Help needed. 81 KZ650-D4 w 81 KZ750-4 engine & VM2

I want to thanks everybody involved I have now planned to purchase:

Pilot Jet:
17,5
20
www.denniskirk.com/ebc/rd-vm22-210-pilot...96.prd/173396175.sku

Main Jets:
112,5
117,5
115
120
www.denniskirk.com/ebc/rd-precision-miku...9.prd/1723991125.sku

Shims:
Sudco Carburetor Needle Shims For Mikuni Carbs - 009-395
www.denniskirk.com/sudco/carburetor-need...73688.prd/173688.sku

Is these a good plan? missing something? wast of money to purchase so many?

Thank you.

God day

Just a quick check you all while I`m waithing for the jets from US to arrive.
The plugs for the carbs, I`m using vaacum valve on the tank, then tube have I connected to B (see attached picture).
And I have blocked A and C (see attached picture) is these correct?
Some says that A is for ventilation ?

Thank you.

A = vacuum port for petcock
B & C = vents

The vent tubes on m 81 650 are routed over the airbxox shoulders & fitted snugly between the airbox & side covers. the left tube has a frame clamp. With individual pod filters route them behind the engine & forward of the swing arm & so they don't flop around.
The tubing helps to direct fuel away from a hot engine in the event of a crash.

martin_csr wrote: A = vacuum port for petcock
B & C = vents

The vent tubes on m 81 650 are routed over the airbxox shoulders & fitted snugly between the frame & side covers. the left tube has a frame clamp.

Thank you, what happens if you block the vent ports?

gordone wrote:
Thank you, what happens if you block the vent ports?

Fuel flow will be very poor. The vents must be left open to the atmosphere.

Nessism wrote:

gordone wrote:
Thank you, what happens if you block the vent ports?

Fuel flow will be very poor. The vents must be left open to the atmosphere.

Think I have to check these out tomorrow, and see what differens it makes.

So you have the (C) vent plugged like the pic shows..... this could be most of your problem... either leave them open or run em like Martin says... I ran hoses behind the motor and down under the pan after just leaving them open for years and the wind flow over the opening was causing it surge and run like crap at speed and as soon as I removed em it was back to normal.

Damn it I just went back to your first picture of the carbs (other thread) and it shows the red plug on it.... can't believe I didn't notice it before.

KZB2 650 wrote: So you have the (C) vent plugged like the pic shows..... this could be most of your problem... either leave them open or run em like Martin says... I ran hoses behind the motor and down under the pan after just leaving them open for years and the wind flow over the opening was causing it surge and run like crap at speed and as soon as I removed em it was back to normal.

Damn it I just went back to your first picture of the carbs (other thread) and it shows the red plug on it.... can't believe I didn't notice it before.

These picture is old, before I started the rebuild of the carbs, so I need to check the bike how I have connected it now and do a test run
I will not be able to test it before of next week, I will keep all updated, when I have checked it

I was in the garage today and checked the vent for the carbs, and I have connected like martin says it shall be...
I took a test drive, and the behaqvior it still the same.

Looking forward to recive the new jests, hopefully will they solve my problem with the engine...?
Plan is to test them after Easter.

Thank you all for taken time to study my issue.

baldy110 wrote: Your way to rich on your jetting. Go to 112.5 on the main jets and 17.5 on the pilot jets. Put the needle clip in the middle slot. And use mikuni jets not the ones that come in those cheap ebay kits. That should get you pretty close.

Today have I installed the new jets 112.5 and 17.5, the nide was not in middle slot, it was one higher up (second from top).
The engine started easy and the sound from the engine was nice (from my point of view as a new beginner).
I started to drive slow on low RPM and it was respond okay to my throttle, just 2-3k RPM.
I started to give more throttle in a hill, and the engine was not going good some like before... going up to 5-6 and "choking" it self, if I tried to give more throttle... on top of the hill I stooped and stopped en engine, I was frustrated now...... I started the engine again, and
was giving full throttle (mad) and the engine was going to max RPM in red zone (in natural), not perfect increase in RPM, but it was going there... to red zone. And then something happened after I release the throttle and tested the throttle, something like something has loosen up ???? hehe because now was there different zone of from the engine, 500% better throttle response, and I have 500% power/torque,
no problem to run each gear to red zone..... I have stopped the engine and started it again and the zone is the same...

So my problem is solved ? but for how long time ? do I have unstable issue ? strange strange... I have tested the engine many times with the old jets never got it run properly....

Summary:
I re jetted to 112,5 and 17,5 and after I was giving full throttle and running the engine to red zone in RPM the engine "wake up"....

What was happened ? hehe

Sounds like the bike wasn't running on all four cylinders, but now it is. Maybe an intermittent contact somewhere causing dropped spark or a plugged up pilot circuit? Not sure, but I'm happy it's running better for you.

Nessism wrote: Sounds like the bike wasn't running on all four cylinders, but now it is. Maybe an intermittent contact somewhere causing dropped spark or a plugged up pilot circuit? Not sure, but I'm happy it's running better for you.

I found these strange, I have taken out the spark plugs several times and cleaned them and I can see there has been ignition on all four plugs, earlier when I have had these problem. Then it must be something when you have higher RPM. Can it be there was something wrong with the ignition system? I have not read how its work, but the timing must increase when the engine increase also?

I have cleaned the carbs... I cross my finger it was a block in the pilot... because then the problem will not come back

Maybe it was a combination that my new jets also have helped?

I don`t see any reason to increase the jets now? I think its run fine? I can wait seeling the jets (I order different sizes around 17,5 and 112,5) to have I have som more driving hours to get more experience from the engine?