2002 Suzuki GZ250 trouble starting

yashbhatt215 · 05-06-2019, 10:20 PM

Hello everyone I am new to the forum. I just purchased a 2002 Suzuki GZ250 for $300. It was originally listed for $600 but the owner was moving to a new apartment where he did not have a place to store the bike so he dropped the price.

He listed the bike explaining that it had a sticky exhaust valve issue. I bought the bike because I want to take up fixing it as a hobby and learn some cool stuff mechanically. I am a complete beginner when it comes to working on motorcycles. As far as my mechanical background goes I have a few months of experience repairing and maintaining CNC machines, but that is all.

The owner said that it had been running before but it is very random. Sometimes it runs and sometimes it doesn't. It sat in his garage for about a year. Surprisingly, my Dad started it the other day and when he shifted it into 1st gear it stalled. It hasn't started since. I read the Owner's Manual and found the troubleshooting section. I started trouble shooting the carburetor to see if it was getting fuel. I drained the carburetor, turned the fuel valve to PRI (prime) and fuel did in fact flow from the drain hole. Then I turned the fuel valve to the ON position, drained the carburetor, and tightened the drain screw. Next, I pushed the electric starter button to crank the engine. Obviously it did not turn on. I then loosened the drain screw to see if the carburetor filled up with fuel and it was empty. No fuel came out. I tried this twice. I then tightened the drain screw again. I turned the fuel valve to PRI and went inside my house to get something. When I came back there was fuel all over the ground! I turned the fuel valve back to ON. I tried to start the engine again but it did not work and the battery started dying. I decided to put troubleshooting on pause to charge the battery.

So two problems: FIRST, when I drained the carburetor and tried to start the engine the carburetor did not fill back up. SECOND, I turned the fuel valve to PRI and the fuel leaked out of the engine all over the ground. I know it did not leak from the carburetor because the drain screw was tight and I had a pan underneath the carburetor to catch any fuel. The fuel leaked from somewhere else in the engine.

My first step is to do as much research possible. I am searching Google and Youtube for anything that can point me in the right direction. I have not read the service manual yet, I will do that tomorrow probably. I briefly skimmed the parts manual. If anyone can point me in the right direction that would be fantastic! Thank you!

wacio · 05-07-2019, 10:18 PM

1. This bike has petcock that is vacuum operated. It will open on Prime and will let fuel thru "on" and "res" only when engine is turning over (vacuum on intake). There should be small rubber tube going from carb (intake side) to petcock.
2. Leak on Pri mins that your float valve is not closing (bad float or valve, level adjustment). Float valve might be stuck open by gunk buildup. It is leaking - most likely thru air box - either thru oil drain tube below air box or thru air filter. Check oil level and condition to make sure its not loaded with gas.

yashbhatt215 · 05-08-2019, 02:24 PM

Quote:

Originally Posted by wacio

1. This bike has petcock that is vacuum operated. It will open on Prime and will let fuel thru "on" and "res" only when engine is turning over (vacuum on intake). There should be small rubber tube going from carb (intake side) to petcock.
2. Leak on Pri mins that your float valve is not closing (bad float or valve, level adjustment). Float valve might be stuck open by gunk buildup. It is leaking - most likely thru air box - either thru oil drain tube below air box or thru air filter. Check oil level and condition to make sure its not loaded with gas.

Hey so I took another look at it yesterday. I actually got the bike to start this time. I had to keep the throttle way open or it stalled really quick. It ran for 30 seconds with the throttle way open and then it ended up stalling. I couldn't get it to turn on again after it stalled. I think the battery is really weak because it had been sitting for a year without any use. I charged the battery overnight and will try again today after I'm home from work.

As far as the carburetor goes I'm not sure what the 'float valve' is because that specific name does not show up in the carburetor section of the parts manual. It is probably called something different. I attached a picture of the exploded view of the carburetor from the parts manual. Can you look at it and tell me which part is the equivalent to the 'float valve'?

