1981 GS400e

[Guest]

Hey guys, I am not sure exactly what the best area of the forum to post this in is, but I figured this would be the spot.

So, I've acquired a gs400e as the title states, it's been painted matte black, all the chrome looks... old, and the frame has some chipped paint where it's started to rust. The engine itself looks pretty oxidized.

Now on to how it runs, it takes quite a bit of time running with choke on for it to be able to idle, with the choke all the way on it seems to idle higher than it should, and honestly it is gutless, the bike seems to want to shake itself apart when i drive in the higher rev ranges and then often stalls after periods of strong acceleration. It also sometimes will lose all power while driving and stall, when this happens any input I have on the throttle does nothing!

Now I am posting here because I figured I'd like to take this bike on as a project, I have worked on cars before, but alas, it turns out I know less about motorcycles than I'd like to imagine I did. Now basically what I'm asking is what do you guys think this bike needs to run well, I'd really like this bike to run well before any cosmetic things are tackled, however if there is extensive work required maybe it would be better to do a ground up restoration, also, is there any way this sucker can make more power?

Sorry for the long winded post, and sorry if this is in the wrong spot!

[AMK]

As you work on it you'll end up in different forums. Getting it running and road worthy is a good place to start before cosmetics.
It sounds like you should head over to the carburetor forum to ask your first questions and use the search on the site to get a general education. There is a lot of information for you here and if you peruse it you will do well.

Since its running you should start with adjusting the valves and next rebuild and clean the carburetors.

I'm sure someone will come along to recommend more than I know, I just wanted to welcome you to the site.


You'll probably want to start here...http://members.dslextreme.com/users/bikecliff/

[John Park]

First, the engine in this bike is the four valve per cylinder GSX400 engine. It was made for Europe mainly, and they sent them to Canada as well because there was so much flak about the GS425 ending up in the over 400cc insurance bracket.

The good thing is that the valves are easily adjustable with screw and locknut tactics; the earlier 400s and the 450s use replaceable shims. There are several bad sides:

1. The compression ratio is 10:1 so you must use premium gas, and preferably the alcohol free stuff like Chevron 94. If you don't, the engine will ping a lot under load and eventually you could have damage. You can putter around on lesser grade, but I could never get regular to go quietly up a steep hill on a hot day.

2. The cooling of the heads is marginal - more valves and fewer fins - and thus the heads are prone to cracking at the exhaust valve seats. If you pull the plugs and shine a flashlight down the threads and see cracks heading for the surface you're already there. They'll run cracked, but eventually there is a limit.

3. Parts for this motor are getting scarce, and some things are just becoming unavailable. If you look on cmsnl.com under GSX400 you will see what is still around; if they're out of stock you're probably hoping for luck on ebay.

The good side is that the whole top end - head and barrel - is replaceable with 450 parts which are still relatively plentiful in the US and many GS500 parts will also fit. You have to do it all at once, but it's easier in my experience to go that route than chase down GSX 4 valve parts. Plus you get more torque.

In my experience, you will end up taking the carbs off and the intake manifold boots; new o rings for the boots are mandatory. The valve cover should be removed and the clearances checked. You'll need a new valve cover gasket and there are two types as I recall, and the early one that you have can be scarce. There's a remote possibility I may still have one...

The fuel taps of that era were - well, I run a 70's one instead. It sounds like you're running the carbs dry under load which means funky fuel tap. Without good supply to the carbs, the motor will shake and stall at higher revs. Try putting the tap on prime and see if it stops pooping out. Just don't leave it there or the carbs may flood gas into the motor.

So, valve adjustment, carbs and fuel tap are the first things I'd attend to. And the Twins forum is probability a better spot for specific info on this bike.

Where in BC are you?

[Flappin]

Awesome, thanks for the info guys.

I will start looking into all of these things asap, luckily those things I would say are within my scope.

I am located in Port Moody!

[Runeight]

Subscribed. Just finishing up a 82 Canadian model.