Jetting problems

[damo1]

Hi all,

Long time no post i'm haveing a drama with my new project bike thought the wisdom of fighterdom may be able to help me out.

Ok ive gone from never owning a kawasaki ever, to having 4 in the last 2 yrs and i'm hooked on them- they are tough as nails aewsome to ride and easy to work on and go like shit off a shovel.

Ive had a zxr750 then a kx125 and now have two left - a gpz 900 a7 and a zzr600 95 mod that will aventually become the dona biek for the gpz for parts.

I ama want ing to build a nice classic with modwern running gear and there are plenty top look at on line.

Ok the story goes like this - i came across a low k's later mod gpz of 1990 vintage the first of the 17" front wheel jobbies for the mesly some of 500$. It had been stored for over 7yrs and only has 35000k's on it and is in what i beleave to be very good orig and complete un molestered condition.

So i ripped the carbs straight out and soaked them for 2 weeks completely submerged in fuel to loosen any varnish in them from the storage period.

I completely dismantled the carbs twice and cleaned , compressed air blew , tooth brushed and carby cleaned all orifeses and passage ways.

I then fitted uni filter individual pods and after alot of web surfing ended up with 140 mains and 3.5 turns out from bottom with the mixture screws.

I them felt it was over mained and bogged down heavily so whent back to 130 mains and with a bit of fucking around ended up with this and a couple of spacers under the needles to richen up the mid range step up off the pilot to the main.

Now i have found out the number 2 cylinder continues to flood the plug and im fucked if i can find why??

Yes it has spark

Yes all the carb settings are the same

yes the plug is new

yes the coil seems fine

yes i have pulled the plug and kicked over the engine to pump out excess fuel from the barrel before refitting the plug.

Yes i know i should go to a dyno and yes it is going to go, once i get it close to the mark.

I want to get the hard yards down first so it's just a quick one or two runs to finish it off.

Please any ideas help will be greatly appreciated - i'm fucked it i know whats going on????????

cheers damo

Below is the bike id like something like when finished!

[RevHead]

sounds like youve got a needle sticking open on that carb flooding the cylinder, u could swap the needle and seat to another carb to see if the problem moves,

[damo1]

Do you mean the Needle and Seat needle or the main needle in the slide??

[Redmohawk]

Float levels need checking but first off check float neadle is shutting off fuel supply when bowl is full, is what Pete is on about.

[RevHead]

Float levels need checking but first off check float needle is shutting off fuel supply when bowl is full, is what Pete is on about.yes sorry ,meant to included that,

[maggs]

I had a similar problem on my 96 zx7r and it turned out to be the o-ring around the needle seat brass tube. They are very easily damaged when inserting them. I had a few goes by pushing them in but each time it would nick the o-ring and cause flooding on one cylinder. I ended up seating them by using the locking screw to wind them in.

[latheboy]

I don't remember the name of the material but the stuff that floats are made of break down after a while and don't float so well anymore.. see what I did there ?? True story bro ... Number 2 needle and seat is worn or the float has failed.

[RevHead]

Bakelite , is that it Ivan!

[latheboy]

It's called Nitrol, after time it sucks fuel in and becomes heavier.

[damo1]

Thanks for the feed back guys - looks like out with the carbs again :(

Sorry Pete i just reread your orig post and you clearly said needle and seat!

[Hillsy]

Check the float needles aren't damaged - they are rubber tipped and even the slightest amount of visible wear can make them leak.

Probably the o ring in the seat as suggested above though.....

Also - does the Gpz have a vaccum tap? Is #2 cylinder the one where the vaccum hose is connected? It's possible the tap needs a re-build and the motor's sucking fuel straight into the port.

[damo1]

Also - does the Gpz have a vaccum tap? Is #2 cylinder the one where the vaccum hose is connected? It's possible the tap needs a re-build and the motor's sucking fuel straight into the port.

Mate it does and i think it does go to number 2 carb!

And teh tap leaks like a fucker and does need a kit put through it, is this a common problem with the taps leaking
back into the carb is it??

Ill have to check closer this arvo!

Cheers hillsy

[Hillsy]

If the vaccum valve in the tap is perished it can suck fuel straight into the port.

