GZ250 exhaust backfire no start - Page 2

raul10141964 · 05-01-2014, 10:57 AM

check if the valves

**jonathan180iq** · 05-01-2014, 03:25 PM

Gun shot sounds mean it's blowing through the exhaust - most people confuse some sputter and popping with backfire, which technically blows back into the intake...

I'll agree with Raul - there is something about your timing. You can check the valve clearances and make sure the timing marks are doing what they're supposed to be doing.

...Did we ever figure out why the rectifier just suddenly burned out? It wouldn't go out without something else failing along the way, right?

gz4me + · 05-01-2014, 06:27 PM

Will check valve clearance as suggested. Will read up on timing marks and go from there. As for the rectifier burning up, that is why I changed out the stator and pick-up coil. I was told if rectifier fails, replace stator at same time. I checked for frayed wires, made sure all connections were clean and locked in place. Really never did find a reason for it burning up. It was suggested to me yesterday that prior to attempting to start bike, I should advise neighbor so no more squad cars will show up. At least I got a laugh at the end of the day.

gz4me + · 05-02-2014, 12:47 AM

I was not able to work on bike today. Going to pull gas tank tomorrow and check valve clearance. Seems like one step foreward and three steps backward. Learning alot from this forum. Hope some time I can assist someone like all of you have done for me. Thanks.....Will let you know what I find tomorrow.

Water Warrior 2 · 05-02-2014, 02:18 PM

Quote:

Originally Posted by gz4me +

Seems like one step foreward and three steps backward.

Sometimes you have to learn to dance to the music in unexpected directions.

gz4me + · 05-03-2014, 02:45 AM

Removed gas tank, valve inspection caps and generator cover cap. It took awhile to get the generator cover cap off. I used a flang that holds the discharge tube in Insinkerator garbage disposer. It was strong enough for the force I had to use to get the cover loose. lThe large hole in the center gave me plenty of grip. I guess I will be adding that to my tool pouch for future use. The real problem came when I went to my toolbox for the 22mm socket to rotate the crankshaft. After searching my garage, my truck, my work trailer and back to my garage, it finally popped into my head!!!!! I let my next door neighbor use the socket set last month. Of course he is not home for me to recover the socket set. Project on hold for now.

**jonathan180iq** · 05-05-2014, 01:00 PM

Just got get one from Walmart as a rental and then take it back... I don't think that's TOO unethical.

gz4me + · 05-08-2014, 12:52 AM

I checked valve clearance today. Exhaust valves were thight. No clearance at all. Adjusted them to specs. Timing marks appear to be right. Put tank back on and attempted start. No backfire, but also no start. Did not have time to do much more. Will brainstorm more tomorrow.

gz4me + · 05-11-2014, 08:49 PM

After reviewing ImaginativeFig and ShaunCW78 posts, I decided to pull the right side cover on mine. Everything was fine. No shaving, sheared off bolts, etc. After I put new gasket on side cover, I will pull the head cover and check for any damage. From there, I guess I go back and recheck everything I have checked 10 times already. (spark,carb., wiring, timing, clearances,etc.)

**jonathan180iq** · 05-12-2014, 10:53 AM

Do a compression check. If it was popping and after firing then it's definitely getting fuel.
See if you can get it to turn over or hit using the old lawn mower mechanic's special tool "starting fluid".

That said, there is still no reason for the rectifier to suddenly just go up in smoke and then expect everything to work fine after that.

AlanTF will be in here once his old man body heals back up. He is our resident electrician. If anyone knows how to break down the wiring schematic for that thing it will be him.

