mixture help !! cv34 carbs.

HELP PLEASE !!!
hi,i have been on all your forums about my cv34 carbs and still cant get it right !! :ohmy:

bike-- kz 750 ltd - 1980
carbs-- 4 x cv34
exhaust-- motad 4 into 1
air filters-- 4 k&n ( oval shape)
prim main-- 68(stock 62)
second main-- 135 (stock 125)

ok here is the problem -- the bike had standard air box and the motad exhaust on it when i got it,however it always run a bit rough...
i decided to drop the k&n filters on and try to get it 100% right..
this is the list of things i have done in stages----

had bike set up on rolling road inluding dynamic testing to get best power etc..
it run worst AFTER than before !! ( he had put a 116 second jet in ).
took it back and they put a 120 jet in..
i then decided to set it myself ( waste of £100)

stripped carbs completely..full clean/degrease and air line jet.. all holes clear
changed jets to above table..
full carb rebuild including 4 new fuel/mixture screws ( including washers and seals)
reset float heights ..
new plugs/leads etc etc

now for the dilemma:angry: --
bike fires up straight away with a little choke,knock it off and she purrs like a kitten at 1000 rpm..
ihave full power and super smooth running straight through all revs and gears !!
the bike does tend to run slightly faster at 1750 rpm when warm. (not a problem though )
why am i on here you are thinking ??

---

3 OF MY PLUGS ARE SUPER SOOTY !! number 2 cylinder that feeds vaccum fuel tap is fine ..
number 4 cylinder gets thick soot within 2 miles :huh:
i also get a slight popping when de accelerating ..
i have tried all the different mixture settings including having screws out 1/4 turn only .. i have checked all over for air leaks etc and all ok ..
i have even run bike with no filters on to see if they were the problem. all carb vaccums have new rubber caps on too.
do i just not worrie and ride it as it is ( if it aint broke dont fix it ..) or does anyone have any ideas ( i have done everythink that has been on this forum ) :S
thanks in advance from over here in england ..

If the bike runs good, gets decent gas milage and does not foul the plugs I would just ride it for a while and see what happens.

malvernmart wrote: ...
reset float heights ....

Would also perform the clear tube test to assure proper fuel level.

Good Fortune!

The older these bikes get, the harder it is to diagnose from description.
So many bikes that are carbed and running rich have totally worn out needle jets, not to be confused with jet needles. The needle jet is the basically female part of the neddle assymbly. These needles wear out the needle jet and it wears oblonged. Once that happens, they run rich and never can be correct until they are replaced. Beyond that Im guessing your float levels are slightly off or lowspeed screws are too rich. Back in the day I diagnosed sooty conditions on these guys sooo much that if flat vales and lowspeed couldnt help, I'd simply replace them, and almost always they ran better. The needle jets are hard to see into as well. They start wearing bad around25k-over miles from constant moving of the jet needles up and down.

If not already done, would assure that the ignition coils are receiving full battery voltage.

And also visually examine spark quality with plugs removed, which should be fat blue sparks (not weak orange sparks).

Good Fortune!

hi patton...
i did do that as well
i set the heights to the same level as number 2 cylinder ( the good plug )
this was one of the last things i did ( after trying everything else ) .
this action made the bike run and tick over super smooth
the whole thing is a puzzle :blink: -- especialy number 4 plug-- i will clean it with wire brush and check it within 1 or 2 miles , and it is thick with soot ( dry , not wet from bad rings etc )
has enyone else hjad or got this problem
cheers again...

cheers oldschoolz..
i looked at the needles and they do look ok, however the bike has 34000 miles on the clock , so that could be the problem -- you have given me an idea now -- il change number 2 needle ( good plug ) over to number 4 and see if that does the trick !!
i will post back soon ..
on a sad note however i have looked for needles before ( no 1a ) and can not find any at all -- guess no one produces pattern needles ?? ( unlike jets )..
cheers again though - this imput from you all has given me a next step approach
martin

If not already done, would ---
Assure valve clearances within specs;
Lube pivot points on ignition advancer;
Assure pilot jet plugs and their o'rings are fitted and serviceable;
Assure pilot air jet is clean and clear.

Good Fortune!

...first #1 would foul,replaced float needle and adjusted float level.now all plugs foul within 10 miles.have turned a/f screws out 1 turn.still foul plugs...real hard to start when cold(thinking thats because 1 turn out)choke on and lots of twisit of throttle and plugs aren't wet and barely smell gas.once starts it will start fine after that....

For reference, turning a/f screw "out" enrichens, and turning "in" leans.
If meaning only turned out 1 turn from seated, that should be plenty lean.

The enrichener circuit (as opposed to a true choke) is designed to operate when the throttle remains fully closed.
When starting a cold engine, it's best to not touch the throttle.
"Pumping" the throttle largely disables the enrichener circuit.

Good Fortune!

Oops, and apologies to rcook52459 for having goofed up and unintentionally "edited" his foregoing post instead of "quoting and replying" in the usual manner.

Good Fortune!

had a 2008 vtx1300 had enrichener. a/f screw 1 1/18th turn out.i turned it out 1/2 turn more and never had to use the enrichener again even in 30 degree weather.was hit and bike totaled.got this to see if i can ride again.just want to ride,won't be anymore long distance,but ride.thinking it was a choke this will help me just knowing an enrichener,forgot about that.still spark is blue/yellow not strong blue.1st got bike had to replace igniter no spark,then had spark 2 3 coil replaced 1 4 coil nd now runs.got to get heating oil for winter then thinking about dyna ignition,just to rule that out and get srong spark.sorry don't want to steal malvernmart thread.was goin start new thread,but thought might have simaler problem.

malvernmart wrote: cheers oldschoolz..
i looked at the needles and they do look ok, however the bike has 34000 miles on the clock , so that could be the problem -- you have given me an idea now -- il change number 2 needle ( good plug ) over to number 4 and see if that does the trick !!
i will post back soon ..
on a sad note however i have looked for needles before ( no 1a ) and can not find any at all -- guess no one produces pattern needles ?? ( unlike jets )..
cheers again though - this imput from you all has given me a next step approach
martin

OldschoolZ is not talking about the needle, he is talking about the jet that the needle goes in and out of.