Loss of power, torque. Sputters at full throttle

pillowpants · 11-03-2013, 04:27 PM

I was riding the other day and suddenly my GZ250 just lost power and torque. Now it sputters at full throttle in every gear. I can't get over 45 mph. I changed the oil and filter and it's still the same. I also added Berrymans b-12, but it hasn't changed. Please help.

raul10141964 · 11-03-2013, 04:33 PM

Change spark plug

**jonathan180iq** · 11-04-2013, 09:21 AM

How does it respond with less than full throttle? Does 1/2 throttle respond better, for example?

pillowpants · 11-04-2013, 11:06 AM

Hey Jonathan, there is no sputtering at half throttle, but the torque/power isn't there. Raul, I changed the spark plug and it hasn't changed anything.

**jonathan180iq** · 11-04-2013, 11:26 AM

Not being able to get over 45 would indicate to me that you have an air leak somewhere, and a big one. Does the bike idle alright? Does it also buck like a bull with a yellow-jacket on it's haunches?

Take some WD-40 or some ether or something similar and give a little spritz to all areas of the carb where a seal or connection exists. If your idle changes at all while you do this, then you need to fix whatever is causing the leak.

pillowpants · 11-04-2013, 12:00 PM

I sprayed all the boots and around the carb and did not notice an idle change.

raul10141964 · 11-04-2013, 12:27 PM

do you check the air filter
my do that when i mod the filter before i change the main jet to 140

JohnC · 11-04-2013, 01:09 PM

When it sputters, try full choke. If there is no improvement then the problem is likely ignition or a plugged air intake. If there is even the slightest improvement then it is likely carburetion.

pillowpants · 11-04-2013, 02:04 PM

Raul, I checked the air filter and box. They both seemed fine. I am mechanically inclined when it comes to jets. JohnC I don't have a choke on my bike, I have never noticed one before and I don't see one. Where would it be? I bought my gz250 used over a year ago and never had any problem with it.

**jonathan180iq** · 11-04-2013, 02:31 PM

These things have a factory choke... Left handlebar control.

Can we see your setup?

Check the "S" tube that runs from the crankcase to the bottom of the air box.

11-03-2013, 04:27 PM	#1
pillowpants Junior Member Join Date: Apr 2013 Location: Florida Posts: 21	Loss of power, torque. Sputters at full throttle I was riding the other day and suddenly my GZ250 just lost power and torque. Now it sputters at full throttle in every gear. I can't get over 45 mph. I changed the oil and filter and it's still the same. I also added Berrymans b-12, but it hasn't changed. Please help. Login or Register to Remove Ads
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11-03-2013, 04:33 PM	#2
raul10141964 Senior Member Join Date: Apr 2012 Location: Elkhart, Indiana Posts: 369	Re: Loss of power, torque. Sputters at full throttle Change spark plug
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11-04-2013, 09:21 AM	#3
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	Re: Loss of power, torque. Sputters at full throttle How does it respond with less than full throttle? Does 1/2 throttle respond better, for example? Login or Register to Remove Ads
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11-04-2013, 11:06 AM	#4
pillowpants Junior Member Join Date: Apr 2013 Location: Florida Posts: 21	Re: Loss of power, torque. Sputters at full throttle Hey Jonathan, there is no sputtering at half throttle, but the torque/power isn't there. Raul, I changed the spark plug and it hasn't changed anything.
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11-04-2013, 11:26 AM	#5
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	Re: Loss of power, torque. Sputters at full throttle Not being able to get over 45 would indicate to me that you have an air leak somewhere, and a big one. Does the bike idle alright? Does it also buck like a bull with a yellow-jacket on it's haunches? Take some WD-40 or some ether or something similar and give a little spritz to all areas of the carb where a seal or connection exists. If your idle changes at all while you do this, then you need to fix whatever is causing the leak. Login or Register to Remove Ads
	0

11-04-2013, 12:00 PM	#6
pillowpants Junior Member Join Date: Apr 2013 Location: Florida Posts: 21	Re: Loss of power, torque. Sputters at full throttle I sprayed all the boots and around the carb and did not notice an idle change.
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11-04-2013, 12:27 PM	#7
raul10141964 Senior Member Join Date: Apr 2012 Location: Elkhart, Indiana Posts: 369	Re: Loss of power, torque. Sputters at full throttle do you check the air filter my do that when i mod the filter before i change the main jet to 140
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11-04-2013, 01:09 PM	#8
JohnC Senior Member Join Date: Aug 2013 Location: New Hampshire Posts: 127	Re: Loss of power, torque. Sputters at full throttle When it sputters, try full choke. If there is no improvement then the problem is likely ignition or a plugged air intake. If there is even the slightest improvement then it is likely carburetion.
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11-04-2013, 02:04 PM	#9
pillowpants Junior Member Join Date: Apr 2013 Location: Florida Posts: 21	Re: Loss of power, torque. Sputters at full throttle Raul, I checked the air filter and box. They both seemed fine. I am mechanically inclined when it comes to jets. JohnC I don't have a choke on my bike, I have never noticed one before and I don't see one. Where would it be? I bought my gz250 used over a year ago and never had any problem with it.
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11-04-2013, 02:31 PM	#10
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	Re: Loss of power, torque. Sputters at full throttle These things have a factory choke... Left handlebar control. Can we see your setup? Check the "S" tube that runs from the crankcase to the bottom of the air box.
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