Advice for a tunned gy6 152qmi efi engine

sgtavs · 12-28-2020, 02:38 PM

Good afternoon,

I have a chinese scooter using a 152qmi engine with injection (euro4 model).

The generic brand/model of the scooter is "Jiajue JJ125T-23" but the spanish imported brand is called "SUMCO". Here a pic of this exact model.

The scooter runs great and it already has 8650km on it. 5000km ago I bought a complete transmission kit from NYC and also a 14 x 36 gear kit.

Last week I've installed new upgrades. A9 camshaft, titanium valve springs, 150cc cylinder with the same head so now I have more compression and a performance exhaust.

The problem now is, when I run slow it runs great but if I fully open the gas the engine practically stalls, so I supose it needs more gas in the mix(it also may need more air as I still use the stock filter and filter box).

Today I went to a specialized shop to see if they can reprogram the Delphi MT05 ECU but before going all in with this (I think it's a must to do this) I need to find a bigger injector and fuel pump for this engine.

Can someone tell me which "performance" fuel pumps could go well for this? And also where I can start to search for bigger injector replacements. I'm a carburettor guy and this injection thing is new for me.

Thank you very much

wheelbender6 · 12-28-2020, 09:45 PM

You are running lean after all those mods. One of our members, Randall, was able to add a rheostat to his wiring to vary the fual/air mixture in his Yamaha. It was not a Delphi system, but it had a mass airflow (MAF) sensor.
He isolated the wire to the mass airflow sensor, and added the rheostat to it.

wheelbender6 · 12-30-2020, 08:10 PM

Here is a thread about working with the Delphi EFI on a CSC RX3. It is possible that you may be able to use some of the same interface cables and software.
http://chinariders.net/showthread.php?t=14758

sgtavs · 12-31-2020, 03:24 AM

Thank you wheelbender6, I readed and participated on the post you linked some months ago

. The truth is I don't have time to investigate and play with this (this is why I went to a specialized shop for the ECU tuning, still waiting for they to call me)

The rheostat method is intresting, I'm going to read about it to see if it can help me.

Also, for the moment I won't change the injector because it's too much work but I'm going to change the air filter and the fuel pump for a "performance" one.

Do you have any prefered brand for the pump? or I can safely go with the generic chinese ones?

Thanks!

12-28-2020, 02:38 PM	#1
sgtavs Join Date: Sep 2020 Location: Spain Posts: 3	Advice for a tunned gy6 152qmi efi engine Good afternoon, I have a chinese scooter using a 152qmi engine with injection (euro4 model). The generic brand/model of the scooter is "Jiajue JJ125T-23" but the spanish imported brand is called "SUMCO". Here a pic of this exact model. The scooter runs great and it already has 8650km on it. 5000km ago I bought a complete transmission kit from NYC and also a 14 x 36 gear kit. Last week I've installed new upgrades. A9 camshaft, titanium valve springs, 150cc cylinder with the same head so now I have more compression and a performance exhaust. The problem now is, when I run slow it runs great but if I fully open the gas the engine practically stalls, so I supose it needs more gas in the mix(it also may need more air as I still use the stock filter and filter box). Today I went to a specialized shop to see if they can reprogram the Delphi MT05 ECU but before going all in with this (I think it's a must to do this) I need to find a bigger injector and fuel pump for this engine. Can someone tell me which "performance" fuel pumps could go well for this? And also where I can start to search for bigger injector replacements. I'm a carburettor guy and this injection thing is new for me. Thank you very much
	0

12-28-2020, 09:45 PM	#2
wheelbender6 Join Date: May 2015 Location: Houston area Posts: 1,902	You are running lean after all those mods. One of our members, Randall, was able to add a rheostat to his wiring to vary the fual/air mixture in his Yamaha. It was not a Delphi system, but it had a mass airflow (MAF) sensor. He isolated the wire to the mass airflow sensor, and added the rheostat to it. __________________ "Its not WHAT you ride; its THAT you ride"
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12-30-2020, 08:10 PM	#3
wheelbender6 Join Date: May 2015 Location: Houston area Posts: 1,902	Here is a thread about working with the Delphi EFI on a CSC RX3. It is possible that you may be able to use some of the same interface cables and software. http://chinariders.net/showthread.php?t=14758 __________________ "Its not WHAT you ride; its THAT you ride" Last edited by wheelbender6; 12-30-2020 at 08:11 PM. Reason: add link
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12-31-2020, 03:24 AM	#4
sgtavs Join Date: Sep 2020 Location: Spain Posts: 3	Thank you wheelbender6, I readed and participated on the post you linked some months ago. The truth is I don't have time to investigate and play with this (this is why I went to a specialized shop for the ECU tuning, still waiting for they to call me) The rheostat method is intresting, I'm going to read about it to see if it can help me. Also, for the moment I won't change the injector because it's too much work but I'm going to change the air filter and the fuel pump for a "performance" one. Do you have any prefered brand for the pump? or I can safely go with the generic chinese ones? Thanks!
	0