Carburetor set up and pipes

[dehanff]

  So glad my request finally got accepted!! I have an currently not working 1982 XZ400. Bike was missing a float and could not order one from the dealers as it was discontinued. So i draw one up on Inventor and still needs a few touches but then I'm going to 3d print my float.

I would really appreciate someone showing me how to connect the pipes, like the one from the top and one from intake manifold and which ports on the carb need vacuum etc. Also have an switch on the petrol tank with two ports one vacuum but hen I also have a what seems like an petrol pump on the carb with one petrol in and one petrol out and presumably a vacuum. The guy who i bought it from disconnected every pipe and this carb (Miking bd34) isn't very common to find photos of.

Appreciated

From South Africa

[skucera]

Welcome to our forum.  I'm a little surprised that nobody has volunteered an answer, but then ZX400's are exotically rare here in the US, since they were never imported here.  Going by memory, they're very similar to the European and Japanese ZX550's, with two disk brakes on the front wheel and lower handlebar risers than we got in the US.  My Haynes manual describes them as being almost identical to a ZX550 too, so maybe your answers lie in a Haynes manual.

I tried to Google a photo of the vacuum lines and their routing, but too many other "paid" search results hid the useful results too well... I just couldn't find a photo, or I would have linked it here.  You may want to just browse through the forum threads for old photos.  The vacuum line routing you're looking for may just accidentally be visible in pictures that forum members posted of their engines.  I'll keep looking, and if I find something I'll add it to this thread.

Scott

[dehanff]

I appreciate the answer so much!! I myself have looked everywhere on the internet to find some sort of photo. I Will do that and thank you!

My next question is why is there two vacuum controlled switches for the petrol? There is one on The tank and one on the carb which is round and three connection ports.

Also which vacuum pipe is used for the carb on the xz550? The one that comes from the front intake manifold? Would that then require a T for the gas tank and carb "Switch"?

Any answers appreciated thank you!!

You guys are the best!!!!

[Prophet Of Doom]

I've not seen one of those on a XZ400 before and I've seen a few, have two in parts bins, and had some adventures with the worst xz400 in the world 
I think that's a BD36 carb, more usually seen on 83year xz550s.  So perhaps a variant, or perhaps a mismatched carb

On my sig there is a link to all the manuals, including XZ400 supplement to the RJ manual, a XZ400 owners manual, XZ400 parts list and XZ400 brochure.  You will find all the carb diagrams you could wish for in these and other manuals
Look at the RK manuals and fiche for pics with your carb as the XZ400 manuals show a BD34 carb with no fuel pump. 


In answer to your Question, 550s have two lines coming off the front manifold, one for the petcock on the tank, one for the thing you rightly identified as a fuel pump.  If you only have one that suggests to me yours is a mismatch.  Also look at the petcock as this carb needs a return line to the fuel tank, so a matching petcock will have 3 lines fuel, in, fuel out and vacuum.  The BD34 matching petcock has only two fuel out and vacuum.

[dehanff]

I just attached some photos. the petcock has two holes, so I'm assuming that the carburetor I got with my XZ400 was one from an 550. Well in that case would I need to switch some of the jets one it? Should i cut the petrol pump out of the system? I managed to figure out that the one black cord attached is for the accelerator jets. Is there any other significant tubes I'll need to attach except the petrol to the pump and the vacuum to the petrol pump?

Thank you so much for replying, I can't wait to take my XZ400 for a spin!!

[Rikugun]

Visions are not particularly easy to own, work on, find parts for, etc. On top of that you have what appears to be a somewhat rare set of BD36's mismatched to a rare 400 model.  You've taken on quite a project!   

Were Visions sold in any quantity in SA such that there may be used parts available locally? How about through E-Bay or bidorbuy?

Can hollow structures like a carb float be easily 3D printed?

[dehanff]

I'm going to print it this week and report back. The 3D sketching is the hardest part and took the most time. Out university has an 3D printing facility which I am going to use.

Can I get some comment on skipping the petrol pump on the carburettor or my other option is to keep the petrol pump hooked up and then try to find another petcock with an return valve or make an hole in the tank and insert on myself?

Any comment would be appreciated.

They did not sell this bike in South-Africa at all, it was imported from another country, so finding an broken one would be quite the mission.

[jefferson]

You will probably want to keep the fuel pump or you will not get all the fuel out of the tank as the level in the tank will drop below the level of the float bowls.
If your carb has the return line to the fuel tank then the easiest way around that is to put a t in the line from the petcock. The bolt spacing on the petcock between the single feed line and the return style petcock is different.

[Prophet Of Doom]

Without a pump, you aren't going to get the fuel going back up anyway.


I think your biggest issue will be jetting.  On a BD34 the jetting for 400 is very different from 550 and from memory different intake diameters, venturi, velocity stacks as well.  On a BD36 you are rather a pioneer



Is 3D printing filament fuel safe?