Anyway, I found where the fuel was leaking from. When I turn the fuel valve to prime it floods the carburetor and comes out of a hose connected to the top of the carburetor. The hose travels to the back of the bike underneath the seat and sits open. I'm assuming this is a relief/overflow tube.

wacio · 05-08-2019, 11:13 PM

In the diagram - float is #20 and float valve is #17. Float valve has needle attached to float (little tab that can be bent a little to adjust level). It is important to verify that the needle has rubber tip that is not worn out or damaged. The valve works similar to valve in toilet tank. Once fuel reached predetermined level it closes float valve. Fuel level is important and affects all circuits in the carburetor. Too low or too high will cause bike to run poor (too lean or flood). Looks like yours ids not closing when it should. Check:
- float condition (cracks) causing float to sink deeper than designed
- float valve needle and seat (wear or gunk)
- correct level adjustment (the tab on the float where needle attaches)
- oring around seat (top item #17) - needle might be closing but fuel leaking in around seat.
Level adjustment (picture kinda sucks but you may be able to decipher):
https://www.manualslib.com/manual/10...age=111#manual

yashbhatt215 · 05-09-2019, 12:24 AM

Quote:

Originally Posted by wacio

In the diagram - float is #20 and float valve is #17. Float valve has needle attached to float (little tab that can be bent a little to adjust level). It is important to verify that the needle has rubber tip that is not worn out or damaged. The valve works similar to valve in toilet tank. Once fuel reached predetermined level it closes float valve. Fuel level is important and affects all circuits in the carburetor. Too low or too high will cause bike to run poor (too lean or flood). Looks like yours ids not closing when it should. Check:
- float condition (cracks) causing float to sink deeper than designed
- float valve needle and seat (wear or gunk)
- correct level adjustment (the tab on the float where needle attaches)
- oring around seat (top item #17) - needle might be closing but fuel leaking in around seat.
Level adjustment (picture kinda sucks but you may be able to decipher):
https://www.manualslib.com/manual/10...age=111#manual

Okay that clears things up. I got the bike to run today again, but once again it stalled out. I kept the throttle way open but it only lasted about a minute before it stalled. After it stalled I tried to start it again but I think I drained the battery because it stopped cranking and kept making a clicking sound.

I figured there must be a deeper issue than the battery so I started to take apart the carburetor. I'm following the disassembly instructions in the service manual and carefully bagging the parts with labels. Looks like the last person that worked on the carburetor didn't take care of it because all the screws are stripped. I couldn't get most of the screws out because they're super stripped. I'm gonna buy some tools and order the rebuild kit for the carburetor tomorrow. Hopefully I can get the screws off with some needle nose pliers. Worst case scenario I'll have to drill them out.

Thanks for the advice. I'll have updates as soon as I get my tools and rebuild kit.

wacio · 05-09-2019, 09:58 PM

As you wait for parts watch some carb vids of this guy:

He has wealth of info - very practical....

yashbhatt215 · 05-21-2019, 02:36 PM

So I was able to get the carburetor apart without drilling any screws, thank god! I ordered the rebuild kit yesterday so it should be here next week. This is the rebuild kit:https://www.ebay.com/itm/All-Balls-C...UAAOSwKEhcnoyI

Honestly the inside looks like its in good shape. I am going to check the float height and the needle valve tonight. I am a little hesitant to take all the jets out because if I don't reassemble them correctly I am going to cause more problems.

I checked to see if the spark plug was working properly and found that it wasn't sparking on a full battery. It has a lot of carbon on the electrode so I am going to order a new one and replace it.

I also decided to check the valve clearances on the engine. I took the valve covers, the valve timing inspection plug, and generator cover cap off. That's when I found a new problem. I tried to crank the engine to TDC and it wouldn't rotate counter clockwise at all. I then rotated it clockwise but it wouldn't even go a full 360 degrees before it hit something. My guess is the piston is hitting the valves because the timing of the cams are off. I also did a compression test. I did one with my finger on the spark plug hole and felt nothing. I also did one with a compression gauge on the spark plug hole and got nothing too. Zero compression.

I'm not really sure about how to adjust the valves. First thing I am going to do after work is make sure the valves are moving when I crank the piston. I really hope I don't have to take the engine off the frame. The valves are in a tricky spot right under the top of the bike's frame so they are hard to see/reach/work on. I might try taking the cylinder head cover off.

