Absolute Beginner at Rebuilding (1983 DOHC Seca 400/XS400)

I'll be honest. I've got no mechanic knowledge whatsoever. I recently turned 16 and bought my first motorcycle, a 1983 Seca 400. Heck, I haven't even ridden it. The bike starts up and everything seems alright, but I was informed there was an oil leak somewhere. The guy I bought it from included a complete gasket kit and 2 parts that I don't know (Picture Included).

Now to my point. My parents and friends do not know anything about motorcycles, and are unable to help me, I own a service manual for the bike, but have no idea what I'm doing, so I decided to grow a pair and ask online. The point of this post is a plea for some guidance on my quest to rebuild this bike. I'm extremely motivated and have always been interested in motorcycles, the problem is, I don't know where to begin, can anyone offer some guidance? Perhaps guide me through a process of restoring my first bike? I'd simply like to replace everything the kit provides, as well as learn a few basics. I'd forever be grateful. Thanks.

Well...the kit you have is a full gasket kit, those two little boxes hold piston rings . If you want to replace all of those it implies a complete engine tear down and rebuild. Check if it runs good first, check where the oil leak is, maybe the leak is just from a single oil seal or a loose bolt or something simple like that...and then if there are no other problems with it...enjoy.
Also check the fork oil seals, brakes (pads,calipers,master cylinder,lines...),are your tires good...?...BASIC SAFETY
Anyway, a lot of time,tools and money goes into an engine rebuild...so unless you are wiling to put time/money into it...
I do not want to discourage you here but it is a lot of work to make sure these old bikes run good and safe
Anyway ask on here and you will get answers...search the forum on specific topics and it should help
Good luck,welcome to the forum
....oh and pics of the bike is always appreciated

First, don't touch anything.. do a lot of reading. The manuals can be found here in the sticky or you can buy a manual. Read, read,read. Then go and get yourself a decent set of tools and a torque wrench

Jeff0133 said:

Well...the kit you have is a full gasket kit, those two little boxes hold piston rings . If you want to replace all of those it implies a complete engine tear down and rebuild. Check if it runs good first, check where the oil leak is, maybe the leak is just from a single oil seal or a loose bolt or something simple like that...and then if there are no other problems with it...enjoy.
Also check the fork oil seals, brakes (pads,calipers,master cylinder,lines...),are your tires good...?...BASIC SAFETY
Anyway, a lot of time,tools and money goes into an engine rebuild...so unless you are wiling to put time/money into it...
I do not want to discourage you here but it is a lot of work to make sure these old bikes run good and safe
Anyway ask on here and you will get answers...search the forum on specific topics and it should help
Good luck,welcome to the forum
....oh and pics of the bike is always appreciated

Click to expand...

Thank you for the replies! The bike runs fine, tires aren't cracked and have a good bit of tread left, turning signals and lights are fine. Just seems to be an oil leak. I will post pictures later today of where I believe the oil leak is coming from. Believe me, I'm willing to give it my all. Again, Thank you!

You can remove the side covers without messing anything up. First, I'd say to remove the cover that has the clutch cable connected to it. It's th cover that goes over the drive chain. I bet the leak is coming from the seal where the clutch push-rod is... that's a common spot.

If you remove the other side covers, be prepared for major oil loss.

The thing that is easy to forget IMO, is simply having patience. Don't start tearing things apart just to see what it looks like and just about everything can be checked without having to tear the bike down. There's tools that are available that you will eventually need to purchase. If th bikes runs OK, leave it alone. Get tools and a manual, fix the leak, learn how to keep the engine tuned up, do a compression test.

As someone who began in the same place you are I'll echo a few things here:

1) Download all of the manuals you can for your bike; pick up a Haynes or Clymer because they have step-by-step rebuild instructions.
2) DO NOT take anything apart without ensuring you have the proper understanding, tools, parts, and time to put it back together; if you take something apart you will want to put it back together while it's fresh in your mind.
3) Ensure it's safe! Check rotors, brake calipers (pads and seals), master cylinders, etc.
4) More often than not fixing one thing will expose another that needs fixing too. Be prepared for things to "go sideways" and keep your hopes up
5) You will learn from experience so enjoy the process of having no clue what something is, then reading about it or asking someone. You'll end up knowing way more about mechanics than you thought possible from a simple project!

Have fun with diagnosing and fixing the engine, you'll have a lot of pride for this bike once you've finished it

I will chime in here as well. I recommend fixing the leak and seeing if the bike runs ok before you tear anything down.
If the bike runs okay after you fix the leak then great, ride it as is for a while! Fix issues as they pop up (they will!) and acquire the skill and tools (little by little) to do so as you go along. Read manuals and ask questions here if you have doubts, problems or questions. By doing this you will give yourself a chance to learn how the bike works and how to fix things, hopefully starting with smaller issues and working up in complexity, without getting in over your head with a full rebuild right off the hop. Then if you decide later on down the line and the bike requires it you can to more comprehensive tear down and rebuild.

Good luck and keep us posted.

All your replies have made my week! Thank you for all the support!

The guy I bought the bike from said he thinks the leak is coming from this gasket here:

Any thing seem wrong?