[damo1]

I just checked it out:

The tap is fucked and the vacume feed comes off the number 2 inlet manifold.

i have seen fuel in the end of the line before when removing the tank and just thought it was exess off the fuel line in it, now im thinking the thing has been drowning in fuel and poring it straight into the port as you mentioned.

It makes sense now that when the tank is off and i pull the plug and dry it then re install and hit the starter
it fires on all four and when i replace the tank its back to a three cyclinder again.

Ive ordered a brand new tap off Kawaski only 130$ to bets rebuilding the old one, that should be here in a couple of days.

Cheers for your feedback hillsy hopefully i'll be on the right track now, i owe you a couple of ales mate.

[Jinx]

If the fuel is running into the cylinder has it contaminated your oil. Had a fucked tap on my Z1300 and fuel filled up my sump.

[damo1]

If the fuel is running into the cylinder has it contaminated your oil. Had a fucked tap on my Z1300 and fuel filled up my sump.

Yeah funny you say that the sump is fuel of fuel as well,
She's got a oil change coming up as well once I get my new tap.
I thought the tank felt lighter two days after putting 20$ in it,
Looks like the internals have been washed clean as well.
Cheers mate

[Redmohawk]

Look at the upside , wont be much sludge in the sump .

[ozzy1100]

in the cars we used to put a cup of diesel in the oil before we warmed up to drop for a change

[MONO]

This might help with your thread Title

CARB VENTING

The CV carb needs the presence of outside air (at atmospheric pressure) inside the carb for several reasons:

--Outside air is needed under the diaphragm to push it up.
--Outside air is needed above the fuel in the float bowl to push down on the fuel and force it up past the various jets and into the starting, pilot and run circuits.
--And outside air is needed to service one or more of the air jets that reside inside the carb body..

How does this outside air get in? It gets in through the breather pipe which sits toward the top of the carb just under the diaphragm. Air jet(s) also reside in this space and have access to it. And drillings in the carb body allow the outside air to go down and enter the space above the fuel in the float bowl.

A breather tube typically attaches to the breather pipe and extends to some point (e.g., behind a side cover, or inside the aircleaner pod) where the air is relatively calm. Why? We don't want wind to be changing the airpressure at the end of this pipe, because this will disturb the operation of the air jets, the diaphragm, and the fuel delivery. These functions need consistant outside air pressure to work properly against the various levels of depression created in the bore, above the diaphragm, etc., as the carb goes about its work.

Hope this helps

[El_Hefty]

in the cars we used to put a cup of diesel in the oil before we warmed up to drop for a change



yep its now sold as 'engine cleaner' or 'engine flush' and available for between $6 and $10/ Litre at the likes of Repco etc...

Bargain

[ozzy1100]

tell you what, dont it work and ill stay with a few cents worth of the stuff out my truck lol

[damo1]

This might help with your thread Title

CARB VENTING

The CV carb needs the presence of outside air (at atmospheric pressure) inside the carb for several reasons:

--Outside air is needed under the diaphragm to push it up.
--Outside air is needed above the fuel in the float bowl to push down on the fuel and force it up past the various jets and into the starting, pilot and run circuits.
--And outside air is needed to service one or more of the air jets that reside inside the carb body..

How does this outside air get in? It gets in through the breather pipe which sits toward the top of the carb just under the diaphragm. Air jet(s) also reside in this space and have access to it. And drillings in the carb body allow the outside air to go down and enter the space above the fuel in the float bowl.

A breather tube typically attaches to the breather pipe and extends to some point (e.g., behind a side cover, or inside the aircleaner pod) where the air is relatively calm. Why? We don't want wind to be changing the airpressure at the end of this pipe, because this will disturb the operation of the air jets, the diaphragm, and the fuel delivery. These functions need consistant outside air pressure to work properly against the various levels of depression created in the bore, above the diaphragm, etc., as the carb goes about its work.

Hope this helps

So the old breathers were from memory hooked up to the air box?? i think??

I have them just hanging up around the frame rails now, should i run them up under the seat so as not to have them affected by air around the frame under the tank or would they be ok there??

Cheers

[MONO]

If yor talking about the 2 big black hoses that come off the top between the 4 carbs.
Dosen't matter their not realy affected.
It's the air jets at the inlet that i was referring to, remember these are CV "Constant Velocity" carbs they work best with a air box.