05-01-2014, 10:57 AM	#11
raul10141964 Senior Member Join Date: Apr 2012 Location: Elkhart, Indiana Posts: 369	check if the valves Login or Register to Remove Ads
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05-01-2014, 06:27 PM	#13
gz4me + Senior Member Join Date: Sep 2013 Location: Santa Maria, California Posts: 234	exhaust backfire no start Will check valve clearance as suggested. Will read up on timing marks and go from there. As for the rectifier burning up, that is why I changed out the stator and pick-up coil. I was told if rectifier fails, replace stator at same time. I checked for frayed wires, made sure all connections were clean and locked in place. Really never did find a reason for it burning up. It was suggested to me yesterday that prior to attempting to start bike, I should advise neighbor so no more squad cars will show up. At least I got a laugh at the end of the day. Login or Register to Remove Ads Last edited by gz4me +; 05-01-2014 at 06:40 PM. Reason: spelling
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05-02-2014, 12:47 AM	#14
gz4me + Senior Member Join Date: Sep 2013 Location: Santa Maria, California Posts: 234	exhaust backfire no start I was not able to work on bike today. Going to pull gas tank tomorrow and check valve clearance. Seems like one step foreward and three steps backward. Learning alot from this forum. Hope some time I can assist someone like all of you have done for me. Thanks.....Will let you know what I find tomorrow.
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05-03-2014, 02:45 AM	#16
gz4me + Senior Member Join Date: Sep 2013 Location: Santa Maria, California Posts: 234	exhaust backfire no start Removed gas tank, valve inspection caps and generator cover cap. It took awhile to get the generator cover cap off. I used a flang that holds the discharge tube in Insinkerator garbage disposer. It was strong enough for the force I had to use to get the cover loose. lThe large hole in the center gave me plenty of grip. I guess I will be adding that to my tool pouch for future use. The real problem came when I went to my toolbox for the 22mm socket to rotate the crankshaft. After searching my garage, my truck, my work trailer and back to my garage, it finally popped into my head!!!!! I let my next door neighbor use the socket set last month. Of course he is not home for me to recover the socket set. Project on hold for now. Last edited by gz4me +; 05-03-2014 at 03:08 AM. Reason: Spelling
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05-08-2014, 12:52 AM	#18
gz4me + Senior Member Join Date: Sep 2013 Location: Santa Maria, California Posts: 234	GZ250 exhaust backfire no start I checked valve clearance today. Exhaust valves were thight. No clearance at all. Adjusted them to specs. Timing marks appear to be right. Put tank back on and attempted start. No backfire, but also no start. Did not have time to do much more. Will brainstorm more tomorrow.
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05-01-2014, 03:25 PM	#12
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	Gun shot sounds mean it's blowing through the exhaust - most people confuse some sputter and popping with backfire, which technically blows back into the intake... I'll agree with Raul - there is something about your timing. You can check the valve clearances and make sure the timing marks are doing what they're supposed to be doing. ...Did we ever figure out why the rectifier just suddenly burned out? It wouldn't go out without something else failing along the way, right?
	0

05-05-2014, 01:00 PM	#17
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	Just got get one from Walmart as a rental and then take it back... I don't think that's TOO unethical.
	0

05-11-2014, 08:49 PM	#19
gz4me + Senior Member Join Date: Sep 2013 Location: Santa Maria, California Posts: 234	GZ250 exhaust backfire no start After reviewing ImaginativeFig and ShaunCW78 posts, I decided to pull the right side cover on mine. Everything was fine. No shaving, sheared off bolts, etc. After I put new gasket on side cover, I will pull the head cover and check for any damage. From there, I guess I go back and recheck everything I have checked 10 times already. (spark,carb., wiring, timing, clearances,etc.)
	0

05-12-2014, 10:53 AM	#20
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	Do a compression check. If it was popping and after firing then it's definitely getting fuel. See if you can get it to turn over or hit using the old lawn mower mechanic's special tool "starting fluid". That said, there is still no reason for the rectifier to suddenly just go up in smoke and then expect everything to work fine after that. AlanTF will be in here once his old man body heals back up. He is our resident electrician. If anyone knows how to break down the wiring schematic for that thing it will be him.
	0