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Sorry Mark. I did wonder if that's what you meant. No offense intended. Who, me, oversimplify? You must have me confused with someone else. 8)

A lot people seem to be intimidated by electrical issues so perhaps I feel like explaining things the way I do helps remove some uncertainty.

I'll just shut up now and go back my Crayons and coloring book.

start unplugging stuff

You can also do the reverse. Start with everything unplugged except for grounds. Begin adding components to the system one at a time until plugging something in creates high amperage load. This method allows you to take your time and not worry so much about burning anything. Once you identify and eliminate the short circuit I recommend testing the resistance of the affected wires. A quick online search will give the desired resistance value for the wires based on gauge and length. Replace any wire you find to have an incorrect or floating value.

Great looking bike; by the way. Please post more pics or even consider adding a build thread. Thanks

I only got to ride it 15 miles before it seized

Just curious if you were able to identify the cause/source of the seizure; and, if so, what was the resolution?

Great looking bike; regardless of paint finish. This has always been my favorite color scheme of all of the 400s. Besides, I appreciate the irony of a 2T being presented as Green. 

Beautiful bike. Very tastefully done. Great balance of form, function and mix of shiny bits.

Ok, it's been a while since the last update but things are getting back on track.

have you ridden the bike before stripping it down?

Yes, the bike ran but had no power. This started the snowball effect that finds me doing an engine build in the middle of 10 other projects.

I'm interested in your engine plans.

No real deviations from anything posted previously; but, if you have specific questions, I'm happy to oblige.

After a lot more research and further discussion with folks who have probably forgotten more than I know about 2 strokes, I've nailed down more details. Since the crank is coming apart to install 400 rods I decided to take the opportunity to upgrade the bearings. I'm going to run Suzuki #09263-22060 on the big end of the rod. These come with a weight penalty due to the greater number of longer rollers. To mitigate the increase in bearing weight, and benefit from an overall lighter rotating assembly, I'm going to use hollow crank pins Kawasaki #13035-1010. See the attached pics to get an idea of differences in mass. I make no claims that my Amazon Warehouse sourced, amateur pharmacist type scale is accurate; so accept these values as reference only. The solid pins shown are Pro-X and not OEM Yamaha but should be representative enough for this exercise. The differences may seem negligible when static but since weight multiplies by the square of the RPM I felt that any practical reduction in rotating mass would pay dividends. Overkill for a mild street bike? Probably; but I could see swapping to a hotter top end at some point. This crank should handle anything I subject it to for a very long time.

As as aside, the Spec II Classics arrived. I was warned that Gary's 3 week delivery estimate translates to 6, in real time, and found this to be the case. However, he does build some sweet pipes; so, worth the wait IMHO. Sure wish he'd do them in a 300 Series Stainless. We discussed it but he's having none of it. Old dog/new tricks/no bueno. I'm happy to see Garrett doing his in Stainless.

[CLEAN!!]

I picked this up earlier in the week form DemoDrew for my granddaughter. Thanks again, Drew; for the smokin' deal. (See what I did there?) Man, you just don't run across 29 year old dirt bikes in original condition like this very often. And, when you do, there typically cost prohibitive. This thing is CLEAN!! One owner, racer/enthusiast maintained, needing abso-f'in-lutely nothing and at a fire sale price. Starts right up cold or hot and runs, well, like new. My granddaughter is going to love it!

Quick update. Got the motor stripped and ready to pull from the frame. A lot of the new parts have arrived. Just waiting on pistons to show up so I can box everything up and send out for boring, porting, head work and cylinder plating. I ordered Spec II Classics from Gary and with a bit of luck everything will arrive back here about the same time. This project has had good momentum up to this point and my goal is to keep that going. 

After discussions with a couple of folks much smarter than me, the decision has been made to do a +5mm longrod conversion, corresponding Banshee pistons, fresh bore and Nikasil cylinder plating. As such, these have been added to the list of short term goals.

Thanks goes out those of you that have offered suggestions, wisdom and even a derail or 2. Please keep it coming. Overthinking is a big character flaw of mine and the flow of solid information helps me keeps this project moving forward.

Also, a couple of sections of old bicycle inner tube with a wrap of electrical tape or a ziptie make great carb slide/needle condoms. I hate to admit it but I have had several bikes in a suspended state of animation for a year and sometimes more; getting wheeled around to different spots in the shop. Having all manner of junk get piled up next to, around, and even on top of the neglected project. A bit of protection for the relatively delicate and vulnerable carb slide and needle goes a long way. Trying to jet a carb with a bent needle ranks very low on my list of ways to have a good time.

Ok, the detour was fun; but, back to the build. I got to spend some shop time the last 2 evenings. I got the top end pulled and cleaned and in doing so, I got to revisit a couple of tips I came up with many years ago working on previous bike projects. I though I would share as some may find these trivial bits as useful as I have.

Those of us living in humid climates know that storing a 2 stroke bike without pipe plugs is a big no-no. Worse yet, is storing a bike with no exhaust pipes. Some guys stuff their exhausts using rags, plastic bags, expandable freeze plugs, etc., etc. This is what I found to work well for me.

I had to make a new one as my original was over 20 years old and made from an inner tube I got from the landfill. It blew out as soon as I put a few PSI in it.

You cut up an old bicycle inner tube, tie the ends up with some insulated bell wire and you have a dedicated exhaust stuffer.

to totally derail this..

my father, who is currently 81, always had a centerfold or 2 up in the shop. he still does have miss 1964 up, im serious. and a fresh new calendar every year at the back of the shop. never hid it, didn't care, mom was ok with it. Funny when i was a kid and my friends would comeover and be like 'boobs!' and i'd be like 'so?' 

It's the white knuckle grasp of conservative, Puritan/Christian sexual oppression that has this country so up-side-down when it comes to openly dealing with human sexuality. Europeans don't have this problem. South and Central Americans don't have this problem. Australians definitely don't have this problem. Hell, our Canuck brothers to the North don't even have this problem. 2021 and the most powerful country on the planet still struggles with open discussion of the basis of human existence. Go figure...............
(steps down from his soapbox)

On a side note, I realized I still haven't solved my wiring woes.

You may want to check/clean ground connections and reinstall with some No-Ox. Then, using a meter, Ohm out the wires in the part of the harness causing an issue (looking for a floating value). If more than one part of the system is faulty (say lights and ignition as opposed to just lights), it's most probably a bad ground. Very little chance all of those wires failed at the same time unless there was a meltdown; in which case, the issue can be identified visually. Electrical gremlins are only an unknown until they become known. I like to know. Using process of elimination, you can identify the issue every time. Buying a used harness is a gamble as you may inherit someone else's issue/s without ever knowing what yours was to begin with.

And this to be wisdom:

Those go on the inside of the cupboard and cabinet doors 

Well, I did say "Suggestions are welcome and wisdom is always appreciated".

As such, I find this to be a suggestion:

Nice, I like it!  It always bothered me the amount of wasted wall space on the back of the garage door.

thats where you hang the nudie pics.