Bike won't go faster than 30 mph

sphinx_57 · 08-14-2011, 04:18 AM

Ok I got a 06 gz250 with 1300 miles. I got it with about a thousand and have put a few hundred miles on it in the last week or so. When I got the bike it had sat for about a year, mabee started twice. Took a little time to get it started the first time, but seemed to run pretty good. I have burned through all the old gas and have fresh gas in the tank and had added some cleaner to the last tank. So today I started to head home on the highway got to about 65mph and started to get a bad surging. I got off the road and found that much more than a few thousand rpms and the bike would surge badly and there was no power in the throttle.
I checked for spark which was good, the spark plug looked pretty new, I drained the bottom of the air box, checked the air filter, and still has the same problem I don't dare try to get past third gear at such a low rpm. It idles fine, starts up easy, and doesn't seem to have any strange noises.
Things I noticed the last week driving it. Power seems decent for me since its my fist bike, but it has always had a hard time getting up to 65 in 5th gear. I did go on a small ride with a buddy the day before and 60mph was tough to maintain. I figuared it was alittle windy. Also there is some rainbow color to the exaust pipes were it exits the heads. Any ideas? :skull:

blaine · 08-14-2011, 08:24 AM

Welcome.You should take your fuel line off at the carb and see if you got good fuel from the tank.Make sure the petcock is on "pri".If you have good fuel flow,try some Sea Foam or Berrymans b12 at double the strength.If that don't help,you will need to dissemble the carb for a good cleaning.Also consider a inline filter when you have things apart.

:cool:

Water Warrior 2 · 08-14-2011, 08:32 AM

Don't worry about the discoloration of the head pipes. They all do it.

Gz Rider · 08-14-2011, 12:06 PM

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sphinx_57 · 08-14-2011, 01:32 PM

Yea I was kinda thinking it was running lean, my thought was that the carb might have got gummed up with crude with me driving it all of a sudden. I was also thinking that that might be why the top speed is a little on the low end. I'll get some see foam and try that next time at work, how often should i get the valves checked, and is there a right up on how to do it. The bike looks like a simpler version of a car so its not to intimidating, but I agree with what I have read on some of the other posts on the forum that the bike is very precision tuned.
Also I disconnected the petcock and switched it to prime and it seems to flow good. I also tried driving it and switching to prime and it does the same thing but starts to bog down even more. I will also add a fuel filter when I fix the problem.

Gz Rider · 08-14-2011, 02:27 PM

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sphinx_57 · 08-14-2011, 07:21 PM

Well I'll take a look at the manuls thanks man. I usualy do the musscle car stuff around october when it gets cold, do you think i should mess with the valves before that or put a k or so miles on it till winter shows its face then do the valves. I figuare it can't be to diffrent from a car but i'll let you know if I have questions when I get to that section.

Gz Rider · 08-14-2011, 08:01 PM

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Water Warrior 2 · 08-14-2011, 10:52 PM

Lynda's GZ did not get the valves done at 600 miles but they were done prior to her ride half way across the country. Only one valve was slightly out but could have been a major SNAFU if left unchecked. Better to be safe than sorry with burnt valves and a major repair. Lynda is not an agressive rider which might have had something to do with the valves staying in spec or close to it.

**jonathan180iq** · 08-15-2011, 09:02 AM

If you have good gas and a good cleaner in the tank, then I would replace the fuel filter (assuming you have one... if you don't, then get one) and I would replace all vacuum lines.

I don't care that the bike is an '06. It's been sitting, unused and rubber and plastic break down faster with disuse.

While you have the tank off, pull the petcock and make sure that running the old tank of gas through there hasn't clogged the petcock screen with gunk.

If the engine fires strong, was running decent can isn't making any strange noises, then your problem air/gas.

-Jonathan

PS: You changed the oil, right?