Vegas Street Rider · 05-21-2019, 07:59 PM

They are a little tough to get to. I believe there is thread on this site with pictures. You might want to research it. Good luck.

wacio · 05-22-2019, 12:41 AM

Its possible that the cam chain tensioner was removed/not working while cranking. Be careful not to cause more damage. If bike had sticking valve - I would start from removing head cover and checking few things - including timing, valve clearances, state if the cam lobes and rocker arms. You will see if valves are moving or stuck open. They'd be stuck if head was not getting oil.

yashbhatt215 · 05-22-2019, 08:23 AM

Quote:

Originally Posted by wacio

Its possible that the cam chain tensioner was removed/not working while cranking. Be careful not to cause more damage. If bike had sticking valve - I would start from removing head cover and checking few things - including timing, valve clearances, state if the cam lobes and rocker arms. You will see if valves are moving or stuck open. They'd be stuck if head was not getting oil.

So last night I checked to see if the valves were moving in the small amount of rotation that I'm able to crank the piston. The intake valves move up and down, but the exhaust valves do not move at all. I tried to take off the cylinder head cover but I'm stuck on these two bolts that are starting to strip. Who knew the hardest part about working on a motorcycle would be taking the bolts and screws off! Anyway, my guess is the exhaust valves are stuck open. I'm gonna have to figure out how to get the head cover off first. There is definitely oil in the head.

If the exhaust valves are stuck open does that mean I can pull on them or loosen them up to get them moving again? I'd imagine that could mess with the timing of the cams?

Also I still need to do a wet compression test. Maybe If I put some oil in the spark plug hole I'll get some compression.

05-08-2019, 11:13 PM	#4
wacio Senior Member Join Date: Apr 2016 Location: Illinois Posts: 174	In the diagram - float is #20 and float valve is #17. Float valve has needle attached to float (little tab that can be bent a little to adjust level). It is important to verify that the needle has rubber tip that is not worn out or damaged. The valve works similar to valve in toilet tank. Once fuel reached predetermined level it closes float valve. Fuel level is important and affects all circuits in the carburetor. Too low or too high will cause bike to run poor (too lean or flood). Looks like yours ids not closing when it should. Check: - float condition (cracks) causing float to sink deeper than designed - float valve needle and seat (wear or gunk) - correct level adjustment (the tab on the float where needle attaches) - oring around seat (top item #17) - needle might be closing but fuel leaking in around seat. Level adjustment (picture kinda sucks but you may be able to decipher): https://www.manualslib.com/manual/10...age=111#manual Last edited by wacio; 05-08-2019 at 11:34 PM.
	1

05-09-2019, 09:58 PM	#6
wacio Senior Member Join Date: Apr 2016 Location: Illinois Posts: 174	As you wait for parts watch some carb vids of this guy: He has wealth of info - very practical.... Last edited by wacio; 05-09-2019 at 10:00 PM.
	1

