Nibbi PEZ28 on 2024 CSC TT250 - Page 3

Bill Hilly · 08-28-2024, 06:05 PM

This is a follow up to my post earlier today. The Nibbi PEZ is not a PZ30 clone, but it is made as a slightly more direct replacement for the PZ30. Basically the PE28FL, and the PEZ look the same, but the PEZ has about 45-46 mm O.D. breather side, and the PE28FL has about a 49mm. I think, (but don't know for sure) the PEZ has a different needle. I don't have a PE28FL around anymore to compare with, BUT I have noticed the needle on my PEZ is very sharp, and thin , and has no taper for about the first 3/4" or so. Any jet bigger than a 115 slides way down the needle. A 120 slides right down it . I realize that's probably why I had to lower the needle so far when I had my hotter motor , and was running a larger main. I don't think the needle in the PEZ is going to be ideal with larger jetting. These are pictures of the needle, and the needle with a 120 main on it. A 115 will not slide over it.http://

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ughmas · Yesterday, 09:05 AM

I have a PE28FL and I have faced similar initial tune/jet challenges with it. I'm betting its almost the exactly the same except the OD of the inlet side. I can take some measurements if you are curious. I just took the bike out since its starting to cool down to a reasonable riding temp, I was about to take a fresh crack at tuning it. following along with your experience and will let you know what I end up with

superjocko · Yesterday, 06:27 PM

For what it's worth, I tried a 40 and a 38 before settling on a 35 pilot. I had to have the pilot air screw out farther than I'd care to with the bigger pilot jets, and could also not achieve as clean a transition to the needle when the bigger pilots were in the carb. With the 35 pilot jet, and the needle clip in the second groove from the top (next to leanest needle position), I run my pilot air screw anywhere from 3/4 to 1-1/4 turns, depending on the elevation that I'm riding at. I just tune the pilot air screw for best idle and throttle response in a manner very similar to that in the already posted youtube video.
I'm using the same natural aluminum colored body Nibbi 28mm flange-type carb that I believe the OP is. However, my engine has the Motocult stage 3 kit installed, so your results may vary.

ughmas · Yesterday, 07:17 PM

Quote:

Originally Posted by superjocko

For what it's worth, I tried a 40 and a 38 before settling on a 35 pilot. I had to have the pilot air screw out farther than I'd care to with the bigger pilot jets, and could also not achieve as clean a transition to the needle when the bigger pilots were in the carb. With the 35 pilot jet, and the needle clip in the second groove from the top (next to leanest needle position), I run my pilot air screw anywhere from 3/4 to 1-1/4 turns, depending on the elevation that I'm riding at. I just tune the pilot air screw for best idle and throttle response in a manner very similar to that in the already posted youtube video.
I'm using the same natural aluminum colored body Nibbi 28mm flange-type carb that I believe the OP is. However, my engine has the Motocult stage 3 kit installed, so your results may vary.

Thanks for this, that was my planned next move when I pull the bowl and needle out - I had not tried leaning out the needle (had been trying to get it to be happy on stock 3 position and 4 position richer) Will report with how it goes. what are you running for main?

Sdmfjon · Yesterday, 11:41 PM

I've learned an interesting pattern with the needle and air screw.

Changing the needle position forces me to change the air screw.

With a 40 idle jet.

Needle position 4 = 3 turns out to achieve highest idle.
Needle position 3 = 2 1/2 turns out
Needle position 2 = 2 turns out.

* At needle position 2 I have to use the choke to start the bike cold, even on a very hot day. At needle 3 I don't really need the choke.*

Also does everyone's bike decel pop? No matter what tuning i do, it decel pops very steadily. No emissions systems on my bike either / no exhaust leaks.

Sdmfjon · Today, 12:18 AM

But anyways. Yup not right.

At this point neither tunes have been correct.

115 main and 38 pilot. Needle 2 (best tune)

Too rich, flat acceleration, back soot from exhaust. Idle was nice but coming off idle sucked. Sometimes it would even just shut off if I tried to rev match, decel popping. Bike wouldn't start without choke no matter outside temperature.

112 main and 40 pilot needle 2 (best tune)

Need choke to start, decel pops the same. Idle is really nice, coming off idle is really good. I can rev match just fine. Still sounds rich but now it bogs when I transition between half and full throttle. The engine makes more power at 3/4 throttle (and sounds better) then at full throttle.

Things I have given up on.
- crack throttle bog. Never gonna go away.
- decel pop. Sounds the same since day one.

