Now what?

6 replies to this topic
  • PK

Posted June 06, 2001 - 03:13 PM


While I was assembling my motor after putting in a new piston/rings and re-shimming one valve that was a little too tight, the oil tube on the back side of the motor on the right just inboard of the exhaust stipped a bolt. The bolt is for the banjo fitting and is tapped into the case. I didn't even get the full torque on bolt, it just gave way. Now my question is does anyone have any experience heli coiling? I have been fortunate so far as to never have had to install one before. My main concern is getting filings down into the case when I have to drill it out to put in the helicoil. I am very apprehensive about splitting the cases to put this in. Any suggestions?

Thanks in advance,
99 YZ400

  • sirthumpalot

Posted June 06, 2001 - 03:58 PM


Before you go the drill out method, check around for a screw/bolt extractor kit. I haven't used one myself, but it looks like you drill a small hole in the center of the broken bolt and then you have a special extractor which looks like a funny drill bit which you twist into the broken bolt. It is reverse threaded so as you tighten it into the broken bolt it unscrews it. I can't promise that this will work, but it may save you a lot of trouble. Good luck!

  • MikeOK

Posted June 06, 2001 - 04:12 PM


I've used screw extractors with some success, the trick is to get the right size and get the holw drilled in axactlty the center. If the extractor breaks off you are almost out of options. I know there is some kind of plasma gizmo that can remove broken bolts, but I hear it is expensive. Another thing you can do is drill the bolt out with a bit that is just slightly smaller than the threads and dig the threads out that are left in with a pair of needle nose. Good luck...


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  • PMK

Posted June 06, 2001 - 06:26 PM


If you stripped the case and are going to heli-coil it, remove the oil fiter and apply compressed air to the oil galley that is fed from the oil filter. Apply the air while drilling and tapping the hole. and MAKE SURE TO GET THE HELI-COIL DRIVE TANG OUT OF THE OIL PASSAGE, it will be very bad to leave it in there floating around. If you can, make a drill and tap guide bushing to keep the hole straight.
PK (same letters different person)

  • daveyg

Posted June 06, 2001 - 06:59 PM


Go the extractor route. I've done it with success on an exhaust stud that busted on my Nissan. Just use a small drill bit, drilling carefully and take your time. You should only have to drill in about a 1/4 inch and then use the extractor bit, which threads in opposite, so like someone else said, as you tighten it, your broken bolt comes out. If it were me, that is the route I would take. Good luck and be patient.

  • PK

Posted June 06, 2001 - 09:47 PM


The bolt isn't broken off in the threads, the threads are stripped out so I'm looking at the heli coil route, thanks for the advice from all who wrote in. Great idea PMK about blowing compressed air into the oil journal. I hate when this stuff but happens but it goes with the territory.

Anymore tips?


  • groundhog

Posted June 07, 2001 - 12:56 AM


Sounds like you already have the help you need. Just another little trick. Coat the drill bit with heavy grease and drill a little at a time - clean the bit & recoat. Most of the filings will stick to the grease.

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