AFR RESULT

Maxbou92 wrote:

Do Carb synchro could be not right?! I tune them with 1/8 drill bit. They look identical!!

that’s a great starting point but you need to vacuum sync to compensate for any efficiency difference between cylinders
PS: are you taking your AFR readings at a constant throttle or wacking it open and taking a reading 

What do you think about first clip from top with 0.5mm washers?

Maxbou92 wrote:

What do you think about first clip from top with 0.5mm washers?

All you can do is experiment, it is that 1/8 - 1/2 where you are rich (and very lean on idle) ideally on an air cooled motor you want to between 12 & 13 across the board (or as close is achievable)

Maxbou92 wrote:

What do you think about first clip from top with 0.5mm washers?

All you can do is experiment, it is that 1/8 - 1/2 where you are rich (and very lean on idle) ideally on an air cooled motor you want to between 12 & 13 across the board (or as close is achievable)

If you are seeing differences between cylinders even though they are jetted identically, I would suspect something is wrong with the individual carbs. Either a clogged passageway or float levels.
Conversely, it could be a weak spark for those two cylinders. You could try swapping the coils. 

Thank youu. I installed 0hms plug cap, new wires (Ton’s wires 0 ohm). My Oem coils has both Oem  resistance. Thats so weird thar my afr is so rich at very light cruise at 60-70 mph. But after that is pretty good. Maybe drop needles from clip 1 or 1.5 (washers) ?!! Maybe its because the carbs are made for Kz900-1000 ?! 😬

Are your pilot jets sized for a 750 or a 1000 ?

Are you using a OEM electronic ignition that has a ignitor box? Those have been shown to be bad but still work, a symptom is weak spark at low RPM. If using Dyna S disregard.

A 650/750 engine is OK with a #15 pilot jet, maximum would be #17.5 for some combinations but never higher than that unless its a race engine.

FYI - I have never heard of anyone using a Mikuni pilot jet of less than #15 and clipping a needle at #1 or #2 position. 

A lot of so called carb issues are actually ignition related. Just because you see a spark does not mean its strong enough to be useable.
 

Thats weird, because with my old CV34 the bike was running fine at low rpm but worse than now at high rpm with Pods!! The VM could be too big for my 750? Yes Im using oem ignition box and coil!!  What ignition box should I use ?!

Maxbou92 wrote:

Thats weird, because with my old CV34 the bike was running fine at low rpm but worse than now at high rpm with Pods!! The VM could be too big for my 750? Yes Im using oem ignition box and coil!!  What ignition box should I use ?!

 

No the VM carbs are not too big for a stock 750 engine, either 26 or 28's work with no issues. I have run RS34 flat slide on a 750 with no issues.

I thought I would mention the ignition only because you pilot and main sizes are fine for your setup. The only thing not normal is the lean needle clip setting. If your set lean on the needle and your running rich thru 1/8-1/4 then its not the jetting, its something else causing the richness.

I am just saying that in the past I have had a couple of Kawi Ignitor boxes that put out weak spark. I was getting spark but it was weak enough to cause combustion issues. If you have weak spark you will have a rich mixture, even if you have adequate compression. As soon as I switched to a Dyna S ignition plate (no box) it fixed the problem.

You can get China copy Dyna S pretty cheaply on Ebay, they work. I have one on my 1200 engine.
 

Thank you, so weak spark can happen at low rpm and can be perfect at WOT ?!

I think about it.. does my Air corrector could be not right for my bike?