Hey guys I have a 1981 xs650 I had a charging problem, so I changed the rotor, brushes, stator, rectifier, and relay. That problem is now fixed. But since my bike will fire up no problem Idle like a champ but any throttle applied causes it to fall in its face and it won't climb past 2k on the tac even at full throttle. Thinking pick up coil or something along those likes any ideas?!
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Help!
- Thread starter TonyK
- Start date
As it's a new-to-you stator, that's as good a place as any to start. Test for ~700 Ohms on each of two pick-ups at the stator connector, then again at the TCI unit plug - maybe coil or broken wire.....
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Couple questions. Are the stator and rotor new parts or used? A new stator does not come with a new pickup far as I know... which means you used your old one... yes or no?
Similarly, a new rotor (Chinese crap basically) can definitely cause your symptoms. I'll elaborate more when we know the answer(s) re: new or used.
Similarly, a new rotor (Chinese crap basically) can definitely cause your symptoms. I'll elaborate more when we know the answer(s) re: new or used.
Thank you I'll grab a voltage meter and check on my lunch break
No one in the US or Japan currently makes a new stator or rotor. They're Chinese junk... if you'll pardon my directness.
Here's the first thing I'd suggest:
Start the bike and verify your problem is still there. If it is, disconnect the reg/rec, start the bike and see if it'll rev OK with it disconnected.
Here's a cut and paste from my rotor thread for some context....
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This all came from this thread. I'm including it here to hopefully help anyone with similar problems.
'81 TCI bike...
"If I ground out the green wire for one of the brushes the “slap test” is very good but the bike will not rev up (sounds like it hits a rev limiter anything past an idle). When I disconnect the ground for the green wire the “slap test” is bad (no ground to one of the brushes) but the bike revs up just fine. Ive also tried both of the regulators I have."
This is commonly known as the "weak magnet syndrome." The theory is that the TCI trigger magnet is so weak the rotors charging magnetism is drowning it out, causing the ignition to misfire.
More details....
"Wiring harness is chopped down to bare minimum due to this being a bobber build. Rotor is from mikesxs (slip rings continuity reads 5.3ohms off bike). Stator is also from mikesxs (phase wires read 1.0 ohms between all 3 white wires). One regulator is a mikesxs and one seems to be stock (no change between either one)."
I referred him to this thread where a similar issue was discussed.... and it's resolution here.
I rewound a TCI rotor and sent it his way. Yesterday I received a reply from him...
"Jim I received the part and recently had the time to install it. Problem fixed!! Ive taken the bike on 4 good rides and no issues. I can't thank you enough for the help."
Someone 6 or 8 yrs ago tried to clean up damaged slip rings on a Chinese rotor. Don't recall who it was.... @MacMcMacmac perhaps?
Anyway, when they chucked it up in a lathe, they cut through the copper rings almost immediately. "Paper thin" I believe was the description used.
The copper rings on the factory rotor are about 1.5mm thick... a fair bit more than "paper thin."
The gist of all this is that I believe the copper rings block most of (enough of) the charging system magnetism. Enough so that the TCI sensor (pickup) can cleanly read the trigger magnet, allowing both normal ignition operation and charging. The Chinese (Mikes) rotors appear to be hit and miss. Perhaps poor quality control on the copper thickness? Dunno...
But, this is the 4th case I'm aware of where a stock rewound rotor fixed a problem such as this, and as far as I know, no cases where it didn't fix this issue (with the Chinese rotor).
So don't throw away those factory TCI rotors. Ya never know when you might need 'em.
Here's a video showing the blocking affect of the copper ring. It was while I was testing for something else that I noticed it.
If you'll reread what I posted, it's the rotor that's the *likely* culprit, not the stator.
Getting good help from Jim.
What comes to my mind is what was happening before, and what diagnostics was done to come to the conclusion all the charging parts had to be replaced........Was the rotor tested, the stator tested, the Reg/rectifier, and what was the voltage at the battery when the bike was running and reved up.
Sure the pickup being changed over could be in a different place to factory due to the screw holes being out jut a hair and affecting the advance. Could also have damaged the TCI unit if the Reg/Rect was faulty causing a voltage spike.
Not enough back story for my liking. Could be chasing cats
What comes to my mind is what was happening before, and what diagnostics was done to come to the conclusion all the charging parts had to be replaced........Was the rotor tested, the stator tested, the Reg/rectifier, and what was the voltage at the battery when the bike was running and reved up.
Sure the pickup being changed over could be in a different place to factory due to the screw holes being out jut a hair and affecting the advance. Could also have damaged the TCI unit if the Reg/Rect was faulty causing a voltage spike.
Not enough back story for my liking. Could be chasing cats
Well, I can rewind your old one.... but we're jumping the gun a fair bit... let's find out if that's the problem first. My rewind is 105 bucks, which is a bargain.... unless it's not the problem. Then it just plain sucks throwing that kinda money away.
First, you need to try what I said above. Disconnect the reg/rec and see if the problem stays or it fixes it. Then we'll proceed from there... in an orderly fashion like Skull suggests.
