improves, I will contact Pete, send him my unit for replacement for the new pamco combo. My battery after all this is still at 13.2...as indicated at all the brown, red, red//white, blue, etc wires that carry or distribute voltage. I think it's weak magnets or a bad sensing unit...and I am not going crazy on pamco, but it pretty much screams "I'm in your ignition, Dude!" So there. I am going to follow through, but I am going on Vacay for two weeks so it will be at least that long before I really know. And what the heck, it's a long cold winter here in ChiTown. Maybe I can freeze that sucker.
Thanks for this discussion. I really appreciate it. No one around me gives a flying crap about this old bike but me. So it's great to have someone to bang ideas off with.
Oh, and when I do my Tour de Illinois, I will be passing through Carbondale, and I will probably have you check the old girl out before I head back up along the Ole Miss. That is if I can ever get this bike running again.
Grace and Peace, Dude ...you can't be that Grumpy

 

[grizld1]

You'll be grossed out by the chaos in my old apple barn, ND, but I'm looking forward to your visit--plan on staying overnight, I'll show you some fine roads. Guys who think for themselves and also listen and work don't try my disposition. Those who get defensive and/or demanding or play yes-but games get my dander up. I've learned to shut up and let 'em natter.

 

[NorazDad]

Thought I had it...but alas. I read and read everything on the pamco and realized I only connected the black wire to ground at coil side of the E-Adv. So I ran a ground to frame from the sensor. Should the wire be grounded to both the E-Adv and the black coming from the sensor or just the sensor? (No) I ran the wire with ground only on the E-Adv side and the red, black and green from the sensor directly into the E-Adv.
Contacted Pete by email and no response yet. I think I will just shell out the money for the new unit with the sensor and the E-Adv and see if that's it. I can't even get it to turn over at this point.

Ok, reread the installation directions and fount that I had installed it correctly from the start. I had actually hoped that I had screwed up somehow, but I did not. I distinctly remember that the bike started and ran great when I installed the new unit last fall. Something died...probably the E-Adv unit.

 

[NorazDad]

What type of battery do you have? If it's one of those tiny batteries, then it's possible that it has lost it's ability to smooth out the power from the PMA. Another possibility is that the PMA is producing an erratic voltage, so if the battery is OK, try fully charging it and then disconnect the PMA and regulator and go for a test ride.

It will not start and when it did, it would not stay running for more than ten minutes.

 

[pamcopete]

It will not start and when it did, it would not stay running for more than ten minutes.

Nothing so far indicates to me that the PAMCO is at fault. If it started but then died, it could be that the battery is bad and just quit, even thoiugh you charged it. Try a standard full size battery, fully charged with the PMA disconnected

 

[NorazDad]

What's the magic going to be with another battery? OK WTF I'll try another battery...and a swap out pamco.
How can a battery cause a sustained failure when it reads 12.5 to 14+ all day. My volt meter is pretty spot on.
I've given it up. I'm handing it off to a pro. I'm only goin to tell you his name if he catches my gremlin.
In the mean time, I will contemplate a closed combustion system.
Grace and Peace All!

 

[pamcopete]

What's the magic going to be with another battery? OK WTF I'll try another battery...and a swap out pamco.
How can a battery cause a sustained failure when it reads 12.5 to 14+ all day. My volt meter is pretty spot on.
I've given it up. I'm handing it off to a pro. I'm only goin to tell you his name if he catches my gremlin.
In the mean time, I will contemplate a closed combustion system.
Grace and Peace All!

Not a good idea to change two things at once because if the problem goes away, you won't know which was the problem.

 

[NorazDad]

Well it didn't. We went to a standard PAMCO and a mechanical advance. Started right up. Ran for half mile and broke up and died. I thought it was in the blue box, but maybe it wasn't. I'm not dissing the system. I just can't find out what causes this break up. The bike is in good hands. If he can't find it...

