1982 Seca Project Newb

ksqrly

ksqrly

XS400 Aficionado
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Whats up everyone?
I am new to this blog and I recently purchased a 1982 xs 400 seca with dohc (dual overhead cams). I think I got this bike for a steal. I paid 300 and it runs...well kind of.

Battery
I picked it up today and jumped and it started right up, it . I popped it into first and it insantly died. I jumped it again and started it and kept it revved more this time and away I went. I made it a couple of miles and was really enjoying the new ride and then a came to a stop light and my bike slowly sputtered out and died. This kind of thing happened to me on my old bike and it turned out just to be a battery issue. Im not sure if this is the same problem can anyone shed some light???

Lights and guages
Also the front assembly with the speedo and tach and neutral light is big and bulky and ugly are these types of parts mostly universal? How hard is it to change these parts? What are the laws on turn signals, can I scrap those all together?

Upgrades
So the good news is that this bike walks all over my buddies xs400 that is a couple years older and only has sohc, but I love the idea of getting as much power as possible from a small engine. What are the best ways to get power gains from this bike not using a turbo or supercharger. Thank you.
 
Welcome the forum! Got any pics to share?

I'd suggest doing a search here for threads regarding carbs. Then you can start cleaning them, replacing diaphragms, and eventually get to jetting.

And clean the carbs, repeatedly!

Dave
 
Very aasy to replace the speedo and tach, got mine from mikesxs.net

http://www.mikesxs.net/product/03-0755.html

ended up bolting right onto the triple clamp, and both speedo and tach wire just screwed right in. Nice improvement, looks almost stock.

Should have trun signals, but can replace the current ones with smaller led ones off ebay, (watch may need resistors to make blink versus current higher drain bulbs), will screw right into the front light (same spot), and back ones have a hole in the frame to bolt to as well.

Enjoy your new bike
 
Awesome purchase, congrats! I love the Seca. And DOHCs are great engines.

If you have a multimeter, you can test the battery easily. Turn bike on. Check Voltage across battery. If numbers reduce to 0, then you've got a problem. But it's likely the carbs (it's almost always the carbs.)

Power upgrades are relatively limited. These are commuter bikes (although the Seca is a sportier commuter.) You can change your air box to pod filters - some people have tuning issues afterwards, as you need to increase the size of your jets, and the amount you have to increase by depends on things like altitude and humidity. Exhaust options are few for these bikes, but if your exhaust is original, and dented or damaged at all, a replacement will reduce back pressure and increase power (with a rejecting, again.)

Here is everything you need to know about your carbs and modifications: http://www.amckayltd.com/carbguide.pdf This guide is for XS650s, but the carb bodies are the same for the years. Just ignore the jet sizes - they're listed for a much larger motor.

All the cleaning information and adjustment and tuning is really good though. Enjoy, and ask questions whenever you get stuck.
 
Ok so here is my update. Battery is shot. So I got a new one. Now I am deciding to re wire the bike and chop this thing up :bike: I am building my own wiring diagram and I was wondering how easy it would be to find all the safety relays and blinker relays. Also I got stuck on the rectifier. I have a brown black green and red wire coming from the rectifier besides the three yellow ones the come from the stator. red comes from the battery Im guessing and the black is a ground???? and the other two are just a/c that comes in from the rest of the bike?? Basically I want to know what wires do what I get what the rectifer does but not sure what wires correspond with functions:banghead:
 
So.... you need the wiring diagram (available somewhere here on this site) and the parts manual, and the service manual (all available on this site.)

All of the relays are really easy to find. Lift your seat, and you'll see two little cubes attached to a crossbar near the front. Those are your clutch safety relay and your kickstand safety relay. Then, remove your gas tank, and feel underneath the spine of the bike. It's all open in there, and you'll find two more cubes. The long thin one is your blinker cutoff relay, and the squat one is your blinker relay (the cutoff relay turns your blinkers off automatically after rolling 100 ft., or counting 30 seconds while moving, whichever comes first.)

One thing to consider - you may want to get the bike running reliably before you chop it up. A non-working stock bike is worth a lot more than a non-working half done project, if you need to sell it.
 
Ok so I have been building my own diagram and I have a question about the voltage regulator and rectifier. Are they in the sam unit on the Seca. In the diagram that I have been using they are two different things and I cant seem to find a regulator on my bike but there is a green and brown wire that is coming from the rectifier. Thank you.
 
full


This is the diagram I am using.
 
Welcome to the forum. Hope you enjoy the dohc as much as I am.
Spend a lot of time reading the threads on here as there are so many really knowledgeable people who love to share.

I can recommend installing a $2 in-line fuel filter to keep your carbs in shape once you get them perfect. I've ridden mine 7,000 miles this year with no change in performance and no need for any adjustments - which I attribute to the filter.
Depending what kind of performance you prefer, you may want to consider changing the front sprocket - several good threads here on that.

You mention changing your gauges. I have a friend with an old Seca who may need a set so don't throw them away but offer them up for sale on here.
 
Here's your manual and wiring diagrams (I'm cross posting, as you've asked the same question in two places)

http://www.xs400.com/forum/showthread.php?p=46729#post46729

Different years are quite different. Regulator and Rectifier are the same on your bike. And I'm not sure about the tanks, but it may work. I'm planning a little experiment my self, so I'll let you know. Tank replacement means tossing your side panels too.
 
Hey I used that wiring diagram and built my own. What do you think? I think it should work but extra eyes are always a good thing. Thanks for the help everyone
 

Attachments

  • Wiring diagram 2.png
    Wiring diagram 2.png
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On this diagram the dim light will be on always even with the brights. Is this going to cause a problem??
 
and lou ranger I took off my gauge panel. you said you had a friend that might want them. They have a broken internal piece of plastic but it still work and looks good from the outside. Do you know somebody that would be interested? I preferably want to trade for other parts but I will always take cash.
 
LOL - I need to connect with Lou, who has a Seca parts bike for his Maxim. Actually, it would probably be easier for him to test fit than for me to ride up to test fit on the exact same model...
 
haha ok...Lou??? Also what do you think of the diagram is it going to be ok??
 

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