1978 Suzuki GS400 Build - Help and advice is much appreciated!!!

G

gob_bluth

New Member
I picked up a 1978 GS400 because I wanted a project and a cheap bike. I have little mechanical experience (oil changes, brake jobs, tune-ups), but I was a carpenter for years so I have tons of tools and aptitude. I have a decent budget but I'd prefer fixing and machining things over buying cafe parts. I want to be able to say I built this thing when its all said and done.

It does not run yet and I've determined 2 things. There's no spark on the left side so a new ignition coil is on the way. The starter wouldn't turn but I think the battery is bad so a new battery is on the way.

Without further adieu, here's the bike. Thanks for any help you guys can provide... I'm going to need it.
 

Attachments

  • 2012-02-05 22.31.37.jpg
    2012-02-05 22.31.37.jpg
    1.6 MB · Views: 1,186
  • 2012-02-08 22.42.33.jpg
    2012-02-08 22.42.33.jpg
    1.6 MB · Views: 715
Welcome aboard! Looks like a good place to start.

New battery is almost always a must for any older bike that you pick up. As to the lack of spark, did you do any testing? Do you know it's the coil that's the problem?
 
Cool.

Don't jump the gun and start ordering parts without proper diagnosis. Is there a reason for you to suspect the coil? Diagnosis by replacing parts can suck up a lot of time and money before you find what is wrong. For instance, once you have a good battery, and the starter still doesn't work, don't just order a new starter. It is more likely to be a corroded ground connection, a bad starter relay, or corrosion in the starter button.

You will, of course, need a new battery anyway, but maybe you aren't getting spark because you need a working battery to have enough voltage to reliably get spark on both plugs. You can use jumper cables from a car battery to operate the electrical system and test things.

The GS400 is a good machine. Suzuki used that engine for a lot of years. A little later it bacame a 450. (I have an '81 GS450.) Then Suzuki make a 500 based on that engine. It's a very smooth, counterbalanced engine. VERY little vibration and a pleasure to ride. Parts are readily available, both from Suzuki, and from used sources like eBay. LOTS of ebay parts. There are some good aftermarket parts still available, too, like a Mac 2-into-1 exhaust system, and an upgraded charging system. Suzuki is waaay better at having parts for the old bikes than Honda is.
 
I did some testing with the help of a small engine mechanic in the family. We got spark by using the kickstart and looking at the arc on the right and not on the left. We did some process of elimination on the plug, wire, etc… I found a coil for >$20 so I just ordered it. I have money but I'm still cheap so I'm not going to drop money on parts unless I'm as sure as I can be that it is the problem. Thanks for reminding me too because I'm liable to jump the gun still.

I've found tons of parts on eBay but none other than that. Can you point me in the right direction for new OEM parts?
 
Kick start with dead battery may not give you reliable troubleshooting results.

If you search for "Suzuki GS450" on eBay, you will get 30+ pages of parts being offered. Pretty much the same bike.
 
Ahh... well we got a spark on the other side so we just figured. Anyways... I'll know more once I get the battery in. The bike is at my parents' house, 30 minutes away so as soon as I borrow a truck and haul it to my place, it will be go time.

Does anybody feel like going over the basics with me? Here's what I know I want:

1. replace old parts that can't be cleaned (headlight, shocks, levers, some of the brake parts, etc...)

2. simplify the bike as much as possible (I'd like a speedometer but that's all I'm sure of)

3. new seat, cowl, and tail lights to be the stereotypical cafe racer (its my first bike so I don't care how overplayed it looks)

Thanks again!
 
gob_bluth said:
I did some testing with the help of a small engine mechanic in the family. We got spark by using the kickstart and looking at the arc on the right and not on the left.
Click to expand...

+1 on testing with a new battery or just hooking it up to your car with jumpers WITHOUT turning the car on (don't want to fry anything), my KZ400 won't fire with dead battery even if I kick (it's fine with a low battery, just not totally dead).
 
gob_bluth said:
Ahh... well we got a spark on the other side so we just figured. Anyways... I'll know more once I get the battery in.
Click to expand...

Spark coil failure is actually the least likely cause of no spark. A corroded connection or bad ground is far more likely. No test is valid until you have a battery, however.

gob_bluth said:
1. replace old parts that can't be cleaned (headlight, shocks, levers, some of the brake parts, etc...)
Click to expand...

I may have a headlight in good condition. The headlight ears are in good condition, too.
Parts that may not clean up well can always be powdercoated, too. These old Jap bikes didn't have the best chrome, and it is often pretty rusty if they have been sitting around. You'd be surprised, though, how well they will clean up with some Turtle Wax chrome polish and #0000 steel wool.

The levers are aluminum, they will clean up nicely.