08-14-2011, 04:18 AM	#1
sphinx_57 Junior Member Join Date: Aug 2011 Location: Idaho Falls Posts: 4	Bike won't go faster than 30 mph Ok I got a 06 gz250 with 1300 miles. I got it with about a thousand and have put a few hundred miles on it in the last week or so. When I got the bike it had sat for about a year, mabee started twice. Took a little time to get it started the first time, but seemed to run pretty good. I have burned through all the old gas and have fresh gas in the tank and had added some cleaner to the last tank. So today I started to head home on the highway got to about 65mph and started to get a bad surging. I got off the road and found that much more than a few thousand rpms and the bike would surge badly and there was no power in the throttle. I checked for spark which was good, the spark plug looked pretty new, I drained the bottom of the air box, checked the air filter, and still has the same problem I don't dare try to get past third gear at such a low rpm. It idles fine, starts up easy, and doesn't seem to have any strange noises. Things I noticed the last week driving it. Power seems decent for me since its my fist bike, but it has always had a hard time getting up to 65 in 5th gear. I did go on a small ride with a buddy the day before and 60mph was tough to maintain. I figuared it was alittle windy. Also there is some rainbow color to the exaust pipes were it exits the heads. Any ideas? :skull: Login or Register to Remove Ads
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08-14-2011, 08:24 AM	#2
blaine Senior Member Join Date: Feb 2010 Location: P.E.I. Canada Posts: 3,784	Re: Bike won't go faster than 30 mph Welcome.You should take your fuel line off at the carb and see if you got good fuel from the tank.Make sure the petcock is on "pri".If you have good fuel flow,try some Sea Foam or Berrymans b12 at double the strength.If that don't help,you will need to dissemble the carb for a good cleaning.Also consider a inline filter when you have things apart. :cool: __________________ If at first you do succeed, try not to look surprised.
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08-14-2011, 08:32 AM	#3
Water Warrior 2 Senior Member Join Date: Dec 2006 Location: Squamish B.C Canada Posts: 11,409	Re: Bike won't go faster than 30 mph Don't worry about the discoloration of the head pipes. They all do it. Login or Register to Remove Ads
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08-14-2011, 12:06 PM	#4
Gz Rider Senior Member Join Date: Aug 2011 Posts: 852	Re: Bike won't go faster than 30 mph ... __________________ *Alert - This person is a douche. Use these comments and advice at your own risk*
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08-14-2011, 01:32 PM	#5
sphinx_57 Junior Member Join Date: Aug 2011 Location: Idaho Falls Posts: 4	Re: Bike won't go faster than 30 mph Yea I was kinda thinking it was running lean, my thought was that the carb might have got gummed up with crude with me driving it all of a sudden. I was also thinking that that might be why the top speed is a little on the low end. I'll get some see foam and try that next time at work, how often should i get the valves checked, and is there a right up on how to do it. The bike looks like a simpler version of a car so its not to intimidating, but I agree with what I have read on some of the other posts on the forum that the bike is very precision tuned. Also I disconnected the petcock and switched it to prime and it seems to flow good. I also tried driving it and switching to prime and it does the same thing but starts to bog down even more. I will also add a fuel filter when I fix the problem. Login or Register to Remove Ads
	0

08-14-2011, 02:27 PM	#6
Gz Rider Senior Member Join Date: Aug 2011 Posts: 852	Re: Bike won't go faster than 30 mph ... __________________ *Alert - This person is a douche. Use these comments and advice at your own risk*
	0

08-14-2011, 07:21 PM	#7
sphinx_57 Junior Member Join Date: Aug 2011 Location: Idaho Falls Posts: 4	Re: Bike won't go faster than 30 mph Well I'll take a look at the manuls thanks man. I usualy do the musscle car stuff around october when it gets cold, do you think i should mess with the valves before that or put a k or so miles on it till winter shows its face then do the valves. I figuare it can't be to diffrent from a car but i'll let you know if I have questions when I get to that section.
	0

08-14-2011, 08:01 PM	#8
Gz Rider Senior Member Join Date: Aug 2011 Posts: 852	Re: Bike won't go faster than 30 mph ... __________________ *Alert - This person is a douche. Use these comments and advice at your own risk*
	0

08-14-2011, 10:52 PM	#9
Water Warrior 2 Senior Member Join Date: Dec 2006 Location: Squamish B.C Canada Posts: 11,409	Re: Bike won't go faster than 30 mph Lynda's GZ did not get the valves done at 600 miles but they were done prior to her ride half way across the country. Only one valve was slightly out but could have been a major SNAFU if left unchecked. Better to be safe than sorry with burnt valves and a major repair. Lynda is not an agressive rider which might have had something to do with the valves staying in spec or close to it.
	0

08-15-2011, 09:02 AM	#10
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	Re: Bike won't go faster than 30 mph If you have good gas and a good cleaner in the tank, then I would replace the fuel filter (assuming you have one... if you don't, then get one) and I would replace all vacuum lines. I don't care that the bike is an '06. It's been sitting, unused and rubber and plastic break down faster with disuse. While you have the tank off, pull the petcock and make sure that running the old tank of gas through there hasn't clogged the petcock screen with gunk. If the engine fires strong, was running decent can isn't making any strange noises, then your problem air/gas. -Jonathan PS: You changed the oil, right?
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