TBR7 Carb Upgrade

Nospark · 01-27-2022, 10:23 AM

What is current approach for upgrading the jetting on a new TBR7? Is there a popular aftermarket carb that drops in with the preferred jetting? Is it better to rejet the factory carb? Where do I source the jet(s) and shims I see so many talking about when modifying their carbs?

buzz · 01-27-2022, 07:24 PM

just rejet yours,put 125 in mine and it runs great. Any new carb will have to be rejetted to your bike save your money,just buy new jets.

buzz · 01-27-2022, 07:25 PM

And 2 shimes on needle

Nospark · 01-28-2022, 09:25 AM

I'm sure the 125 works well for your bike. I'm concerned it would be oversize for me @ 600ft elevation. I guess the answer is get a jet kit and needle shims and dial my own bike in.

**JerryHawk250** · 01-28-2022, 09:32 AM

Start with a 110 or 115 on a stock exhaust.

Nospark · 01-28-2022, 11:12 AM

Got it. Makes sense you're running a bigger jet if also running performance exhaust. I'm going to start with just the carb modification. Can you direct me to a source for the jet kit and needle shims?
BTW, what exhaust are U running? Do you feel it's a good bang for the buck upgrade as far as performance or was it more of a styling upgrade for you?

Thumper · 01-28-2022, 01:01 PM

While you wait for a pack of main jets, just shim the needle a couple of millimeters and open up the pilot jet adjustment if needed. This will give you a first change impression to see how that goes.

My Storm has a PZ30 clone ("YouALL" branded), and I was happy to find that even after opening up the exhaust, a needle shim and pilot adjustment was sufficient to make it start and idle perfectly, and the low/midrange is much more willing and I can feel more power. Also, no back-firing. This was a good experience already.

The carb is fine and I really don't think anything beside an Elektron (sp?) pumper carb could make a real world difference. Yes, I will continue to dial it in with a bigger pilot jet so the adjustment screw doesn't have to be out at 4 turns!! And I will also get a bigger main jet in place and retune it after I modify the airbox. I think you may have the two piece pilot jets (apparently, PZ30 clones do). I ordered main jets with standard one piece pilot jets in one kit ($11) to explore the possibility of replacing the two piece pilot with a one piece pilot. If that does not work, I ordered the jet half of the two piece pilot jet (an assortment in a kit), and will go with that.

Nospark · 01-28-2022, 03:22 PM

Is it safe to purchase the jet kit without verifying what carb will be on the bike when it's delivered? If it's a given what will be on the bike, is this the kit I need?
https://www.amazon.com/labwork-parts...ve%2C91&sr=1-9

krat · 01-28-2022, 04:24 PM

Quote:

Originally Posted by Nospark

Is it safe to purchase the jet kit without verifying what carb will be on the bike when it's delivered? If it's a given what will be on the bike, is this the kit I need?
https://www.amazon.com/labwork-parts...ve%2C91&sr=1-9

Not a smart move. I discovered that I could not purchase replacement jets for my carb anywhere. They exist I am sure, but I could not find them.

But what no one tells you is that those jet numbers are the size of the hole in MM. You can go to a good hardware store and buy a 1.05mm= 1.10mm drill bit, remove the jet, and just drill it out. 105 to 110 sizes are what 90% of the bikes require.

It is also much cheaper than the entire "jet kit" which will leave you with 5-10 unusable jets.

You can also buy micro drills and drill out the pilot jet if needed.

Nospark · 01-28-2022, 04:51 PM

I don't mind buying a jet kit. Using quality jets will remove any doubts I have about carb performance issues being the result of my jet drilling skills. And I would need new jets if I find I went too big and want to back up to the sweet spot.

Magician16 · 01-28-2022, 09:23 PM

I'm with Thumper. I think the PZ30 works great. Mine says Keihin Japan on it, but I don't think a real Keihin comes with tamper proof screws. The one that was on a Honda I had had no tamper proof screws. My Bashan storm runs great with a 37 pilot and 110 main. When I took my Storm's carb apart, it had so much crap in it that I was amazed it ran at all in the lower rpms. My Magician has a 42(can't remember for sure) pilot and 105 main.

Nospark · 01-28-2022, 09:56 PM

I haven't seen complaints about PZ30 performance so, I see no reason not to work with it. Are the jets difficult to source for the PZ30, assuming that's what shows up on the bike? Does the PZ30 have the adjustable needle or does needle height adjustment require shims?

