Last year my bike was not charging the battery. If I start the bike up the voltage will read 14.3v then after 20 sec or so it will start to drop.
and at idle will only put out 11.8v to 12.1v if I rev it up to 4,000 rpm it only goes to 12.3v. After testing using the electrical testing print out
it indicated a bad stator. So today I change out the stator for a brand new oem and I did notice some of the sheilding on some of the wires
is flaking off. After starting it up again it is doing the same thing. voltage dropping after only like 20 sec.

Can a bad rectifier cause this? I was under the impression that when they fail they let out too much voltage.

Which year of R1 rectifier works with the least amount of moding?

check out the other (2) R/R posts going on right now...

If your battery voltage is at 11.8, I'd guess your battery has lost a cell... Test that first...

Mike

When I check the battery when the engine is not running it is reading at 12.65

I've had about half the batteries I've seen that fail say 12.5V when there was no load on them, but they drop to about 10 when there is load on them... I'd take it and have it tested... Any Auto Zone or ORieley's or wherever can do it for you for free...

MIke

Forgot to mention it was a new battery. Bought it last year and never used it. I kept it on a battery tender all winter

If the voltage is ever below 12v with engine running, I'd check the battery before buying anything...

Mike

I did that last year. I thought the battery was dead so I got a new one and it was doing the same thing.
Then after going through the trouble shooting charts it looked to be the stator.

I'm guessing it's your stator, too, but a stator costs $200+, and checking the battery costs $0 + a trip to town... I'd have the battery checked first.

Mike

Brand new stator I put on today. So brand new stator and brand new battery doing the same thing as old stator and old battery.

Did you get a new battery, instead of just testing this one you've had for a few months? If not, I'd still check that one. Seriously... it's free.

Mike

I will get the new battery tested. I only had the new battery a few months and it was kept on a battery tender the whole time.

I know that, but testing the battery is free, and faster than waiting for parts to come mail-order... I wouldn't tell you to go out and buy a new battery again, but if it's free to test, why not?

Mike

Just got back from thw bike shop. They tested the battery and it tested fine. They even gave me a battery they use there all the time to try and it does the same thing. The only fifferenec between the 2 are the one they gave me is a little taller (same brand yusa).

OK, then if you just replaced the stator, the battery is good, and the connectors are good and shiny, with no sign of corrosion or melted wires, that pretty much narrows it down to the R/R, I guess...

I ordered the '99 Yamaha R1 R/R from University Motors for like $48...

Mike

Hey mike, how much does it cost to have a battery tested at auto zone?

I don't know... I think it's free...

Mike

Jeez, get it over with, change the fucking R/R.