*I know it's been said before to look into a different needle but at this point I don't want to throw another variable into the mix. I really just want this bike to start up, run good and be a reliable ride around the city. So far, it's starts up.

08-28-2024, 06:05 PM	#31
Bill Hilly Join Date: Feb 2021 Posts: 991	This is a follow up to my post earlier today. The Nibbi PEZ is not a PZ30 clone, but it is made as a slightly more direct replacement for the PZ30. Basically the PE28FL, and the PEZ look the same, but the PEZ has about 45-46 mm O.D. breather side, and the PE28FL has about a 49mm. I think, (but don't know for sure) the PEZ has a different needle. I don't have a PE28FL around anymore to compare with, BUT I have noticed the needle on my PEZ is very sharp, and thin , and has no taper for about the first 3/4" or so. Any jet bigger than a 115 slides way down the needle. A 120 slides right down it . I realize that's probably why I had to lower the needle so far when I had my hotter motor , and was running a larger main. I don't think the needle in the PEZ is going to be ideal with larger jetting. These are pictures of the needle, and the needle with a 120 main on it. A 115 will not slide over it.http://http://
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Yesterday, 09:05 AM	#32
ughmas Join Date: Feb 2016 Location: NY Posts: 174	I have a PE28FL and I have faced similar initial tune/jet challenges with it. I'm betting its almost the exactly the same except the OD of the inlet side. I can take some measurements if you are curious. I just took the bike out since its starting to cool down to a reasonable riding temp, I was about to take a fresh crack at tuning it. following along with your experience and will let you know what I end up with __________________ 2005 CBR600RR 2016 CSC TT250 Coming Soon
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Yesterday, 06:27 PM	#33
superjocko Join Date: Aug 2022 Location: Lincoln CA Posts: 126	For what it's worth, I tried a 40 and a 38 before settling on a 35 pilot. I had to have the pilot air screw out farther than I'd care to with the bigger pilot jets, and could also not achieve as clean a transition to the needle when the bigger pilots were in the carb. With the 35 pilot jet, and the needle clip in the second groove from the top (next to leanest needle position), I run my pilot air screw anywhere from 3/4 to 1-1/4 turns, depending on the elevation that I'm riding at. I just tune the pilot air screw for best idle and throttle response in a manner very similar to that in the already posted youtube video. I'm using the same natural aluminum colored body Nibbi 28mm flange-type carb that I believe the OP is. However, my engine has the Motocult stage 3 kit installed, so your results may vary. __________________ -2024 CSC TT250, stage 3 motocult kit, Nibbi PE28FL with custom-made cable controlled choke, modified stock muffler (larger diameter tailpipe), custom oil cooler installation with relocated stock evaporative emissions canister, oversized stainless steel footpegs, IMS folding tip shifter, a few little blingy bolts and bits. More personal preference mods to come.
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Yesterday, 11:41 PM	#35
Sdmfjon Join Date: Oct 2023 Posts: 31	I've learned an interesting pattern with the needle and air screw. Changing the needle position forces me to change the air screw. With a 40 idle jet. Needle position 4 = 3 turns out to achieve highest idle. Needle position 3 = 2 1/2 turns out Needle position 2 = 2 turns out. * At needle position 2 I have to use the choke to start the bike cold, even on a very hot day. At needle 3 I don't really need the choke.* Also does everyone's bike decel pop? No matter what tuning i do, it decel pops very steadily. No emissions systems on my bike either / no exhaust leaks.
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Today, 12:18 AM	#36
Sdmfjon Join Date: Oct 2023 Posts: 31	But anyways. Yup not right. At this point neither tunes have been correct. 115 main and 38 pilot. Needle 2 (best tune) Too rich, flat acceleration, back soot from exhaust. Idle was nice but coming off idle sucked. Sometimes it would even just shut off if I tried to rev match, decel popping. Bike wouldn't start without choke no matter outside temperature. 112 main and 40 pilot needle 2 (best tune) Need choke to start, decel pops the same. Idle is really nice, coming off idle is really good. I can rev match just fine. Still sounds rich but now it bogs when I transition between half and full throttle. The engine makes more power at 3/4 throttle (and sounds better) then at full throttle. Things I have given up on. - crack throttle bog. Never gonna go away. - decel pop. Sounds the same since day one. *I know it's been said before to look into a different needle but at this point I don't want to throw another variable into the mix. I really just want this bike to start up, run good and be a reliable ride around the city. So far, it's starts up.
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