Megadan · 01-29-2022, 06:51 AM

I run a PZ30B (pumper version of your stock carb) on my Hawk, which has a mild cam, ported head, and exhaust on it. Before that I ran a PE30, PWK30, PWK32 (didn't last long on that one) and even a PWK28. I went back to the PZ30 style carbs specifically because, while the others did give some slight benefit to the top end, they came at the cost of a handful of headaches or annoyances. They also came at the cost of overall rideability and fuel economy in some cases.

Fact is, most bikes don't need anything more than a PZ30, or the Mikuni clones - the "30mm" VM26 - which is basically the same carb as the PZ30, but it has an extra bowl screw and takes mikuni jets. Finding intakes that work is also easy, unlike the others.

If you are after an adjustable needle, you can also simply pick up a PZ30 rebuild kit, which usually comes with a new adjustable needle, float, O rings, main jet and other bits. Spare bits are handy to have

Also, instead of a jet "kit" you can simply order 2 or 3 main jets from jetsrus.com and cover almost every upgrade you may wish to do. Order a 105, a 110, and a 115. If you feel froggy order a 107.5 and 112.5 to cover all the little in betweens if you really want to dial that fueling in.

Magician16 · 01-29-2022, 09:02 AM

Whatever happened to NZBRAKELATHES? I bought a kit from him after I bought the Magician, and it had everything you might need to upgrade a PZ30, including adjustable needle, pilot and main jet assortments, etc.

Nospark · 01-29-2022, 09:40 AM

Megadan, Thank you for the specifics on the carbs. I'm curious why you didn't mention a change to the pilot jet as well. Is there not a concern going to 115 main will be ahead of the stock pilot jet during transition? My thinking now is stick with the PZ30 until the mods get to a point someday where I want to look at other intakes. I can envision performance exhaust,air box delete & sprocket size changes but doubt I'd go further with mods.
I tried to locate NZbrakelathes as well but, no success.

01-27-2022, 10:23 AM	#1
Nospark Join Date: Jan 2022 Location: Milwaukee, WI Posts: 167	TBR7 Carb Upgrade What is current approach for upgrading the jetting on a new TBR7? Is there a popular aftermarket carb that drops in with the preferred jetting? Is it better to rejet the factory carb? Where do I source the jet(s) and shims I see so many talking about when modifying their carbs?
	0

01-28-2022, 09:32 AM	#5
JerryHawk250 Moderator Join Date: Oct 2016 Location: Houma, La. Posts: 11,585	Start with a 110 or 115 on a stock exhaust. __________________ 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S (Sold) 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel
	0

01-28-2022, 09:23 PM	#11
Magician16 Join Date: Aug 2019 Posts: 469	I'm with Thumper. I think the PZ30 works great. Mine says Keihin Japan on it, but I don't think a real Keihin comes with tamper proof screws. The one that was on a Honda I had had no tamper proof screws. My Bashan storm runs great with a 37 pilot and 110 main. When I took my Storm's carb apart, it had so much crap in it that I was amazed it ran at all in the lower rpms. My Magician has a 42(can't remember for sure) pilot and 105 main. __________________ 2018 Bashan Storm(sold) 2016 Magician 250
	0

01-29-2022, 06:51 AM	#13
Megadan Join Date: Apr 2017 Location: Omaha, NE Posts: 8,051	I run a PZ30B (pumper version of your stock carb) on my Hawk, which has a mild cam, ported head, and exhaust on it. Before that I ran a PE30, PWK30, PWK32 (didn't last long on that one) and even a PWK28. I went back to the PZ30 style carbs specifically because, while the others did give some slight benefit to the top end, they came at the cost of a handful of headaches or annoyances. They also came at the cost of overall rideability and fuel economy in some cases. Fact is, most bikes don't need anything more than a PZ30, or the Mikuni clones - the "30mm" VM26 - which is basically the same carb as the PZ30, but it has an extra bowl screw and takes mikuni jets. Finding intakes that work is also easy, unlike the others. If you are after an adjustable needle, you can also simply pick up a PZ30 rebuild kit, which usually comes with a new adjustable needle, float, O rings, main jet and other bits. Spare bits are handy to have Also, instead of a jet "kit" you can simply order 2 or 3 main jets from jetsrus.com and cover almost every upgrade you may wish to do. Order a 105, a 110, and a 115. If you feel froggy order a 107.5 and 112.5 to cover all the little in betweens if you really want to dial that fueling in. __________________ Hawk Information and Resource guide: http://www.chinariders.net/showthread.php?t=20331 2018 Hawk 250 - Full Mod list here. http://www.chinariders.net/showpost....62&postcount=1 2024 Royal Enfield Shotgun 650 https://chinariders.net/showthread.php?t=34124
	2

