Generator / Rotor Bolts - Sheared and Damaged

clofan · 03-11-2014, 10:25 PM

Hello everyone! I was glad to find this forum, and hopefully I can get some advice in a dire situation.

A few weeks back my buddy was riding his 2001 GZ250 home, and he heard some metal-on-metal noises coming from the engine, followed by a lockup. I came over and helped him look at it, and we were able to get it push-started after a decent number of attempts. I ran it maybe 150 yards-- it backfired a lot and died when I came to a stop. I thought it was a timing issue. Turns out, I was half right..

There are three bolts holding the generator (edit- These: http://i.imgur.com/JW40nuA.png) onto the roller bearings that touch the crankshaft. As soon as I took off the left side cover, I could see that one of the bolts had sheared off and was stuck in the gap of the large starter idle gear. Turns out, two of them sheared off and were being grinded up and stopping the engine from rotating cleanly.

Without further ado, pictures of the damage:

Back of the generator area. You can see one bolt still standing-- the others are in the bowels of the beast.

What I'm calling the large starter idle gear-- maybe not the correct name, but still. Not a lot of damage here, but you can see bits of bolt (and the bolt itself!) in the bottom of the case.

This is the part I'm most worried about. Actual case damage. Could I patch this with a weld? Any other ideas on how to fix it?

Damage to the interior left side. That lower right hand threaded bolt hole is missing about 1/4 of the walls, where you can see it's chewed up

Finally, the lower half of the two bolts still stuck in the generator outside part. I should be able to drill these out, just need to take it slow.

clofan · 03-11-2014, 10:29 PM

I had seen a thread on here earlier with someone with a similar problem, but I'm having trouble finding it now. I'll keep looking and link it if I find it.

So, a few questions:
1) Those three holes on the interior case wall-- what is supposed to thread into them? I originally thought this is where the sheared bolts came from, but now I realize they came from the back of the generator. One of the holes is significantly damages.

2) Will that wall damage affect anything? I'm planning on patching it with JB Weld (or an actual aluminum weld), if that will work. Or, is it supposed to be open-- an oil passageway? I need to get a picture of an undamaged one.

3) Any other advice?

Thanks!!

mainlinecoffee · 03-12-2014, 02:34 AM

I would patch the holes with quicksteel,really don't have much t offer in the way of what to do but I wish you the best. Ever find the cause?

**jonathan180iq** · 03-12-2014, 08:06 AM

I'm going to have to open this thread on another computer where I can see the actual damage.

In the meantime, BabBob once did a write up on the left side cover removal and replacement I think... Or was it right side? I don't recall at the moment but look for his sticky in the How-To section.

clofan · 03-12-2014, 09:48 AM

Mainlinecoffee, nope, no idea on the cause. I was hoping someone here might have an idea. Bad / non-existent locktite? The bolts are defiantly getting some red when they go back in!

Jonathan, thanks, I'll search around, and I think I actually found that thread(or another, similar one) the other day but haven't been able to find it again.

raul10141964 · 03-12-2014, 10:08 AM

this is my tread about the same problem
http://www.gz250bike.com/forum/showt...7146#post67146

I weld the broken gear and is working

clofan · 03-12-2014, 11:06 AM

Quote:

Originally Posted by raul10141964

this is my tread about the same problem
http://www.gz250bike.com/forum/showt...7146#post67146

I weld the broken gear and is working

Thank you Raul, that's the one! Dang, I didn't see pictures yesterday, your gear just exploded! Did you have any damage to the crank case?

Water Warrior 2 · 03-12-2014, 06:02 PM

You may want to use Blue Loktite. Red is too permanent if you ever want to take it apart again.

raul10141964 · 03-12-2014, 09:40 PM

I re-upload the pictures
no damage to the crank case

clofan · 03-12-2014, 11:07 PM

Those three threaded holes in the crankcase... does anything go in them? Looking at parts fiches, it seems like no, but why would the holes be there if not for a bolt?