I'm going to spend some time thinking and testing it all out, I'll get back to you all if I have any further questions. You guys are awesome! Thanks again

Honestly, that picture kinda scares me! I cant tell if youre talking about the valve cover or the head gasket. I cant tell if the head gasket was siliconed over or something? either way, you will need a torque wrench.

Top off the oil and let the bike warm up, give it a couple revs or take it up the street. Or you can just try to look for oil seepage.

Just noticed you have a DOHC model.. mine is SOHC so im not 100% about your engine.

NewHavenMike said:

Honestly, that picture kinda scares me! I cant tell if youre talking about the valve cover or the head gasket. I cant tell if the head gasket was siliconed over or something? either way, you will need a torque wrench.

Top off the oil and let the bike warm up, give it a couple revs or take it up the street. Or you can just try to look for oil seepage.

Just noticed you have a DOHC model.. mine is SOHC so im not 100% about your engine.

Click to expand...

Yeah... I forgot to mention I own A DOHC, I apologize. I was initially trying to show how the head gasket looks like it is (like you said) siliconed over. Does there seem like there's something off about the valve cover?

It's also snowing here, and I've got exams coming up. I'd like to dedicate 100% of my time into the bike, but I don't have a chance until the weekend or Christmas break

Anyways, I'll have to wait until the weekend until I can top off the oil and check where it's seeping out, until then. Thanks for all your help!

Hi Martin, and welcome to the XS Madhouse! Thing's to remember, when owning an old bike like our's, is "IF it ain't broke, don't fix it!" Meaning Don't tinker with the mechanicals, until you are having a problem with it! Another principle to consider is the K.I.S.S. (Keep it simple stupid) Meaning that find the easiest way of doing thing's before you pick up a spanner (wrench) or screwdriver.

After looking at the photo's you posted, I doubt that you have a top end oil leak, as you would have a brownish residue, around the site of the leak. If the engine is running well, LEAVE IT ALONE! Just top up the oil, to the correct level (sight glass, on the right hand engine case.) Start the engine and let it run, until the engine and oil are hot, then check everywhere, for any oil seepage. IF, you can't find any, just leave thing's as they are, and just enjoy riding your Maxim! Get yourself a good set of tools, and a torque wrench, then do all the reading you can about the workings of an ICE (Internal Combustion Engine) and in particular on motorcycle engines, I see from your original post that you have a workshop manual? I suggest that you read it from cover to cover, at least half a dozen times, paying special attention to the photo's, as they will give you visual cue's as what to look for IF you have to do any Surgery, on your engine! This is a good way of thinking as like a Surgeon, you will have to Diagnose the problem, and then to Operate on your engine, and to Transplant, the offending organ (broken part)
Have fun riding, and ALWAYS Ride Safely!

I myself own a 1982 Maxim, which has undergone some Surgery, over the last couple of years! Haha!

Merlin

Hello everyone! I thought I'd get back to you all on the bike. Winter break finally started, so I've got a ton of time to work on the bike. I believe I've found the oil leak too (thanks to all your tips). I may or may not have a small oil leak in the head gasket:

However, the main oil leak is coming from here:

I should've known by the oil stains on the exhaust pipe...
Anyhow! Anybody know where to start from here? I'd be forever thankful. Merry Christmas Lifesaver's!

looking at the pic
i would bet that lower oil puddle is just a drip down from the head gasket

You'll have to take the head off and replace the gasket, whilst being there,since you have the new piston rings...replace those,clean the pistons give the cylinders a good hone, maybe reseat the valves, reshim the valve buckets...here we go again....

Or maybe...just maybe hehe torque on the head is out of whack. ..retorque first....the four acorns on the head...

Hey everyone! It's been a couple months and all has been going well! I've spent the last few months carefully ready and soaking up all the knowledge I could about motorcycles, good news is, piston rings, gaskets, seals, all of them have finally been replaced! The bike now starts and behold! No leaking! I'm quite proud of myself, so thank you all for the tips.

I now have a new problem however, the bike runs better than ever, but the high beams don't work. This has been a problem since day one, but I honestly never thought I'd get this far, so onto learning electricals!

Here's what I've learned so far: The high beam wire was never connected when I got the bike, no bullet connectors or anything. Along with that, the original wiring seems to be changed, the previous owner seems to have found another way to wire the headlights. The "low beam" works fine, the high beam indicator doesn't turn on when the switch is flipped.

So, again, I'm here to ask for your help, could anyone tell me where to start? It could be the relay, switch, or the wires that are the problem. Obviously the previous owner didn't think it was worth the hassle to figure out what it was.

Thanks again Lifesavers!

~Martin

There is no relay, just the ignition switch, fuse, headlight switch and headlight. I'm not going to make any guesses, because I've seen enough butchered wiring on bikes to know that I'd just be mis-directing you. The manual has a complete chapter on electrical and detailed wiring diagrams...

not to be blunt but have you checked to see the high beam is actually not burned out? may require getting a new headlight but it could be that simple had that problem chasing my charging system seemed that all my hours of chasing wires and voltages was do to a faulty "new" rectifier that after I exhausted everything I ordered another one to find my problem solved with the newest one

Make A copy of the wiring diagram and trace/out/follow the circuit path of the particular item you need to trouble shoot.
Check for adequate ground
Old handlebar switches need cleaning,use dielectric grease on contacts
Check bulbs
Check fuses
Check wires for continuity as wires may be cut/Broken
Etc...
Good luck