| Author | Message | ||
     12mpghwy |
I rode to work today, got off the bike, as I was walking into the office I noticed that the O2 sensor wire could allmost touch the rear header. I adjusted this and at some point saw that the upper rear exhaust stud was completly gone, not broken off just missing. I came out durring lunch with a flashlight. I can see that there are no threads in the hole and the outer 1/4in of the hole is ovaled and looks like shit. I think a PO broke a stud off, drilled it out poorly, ran a tap into it and set it up with a stud having very little purchase on the head. So whats next? Can these be drilled and tapped to 3/8's? | ||
| Reepicheep |
I might just heli coil it, but a Time Sert would probably be the proper hack. http://www.timesert.com/ Wes Brown could no doubt weld it back up and re-tap it when he ports your heads as well, if you were thinking about that anyway... | ||
| 12mpghwy |
Update, I got the header off. Its actually worst then I thought, there is actually a piece. I would say the upper 1/8th of an inch of the original stud, the exhaust clamp is ovaled to allow the stud to come in a bit more Ok so previous owner broke the stud off, drilled it out off center, tapped it with a 5/16 tap, put another stud in a good 8th inch closer to to the opposite stud without removing whats left of the original stud and ovaled the exhaust clamp bolt hole to make it all go back together. so I think I can use a carbide burr on a dremel tool and some picks and punches to get whats left of the original stud out. I then need to drill somehow on center a larger hole to use either a helicoil or timesert. Or: Can the studs for the rear be re drilled and tapped 180 degrees out? (Message edited by 12mpghwy on July 20, 2009) | ||
| Reepicheep |
The Jims tool (drilling jig) will give you your best shot at getting the hole trued again, and it will happily drill out whatever old stud stuff is left in there. Better that then breaking off an easy out in there, or removing too much material with the dremel. That's if there is material to go into left...  Is that an easy out tip in there? Or really a stud? If it's an easy out tip, they really should have their asses kicked for selling it to you that way, and that you *do* want to get out with a tungsten carbide dremel bit. Take your time, it'll probably take two of the bits. It'll leave littl micro slivers of steel in your hand as well. Ouch. If the top of the hole is a mess, maybe the TimeSert will help... Probably depends on how long the TimeSert is and how much supporting material is left. If the hole is off center down deep, and you are going into half aluminum and half steel, I think that doesn't much matter. That old stud sure as heck won't pull out if it's been half mooned by the new hole. | ||
| 12mpghwy |
I got the bike for 900 dollars, in running but not drivable condition I really can't complain I suppose. It is stud for sure, not easy out. I am thinking that grinding whats left of the stud, and re drilling either for the next larger timesert or helicoil is the way to go. I don't think the jims guide will help much unless it has bushings which go much larger than the stock studs. | ||
| Preybird1 |
Just a recommendation: I would take it to a professional and get this done correctly. I have played the ez-out game and lost twice, By the time i got it to a pro it was messed up! I had him channel out the old material and sleeve it back into the head. This repair is better than the best heli coil repair i have ever seen. | ||
| 12mpghwy |
I'm not playing the easy out game, there would be nothing for an ez-out to grab onto anyways, I have started grinding out whats left of the old stud, and am half way done. When I get it out I will probably go with something like the timesert. | ||
| 12mpghwy |
I got the remainder of the stud out, the hole is nasty ovaled. but the threads are perfectly intact were they were hidden by whats left of the bolt. I think a 3/8 drill would just round out the hole. The POs pilot hole extends at least an inch and a half, thats right 1.5 inches into the block. I can't help but wonder how close it to to the exhaust valve stem or perhaps the exhaust port itself. I would certainly worry about having this head ported. | ||
| Oldog |
Wes Brown could no doubt weld it back up and re-tap it when he ports your heads as well, if you were thinking about that anyway... well worth the time and expense  Wes repaired the head mounting bolt hole for me (front head) weld up, drill and tap mill mounting pad flat. & did a "tidy up" while they were at it repair only was quite reasonable, of course so was the rest new guides, & seals spring & keepers multi angle valve job port & polish heads (stage 1) work and workman ship first class! I would be concerned about proximity to the combustion chamber, pull it call pammy you would be amazed at what they can fix I lost the exhaust nut ( in the port ) you can guess what happened next, the head was repaired and returned to me in less than 3 weeks and it was impossible to tell where it had been repaired. a good welder can plug weld that hole and then it can be re-machined better than any insert} I recently priced a new head 370$ with valves and springs IIRC | ||
| Reepicheep |
What a shame the "idiot previous owner" (same guy must have owned the KDX-200 I am currently restoring) didn't just fix it right the first time. It's not a big deal if you don't screw it up... If you drilled whatever size hole was required for a heli-coil for the stock stud, would that round it back out? If so, and it were me, I would just do that and heli-coil it... maybe two heli-coils deep. I don't think those studs are under that much actual "pull out" pressure, they vibrate and shear instead, and then only when something else in the system is screwed up. So a TimeSert would be better, but I'd probably just heli coil it as I can get the parts locally and be done today. For the "other hole", that's unfortunate. I am assuming that is threaded, and I would be inclined to cut the shaft off a bolt of the right thread, slot a screwdriver head into it, and sink it into the head. That way if something does break through the other side, it might not hurt anything. |
