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-   -   Generator / Rotor Bolts - Sheared and Damaged (http://www.gz250bike.com/forum/showthread.php?t=6938)

clofan 03-11-2014 10:25 PM

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.

http://i.imgur.com/rB68r2y.jpg

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.

http://i.imgur.com/4HSAqmT.jpg

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?

http://i.imgur.com/EDMdbrK.jpg

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

http://i.imgur.com/jIl4nKY.jpg

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.

http://i.imgur.com/pHVAens.jpg

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 (Post 78309)
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?


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