Z1000J carb advice needed.

[Dark Skies]

At the front of the carbs on my CSR (same as Z1000J) there are two vacuum pipes. A long pipe linking carbs 1 & 4 and a short pipe linking carbs 2 & 3.

The pipe linking carbs 1 & 4 has a T piece in the middle with another pipe running back to the US spec anti-emissions vacuum switch.

The pipe linking carbs 2 & 3 has a T piece in the middle with a pipe going to the vacuum operated petrol tap.

I've dumped the original petrol tap because it kept leaking - despite me fitting a repair kit it still gently wept. I've now installed a Pingle tap - doing away with the vaccum nonsense.

I've also dumped the air filter box and emissions stuff too - using K&Ns with a dynakit.

Consequently I've now fitted a single pipe linking carbs 1 & 4 and another linking 2 & 3.

My question is do these pipes actually need to be fitted at all? Now I've dumped the vacuum operated stuff could I jusy blank off the brass pipes coming off the carbs? Or do these pipes also double up as some kind of balance arrangement?

[Al]

On my J1 there is only one pipe from carb 2 to vac tap.
The others have special rubber grommetts on them. They dont blow off and they are where you balance the carbs with vacuum gauges.
If you need a picture i will arrange one to be put on here.

AL

[Dark Skies]

On my J1 there is only one pipe from carb 2 to vac tap.
The others have special rubber grommetts on them. They dont blow off and they are where you balance the carbs with vacuum gauges.
If you need a picture i will arrange one to be put on here.

AL

Thanks. I figured that was the case.

As luck would have it I have some blanking caps that I found in a bin at our local scrappy. I had no idea what they were for originally but that didn't stop me loading fistfuls into my pockets thinking they might be jolly handy one day.

[RALPHARAMA]

As luck would have it I have some blanking caps that I found in a bin at our local scrappy. I had no idea what they were for originally but that didn't stop me loading fistfuls into my pockets thinking they might be jolly handy one day.

A man after my own heart When I go down the scrappy I'll buy any 316/304 stainless or ally regardless of shape - it goes into stock, and it always comes in one day

[Al]

Hey voila ici.






AL

[Dark Skies]

So today I blanked off ALL FOUR of the vacuum points on the carbs and started her up and ...

... fuel absolutely PISSED out of carb 2 via the bottom of the K&N.

Looks like I might have to retain the vacuum pipe between carb 2 & 3 and just blank off 1 & 4.

[Taffus]

hi
have you got more pics of the carbs? my Gpz 1100 b1 has had the carb conversion and the jury is out asto where the carbs come from. If I leave it standing for too long (including running I get the same problem but from no 1 carb) though it is getting better when running.....

[Dark Skies]

hi
have you got more pics of the carbs? my Gpz 1100 b1 has had the carb conversion and the jury is out asto where the carbs come from. If I leave it standing for too long (including running I get the same problem but from no 1 carb) though it is getting better when running.....

My carbs are Mikuni BS34s - standard fitment for the Z1000J and K1 etc.

I can post a pic - just got to get some batteries for the camera.

Anyroadup. I may have been jumping the gun on the vacuum pipe being necessary on carbs 2 & 3. I put the hose back on. Put the tap to the on position and ... fuel pissed out of carb 2 again.

Thoroughly pissed off now. I reckoned the valve needle was stuck and pulled the carbs off to check that and the fuel float heights. Sure enough the valve needle did feel a little gritty when I had a look. I pulled them all to check those too. Quite a bit of residue in two of them. A bit piss poor given the previous owner had taken the bike in to have it serviced prior to putting it up for sale - reckoned the carbs had been serviced.

I had a full carb repair set given to me by the previous owner so I just cleaned everything up and replaced the valves - one or two looked slightly worn. Float heights look too high as well but I have to do some research on the correct heights. I think they need to be about 18 mm

Unfortunately I found one of the O rings on the plug in front of the main jet had split too - so now I have to wait for Z power to get back to me and let me know if they stock them.

So ... could be that when I put everything back together I CAN blank off carbs 2 & 3

[Al]

Hi all i am getting a bit muddled now.

Taffus
PostPosted: Sat Aug 02, 2008 8:45 pm Post subject:
hi
have you got more pics of the carbs? my Gpz 1100 b1 has had the carb conversion and the jury is out asto where the carbs come from. If I leave it standing for too long (including running I get the same problem but from no 1 carb) though it is getting better when running.....

