Engine stumbling on acceleration

sams2017 · 06-25-2017, 10:14 AM

HELP PLEASE! I'am not a mechanic.

I purchased a Dirt Bike on Craigslist still in the crate. It says Rickypowersports on the 162FMJ engine and Viper on seat.

It starts very easy and idles good, but when I start down the road when it gets a a high rpm it starts to stumble, I let off the gas very little and it will smooth out again until I give a lot of gas.

Weldangrind · 06-25-2017, 01:39 PM

Welcome! Just to be sure that we're providing appropriate guidance, please show us a few pics of the motor.

sams2017 · 06-25-2017, 02:35 PM

The Carb is a Sheng Wey PZ27 KSL03/HS150GY

Weldangrind · 06-26-2017, 11:13 AM

I recommend that you remove the carb and then remove the main jet for cleaning. I suspect that something is clogging it.

Just unscrew the cap from the top of the carb and withdraw the slider and spring assembly; let it hang to the side. Close the fuel valve on the tank. Loosen (but do not remove) the screw at the very bottom of the bowl to drain out the fuel. Remove the airbox and then detach the carb from the intake tube. You might have a choke cable on the left side of the carb, but it is easy to remove.

Once the carb is out, remove the three bowl screws and remove the bowl. Once the bowl is out of the way, you'll see the brass round main jet in the center of the carb. unscrew it and see if it is clogged. I use a single strand of wire from a wire brush to gently remove deposits. Clean the inside of the carb with aerosol carb cleaner from an auto parts store (please wear eye protection). Reassemble and reinstall.

When you put the slider and spring assembly back in, ensure that the long vertical groove is on the left side of the carb; it lines up with a small pin inside the bore, which keeps the slider in the correct orientation.

Let us know the result.

BlackBike · 06-26-2017, 11:13 PM

Good copy weld. Not suguesting he try it but one could almost accomplish it without removing the carb. There is a lot of room on this one. Still better to take time , especially if first time fooling with one to take off bike and will give a chance to see how it all works...its so simple even I can do it.

He says he is not a mechanic but I predict he will be all the wiser pretty soon.

sams2017 · 06-27-2017, 07:52 AM

Great directions Weldangrind

Carb is off.

On problem the carb is sealed and does not have screws. I am not a mechanic, but I am a machinist so the sealed carb will be no problem.

Would it be better to just buy a new PZ27 Carburetor ? Can't find a Sheng Wey carb, but when I do a search the name Keihin pops up under PZ27 is the Shen Wey carb and other PZ27's just a copy of the Keihin?

Weldangrind · 06-28-2017, 12:05 PM

This is the carb I've installed several times: http://www.ebay.com/itm/MIKUNI-30mm-...FZIE9E&vxp=mtr
It's easy to find jets for and the bowl has four screws (real screws) instead of three.

Weldangrind · 06-28-2017, 12:05 PM

BTW, you can save a few dollars by buying directly from China on eBay, but it'll take three weeks to receive your new carb.

sams2017 · 07-10-2017, 03:05 PM

It works, no more stumbling on acceleration

Thank you Weldangrind. I took out the what people call the EPA screws cleaned the carb and put it back together with M4-16 screws.

Can I ask another question please.

Before I had the stumbling on acceleration it also would backfire when I let the throttle off on shifting, not all the time and it sound more like a misfire the hard sounding backfire. Kinda hard to explain.

Rangerscott · 07-10-2017, 04:31 PM

Most likely from the air injection system.

Weldangrind · 07-11-2017, 12:29 AM

Quote:

Originally Posted by sams2017

It works, no more stumbling on acceleration

Thank you Weldangrind. I took out the what people call the EPA screws cleaned the carb and put it back together with M4-16 screws.

Can I ask another question please.

Before I had the stumbling on acceleration it also would backfire when I let the throttle off on shifting, not all the time and it sound more like a misfire the hard sounding backfire. Kinda hard to explain.