03-11-2014, 10:25 PM	#1
clofan Junior Member Join Date: Mar 2014 Posts: 29	Generator / Rotor Bolts - Sheared and Damaged Hello everyone! I was glad to find this forum, and hopefully I can get some advice in a dire situation. A few weeks back my buddy was riding his 2001 GZ250 home, and he heard some metal-on-metal noises coming from the engine, followed by a lockup. I came over and helped him look at it, and we were able to get it push-started after a decent number of attempts. I ran it maybe 150 yards-- it backfired a lot and died when I came to a stop. I thought it was a timing issue. Turns out, I was half right.. There are three bolts holding the generator (edit- These: http://i.imgur.com/JW40nuA.png) onto the roller bearings that touch the crankshaft. As soon as I took off the left side cover, I could see that one of the bolts had sheared off and was stuck in the gap of the large starter idle gear. Turns out, two of them sheared off and were being grinded up and stopping the engine from rotating cleanly. Without further ado, pictures of the damage: Back of the generator area. You can see one bolt still standing-- the others are in the bowels of the beast. What I'm calling the large starter idle gear-- maybe not the correct name, but still. Not a lot of damage here, but you can see bits of bolt (and the bolt itself!) in the bottom of the case. This is the part I'm most worried about. Actual case damage. Could I patch this with a weld? Any other ideas on how to fix it? Damage to the interior left side. That lower right hand threaded bolt hole is missing about 1/4 of the walls, where you can see it's chewed up Finally, the lower half of the two bolts still stuck in the generator outside part. I should be able to drill these out, just need to take it slow. Login or Register to Remove Ads Last edited by clofan; 03-11-2014 at 10:40 PM.
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03-12-2014, 02:34 AM	#3
mainlinecoffee Senior Member Join Date: Oct 2013 Location: lexington ky Posts: 223	I would patch the holes with quicksteel,really don't have much t offer in the way of what to do but I wish you the best. Ever find the cause? Login or Register to Remove Ads
	0

03-12-2014, 09:48 AM	#5
clofan Junior Member Join Date: Mar 2014 Posts: 29	Mainlinecoffee, nope, no idea on the cause. I was hoping someone here might have an idea. Bad / non-existent locktite? The bolts are defiantly getting some red when they go back in! Jonathan, thanks, I'll search around, and I think I actually found that thread(or another, similar one) the other day but haven't been able to find it again. Login or Register to Remove Ads
	0

03-12-2014, 10:08 AM	#6
raul10141964 Senior Member Join Date: Apr 2012 Location: Elkhart, Indiana Posts: 369	this is my tread about the same problem http://www.gz250bike.com/forum/showt...7146#post67146 I weld the broken gear and is working Last edited by raul10141964; 03-12-2014 at 10:12 AM.
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03-11-2014, 10:29 PM	#2
clofan Junior Member Join Date: Mar 2014 Posts: 29	I had seen a thread on here earlier with someone with a similar problem, but I'm having trouble finding it now. I'll keep looking and link it if I find it. So, a few questions: 1) Those three holes on the interior case wall-- what is supposed to thread into them? I originally thought this is where the sheared bolts came from, but now I realize they came from the back of the generator. One of the holes is significantly damages. 2) Will that wall damage affect anything? I'm planning on patching it with JB Weld (or an actual aluminum weld), if that will work. Or, is it supposed to be open-- an oil passageway? I need to get a picture of an undamaged one. 3) Any other advice? Thanks!!
	0

03-12-2014, 08:06 AM	#4
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	I'm going to have to open this thread on another computer where I can see the actual damage. In the meantime, BabBob once did a write up on the left side cover removal and replacement I think... Or was it right side? I don't recall at the moment but look for his sticky in the How-To section.
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03-12-2014, 06:02 PM	#8
Water Warrior 2 Senior Member Join Date: Dec 2006 Location: Squamish B.C Canada Posts: 11,409	You may want to use Blue Loktite. Red is too permanent if you ever want to take it apart again.
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03-12-2014, 09:40 PM	#9
raul10141964 Senior Member Join Date: Apr 2012 Location: Elkhart, Indiana Posts: 369	I re-upload the pictures no damage to the crank case
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03-12-2014, 11:07 PM	#10
clofan Junior Member Join Date: Mar 2014 Posts: 29	Those three threaded holes in the crankcase... does anything go in them? Looking at parts fiches, it seems like no, but why would the holes be there if not for a bolt?
	0