PWK28 jetting

95solster · 06-12-2023, 02:49 AM

Hello I'm new to the forum here.

I recently purchased a Templar 250 knowing that the carburetors on these bikes are usually not the best from the factory so I purchased a Nibbi PWK 28mm.
This carburetor came factory with a 118 main jet and 32 pilot jet.

I have since changed the main jet over to a 120.
The problem I'm having is the bike seems to run okay (I haven't ridden it yet) but I noticed that the exhaust got real hot real quick (it started to turn red) this would indicate to me that this jet is way too lean.
So before I go spending a bunch of money on Jets and ending up with stuff that I don't need what would be a good starting point with the PWK carburetor on the 249cc motor
I can find a lot of information on the PE carburetor however I decided to go with the PWK slide type as I was familiar with it from other bikes and quads.

nobade · 06-12-2023, 10:00 AM

An easy way to tell on the pilot size is, will it run with the air screw all the way seated? If so it needs more pilot jet.

95solster · 06-12-2023, 08:59 PM

Pilot jet seems to be fine. Anything less then 1 full turn and the bike dies. RPM did pick up at 2 turn and went back down at 2 1/2 turn so I left it at 2 turns.

The 122 main jet left the plug black and was making the catalytic converter glow red the 118 was making the pipe from the head to about 4 inches past the catalytic converter glow currently using a 120 jet pipe gets hot but didn't see it glow. Also thinking about removing the cylinder warmer from the pipe and using a wideband oxygen sensor to see if it is running a good fual ratio.

I was going to just get a new pipe but that all looks to have the cylinder warmer on them.

95solster · 06-14-2023, 05:40 PM

Here's an update for today.

The PWK carburetor has a great throttle response absolutely love it.

The 122 main jet is still to small. Turns out there junk holding the needle valve open and drowning the carb. (I discovered this when I woke up the next morning and the gas tank was just about empty but the engine was completely full of gasoline)Clean that out and bike ran better then the stock carb but still not right.

Reading the plug it's still lean. So I decided to dig out my wideband O2 to help this along. After a quick test the the idle was showing 22.1 AFR this is very lean so I'm going from a 32 pilot to a 40 pilot.
The ¼ to½ throttle was 21.4 AFR and WOT was 18.4 AFR so the Main jet will be going from 122 to 132 and it would appear the Power jet is functioning.
The goal will be

14.5 to 15.3 at idle
13.2 to 14.1 light acceleration
14.5 to 15.3 Cruse
And 12.7 to 13.1 WOT

95solster · 06-14-2023, 08:01 PM

So the jet kit is here.

Started off with a 40 pilot.
This seems to be a happy spot bike runs from ¾ to 2 ½ turns on the air screw. wideband shows lean at 1¾ turns but bike does like it at less then 2 turns (dies it you twist the throttle).

Main jet is still lean at 135 going to a 140. If this gets me down to the 15 afr range I'll mess with needle height as the next jet in the set is 145.

WOT is was reading 11.2 the adjustment was at 1½turns
Turned this down to 1 turn and WOT went to 13.2 so with the 140 I may have to turn down to ½ turn.

95solster · 06-15-2023, 02:08 AM

Ok so final jetting

40 pilot jet
140 main jet
Position 3 on the Needle
Power jet is 25 and adjustment is at ½ turn
Bike is crisp.

nobade · 06-21-2023, 12:42 PM

Wideband AFR meter makes this so much easier. I gotta get one of those. Good to hear that you got it working well.

bigdano711 · 06-21-2023, 01:34 PM

95solster, I'm curious as to your elevation. For arguments sake, if you're at sea level, would you have to re-jet the carb if you took it above say 5000'?

95solster · 06-29-2023, 07:01 PM

I'm at 500' ASL. I should be good to about 2000' ASL after that I will need to rejet.

Usually you have to rejet every 2000' but depending on you base elevation and how you are set you could have som wiggle room.

For example friend lives at 4500' he rides between 3000' and 5000' so he has his jetting set at 1½ turn when home. If he go and rides at 5000' he has to turn out ½ ~¾ but at 3000' he turns in ½~1 turn. This allows him to run better as hsi elevation changes.

Also keep in mind I'm using a PWK carburetor so my jetting is WAY different then the PE everyone is using.
With the PE most end up with a 125 main and 42 Pilot jet from 0 to 2000'ASL anything less then a 140 and I was lean even in position 5 on the needle and and if I used a 42 Pilot jet I was over 3 turns on the air screw.

