GZ-250 With no Top End

PeterSeymour · 01-27-2011, 10:43 PM

I posted on this forum in November regarding my GZ dropping a valve. I have completely gone through the engine and the remainder of the bike and determined that the only components in need of replacing are the piston, head and valves. I was planing on rebuilding the top end myself but I decided instead to move to a larger bike more suited to my style of riding. Ultimately I am posting on here to see if anyone would be interested in the remaining parts or the bike as a whole. I will entertain any reasonable offers, especially if anyone in the Phoenix area is looking for parts.

On the other hand, if anyone has a top end or a running engine they would be willing to sell for a reasonable price I might attempt to rebuild the bike and keep it for riding around town. Feel free to e-mail me either way, thanks for the interest. I will post pictures shortly but the bike is in perfect condition with only minor cosmetic damage to the front fender and muffler due to a low speed lay-down on gravel.

Blitzburgh7sb · 01-31-2011, 11:13 PM

I would be interested in the forks and handlebar.

Edit: Also the rear shocks.

Zdoes · 02-24-2011, 07:53 PM

Haha, wow! It seems as though this is a re-occurring event for GZ riders. I also broke my valve and it chewed up the piston and cylinder head. So far I have already read about 3 other people on this forum that had the same problem. It's also funny that the only other damage that was done to my bike was from a low-speed lay down on gravel as well.

Sorry to get your hopes up, but I don't have anything to offer you AND I'm not really interested in any other parts. Just thought it was strange that this is such a common failure amongst the GZ riders.

Cooteboy · 05-19-2011, 12:41 AM

I just bought a bike in this very condition. The previous owner had taken it to a Harley Dealer to get it looked at - they too stated that it had "dropped" a valve.

Upon my inspection - this was not completely true. It appears that what actually happened was, the timing/cam chain jumped teeth/time. The head and camshaft were/are severely worn. It appears to have wallowed the head so much as to have enough play to jump several teeth on the chain - causing it to be out of time, causing the valve to be down at the wrong time and "bam" - no more top end.

Is there any way to ensure that the next head I get will receive enough oil up above to keep this from happening?

Also sorry, wasn't quite sure where to post this.

Water Warrior 2 · 05-19-2011, 01:16 AM

I don't think it is so much an oiling problem up top as it is high revs and hard riding. These are good bikes but some folks find out the hard way that they are not a powerhouse or sport bike. If you ride it like you stole it the life expectancy of the engine goes way down.

Cooteboy · 05-19-2011, 08:36 PM

That's comforting to hear Water Warrior.

I'm planning on riding this one for mileage, so shouldn't be in fear of that then. The price I paid was techinically a steal, but I'll try not to ride like that :tongue:

01-27-2011, 10:43 PM	#1
PeterSeymour Junior Member Join Date: Nov 2010 Location: Mesa AZ Posts: 11	GZ-250 With no Top End I posted on this forum in November regarding my GZ dropping a valve. I have completely gone through the engine and the remainder of the bike and determined that the only components in need of replacing are the piston, head and valves. I was planing on rebuilding the top end myself but I decided instead to move to a larger bike more suited to my style of riding. Ultimately I am posting on here to see if anyone would be interested in the remaining parts or the bike as a whole. I will entertain any reasonable offers, especially if anyone in the Phoenix area is looking for parts. On the other hand, if anyone has a top end or a running engine they would be willing to sell for a reasonable price I might attempt to rebuild the bike and keep it for riding around town. Feel free to e-mail me either way, thanks for the interest. I will post pictures shortly but the bike is in perfect condition with only minor cosmetic damage to the front fender and muffler due to a low speed lay-down on gravel. Login or Register to Remove Ads
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01-31-2011, 11:13 PM	#2
Blitzburgh7sb Member Join Date: Oct 2010 Location: Palm Bay FL Posts: 32	Re: GZ-250 With no Top End I would be interested in the forks and handlebar. Edit: Also the rear shocks. __________________ "From my perspective, you learn more in failure than you do in success."
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02-24-2011, 07:53 PM	#3
Zdoes Junior Member Join Date: Feb 2011 Location: State College, PA Posts: 9	Re: GZ-250 With no Top End Haha, wow! It seems as though this is a re-occurring event for GZ riders. I also broke my valve and it chewed up the piston and cylinder head. So far I have already read about 3 other people on this forum that had the same problem. It's also funny that the only other damage that was done to my bike was from a low-speed lay down on gravel as well. Sorry to get your hopes up, but I don't have anything to offer you AND I'm not really interested in any other parts. Just thought it was strange that this is such a common failure amongst the GZ riders. Login or Register to Remove Ads
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05-19-2011, 12:41 AM	#4
Cooteboy Junior Member Join Date: May 2011 Location: Washington State Posts: 22	Re: GZ-250 With no Top End I just bought a bike in this very condition. The previous owner had taken it to a Harley Dealer to get it looked at - they too stated that it had "dropped" a valve. Upon my inspection - this was not completely true. It appears that what actually happened was, the timing/cam chain jumped teeth/time. The head and camshaft were/are severely worn. It appears to have wallowed the head so much as to have enough play to jump several teeth on the chain - causing it to be out of time, causing the valve to be down at the wrong time and "bam" - no more top end. Is there any way to ensure that the next head I get will receive enough oil up above to keep this from happening? Also sorry, wasn't quite sure where to post this.
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05-19-2011, 01:16 AM	#5
Water Warrior 2 Senior Member Join Date: Dec 2006 Location: Squamish B.C Canada Posts: 11,409	Re: GZ-250 With no Top End I don't think it is so much an oiling problem up top as it is high revs and hard riding. These are good bikes but some folks find out the hard way that they are not a powerhouse or sport bike. If you ride it like you stole it the life expectancy of the engine goes way down. Login or Register to Remove Ads
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05-19-2011, 08:36 PM	#6
Cooteboy Junior Member Join Date: May 2011 Location: Washington State Posts: 22	Re: GZ-250 With no Top End That's comforting to hear Water Warrior. I'm planning on riding this one for mileage, so shouldn't be in fear of that then. The price I paid was techinically a steal, but I'll try not to ride like that :tongue:
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