Keihin PWK TPS connecting on CR125.

Yotam
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Yotam
Edited Date/Time 9/14/2018 11:03am
on other topic about STIC metering block running too rich:

https://www.vitalmx.com/forums/Tech-Help-Race-Shop,42/STIC-Metering-blo…

i talked few people include George himself and understood that i need to go up on the carb bore diameter
right now i have 36mm and i will piut YZ250 38mm PWK on my CR125.
now it works good without the TPS but i still want to activate it.
my previous carb before the pwk had a TPS connector that still there

first thing, i see that the YZ carb has 2 connectors:
one connector has: black, yellow, blue.
second connector has 2 red wires.

my mikhuni had only one connector with 3 wires: yellow green, yellow red, and blue

so the question is, why the YZ carb has 2 connectors with 5 wires in total, while the CR125 has only one connector with 3 wires?
how can i activate the TPS and what should i do if i want the YZ carb to perform in the best way?

Thanks, Yotam.
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40
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40 9/13/2018 3:00pm
9/13/2018 3:00pm Edited Date/Time 9/13/2018 3:01pm
There is a guy on TT who sells complete kits to retrofit the YZ, RM and KX carb TPS's to the stock Honda Sumitomo ECU connector. Think he goes by Hondamxracer or something like that over there. His kits are very nice.
Yotam
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Yotam 9/13/2018 4:32pm
9/13/2018 4:32pm
40 wrote:
There is a guy on TT who sells complete kits to retrofit the YZ, RM and KX carb TPS's to the stock Honda Sumitomo ECU connector...
There is a guy on TT who sells complete kits to retrofit the YZ, RM and KX carb TPS's to the stock Honda Sumitomo ECU connector. Think he goes by Hondamxracer or something like that over there. His kits are very nice.
Yeah i sent him message 2 days ago and he still didn’t reply
If any one have his email shoot me a pm
Paw Paw 271
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Paw Paw 271 9/13/2018 6:26pm
9/13/2018 6:26pm
My question has to be......Why do you want a TPS on a carbureted engine anyway?
I mean, TPS's work great in fuel injected engines as they are set up to alter the fuel delivery and are a very good item in the chain of engine controls in EFI engines, but they can't alter the fuel mix on non EFI engines. All they can do is effect the engine timing a bit in the ECU. If you have a very good running carb style engine and disconnect the TPS you will never see any difference in performance.

Paw Paw
Yotam
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Yotam 9/13/2018 11:16pm
9/13/2018 11:16pm Edited Date/Time 9/14/2018 5:15am
Paw Paw 271 wrote:
My question has to be......Why do you want a TPS on a carbureted engine anyway? I mean, TPS's work great in fuel injected engines as they...
My question has to be......Why do you want a TPS on a carbureted engine anyway?
I mean, TPS's work great in fuel injected engines as they are set up to alter the fuel delivery and are a very good item in the chain of engine controls in EFI engines, but they can't alter the fuel mix on non EFI engines. All they can do is effect the engine timing a bit in the ECU. If you have a very good running carb style engine and disconnect the TPS you will never see any difference in performance.

Paw Paw
Well, i know that there is doubt about the influence of the TPS on the performance, some says that the throttle response increased and some they didn’t feel anything but it’s a discussion, after all, engineers decided to put it on their bikes for many years despite the reason it’s way more expensive than non TPS carb.
And along all this i am nerd, and if there is a function that made to work I would like it to
The ldea of 2 connectors zip tied to the frame will blow my mind.

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40
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40 9/14/2018 6:57am
9/14/2018 6:57am
Yotam wrote:
Well, i know that there is doubt about the influence of the TPS on the performance, some says that the throttle response increased and some they...
Well, i know that there is doubt about the influence of the TPS on the performance, some says that the throttle response increased and some they didn’t feel anything but it’s a discussion, after all, engineers decided to put it on their bikes for many years despite the reason it’s way more expensive than non TPS carb.
And along all this i am nerd, and if there is a function that made to work I would like it to
The ldea of 2 connectors zip tied to the frame will blow my mind.
On the CR250, you can notice better throttle response with the TPS connected. The bike will run fine with either the TPS connected or disconnected, but the ECU defaults to 2D map when the TPS is disconnected.

In the carb retrofits that we've seen (YZ, RM, and KX Keihin PWK variants installed on a CR250), the PWK has always had 3 wires for the TPS circuit. The PWK does have 2 wires for the powerjet soleniod, but always 3 wires for the TPS.

If you can not contact Hondamxracer, you can purchase genuine Sumitomo connectors from Eastern Beaver and fabricate your own harness. http://www.easternbeaver.com/Main/Elec__Products/Connectors/Sealed/SM-H…

Hondamxracer states that when installing a YZ carb onto a CR250 you should use the following wiring connections:
(CR125 might be different)

Yamaha PWK Black connects to Honda Green/blue
Yamaha PWK Yellow connects to Honda Blue/yellow
Yamaha PWK Blue connects to Honda Red/yellow

Also, the powerjet circuit will need to be deactivated or it will be flowing fuel continuously which will mess up your overall jetting. Most guys install a set screw in place of the brass powerjet jet. However you can also epoxy or solder the brass jet closed, then reinstall it. In either case, the powerjet circuit will need to be deactivated.
Yotam
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Yotam 9/14/2018 10:08am
9/14/2018 10:08am
Yotam wrote:
Well, i know that there is doubt about the influence of the TPS on the performance, some says that the throttle response increased and some they...
Well, i know that there is doubt about the influence of the TPS on the performance, some says that the throttle response increased and some they didn’t feel anything but it’s a discussion, after all, engineers decided to put it on their bikes for many years despite the reason it’s way more expensive than non TPS carb.
And along all this i am nerd, and if there is a function that made to work I would like it to
The ldea of 2 connectors zip tied to the frame will blow my mind.
40 wrote:
On the CR250, you can notice better throttle response with the TPS connected. The bike will run fine with either the TPS connected or disconnected, but...
On the CR250, you can notice better throttle response with the TPS connected. The bike will run fine with either the TPS connected or disconnected, but the ECU defaults to 2D map when the TPS is disconnected.