 

[starkt]

I've been fighting what sounds like a very similar problem to your original one with my '81 breaking up above 4000 RPM. It didn't have to be under a load...it happened even on the stand. It acted almost like a rev limiter was kicking in. Ignition was my first thought, but after troubleshooting to the point of no longer having any spark at all, I had to step away for a couple weeks. I got back on it this last weekend and found the lack of spark I caused was due to a blown fuse in the ignition circuit. When troubleshooting, it seems I grounded the bare end of a wire that was somehow tied to the ignition circuit. I insulated it then started focusing on the plug boots, again, because they were my first suspect. They are the kind that pulse with light when the bike is running. I pulled the boot off the right side wire and the conductor that penetrates down the middle of the plug wire came out of the plug cap. I guess it was just pressed in. The same thing happened a few weeks ago before I gave up but the details are fuzzy. I pulled the conductor out of the plug wire and pressed it back into the plug cap with some pliers, then jammed the wire back into the plug cap. I started the bike, and after I remembered to turn the gas back on, it ran great, with no problem above 4K. I have some new NGK plug caps coming, but I've been over 40 miles as it is with no stumble. I'm almost certain a bad connection inside the plug cap was the issue, but the bare ignition circuit wire is still in the back of my mind...the chances of it being an issue enough to have caused a problem without blowing the same fuse it did are slim, so I'm betting the plug cap was the culprit. Good luck.

 

[NorazDad]

Ok, for anyone watching this thread, I have reached a most satisfactory conclusion. But it did not happen alone. I finally hit the wall and took it to my friend and genius Michael R Coffey at "Kiwi As, LLC" in Monee, Il. We went through all the steps I took and made some decisions concerning spark and carbs. Initially, we noticed an intermittent/weak spark and we suspected the electronic advance. So we replaced it with a mechanical auto advance (old school) and things went very well for the half mile or so that it usually did and then died. At that point I gave up an said I would leave it with him.
Solution!!! Michael completely cleaned the carbs and vapor blasted them and found the ultimate culprit: The o rings in the air/fuel mix. He dug them out and replaced them and then all was well.
I don't know why I didn't do that myself, but of course I assumed they were ok. Wrong. So now I am running a modified Pamco with a mechanical advance and I guess I never knew how peppy theses bikes could be when they were running right.
So, thanks to all the members who chimed in and to those who said from the start it was the carbs, you win.
Now I feel I have experienced everything carb related and I like the concept of running a mechanical advance. By the way, it timed right up and all is running fantastically.
Persistence paid off, but I did need help and got it professionally and expertly. Thank you Michael Coffey.
Now it's on to a total rehab of the front end.
Grace and Peace, All.

 

[grizld1]

Congrats! Keep an eye on that mechanical advance unit, though. It can be a killer when it goes rogue.

 

[NorazDad]

Other than the springs breaking or going slack, what else can go wrong?

 

[650Skull]

the weights wear in the cam slots, throws the advance off. If its a Yamaha original that is the usual culprit and its age related...........if its a MikesXS bought one then it could be a couple of issues. The main one was a problem with the rod/shaft that holds the weights breaking off. If you still have the E-advance then it should also work as the problem was carb related

 

[5twins]

If you keep the unit clean and lubed, and the advance rod well greased, it will last a long, long time. I've been running my original unit, first few years with points then with a Pamco, for more than 10 years. It does show some signs of wear but I'm still able to time the engine within the spec. I'm aware of the issue so I do check the timing every year or so to make sure wear hasn't "stretched" the timing curve and over-advanced the timing on me.

As mentioned, the usual wear points are on the little tabs that fit into the slots of the center disc, circled in red below .....

As the sharp corners on the disc slots cut into the weight tabs, that allows the disc to rotate a little more in the counter-clockwise direction. That retards the timing but also adds to the total amount the disc can rotate. This begins to make the total amount it can advance your timing grow. When new and unworn, the unit advances the timing 25°. That amount starts to grow (26°, 27°, etc.) as the unit wears. There are several ways to keep an eye on this. Obviously, you can do regular timing checks with a timing light. I'd suggest once a season or so. You can also look at the advance unit, at the alignment marks on it. There's a slash mark on the little disc and one on the backing plate. Unworn, these 2 marks should align pretty much perfectly. As wear sets in, they won't anymore. Here's mine and as you can see, the slash marks (yellow arrows) no longer align. Wear has caused my center disc to rotate a little more in the counter-clockwise direction .....

..... but as I said, I'm still able to time it OK, so I'll continue using it until I can't. Then it will be E-advance time (or another better advance unit).