06-12-2023, 02:49 AM	#1
95solster Join Date: Jun 2023 Posts: 6	PWK28 jetting Hello I'm new to the forum here. I recently purchased a Templar 250 knowing that the carburetors on these bikes are usually not the best from the factory so I purchased a Nibbi PWK 28mm. This carburetor came factory with a 118 main jet and 32 pilot jet. I have since changed the main jet over to a 120. The problem I'm having is the bike seems to run okay (I haven't ridden it yet) but I noticed that the exhaust got real hot real quick (it started to turn red) this would indicate to me that this jet is way too lean. So before I go spending a bunch of money on Jets and ending up with stuff that I don't need what would be a good starting point with the PWK carburetor on the 249cc motor I can find a lot of information on the PE carburetor however I decided to go with the PWK slide type as I was familiar with it from other bikes and quads.
	0

06-12-2023, 10:00 AM	#2
nobade Join Date: Apr 2021 Posts: 6	An easy way to tell on the pilot size is, will it run with the air screw all the way seated? If so it needs more pilot jet.
	0

06-12-2023, 08:59 PM	#3
95solster Join Date: Jun 2023 Posts: 6	Pilot jet seems to be fine. Anything less then 1 full turn and the bike dies. RPM did pick up at 2 turn and went back down at 2 1/2 turn so I left it at 2 turns. The 122 main jet left the plug black and was making the catalytic converter glow red the 118 was making the pipe from the head to about 4 inches past the catalytic converter glow currently using a 120 jet pipe gets hot but didn't see it glow. Also thinking about removing the cylinder warmer from the pipe and using a wideband oxygen sensor to see if it is running a good fual ratio. I was going to just get a new pipe but that all looks to have the cylinder warmer on them.
	0

06-14-2023, 05:40 PM	#4
95solster Join Date: Jun 2023 Posts: 6	Here's an update for today. The PWK carburetor has a great throttle response absolutely love it. The 122 main jet is still to small. Turns out there junk holding the needle valve open and drowning the carb. (I discovered this when I woke up the next morning and the gas tank was just about empty but the engine was completely full of gasoline)Clean that out and bike ran better then the stock carb but still not right. Reading the plug it's still lean. So I decided to dig out my wideband O2 to help this along. After a quick test the the idle was showing 22.1 AFR this is very lean so I'm going from a 32 pilot to a 40 pilot. The ¼ to½ throttle was 21.4 AFR and WOT was 18.4 AFR so the Main jet will be going from 122 to 132 and it would appear the Power jet is functioning. The goal will be 14.5 to 15.3 at idle 13.2 to 14.1 light acceleration 14.5 to 15.3 Cruse And 12.7 to 13.1 WOT
	3

06-14-2023, 08:01 PM	#5
95solster Join Date: Jun 2023 Posts: 6	So the jet kit is here. Started off with a 40 pilot. This seems to be a happy spot bike runs from ¾ to 2 ½ turns on the air screw. wideband shows lean at 1¾ turns but bike does like it at less then 2 turns (dies it you twist the throttle). Main jet is still lean at 135 going to a 140. If this gets me down to the 15 afr range I'll mess with needle height as the next jet in the set is 145. WOT is was reading 11.2 the adjustment was at 1½turns Turned this down to 1 turn and WOT went to 13.2 so with the 140 I may have to turn down to ½ turn.
	1

06-15-2023, 02:08 AM	#6
95solster Join Date: Jun 2023 Posts: 6	Ok so final jetting 40 pilot jet 140 main jet Position 3 on the Needle Power jet is 25 and adjustment is at ½ turn Bike is crisp.
	3

06-21-2023, 12:42 PM	#7
nobade Join Date: Apr 2021 Posts: 6	Wideband AFR meter makes this so much easier. I gotta get one of those. Good to hear that you got it working well.
	0

06-21-2023, 01:34 PM	#8
bigdano711 Join Date: Jun 2023 Location: Big Piney, WY Posts: 438	95solster, I'm curious as to your elevation. For arguments sake, if you're at sea level, would you have to re-jet the carb if you took it above say 5000'?
	0

06-29-2023, 07:01 PM	#9
95solster Join Date: Jun 2023 Posts: 6	I'm at 500' ASL. I should be good to about 2000' ASL after that I will need to rejet. Usually you have to rejet every 2000' but depending on you base elevation and how you are set you could have som wiggle room. For example friend lives at 4500' he rides between 3000' and 5000' so he has his jetting set at 1½ turn when home. If he go and rides at 5000' he has to turn out ½ ~¾ but at 3000' he turns in ½~1 turn. This allows him to run better as hsi elevation changes. Also keep in mind I'm using a PWK carburetor so my jetting is WAY different then the PE everyone is using. With the PE most end up with a 125 main and 42 Pilot jet from 0 to 2000'ASL anything less then a 140 and I was lean even in position 5 on the needle and and if I used a 42 Pilot jet I was over 3 turns on the air screw.
	0