TOPIC:

Hello everbody!

My name is Marcus and I am new to this forum, so there might be a chance this has resolved in another thread.
I bought a 1983 Z400 here in Sweden (Z400R2), this is kind of a projectbike so there was some issues with it when I bought it

Most of the problems have been resolved, for example it would not rev above 4000rpm, this was fixed with a cleaning of the Carbs, bought a original airbox, (Had podfilters before) 
changed spark plugs, new oil and all the service stuff...

The problem that I just can´t figure out is the idle. It just refuses to idle, when I set it to about 1000rpm it will idle for a few seconds and then just die. 
There are no problems with starting it up again and it runns great when riding it. 

What I have tried..

1: Clean the carbs (Jets and bowl) might need a full teardown?
2: Spray starter fluid around the sealing rubber around the carbs.
3: Adjusting mixing screw, from 1 revolution all the way to 3 revolutions.
4: New vacuum hoses from petcock down.
5: Adjust throttle cable.

Will link a video to when i use the starter fluid.....



Any suggestions are very welcome   

Have a great weekend

 

The only way to insure that the carbs are actually clean is to tear each of them completely down and soak all of the hard parts in a high quality carburetor cleaner, and then carefully insure that ALL of the tiny passageways are perfectly clear. Do not soak any soft parts like o-rings and gaskets. Some cleaners will dissolve them.

The problem you describe can be caused by clogged pilot circuits. A small e-string from a guitar can be a life saver when trying to clean those tiny passageways. After doing all that, I blow them out with compressed air and then shoot carb cleaner in a can, through its little straw to see that there is a nice spray pattern in the carb throat. Good eye protection is a must.

Thanks for the reply!

Would a Ultrasonic cleaner be even better for cleaning? 
I have one on order for all PCB cleaning I do, so maybe i can just throw them into the bath aswell?

And just throw another question in here about parts list for a z400R2, i just can´t find a parts catalog or service manual for this specific model... 
Would be great to have a teardown giude for the carbs before jumping in head first

There are mixed opinions about the effectiveness of ultrasonic cleaners. I think what is more important is the cleaning agent. It must be able to dissolve fuel residue and it must not be damaging to zinc, aluminum or brass. A dedicated carburetor cleaner will do the trick.

I think that was a European model, so maybe one of our members there can help with the manual. I bet it has the same carbs as the North American models, so the factory service manual here at KZR may be sufficient. Look under the Articles tab.

The pilot may be covered by an aluminum plug. Make sure you find it and clean it. 

TexasKZ wrote:

There are mixed opinions about the effectiveness of ultrasonic cleaners. I think what is more important is the cleaning agent. It must be able to dissolve fuel residue and it must not be damaging to zinc, aluminum or brass. A dedicated carburetor cleaner will do the trick.

I think that was a European model, so maybe one of our members there can help with the manual. I bet it has the same carbs as the North American models, so the factory service manual here at KZR may be sufficient. Look under the Articles tab.

Took it apart today, and have put in a order for some E string
Also took a quick look at the vaccum membranes and they look great.

Haven´t cleanes alot of carbs before but I suppose I focus on the jets with the E string and the carb cleaner.?

I only had a rubber plugg on mine..... 

Those rubber plugs are essential to the carburetors. Treat them very gently, they are no longer available new. 

Once all of the removable parts are off the bodies, they all need to be carefully submerged in carburetor cleaner. Do not submerge soft parts like the diaphragms and those rubber plugs. All the metal bits need to be soaked.
Also, the brass tube that is pressed into the bottom of the fuel bowl is notorious for developing tiny cracks near its base. Inspect them very carefully.

Also, also, the carburetor bodies need to be separated from each other. That is the only way the fuel transfer tube can be removed, and the orings replaced.

The rubbers are in a safe place  

When I was tearing the carb down i noticed that some parts was missing XD
(Adding picture)

Right side of the carb had the spring for the screw pilot adjuster, but no washer or O-ring.
The left side, had NO spring, washer or O-ring..... I suppose this might be the problem with my idle? 

The parts list is for a 1979 z400H 
I got a Z400R2 (But impossible to find the parts catalogue for the euro version) 

 



 

Look close down into the carb passage for those pilot screw parts.  The washer and O-ring typically stay down into the passage, and needs to be fished out with a hook tool.

So i took a closer look inside the carb and have some pictures. 
Is it the smal black center hole that is the O-ring? 
It was not easy to get a photo inside the hole XD