Taffus did you mean me or Dark Skies.
If you meant me then tell me which bits you want photographed and i will post them up.

Dark Skies
PostPosted: Sat Aug 02, 2008 3:54 pm Post subject:
So today I blanked off ALL FOUR of the vacuum points on the carbs and started her up and ...

... fuel absolutely PISSED out of carb 2 via the bottom of the K&N.

Looks like I might have to retain the vacuum pipe between carb 2 & 3 and just blank off 1 & 4.

In so far as i am aware there is no difference in the carb bodies or vacuum arrangement in this regard only, that would suggest a reason that it should leak from no 2 rather than any other carb. Or Taffus; from number 1 only.

If 'leaking when standing' you mean on the side stand then that is a different matter. Gravity and vapour pressure i would suspect play the leading roles here.

With regard to float height i use a bit of windscreen washer tubing. First drain a cap full (aerosol lid) full of fuel from each carb. Examine the contents and then straight back into the tank with the top 95% of it. The rest to waste. I cable tie one end of the tube to the side of float bowl 4 and starting at no 1 carb; open the drain screw again having fixed the other end of the open pipe to the drain boss. (needless to say; bike on the centre stand or brace bar)

Repeat for 2, 3 and 4 and adjust any float height that does not conform.
I do this with the engine stopped and again with the engine running. Careful here or you'll blow the shed to kingdom come.

If there is a discrepancy with the float hight engine stopped it is with the float and with the engine running it is with the needles.

'Service fuel level in the manual' is 2-4mm below the 'carb body to float bowl mating surface'.ie. the location of the fibre gasket.

Hope this helps

Edit p.s. forgot to mention; when transfering tube from 1 to 2 and 2 to 3 etc etc put finger over open end of tube where it's cable tied to the side of the carb or the fuel will fall out onto the hot engine!!!!!!!!!!!!!!!!!!!


AL

[Dark Skies]

In so far as i am aware there is no difference in the carb bodies or vacuum arrangement in this regard only, that would suggest a reason that it should leak from no 2 rather than any other carb. Or Taffus; from number 1 only.

If 'leaking when standing' you mean on the side stand then that is a different matter. Gravity and vapour pressure i would suspect play the leading roles here.

With regard to float height i use a bit of windscreen washer tubing. First drain a cap full (aerosol lid) full of fuel from each carb. Examine the contents and then straight back into the tank with the top 95% of it. The rest to waste. I cable tie one end of the tube to the side of float bowl 4 and starting at no 1 carb; open the drain screw again having fixed the other end of the open pipe to the drain boss. (needless to say; bike on the centre stand or brace bar)

Repeat for 2, 3 and 4 and adjust any float height that does not conform.
I do this with the engine stopped and again with the engine running. Careful here or you'll blow the shed to kingdom come.

If there is a discrepancy with the float hight engine stopped it is with the float and with the engine running it is with the needles.

'Service fuel level in the manual' is 2-4mm below the 'carb body to float bowl mating surface'.ie. the location of the fibre gasket.

Hope this helps

Edit p.s. forgot to mention; when transfering tube from 1 to 2 and 2 to 3 etc etc put finger over open end of tube where it's cable tied to the side of the carb or the fuel will fall out onto the hot engine!!!!!!!!!!!!!!!!!!!


AL

Thanks for all the info. Unfortunately the fuel pissed out (on centre stand) with the engine running and switched off. I'm pretty sure that this was an existing problem masked by the the fuel tap problem that I knew about.

When I bought the bike fuel pissed out from the bottom of the standard air filter box - even with the tap switched to on and reserve (supposedly off on vacuum taps). The previous owner said it sometimes happened in cold weather and thought it was something to do with the rubber membrane in the fuel tap becoming hard when cold. Hmm. Maybe. But I reckoned it was more likely because the fuel tap rubbers were 26 years old and most probably shagged beyond all recognition. As it turned out they were. However, a repair kit still proved unsatisfactory because it wept around the back of the tap. I thought the Pingle would nail the problem once and for all.

Nope. It just cured one problem and obviously the valve needle and / or the float height is responsible for the overflowing problem. It's just that I can now temporarily stop it by switching the tap off.