[Rikugun]

POD, did the 400 not come with a pump as original equipment? If so, was that due to shorter barrels and subsequently lower mounted carbs relative to the tank? If any of this is true, then I suppose eliminating the pump and blocking of the carb return fittings might work??
'
On the other hand if I'm completely wrong on those assumptions, I seem to recall someone having used a set of '83 carbs on a single outlet '82 tank utilizing a T fitting like Jefferson noted.

Either way, I agree with POD's jetting concerns.

[Prophet Of Doom]

That's right, no pump (or regulator) on the 400, no vacuum flapper, and even though it is a BD34 carb it's a lot smaller internally, with different jets, smaller intake on the air box etc.  Quite a different beast.  I've seen it mentioned that the carbs are lower, but I never bothered to measure, and no longer have a 400 motor to compare with.


I would think a no-pump BD36 could be made to work, maybe, but with a LOT of hassles to get the jetting right. Keeping in mind the impossibility of dropping the venturi, if it was me, I would just ask around for a new set of carbs.

[Ken Williams]

If you are using an 83 style fuel pump the fuel return must terminate at least as high as the carb fuel level for the pump to function properly.  If you return the fuel to a t in the line from the petcock, you might as well eliminate the pump. 

[dehanff]

Hope you re all ready for this information

Firstly the float:
-I have left an sample material of the 3d printed filament in petrol overnight and it is still A-okay.
-I have successfully printed the float and it fits in the carburetor perfectly.
-Have not yet checked if it works as it should.

Secondly the jets: (Luckily ROV ain't shy with the info )
-I checked the jets and i think the pilot jet was 125 and main jet 110 or other way around.
-So I'm planning on getting: AIR front and rear either 146 or 145
                                             FUEL front 107.5 and rear 110
                                             Not sure about emulsifying jet?
If I have it correct the main jet is the two screws next to eachother?(The one ratchet head an other one the star)
And the pilot jet is in the opening in the rim of the top of the carburetor?

Third the Venturi and intake diameter :
-Would the venturi and intake diameter make a markable difference if I fix the jets?

Fourth the pump situation:
- After inspection and checking, the carburetor float intake does not seem to be higher as the tank's lowest point. It seems that the top of the float chamber aligns with where the petcock attaches to the tank.(I'll attach photos)

Please can you guys just confirm if all of this is correct!

I'm really overwhelmed by the generosity of the people with their knowledge on here!

[dehanff]

Can I possible get help on jetting the 550 carb to fit on a 400?

[fret not]

I would think that 550 jetting in a 550m carb should be reasonably close for a 400.  The carbs work in proportion to the amount of air drawn through, not the size of the motor so much.

Does your printed float actually float in fuel?  And if it does, is it as buoyant as the original floats?

Looking at your printed float, in the area where the float needle will contact, I think a tiny piece of stainless steel sheet attached with a small screw or two could replicate the function of the original 'ramp'.  Otherwise how would you intend to make float level adjustments?

[dehanff]

I've gotten the o'l XZ to start up but with full choke only. When I pull on the accelarator, the revs drop and it stalls. If i get the revs high (6000 ish) it keeps there and i can rev it up from there.- Thinking this may mean a too lean engine? Could not having the air filter on make a difference? I got it without one and I am still to replace it with two cone filters.

Ive put some epoxy on that tip in a pointy form so to raise the fuel level i just sanf a bit off.

The buoyancy was bad it first, then I cut of a piece of plastic and replaced with cork, and sealed the whole thing again. The plastic would go soft after a week in direct contact with fuel. Painting on a thinned epoxy epoxy solution eleviated this problem.

Any comment on hoe high the fuel level in the bottom part of the carburetor should be? the length it should be below the drainage hole? Perhaps how much ML of fuel should be in the bowl? Then i can adjust float height and measure this?
 

[Rikugun]

I have no experience jetting those carbs to work with that engine so can't help there. Given how finicky fueling is on these bikes with the proper carbs, I'd think it very lucky indeed if you "stumble" upon the perfect setup through trial and error.

Given what you've written, I'm not feeling confident about the float. I've also deduced you've not read a service manual yet? Some of the questions you've raised are well covered in a manual and there is one available free here:
http://ridersofvision.net/rovforum/index.php?topic=12221.msg131181#msg131181

It's difficult to accurately diagnose with such limited info but it could be lean. That covers a lot of territory. I'm suspicious of your float, fuel delivery in general, possible vacuum leaks, jetting, etc. Before looking at any of these possibilities I'd perform a cylinder leak down test or compression test at the very least. How are the valve clearances?

For what it's worth I'll measure the fuel volume that drains from my '82 carbs and post it here later.

Edit Both carbs drained into a container equals about 90ml so about 45 per carb. Keep in mind this is a set installed on the bike. I've never checked the fuel height on this bike but it runs well. I'm sure fuel lines, filter, etc. effect the number.