Brake parts are readily available from Suzuki.

gob_bluth said:
2. simplify the bike as much as possible (I'd like a speedometer but that's all I'm sure of)
Click to expand...

I fabricated a bracket to have speedometer only. The other thing I did to the front end was to braze a piece of 1/4" stainless to the bottom triple tree to mount dual headlights. I re-wired the whole bike to eliminate a bunch of wire, like the gear indicator. I ran the power to the headlights through their own dedicated heavy gauge circuit controlled by relays. Now way could I run the upgraded headlight through the original circuit. I also had to upgrade the charging system to handle the extra load. Took no time at all to cook the original stator.

(A bit dusty in this picture)

dualhead.jpg
 
Welcome to the board! I just got my 450 back on the road just before Christmas, and yeah I love it...

Common issue with the spark is also the plug caps, cheap as to replace too.

I ended up with a Dynatek setup on mine as the ignitor was toast, but on the 400 you'll have points. It's more likely a condensor issue than the coil, but AlphaDog's right, diagnosis is your friend :)

Keep us up to date with progress and if there are technical issues you can't sort, get over on www.thegsresources.com as there's heaps of help over there (my forum home).

And AlphaDog, love that stator cover! Mine aren't quite that shiny... although it'll be coming off again this week I hope to replace the stator...
 
I used the Electrosport stator. Supposedly, 20% more output than stock. I needed it due to upgrading from a 30W/50W headlight to dual 55W/65W H4 headlights. I used their regulator, too, because the stock regulator doesn't regulate all three phases from the stator. The new regulator was at least double the size of the old one. I never had trouble with low battery again.

I didn't know whether the 400 had points or not. Good chance that running a piece of heavy paper from a matchbook cover between the points will make it have spark again.
 
Re: 1978 Suzuki GS400 Build - Help and advice is much appreciated!!!

What do you think about this cam plug thing? The previous owner had it jb welded like crazy. Should I just order a new plug?
60f38863-d5c9-5cee.jpg
 
Ugh! That's ugly as sin!

They're still available from Suzuki and are cheap as chips, I had to replace all four of mine as they were brittle and cracking.

I get my parts from www.boulevardsuzuki.com in Florida, excellent prices.

Also, get a genuine valve cover gasket too. I used an Athena on mine initially and it wept oil continuously until I replaced it with a genuine one. No more leaks at all.
 
peteGS said:
Ugh! That's ugly as sin!

They're still available from Suzuki and are cheap as chips, I had to replace all four of mine as they were brittle and cracking.

I get my parts from www.boulevardsuzuki.com in Florida, excellent prices.

Also, get a genuine valve cover gasket too. I used an Athena on mine initially and it wept oil continuously until I replaced it with a genuine one. No more leaks at all.
Click to expand...

I found it and its on the way.
 
Re: 1978 Suzuki GS400 Build - Help and advice is much appreciated!!!

gob_bluth said:
Should I just order a new plug?
Click to expand...

Yes. Suzuki still stocks them, and they are only $4.00 each. The same part for a 1985 Nighthawk 600 I have in my shop right now... $20 ea! Get four of them, and the gasket for the head cover, too. There is also a breather gasket in the middle of the cam/head cover. You might have to remove that breather to have enough clearance to remove the head cover. That gasket is only about $4.00, so order it too, just in case you need it.

The new gasket will have a bridge on it that helps it hold its shape during installation. After all is tightened down, you cut that little section out.
 
While I'm waiting for parts to come in... What do you guys know about front disc brakes on this bike? I'm not able to find the parts for my specific bike. I've got a good disc but no caliper(s). Do you know if these even came with disc brakes and which bikes I can get the caliper off of to get some front brakes going?
 
Glad your getting the genuine bits, they're cheap enough that it really is worthwhile.


Do you have a drum on the front wheel? Not sure when Suzuki changed from drum to disc...


If you don't have a caliper, then there's a fella over on the GS Resources with the screen name "Salty Monk" who makes an adapter that will let you put a Kawasaki twinpot caliper onto the 450E forks which is a nice upgrade. I'm not sure how that would go with 400 forks but I took some measurements for him to confirm the 450E ones should be ok. I haven't gone down that path myself at the moment but am keeping it in the back of my mind...
 
Re: 1978 Suzuki GS400 Build - Help and advice is much appreciated!!!

I don't have the drum for the front but I'm not opposed to it. I'll check him out to see if that can happen. At this point, I'd take a cheap drum if I could find it.
 
I would like to find a set of spoke wheels for my GS450L. They didn't sell that many of the GS450TX, which was the one with spoke wheels.
 
You must log in or register to reply here.

DTT Light or Dark

  • DTT Light
    • www.jadusmotorcycleparts.com
    www.lostapostle.ca/
    www.sparckmoto.com

    Spread the Love

    Back
    Top Bottom