In the carb retrofits that we've seen (YZ, RM, and KX Keihin PWK variants installed on a CR250), the PWK has always had 3 wires for the TPS circuit. The PWK does have 2 wires for the powerjet soleniod, but always 3 wires for the TPS.

If you can not contact Hondamxracer, you can purchase genuine Sumitomo connectors from Eastern Beaver and fabricate your own harness. http://www.easternbeaver.com/Main/Elec__Products/Connectors/Sealed/SM-H…

Hondamxracer states that when installing a YZ carb onto a CR250 you should use the following wiring connections:
(CR125 might be different)

Yamaha PWK Black connects to Honda Green/blue
Yamaha PWK Yellow connects to Honda Blue/yellow
Yamaha PWK Blue connects to Honda Red/yellow

Also, the powerjet circuit will need to be deactivated or it will be flowing fuel continuously which will mess up your overall jetting. Most guys install a set screw in place of the brass powerjet jet. However you can also epoxy or solder the brass jet closed, then reinstall it. In either case, the powerjet circuit will need to be deactivated.
the 125 & 250 shares the same carb and same TPS (same PN) so i believe that same instruction should work
is there any reason of getting a kit or something?
as long as i know the wire colors that should fit each other i can use any connector that is water proof

now when you're talking about the power jet circuit i am little confuse i thought that the power jet circuit should work isnt it?
its the small jet that located on the air box side isn it?
how do i block it with set screw and now i would to understand whats going on there because it seems like i dont know much about this TPS as i thought

Thanks!

40
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40 9/14/2018 10:41am
9/14/2018 10:41am Edited Date/Time 9/14/2018 10:42am
Yotam wrote:
Well, i know that there is doubt about the influence of the TPS on the performance, some says that the throttle response increased and some they...
Well, i know that there is doubt about the influence of the TPS on the performance, some says that the throttle response increased and some they didn’t feel anything but it’s a discussion, after all, engineers decided to put it on their bikes for many years despite the reason it’s way more expensive than non TPS carb.
And along all this i am nerd, and if there is a function that made to work I would like it to
The ldea of 2 connectors zip tied to the frame will blow my mind.
40 wrote:
On the CR250, you can notice better throttle response with the TPS connected. The bike will run fine with either the TPS connected or disconnected, but...
On the CR250, you can notice better throttle response with the TPS connected. The bike will run fine with either the TPS connected or disconnected, but the ECU defaults to 2D map when the TPS is disconnected.

In the carb retrofits that we've seen (YZ, RM, and KX Keihin PWK variants installed on a CR250), the PWK has always had 3 wires for the TPS circuit. The PWK does have 2 wires for the powerjet soleniod, but always 3 wires for the TPS.

If you can not contact Hondamxracer, you can purchase genuine Sumitomo connectors from Eastern Beaver and fabricate your own harness. http://www.easternbeaver.com/Main/Elec__Products/Connectors/Sealed/SM-H…

Hondamxracer states that when installing a YZ carb onto a CR250 you should use the following wiring connections:
(CR125 might be different)

Yamaha PWK Black connects to Honda Green/blue
Yamaha PWK Yellow connects to Honda Blue/yellow
Yamaha PWK Blue connects to Honda Red/yellow

Also, the powerjet circuit will need to be deactivated or it will be flowing fuel continuously which will mess up your overall jetting. Most guys install a set screw in place of the brass powerjet jet. However you can also epoxy or solder the brass jet closed, then reinstall it. In either case, the powerjet circuit will need to be deactivated.
Yotam wrote:
the 125 & 250 shares the same carb and same TPS (same PN) so i believe that same instruction should work is there any reason of...
the 125 & 250 shares the same carb and same TPS (same PN) so i believe that same instruction should work
is there any reason of getting a kit or something?
as long as i know the wire colors that should fit each other i can use any connector that is water proof

now when you're talking about the power jet circuit i am little confuse i thought that the power jet circuit should work isnt it?
its the small jet that located on the air box side isn it?
how do i block it with set screw and now i would to understand whats going on there because it seems like i dont know much about this TPS as i thought

Thanks!

You will not be able to use the Keihin powerjet circuit with the stock Honda ECU.
The Throttle Position Sensor (TPS) is a separate circuit which you will be able to use.
There are detailed instructions on how to block off the powerjet circuit on TT. Search the Honda two stroke forum over there.
40
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40 9/14/2018 11:02am
9/14/2018 11:02am


Reference the parts diagram closely:
Part 30 is the powerjet solenoid. Trace the electrical wire to the connector and note that it has 2 wires.
Part 27 is the powerjet jet. It wiill need to be deactivated by blocking off with set screw or solder/epoxy and then reinstall. Note that you will need to remove the float bowl to gain access to the jet.
Part 38 is the TPS. Trace the electrical wire to the connector and note that it has 3 wires. You will need to fabricate a harness to your Honda ECU from this connector. This is what Hondamxracer sells on TT.




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