05-06-2019, 10:20 PM	#1
yashbhatt215 Junior Member Join Date: May 2019 Posts: 10	2002 Suzuki GZ250 trouble starting Hello everyone I am new to the forum. I just purchased a 2002 Suzuki GZ250 for $300. It was originally listed for $600 but the owner was moving to a new apartment where he did not have a place to store the bike so he dropped the price. He listed the bike explaining that it had a sticky exhaust valve issue. I bought the bike because I want to take up fixing it as a hobby and learn some cool stuff mechanically. I am a complete beginner when it comes to working on motorcycles. As far as my mechanical background goes I have a few months of experience repairing and maintaining CNC machines, but that is all. The owner said that it had been running before but it is very random. Sometimes it runs and sometimes it doesn't. It sat in his garage for about a year. Surprisingly, my Dad started it the other day and when he shifted it into 1st gear it stalled. It hasn't started since. I read the Owner's Manual and found the troubleshooting section. I started trouble shooting the carburetor to see if it was getting fuel. I drained the carburetor, turned the fuel valve to PRI (prime) and fuel did in fact flow from the drain hole. Then I turned the fuel valve to the ON position, drained the carburetor, and tightened the drain screw. Next, I pushed the electric starter button to crank the engine. Obviously it did not turn on. I then loosened the drain screw to see if the carburetor filled up with fuel and it was empty. No fuel came out. I tried this twice. I then tightened the drain screw again. I turned the fuel valve to PRI and went inside my house to get something. When I came back there was fuel all over the ground! I turned the fuel valve back to ON. I tried to start the engine again but it did not work and the battery started dying. I decided to put troubleshooting on pause to charge the battery. So two problems: FIRST, when I drained the carburetor and tried to start the engine the carburetor did not fill back up. SECOND, I turned the fuel valve to PRI and the fuel leaked out of the engine all over the ground. I know it did not leak from the carburetor because the drain screw was tight and I had a pan underneath the carburetor to catch any fuel. The fuel leaked from somewhere else in the engine. My first step is to do as much research possible. I am searching Google and Youtube for anything that can point me in the right direction. I have not read the service manual yet, I will do that tomorrow probably. I briefly skimmed the parts manual. If anyone can point me in the right direction that would be fantastic! Thank you! Login or Register to Remove Ads
	0

05-07-2019, 10:18 PM	#2
wacio Senior Member Join Date: Apr 2016 Location: Illinois Posts: 174	1. This bike has petcock that is vacuum operated. It will open on Prime and will let fuel thru "on" and "res" only when engine is turning over (vacuum on intake). There should be small rubber tube going from carb (intake side) to petcock. 2. Leak on Pri mins that your float valve is not closing (bad float or valve, level adjustment). Float valve might be stuck open by gunk buildup. It is leaking - most likely thru air box - either thru oil drain tube below air box or thru air filter. Check oil level and condition to make sure its not loaded with gas. Last edited by wacio; 05-07-2019 at 10:20 PM.
	2

05-21-2019, 02:36 PM	#7
yashbhatt215 Junior Member Join Date: May 2019 Posts: 10	So I was able to get the carburetor apart without drilling any screws, thank god! I ordered the rebuild kit yesterday so it should be here next week. This is the rebuild kit:https://www.ebay.com/itm/All-Balls-C...UAAOSwKEhcnoyI Honestly the inside looks like its in good shape. I am going to check the float height and the needle valve tonight. I am a little hesitant to take all the jets out because if I don't reassemble them correctly I am going to cause more problems. I checked to see if the spark plug was working properly and found that it wasn't sparking on a full battery. It has a lot of carbon on the electrode so I am going to order a new one and replace it. I also decided to check the valve clearances on the engine. I took the valve covers, the valve timing inspection plug, and generator cover cap off. That's when I found a new problem. I tried to crank the engine to TDC and it wouldn't rotate counter clockwise at all. I then rotated it clockwise but it wouldn't even go a full 360 degrees before it hit something. My guess is the piston is hitting the valves because the timing of the cams are off. I also did a compression test. I did one with my finger on the spark plug hole and felt nothing. I also did one with a compression gauge on the spark plug hole and got nothing too. Zero compression. I'm not really sure about how to adjust the valves. First thing I am going to do after work is make sure the valves are moving when I crank the piston. I really hope I don't have to take the engine off the frame. The valves are in a tricky spot right under the top of the bike's frame so they are hard to see/reach/work on. I might try taking the cylinder head cover off.
	0

05-21-2019, 07:59 PM	#8
Vegas Street Rider Senior Member Join Date: May 2015 Location: Henderson, NV Posts: 1,107	They are a little tough to get to. I believe there is thread on this site with pictures. You might want to research it. Good luck.
	1

05-22-2019, 12:41 AM	#9
wacio Senior Member Join Date: Apr 2016 Location: Illinois Posts: 174	Its possible that the cam chain tensioner was removed/not working while cranking. Be careful not to cause more damage. If bike had sticking valve - I would start from removing head cover and checking few things - including timing, valve clearances, state if the cam lobes and rocker arms. You will see if valves are moving or stuck open. They'd be stuck if head was not getting oil.
	1