After drilling a hole in the piston, my engine now revs less.

[Delta0413]

After drilling a hole in the piston, my engine now revs less.
I use NT carburetor. A hole in my piston. I tried both possibilities. With and without holes. I turned more rpm without the hole. After the hole was drilled, the rpm dropped. and the smoke increased. I thought it had something to do with the carburetor. I bought and installed OKO PWK. But unfortunately the problem is the same. It chokes at the last throttle and the revs do not increase as before. I use a G2 reed valve. Are full gas mixtures rich or lean? Main jet 115. Pilot jet 38.

What matters to me is top speed

 

[Sidewinder Jerry]

After drilling a hole in the piston, my engine now revs less.
I use NT carburetor. A hole in my piston. I tried both possibilities. With and without holes. I turned more rpm without the hole. After the hole was drilled, the rpm dropped. and the smoke increased. I thought it had something to do with the carburetor. I bought and installed OKO PWK. But unfortunately the problem is the same. It chokes at the last throttle and the revs do not increase as before. I use a G2 reed valve. Are full gas mixtures rich or lean? Main jet 115. Pilot jet 38.

What matters to me is top speed

What kind of brakes do you have?

 

[MinimumVK]

After drilling a hole in the piston, my engine now revs less.
I use NT carburetor. A hole in my piston. I tried both possibilities. With and without holes. I turned more rpm without the hole. After the hole was drilled, the rpm dropped. and the smoke increased. I thought it had something to do with the carburetor. I bought and installed OKO PWK. But unfortunately the problem is the same. It chokes at the last throttle and the revs do not increase as before. I use a G2 reed valve. Are full gas mixtures rich or lean? Main jet 115. Pilot jet 38.

What matters to me is top speed

Had the same issue as you. I drilled a 12mm hole in the centre of my piston, installed a G2 reed valve and a PWK 21mm carb. I tried the stock jets and had the same bogging issue. I then changed out the pilot for a 32 jet and main 85. Then the bike ran good but i settled on a 88 main.
You can get main jets on aliexpress (5 euros for a pack of 10 from your choosing, take the smallest set or what i got 80-102)
Best of luck!

 

[Delta0413]

What kind of brakes do you have?

hydraulic disc

 

[Sidewinder Jerry]

hydraulic disc

Yes, because speed kills if you can't stop.

 

[Delta0413]

Had the same issue as you. I drilled a 12mm hole in the centre of my piston, installed a G2 reed valve and a PWK 21mm carb. I tried the stock jets and had the same bogging issue. I then changed out the pilot for a 32 jet and main 85. Then the bike ran good but i settled on a 88 main.
You can get main jets on aliexpress (5 euros for a pack of 10 from your choosing, take the smallest set or what i got 80-102)
Best of luck!

Thanks for the message. I changed the needle setting. Better now. But I'm still not satisfied. I would like to try what you said. But here's the problem. I live in Turkey and extra jets are expensive for me. In your country the product is $5. But if I want to buy from Aliexpress, tax + shipping + product = 400 Turkish Liras . I'll try something though.

 

[Delta0413]

Yes, because speed kills if you can't stop.

You are right.

 

[Sidewinder Jerry]

You are right.

Sadly, many come on here only concerned with going faster but just have a rear coaster brake. Are you able to get ethanol free gas (100% gas)?

 

[Wyvern]

Yes, because speed kills if you can't stop.

You'll still stop... suddenly.

 

[Chainlube]

Thanks for the message. I changed the needle setting. Better now. But I'm still not satisfied. I would like to try what you said. But here's the problem. I live in Turkey and extra jets are expensive for me. In your country the product is $5. But if I want to buy from Aliexpress, tax + shipping + product = 400 Turkish Liras . I'll try something though.

If you can get your hands on a set of mini drill bits, you can solder up the stock one and redrill it smaller.