Dad's 1978 Yamaha DT400

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

adray96

I'm Awesome
Joined
Jul 26, 2016
Messages
166
Reaction score
48
Location
Illinois
My dad had this bike since the 70s, and I have memories have him taking me around the block on this bike. Now that I'm of driving age, I've been wanting a bike of my own, but don't have money or a license for one, so I decided to get the Yamaha running. I started this a month or so again, but I figured someone might be somewhat interested, and I figured this would be decent way to document progress. This isn't so much of a "build," but more of me getting it running and I'm safe driving condition.

So, this is my dad's 1978 Yamaha DT400, street legal dirt bike.
You must be registered for see images attach
You must be registered for see images attach


Since it hasn't started I'm 3 years, I took the carb off and brought it to a buddy at work that is good with dirt bikes. He was pretty amazed at how dirty it was, and was more surprised at how well it cleaned up. He got bored and took it apart at work and filled the bowl with carb cleaner, and this was the result.
You must be registered for see images attach


I threw the carb on and my dad tried kicking it over to see if that'd be enough to start, unsurprisingly, it wasn't. We noticed the filter wasn't getting any fuel, and decided the petcock was clogged. I had to replace the fuel system on my truck, so the bike was on the back burner for a while.

Yes, I know I need a belt, but these were just some work clothes, and my appearance wasn't really a concern
You must be registered for see images attach


Now that the truck is running, though, I orders a new petcock, and took the old one off. That was definitely the problem.

My creative fuel drain
You must be registered for see images attach


Clogged petcock
You must be registered for see images attach


Clogged strainer
You must be registered for see images attach


While I have everything off, I'm going to take the fuel lines and filter to Napa to get replacements. Also on the list are new tires, the originals are still on it, new spark plug, battery, and possibly a carb rebuild. It probably should be rebuilt regardless, but I'm going to see how it runs first.




Sent from my iPhone using Tapatalk
 

adray96

I'm Awesome
Joined
Jul 26, 2016
Messages
166
Reaction score
48
Location
Illinois
Not much, but I pulled the tank off to check the insides with my buddy's borescope. I can hear rust shaking around inside, and a couple parts looked a little rough, but I'll probably hit clean it out and put it back on until it becomes a problem.

Any suggestions for cleaning out a gas tank?
You must be registered for see images attach



Sent from my iPhone using Tapatalk
 

skylark

I'm Awesome
Joined
Nov 15, 2011
Messages
7,836
Reaction score
7,653
Location
Grants Pass, OR
Pretty cool! There is an acid-based cleaner that I have used previously to clean out tanks. It also has a coating that you pour in and shake the tank around and it will seal the inside. Unfortunately I don't remember the name of the product right now.
 

adray96

I'm Awesome
Joined
Jul 26, 2016
Messages
166
Reaction score
48
Location
Illinois
I ended up using WD40 Rust Soak to clean the tank.
You must be registered for see images attach

I only bought a bottle, because it's $20 for one. I emptied the whole thing into the tank, and rotated it periodically while I soaked it for a few days, to make sure everything got touched. I rinsed it and shook it out with distilled water. While I was emptying out the water, I was able to pull a piece of the inside coating out.
You must be registered for see images attach

Probably not good, but I put the new fuel hoses together, and threw some gas into it anyway to prevent flash rust, we'll see if it'll start later.
You must be registered for see images attach


I also took off the battery try to Soak, since it was rusty as well. Then, I decided to torture myself by sanding it and painting it. A new battery will probably be the next step.
You must be registered for see images attach



Sent from my iPhone using Tapatalk
 

adray96

I'm Awesome
Joined
Jul 26, 2016
Messages
166
Reaction score
48
Location
Illinois
So, as mentioned in the previous post, some of the coating inside the tank came out, and I can see more inside the tank coming up. I was told about Red Kote gas tank sealant, and I'm going to try that, but does anyone have any suggestions on getting the rest of the current coating in the tank out?


Sent from my iPhone using Tapatalk
 

skylark

I'm Awesome
Joined
Nov 15, 2011
Messages
7,836
Reaction score
7,653
Location
Grants Pass, OR
5000 bb's. Put 1/2 of them in the tank and start shaking. I usually pour in some atf as well. Dump bb's, rinse with gas and repeat with the rest of the bb's.
 

__CHI__

Low Life
Joined
May 26, 2017
Messages
259
Reaction score
161
Location
Ohio
that's a sweet looking vintage ride my man! I've always loved enduros,especially the old but gold ones lol. Nice shirt BTW :cheers:
 

Dr.Zoom

Hi Tech Redneck
Joined
Jun 9, 2014
Messages
1,170
Reaction score
201
A friend of mine rides one. She had one back in the day and found another one recently. She loves it. She also has a grom, a multistrada 1200 and a handful of other fun bikes.
 

adray96

I'm Awesome
Joined
Jul 26, 2016
Messages
166
Reaction score
48
Location
Illinois
I went ahead and there the tank on as is, there's a filter/strainer on the petcock, and of course an online fuel filter, it should be fine for now. The bike still wouldn't start.

The spark plug was pretty fouled, so there was an obvious no spark, and I went ahead and orders a new coil and plug.
You must be registered for see images attach


I went to take the old cool off today, and there is a wire coming off of the old coil, that the new coil doesn't have, and is connected to the wiring harness. Not knowing what it do, I threw the new plug into the old plug wire to check for spark. I thought I heard something that sounded like a spark when I kicked it, but didn't actually see anything. I threw the plug into the motor and tried starting it, and still nothing. I gave up for a while to get get dinner, came back, tried checking for spark again, but didn't see or hear anything, so I need to figure out what to do with the coil.

New coil:
You must be registered for see images attach


Old coil with the wire
You must be registered for see images attach


Connection
You must be registered for see images attach


I thought about courting the black wire coming from the coil off, and soldering it to the plate in the new one, but I wanted extra input before I did anything.

I also decided to check the air filter, and oh boy...
You must be registered for see images attach
You must be registered for see images attach


So, next check will probably go towards a new air filter.


Sent from my iPhone using Tapatalk
 

adray96

I'm Awesome
Joined
Jul 26, 2016
Messages
166
Reaction score
48
Location
Illinois
Okay, I tried two different coils, and two different plugs, and the plugs won't fit into the coil. I feel like this may be a dumb question, but does that little pin thing need to come out of the coil?
You must be registered for see images attach



Sent from my iPhone using Tapatalk
 
Top