Nibbi PEZ28 on 2024 CSC TT250

[superjocko]

Putting the float bowl back on this carb is just a bit fiddly. I start the stand-off tube into the well in the bowl and then gently help the bowl find its way home at a slight angle until everything goes freely. If you're not careful to do that, it would be fairly easy to knock your float level out of adjustment.

Don't get yourself too worked up over it. Making little mistakes and learning from them is how you know better than to make them next time.

[bigdano711]

Originally Posted by Sdmfjon

Update. That worked. No stumbling, no gassy smell.

I still can't crack throttle from idle to anything 1/2 or beyond. If I bring the bike off idle it's fair game. Oh well. I don't want to spend 300 dollars on a really nice genuine pumper carb like my hondas have.

Final tune for now.

Stock bike. Emissions removed and a Nibbi PEZ28 fitted.

38 idle jet
Needle position 2
Air screw 1 1/2
Main jet 115.

I think this is a good "base tune". I think your 35 pilot is too lean. If I were you, I'd go back to this tune and try dropping the main jet one at a time and see if things don't improve.

[Sdmfjon]

Originally Posted by bigdano711

I think this is a good "base tune". I think your 35 pilot is too lean. If I were you, I'd go back to this tune and try dropping the main jet one at a time and see if things don't improve.

I agree. I am going to go back to that tune when I resolve the float issue. Looking at the float visually I can see it is angled up, so I must have beat it up when changing jets.

I ordered a float gauge. I'm going to set it at 19 like the factory manual says and go from there.

Until then I put the stock carb back on so I can get around the city. 35 pilot 112 main needle 4. (Fuel screw about 3 1/2 turns out.)

[ProDigit]

Mid throttle issues are usually caused by jet needle height.
Most of the time it's set to too rich, as too lean will work but with lower power.
Too rich will feel like a more abrupt power loss.

[Thumper]

So what have you decided to buy??

Originally Posted by Sdmfjon

Hello

I can now confirm the Nibbi PEZ28 is a direct fit for the 2024 TT250. I did not have any issues with fitment. This carburetor sits almost exactly where the stock Keima sits. The throttle cable is just long enough to work. I did not have to modify anything to make it fit.

Tuning on the other hand, this is where I'm at.

Fully stock bike with emissions removed and a Nibbi PEZ28 carburetor fitted. I am in Maine and live at the beach. My elevation is less than 50' and it is summertime. Sunny day and about 85 degrees air temp.

Idle jet - 38 (factory was a 40 and too much for my stock setup)
Air screw 1 and 1/4 turn out ( factory is 1 and 1/2 )
Needle - position 3
Maine jet - 110

Idle is beautiful and strong. WOT is ok. Midrange needs adjustment.

I still can't quick throttle without it dying. I can roll on and it is fine. Only had like 45 mins to tune before having to go to work.

The max jet the carb came with is a 110. I think I either need to mess with the needle or change to a 112.

The air screw on the side is awesome.

[Sdmfjon]

Originally Posted by Thumper

So what have you decided to buy??

Nibbi PEZ28. Direct fit for a hawk/tt250

Here is a link to it.

https://nibbiracing.com/products/pez...waAjo-EALw_wcB

[bigdano711]

Originally Posted by Sdmfjon

Hello

I can now confirm the Nibbi PEZ28 is a direct fit for the 2024 TT250. I did not have any issues with fitment. This carburetor sits almost exactly where the stock Keima sits. The throttle cable is just long enough to work. I did not have to modify anything to make it fit.

Tuning on the other hand, this is where I'm at.

Fully stock bike with emissions removed and a Nibbi PEZ28 carburetor fitted. I am in Maine and live at the beach. My elevation is less than 50' and it is summertime. Sunny day and about 85 degrees air temp.

Idle jet - 38 (factory was a 40 and too much for my stock setup)
Air screw 1 and 1/4 turn out ( factory is 1 and 1/2 )
Needle - position 3
Maine jet - 110

Idle is beautiful and strong. WOT is ok. Midrange needs adjustment.

I still can't quick throttle without it dying. I can roll on and it is fine. Only had like 45 mins to tune before having to go to work.

The max jet the carb came with is a 110. I think I either need to mess with the needle or change to a 112.

The air screw on the side is awesome.

It appears your original tune was very close, and this entire thread was a lesson in hair pulling. There is something in your head that tells you that you can get it to not die when you crack the throttle if you JUST find the right tune. That is a lie from Satan whispered into your ear. I know, I've been down this rabbit hole.


I think Thumper is wondering what kinda pumper carb are you gonna buy?

[Thumper]

I'm thinking best way out is a new Nibbi PE28. It doesn't have the throttle pump, but would probably be easier to set up.

[Sdmfjon]

I'm not, but If I did go down the rabbit hole of premium carbs. I would want to use a vacuum slide / acceleration pump carb like the one on the rebel 250.

[Sdmfjon]

Zero to full throttle rips on the stock carburetor. Barely any hesitation. Comes right back to idle.

My tt250 has never run this well. Maybe my answer is to just leave the stock carb on lol.

Stock carb.
35 idle jet
Main jet 112
Needle position 4
Fuel screw 2 3/4 turns out.

Here's a video.

[bigdano711]

I'll give a thumbs up to the stock carb, although I don't like where your fuel screw is at; 2 3/4 turns out.


I'm starting to think these Nibbi's aren't all they're cracked up to be. I think I made mine as good as it's gonna get with the JJH needle. Megadan switched to a Mikuni or a Mikuni clone...starting to think about going that route.

[Bill Hilly]

Originally Posted by bigdano711

I'll give a thumbs up to the stock carb, although I don't like where your fuel screw is at; 2 3/4 turns out.


I'm starting to think these Nibbi's aren't all they're cracked up to be. I think I made mine as good as it's gonna get with the JJH needle. Megadan switched to a Mikuni or a Mikuni clone...starting to think about going that route.

I eventually put a Nibbi PE28FL on my old TBR7 after installing full exhaust, and pod filter, and had no trouble tuning it, but I had already rejetted the stock PZ30 that was on it. I was lucky because it actually came with a 36 pilot. I ended up selling the TBR7, but kept the old stock carb. I ended up putting it on my Hawk, and it always performed flawlessly. I did end up going with the Nibbi PEZ after building the Hawk's motor for more power. It was hard to tune,which I realize now was probably because of the needle. After I put a stock motor, which had a VM26 Mikuni style on it, I went ahead, and stuck with that carb, and while I did play with the jetting just a little, it now performs flawlessly. Most people on this forum are more level headed than some on the Facebook groups. You have people buying a stock bike, and asking about carbs, and someone always recommends a PE30, claiming " really wakes up the bike", AND the sad
thing is they often buy the PE30, and put it on a stock bike, with stock exhaust, and wonder why they can't tune it.

[Thumper]

Or reinstall the original PE28 carb in you high performance CG230 clone.
Glad that worked.
The simpler way to higher hp is a 172FMM
(20hp) In a different bike. For about the same price, or less.

We

Originally Posted by Sdmfjon

Zero to full throttle rips on the stock carburetor. Barely any hesitation. Comes right back to idle.

My tt250 has never run this well. Maybe my answer is to just leave the stock carb on lol.

Stock carb.
35 idle jet
Main jet 112
Needle position 4
Fuel screw 2 3/4 turns out.

Here's a video.