Could it be the cause pulse generator?

[Artur POLSKA]

My problem with the motorcycle has not been solved, because unfortunately I have little time. Now I have a little more of it, so I decided to make another attempt to fix it. I will write briefly. The maximum speed I can reach is 130 km/h. (about 5000 rpm). It also uses a lot of fuel. Today I checked the pulse generator and I'm sure my vacuum device is out of order. Can the vacuum valve be purchased separately? If it can't be purchased, is there an OEM replacement? How to measure the resistance on the sensors and how many ohms should they have? Could this valve cause the bike not to go faster? Also, it accelerates very slowly. I changed the carburettors (I did not synchronize them) is exactly the same as on the previous carburetors. I'm running out of ideas what could be causing the malfunction . Sorry for my English.

[Rambozo]

That was only available as a unit and was discontinued long ago.
Test the advancer with a hand pump to confirm it has failed.
It will be a little down on power without the vacuum advance, but not that much.
Verify that the mechanical advancer is working properly. You can also modify the mechanical advancer to not require a vacuum advancer if you are unable to find a working unit.
Another option is to use an aftermarket ignition unit that handles the advance internally, locking out vacuum and mechanical advancers.

[Artur POLSKA]

I checked with a hand vacuum pump. There is no vacuum at all. How to modify the mechanical feed you mentioned? You also talk about using an aftermarket ignition unit. What does it look like?

[Rambozo]

Typically, you can alter the mechanical advance by changing the springs and limit stops to reset the advance curve. Might be a little tricky for the bike since you can't just put the pickup system into a distributor machine. I've done this to lots of automotive distributors, but would need to make some kind of adapter to work with a bike, or just do it in place on the bike with a timing light and degree wheel.
One thing is what kind of fuel quality you have there. That can impact how much timing you can run without engine knock. I'm sure local shops will know what works for your fuel.
There are a ton of aftermarket ignition boxes to pick from.
Here is one example. Some may be able to use dual pickups, but most will just use a single pickup and create the other pulse internally. Depending on the unit, you can keep the wasted spark dual coils or update to coil-on-plug or other four coil setup.
https://www.cbperformance.com/product-p/2013.htm
I would not go throwing parts at anything until you have checked over what you have for any problems besides the bad vacuum advance. Put the bike on an engine scope and see what it is doing. Make sure your mechanical advancer is not rusted solid.
I think you would have to have more than just missing vacuum advance to top out at 130kph.

[Artur POLSKA]

I definitely need to check the valve setting. I did not set the valves according to the instructions, i.e. at point T-1, I just turned the crankshaft so that the valve springs were not compressed and then I set the valve clearance. Maybe that's my mistake too. At the thought that I have to disassemble pulse generator , I'm nervous, because access to it is difficult.

[Tparr]

Arturo, have you changed the timing belts? Perhaps the valve timing is off a tooth.
You can easily check the pulse generators(pick up coil) with an ohm meter. ( approx. 530 ohms ). The four wire connector is under the left side battery cover, right next to the three yellow wire stator plug. Ohm the blue/ blue white pair and then the white/ yellow pair.
From information i have gathered, If the vacuum advance is no longer functional it should not have a major effect on engine operation. A slight increase in fuel consumption. Just block off the vacuum port on number 3 carb.
Syncing the carbs is important and should be accomplished first. If the cylinders are not pulling equally the engine will Rev poorly and lack low end power.

[Artur POLSKA]

I checked the timing again today and it seems fine. I set the wheel to the T1 mark, The marks on the timing gears coincide with the marks on the casing. In this position, piston 1 and piston 2 are in the upper position. When it comes to carburetor synchronization, what vacuum values ​​should the vacuum gauge show?

[Tparr]

A link to a step by step tutorial of synching the carbs.
viewtopic.php?f=11&t=81
I use a carbtune pro. The overview is that the number 3 carb is the base, all other carbs will be adjusted to it. First adjust carb 1 to match carb 3, the value is not relevant you are just looking for the same reading. next adjust carb 2 to read the same as carb 4. Finally adjust bank 2 and 4 to match bank 1 and 3. Easy once you do it.

[Artur POLSKA]

I set it up completely differently. I certainly didn't do it in the order you wrote about. First, I set the carburetor 3 and the revolutions around 1150rpm. The next step was to adjust the other carburettors, without keeping the order. I was only interested in making them all work the same. .
I will follow your advice and do as you do.
I also set with Carbtune PRO.

[Tparr]

I just went through all your posting about your motorcycle. I watched the youtube video of your problem. First I noticed your carbs were synced well, doesn't matter how you did the process the end result was good. So that is not the issue. I do not have any ideas about what is going on with your bike at high revs. Can you isolate where the sound is coming from? Valve noise, carbs, timing chain?