Glad to hear that you got it sorted. I'm not exactly sure what your question is, since you're telling us how it was, before you cleaned the carb. Is that how it's behaving now, since you cleaned the carb? I'm happy to offer guidance however I can, but I'd like to be more clear on what you're asking.

sams2017 · 07-28-2017, 09:19 AM

Running perfect now. All I did was change the spark plug and started using REC 90 Gas.

06-25-2017, 10:14 AM	#1
sams2017 Join Date: Jun 2017 Posts: 18	Engine stumbling on acceleration HELP PLEASE! I'am not a mechanic. I purchased a Dirt Bike on Craigslist still in the crate. It says Rickypowersports on the 162FMJ engine and Viper on seat. It starts very easy and idles good, but when I start down the road when it gets a a high rpm it starts to stumble, I let off the gas very little and it will smooth out again until I give a lot of gas.
	0

06-25-2017, 01:39 PM	#2
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Welcome! Just to be sure that we're providing appropriate guidance, please show us a few pics of the motor. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

06-26-2017, 11:13 AM	#4
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	I recommend that you remove the carb and then remove the main jet for cleaning. I suspect that something is clogging it. Just unscrew the cap from the top of the carb and withdraw the slider and spring assembly; let it hang to the side. Close the fuel valve on the tank. Loosen (but do not remove) the screw at the very bottom of the bowl to drain out the fuel. Remove the airbox and then detach the carb from the intake tube. You might have a choke cable on the left side of the carb, but it is easy to remove. Once the carb is out, remove the three bowl screws and remove the bowl. Once the bowl is out of the way, you'll see the brass round main jet in the center of the carb. unscrew it and see if it is clogged. I use a single strand of wire from a wire brush to gently remove deposits. Clean the inside of the carb with aerosol carb cleaner from an auto parts store (please wear eye protection). Reassemble and reinstall. When you put the slider and spring assembly back in, ensure that the long vertical groove is on the left side of the carb; it lines up with a small pin inside the bore, which keeps the slider in the correct orientation. Let us know the result. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	1

06-26-2017, 11:13 PM	#5
BlackBike Join Date: Feb 2016 Location: George West, Texas Posts: 4,097	Good copy weld. Not suguesting he try it but one could almost accomplish it without removing the carb. There is a lot of room on this one. Still better to take time , especially if first time fooling with one to take off bike and will give a chance to see how it all works...its so simple even I can do it. He says he is not a mechanic but I predict he will be all the wiser pretty soon. __________________ ***************************************** 2015 Bashan"Blaze" BS250GY-31 (DB-07K-250) GONE 2017 Suzuki V Strom 650 XT "We are all born ignorant, but one must work hard to remain stupid." ~Benjamin Franklin~
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06-28-2017, 12:05 PM	#7
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	This is the carb I've installed several times: http://www.ebay.com/itm/MIKUNI-30mm-...FZIE9E&vxp=mtr It's easy to find jets for and the bowl has four screws (real screws) instead of three. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

06-27-2017, 07:52 AM	#6
sams2017 Join Date: Jun 2017 Posts: 18	Great directions Weldangrind Carb is off. On problem the carb is sealed and does not have screws. I am not a mechanic, but I am a machinist so the sealed carb will be no problem. Would it be better to just buy a new PZ27 Carburetor ? Can't find a Sheng Wey carb, but when I do a search the name Keihin pops up under PZ27 is the Shen Wey carb and other PZ27's just a copy of the Keihin?
	1

07-10-2017, 03:05 PM	#9
sams2017 Join Date: Jun 2017 Posts: 18	It works, no more stumbling on acceleration Thank you Weldangrind. I took out the what people call the EPA screws cleaned the carb and put it back together with M4-16 screws. Can I ask another question please. Before I had the stumbling on acceleration it also would backfire when I let the throttle off on shifting, not all the time and it sound more like a misfire the hard sounding backfire. Kinda hard to explain.
	0

07-10-2017, 04:31 PM	#10
Rangerscott Join Date: Sep 2016 Location: Texas Posts: 165	Most likely from the air injection system.
	0

07-28-2017, 09:19 AM	#12
sams2017 Join Date: Jun 2017 Posts: 18	Running perfect now. All I did was change the spark plug and started using REC 90 Gas.
	0