1977 GS400

So, in order to rescue a friend from the ire of his wife, I have relieved him of a 1977 Suziki GS 400. Kick-only, drum brakes.

It is a so much cheaper feeling bike than Yamahas. Thin plastic, ignition that is basically an on/off switch. Manual petcock. Airbox is so flimsy...

Carb are Mikuni, the slides are free, so I have some good hopes for carb cleanup.

Funny thing is, the rubber couplers from carbs to airbox have these rubber horns protruding into the box. I suppose they are velocity stacks. I'm wondering if it can run fine without box but with the stacks, if I put some filters on the ends of them. Airbox is missing it's top, so I'm thinking of redoing the intake somehow.

Tank has some rust spots, but I don't suppose I'll know if it leaks until I put some gas in it.

This may be a prime candidate for some sort of a cafe racer project.

 

'77 ? are the carbs CV or older style round slide carbs ?

 

CV. Not quite sure what size.

 

So, I ripped into the carbs. Gunk is pretty minimal, jets are cleaning up nicely. Diaphragms are solid. Needles are metal tipped, don't look worn.

More bad found along the way - rusty seat pan, rusty battery bracket. Not too terrible, but sort of iffy. Muffler has a rust hole. Ignition lock is a generic replacement. Seat lock is gone. Tank lock is ok, but no key. The cover is removable, so no big deal.

I think I might build a box for electronics and get rid of the airbox/battery holder setup, then try running it with just the stacks. Seen some cheap Harley tanks on Ebay. Could become an actual rat bike, built from random junk.

 

i think the older mikuni "vm" style carb would take to stacks and pods better than the "cv" type and the smaller sizes are kind of cheap on e-bay. but your plate is full now, keep going.
remember it never happened without pictures

 

Well, I do have this perfectly functional set of CV-type Mikunis. Also, what makes me curious is that the stacks are factory, and so would be designed for these carbs.

These Mikunis are pretty weird - each carb has two vent hoses, one from bowl and one from body, the main jet is in the bowl and accessible via a plug in the bowl bottom.

 

that's going to be sweet

 

I am considering cobbling up something with a small automotive air cleaner and some tubing, and ditching the airbox and side panels. Don't want to do pods, everybody has pods.

 

Wow. Only two carbs. Everything fits in ONE egg carton! Looks like child's play! I'm kinda jealous. Very tidy bike for a 77. Keep us posted!

 

Yeah, this is a superbasic bike.

There is no fusebox - just one fuse. Drum brakes front and back. Electric components are minimal, only three small pieces.

 

You only need three wires to make an engine run.
-Magneto to contact breaker
-Contact breaker to ignition coil
-Ignition coil to plug.
Motorcycle wiring can be so simple.

 

Yep, I know.

This will be an interesting experiment in not-fanciness.

 

And... it runs.



I took out the airbox, but put the air horns back on the carbs. I think they are velocity stacks and it seems to run fairly well.

Starting blew a hole in the muffler and made a pile of rust come out of it.

Things to get it road worthy:

Build a battery box
Figure out air filtration
Get a working headlight
Register it