The carbs are on my bench at the moment. According to the manual the float height is measured by turning the carbs upside down on a flat surface and measuring the vertical distance between the top of the float to the mating surface of the carb body. This should be 18.6 mm Unfortunately the manual fails to mention if the gasket should be in place or removed. Anyone know?

[big green bus]

I had similar prob with mine messed about with the floats etc but in the end it was shit in the tank jamming the float valves open. i had put a high flow tap on but no fuel filter and that was the prob. i fitted a car type inline one and had no probs since

[Al]

Sorry fellas but this has taken forever to sort out. Vacuum gauges out on loan to someone else.

(Dark Skies) i may not have made myself clear when gabbing on about fuel service level so here is my fuller explanation. Manual says something like 3mm below Lower face of carb body plus or minus 1 mm. Section 3-4 in the manual

Just got back with the gauges and bike red hot so a little unconfortable in the tickover department and as i filmed this four times it was at meltdown when i had finished.


This is the static fuel level for carb #4. It makes no difference if you have the bleed screw open or shut it reads the same after you blow backwards down the tube to push the air bubbles back into the float bowl.


This is the onboard tacho reading for tickover for the by now very hot engine i estimate this to be about 750 RPM or thereabouts.



This is the plug in analoguge tacho and it reads about 1500 RPM which i take to mean about 750 RPM if you divide by two


This is the vacuum reading that i set about 2 years ago. It has not drifted much in that time although the bike has been used very well since then. As you can see they are broadly in agreement but you would have to be very anal about getting it any closer. The state of tune of the bike, its general performance, its brakes and handling and the age of the instruments (carburettors) does not in my opinion warrant better or closer agreement. Each to their own. I rarely drive the bike with less than two thirds throttle so its not so important to me but if you are a potterer then it would be worth spending more time getting the balance correct. Of more interest to me is the vacuum of acceleration and and of full throttle and if you look below thats' exactly what you should see. Sorry about the over exposure but we had our summer here yesterday and the big orange thing made its annual appearance.


To show that they are the same in the fuel service level department simply move the tube to the next fuel drain and open the screw whilst running the engine. May not be obvious from the picture but this is number three and as you can see it is more or less the same as number four. Must point out here that because the float bowls are on an angle the tube needs to be in the same position on the float bowl of the reference carb in order to make a proper comparison. Obvious i know but i just wanted to be sure.


When you put it all together you get the following.
If you look closely you can just see the fuel level in the tube rise a quarter of an inch or so as the drain screw is opened. I had already done this several times by now so had emptied a little fuel from the tube to try to show the situation visually.

Click on the clip to open the video.



I did do a short video clip of pulling the choke out to show the effect of choke circuits on the vacuum gauges which i had intended to put in at the top since it needs to be done first. However the bike will not take choke at all when its in fission state and the video was a little difficult to make sense of. I can tell you that all chokes were operating perfectly and in closer agreement than are the throttle butterflies in the above clip.
What you cant see from the video is the individual bars osscillating and its one reason why i dont like Carbtune gauges. I had to sell the very posh gauges i bought for this bike and have regretted it since. You cant adjust the dampers on these gauges and you cant regulate the response either. When you look at these gauges they tell you nothing really but the other gauges had the capability to be manually tuned and this highlights a range of other potential issues with the carbs. Example; you can open the dampers and then tweak the air screws on tickover to get a stable air flow without fluctuation which i take to be a standing wave of pressure or a blocked jet which ever seems most appropriate, knowing your own carbs.

I hope this clears things up a bit. There is a size limit for vid clips on Photobucket so have had to limit the size for their benefit and for those on dial up on this site also.






AL

P.S. this did give me a guilty conscience so i went and balanced them perfectly afterwards!!!!

[Pigford]

Al, ditch those CV carbs.... you'll never get them sorted....

Proper slide carbs are the only way to go

[FER]

The J carbs have a filter fitted to each carb above the float needle . Remove the screw and holding plate then pull out the float needle seat . You will be amazed at how much crap is on the filter . Remove all 4 and blow out the passage way with an air line . It only takes a small bit of crap to allow fuel to flow past the needle .






fer

[Rich]

The reason it says do the fuel heights with the engine running is because the fuel tap is vacuum operated. As you have replaced this with a manual one you shouldn't need to burn your fingers so much as you do not need the engine running