01-29-2022, 09:02 AM	#14
Magician16 Join Date: Aug 2019 Posts: 469	Whatever happened to NZBRAKELATHES? I bought a kit from him after I bought the Magician, and it had everything you might need to upgrade a PZ30, including adjustable needle, pilot and main jet assortments, etc. __________________ 2018 Bashan Storm(sold) 2016 Magician 250
	0

01-27-2022, 07:24 PM	#2
buzz Join Date: Dec 2020 Location: Dayton Pa. Posts: 880	just rejet yours,put 125 in mine and it runs great. Any new carb will have to be rejetted to your bike save your money,just buy new jets.
	1

01-27-2022, 07:25 PM	#3
buzz Join Date: Dec 2020 Location: Dayton Pa. Posts: 880	And 2 shimes on needle
	0

01-28-2022, 09:25 AM	#4
Nospark Join Date: Jan 2022 Location: Milwaukee, WI Posts: 167	I'm sure the 125 works well for your bike. I'm concerned it would be oversize for me @ 600ft elevation. I guess the answer is get a jet kit and needle shims and dial my own bike in.
	0

01-28-2022, 11:12 AM	#6
Nospark Join Date: Jan 2022 Location: Milwaukee, WI Posts: 167	Got it. Makes sense you're running a bigger jet if also running performance exhaust. I'm going to start with just the carb modification. Can you direct me to a source for the jet kit and needle shims? BTW, what exhaust are U running? Do you feel it's a good bang for the buck upgrade as far as performance or was it more of a styling upgrade for you?
	0

01-28-2022, 01:01 PM	#7
Thumper Join Date: Feb 2021 Location: Kansas City Posts: 2,406	While you wait for a pack of main jets, just shim the needle a couple of millimeters and open up the pilot jet adjustment if needed. This will give you a first change impression to see how that goes. My Storm has a PZ30 clone ("YouALL" branded), and I was happy to find that even after opening up the exhaust, a needle shim and pilot adjustment was sufficient to make it start and idle perfectly, and the low/midrange is much more willing and I can feel more power. Also, no back-firing. This was a good experience already. The carb is fine and I really don't think anything beside an Elektron (sp?) pumper carb could make a real world difference. Yes, I will continue to dial it in with a bigger pilot jet so the adjustment screw doesn't have to be out at 4 turns!! And I will also get a bigger main jet in place and retune it after I modify the airbox. I think you may have the two piece pilot jets (apparently, PZ30 clones do). I ordered main jets with standard one piece pilot jets in one kit ($11) to explore the possibility of replacing the two piece pilot with a one piece pilot. If that does not work, I ordered the jet half of the two piece pilot jet (an assortment in a kit), and will go with that.
	0

01-28-2022, 03:22 PM	#8
Nospark Join Date: Jan 2022 Location: Milwaukee, WI Posts: 167	Is it safe to purchase the jet kit without verifying what carb will be on the bike when it's delivered? If it's a given what will be on the bike, is this the kit I need? https://www.amazon.com/labwork-parts...ve%2C91&sr=1-9
	0

01-28-2022, 04:51 PM	#10
Nospark Join Date: Jan 2022 Location: Milwaukee, WI Posts: 167	I don't mind buying a jet kit. Using quality jets will remove any doubts I have about carb performance issues being the result of my jet drilling skills. And I would need new jets if I find I went too big and want to back up to the sweet spot.
	0

01-28-2022, 09:56 PM	#12
Nospark Join Date: Jan 2022 Location: Milwaukee, WI Posts: 167	I haven't seen complaints about PZ30 performance so, I see no reason not to work with it. Are the jets difficult to source for the PZ30, assuming that's what shows up on the bike? Does the PZ30 have the adjustable needle or does needle height adjustment require shims?
	0

01-29-2022, 09:40 AM	#15
Nospark Join Date: Jan 2022 Location: Milwaukee, WI Posts: 167	Megadan, Thank you for the specifics on the carbs. I'm curious why you didn't mention a change to the pilot jet as well. Is there not a concern going to 115 main will be ahead of the stock pilot jet during transition? My thinking now is stick with the PZ30 until the mods get to a point someday where I want to look at other intakes. I can envision performance exhaust,air box delete & sprocket size changes but doubt I'd go further with mods. I tried to locate NZbrakelathes as well but, no success.
	0