Wes, copy and paste it in word or another such program then you can save it as well as print it.

Thanks Tony that’s what I did worked perfect printed it out you can’t have to much info on these old bikes. 

Brzn do you have a good name brand battery mine has a cheap Walmart battery so that could be my problem also

I have seen this problem listed on the forum many times in the past. However i have never seen a person come back with a solution or answer to what fixed there bike or if they ever did fix there bike? What everyone do, just live with it?  

Sky mine works fine with the engine running I really haven’t dug deep since they work when running 

Ha, I'd been working on my GTO the past couple days, sorry. Let me answer the posts and let you know where I'm at now.

RT325, Yes my taillight, brake light and flashers are all DC and run off the battery. The bulbs are good quality Sylvania bulbs and I've blown 5 in less than 1,000 miles, the taillight filament isn't touching the brake light filament.
You may have helped considerably! Key in position 1 front and rear brake switch will light both filaments. Where do I go from here? What do I start checking?

Bill, 1971DT250, I've contacted DEET again and have him building me a new wire harness and a new wired front brake light switch. The 50+ year old wires are shot as shown below.

The grey sheathing around the two harnesses coming up into the headlight bucket from under the left side of the gas tank were cracked open when I purchased the bike. I wrapped the lower piece with Duct Tape and have a piece of fuel hose zip tied around where the break is on the upper piece.


The insulation on one of the wires from the Flasher Relay was split through. I'd wrapped it with a piece of Electrical Tape.


The sheathing on the front brake light switch wire is cracked.


Who knows, wires under the insulation could be damaged where the cracked sheathing is, or anywhere else inside the harness. At it's age and condition, I figure it's best just to replace. DEET did explain to me that, in fact, todays wire is much more heat resistant than what was used on our bikes originally.

PEDALCRAZY I can see the wires okay in my garage. I did use a nice LED flashlight when putting everything back together so I wouldn't mix the wrong connections.

HT1KID Does the same with the bike running or off. The battery's a good one, Parts Unlimited, that came directly from the company since the shop I'd bought it from didn't have it in stock, it should be fresh and was recommended by DEET. DEET said the Yuasa batteries sometimes aren't fresh. The one year old Yuasa would charge to 6.44 volts and drop to 6.31 in 24 hours. The new Parts Unlimited battery stays closer to 6.44 volts for more than 24 hours after fully charged.

MARKT Thanks, some great information on trouble shooting electrical issues! The issue doesn't resolve reving the engine.

JAMMYYAMMY The flasher Relay I'd purchased is a NOS Yamaha one of the correct part number. I checked voltage everywhere I showed in my original post, but not wattage.

I would bet you would find the neg. problem in the harness by the steering neck. Lots of flex there over the years. Your new harness will probably fix your problem.

Brzn,

Be sure to let us know if your new wiring harness fixes your issue. I'm not convinced it will but hopefully after spending the money and time replacing it your good to go. If it does then you will still need to dissect the old harness to pin point the issue. Fingers crossed. 

Does look like a negative problem, or lack of negative & trying to find Neg anyway it can. Just my guess. I've even seen problems with the piece down in the bulb socket where the bulb touches the terminals.