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Post by brainpup on Jan 6, 2017 21:34:19 GMT -5
![]() My exhaust bolt (female side, up in the head) just stripped out the threads on the inside completely today.
A new, same size/factory stud just spins and the original stud came out with shavings in the threads so I know its stripped inside. The acorn bolt vibrated loose about a month ago, but didn't fall out, so I thought it was from vibration so I put red Loctite on it and it tighten down just fine, so I thought I was kool. Well I was wrong, and so the pipe started getting loud so I thought I had blown the gasket, it was. so when taking the pipe off I found out about the stripped bolt. What do you think is the best way to fix it ? tap it a size bigger and get a new stud ? put a Heli-coil in ? put an Insert in ? get some J-B weld High Heat and put the new stud in and hope it holds ?
as most of you know its really close quarters under there, (hard to get a drill in) and I don't want to pull the engine.
postimg.org/image/5dvu78w19/
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Post by rockynv on Jan 7, 2017 0:08:42 GMT -5
Usually to heli-coil or tap a size larger you still have to drill. Personally I am not a big fan of using high temp epoxy on the exhaust bolts of an air cooled engine.
If you have enough vibration to rattle off the exhaust you need to fix that problem too. Check for grooved drive faces, broken weights on the clutch and excessive wobble in the clutch shaft plus for a stretched out or defective belt. Exhausts coming loose are many times a symptom of a problem in the CVT case or gearbox.
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Post by brainpup on Jan 7, 2017 4:15:15 GMT -5
The vibration came from the rough roads here in Charlotte making a rear exhaust bolt come loose which put lots of pressure on the front 2 at the exhaust port. I had rode the scoot home from work about 10 miles before I found out.
My belt (new Gates Powerlink) is fine, as is my Clutch and Variator. I check and clean the rollers every oil & tranny fluid change (every 1000km) so no problem with the CVT or motor, the scoot runs smooth, dam bolt just got loose the 1st time due to rough roads and then the front one got wobbly at the exhaust port/gasket as kind of an after effect and reamed the hole out.
I measured earlier and I think I can get a drill under her ( I might have to take the center stand off and just use the side stand) so maybe I can, drill & tap new threads rather than use a heli-coil or J-B Weld.
BTW, I found some J-B Weld that's good up to 2000 degrees...?
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Post by tvnacman on Jan 7, 2017 7:04:19 GMT -5
stock is 6mm go with 7mm use a self tapping bolt 7mm x 15-20mm long.
John
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Post by rockynv on Jan 7, 2017 9:26:08 GMT -5
I have tried high temp JB Weld on exhaust system parts with less heat and stress than a head bolt and it did not last very long however I have not used the one that you have to knead and comes in a small jar in some time. You have to be OCD about getting everything perfectly clean and free of any oil, grease and silicone but even then it still shrinks a bit as it cures and you will still need to tap the hole the next size up before you apply it to give it some bite. Heads are usually made of an aluminum alloy with some silicon and ceramic in them so the cam journals will last longer and to withstand higher heat than raw aluminum which presents some problems to overcome in order to get a good bond when using epoxies.
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Post by brainpup on Jan 7, 2017 12:20:13 GMT -5
Thanks for the extra info "rockynv" and after checking around some more with a couple of mechanics this morning they said "good luck with the J-B weld trick" and one added that if it doesn't hold, I've ruined the head completely with no options left because of all the J-B left inside...Soooo, I'm not gonna try it.
"tvnacman" what you are suggesting (going with a self-taping bolt) is my other path of thinking because of the difficulty of getting a drill under my scooter and around the center stand & kickstand & crossbar that's all in the way.
I can easily get a bolt on the end of my socket extension, I'm just wondering if I need to screw it in once and then back out to remove any old threads or just crank it right on in with some Loctite ?
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Post by cyborg55 on Jan 7, 2017 12:56:04 GMT -5
I'd go next size up with a short flange head bolt myself
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Post by brainpup on Jan 22, 2017 8:19:09 GMT -5
OK UPDATE, UPDATE...Wheeeel the "Cold Weld" stuff I bought and coated the exhaust stud with and then screwed up into the head, didn't work, after 3 days of waiting for it to cure I tried to tighten the acorn nut down on it and it just spun like a top @#$%^&...and when I pulled the stud out the "Cold Weld stuff was still wet, it never cured !@#$%^&...turns out while being screwed up inside the head it never got any air...so like duh huh it never had a chance to dry/cure.
So I got me a 7 mm tap (original is 6 mm) and drill bit and took the bottom fairing off and low and behold, I can't frakin get a drill bit to line up straight into the hole because of the 2 cross members in the dang way...
My question: my tap is in my T handle, do you think I could just use it to make the new threads, without drilling the old ones out ? you know...in a little, out a little, in a little, out a little and use some lubricant to help with cutting the new threads ?
I don't really want to drill in at an angle and mess my head up. Of course an angle drill would be nice, but I don't know anybody who has one, my local scooter shop has one, but it's way to big to get under there with. They said "oh yeah, you got to pull the motor to do that...$200 please"...and I'm like nanooooooo.
Has anybody used a tap by hand with out drilling out the old threads ? did it work ? was it easy or a pain in the behind ?
But in the meantime, I put one of the round donut exhaust gaskets in the exhaust port and tapped it in pretty flush and then put a new full size flange gasket ( the ones that go from stud to stud ) over top of that and tightened down the right side/good side as much as I could and then put some locktite on the other one and snugged her up as best I could...cranked her up and she's quiet again.
It's been 4 days and about 50 miles and she's still running quiet...I know it's not going to last, so I'd appreciate any comments on the hand tapping I asked about...oh and I couldn't find any 7 mm self tapping sheet metal/flange bolts at Autozone/Advance/NAPA/Home Depot ?? any clues there ?
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Post by cyborg55 on Jan 22, 2017 9:14:08 GMT -5
You can cut it with the tap,,,not the best situation but it can be done,,take your time and GO SLOW! In and out cleaning with compressed air frequently and oil oil oil,,,don't force it,,,taps are very hard and you don't want to snap one of those babies off in there
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Post by tvnacman on Jan 22, 2017 20:25:34 GMT -5
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Post by brainpup on Jan 23, 2017 14:44:12 GMT -5
Hey cyborg55, tvnacman and rockynv. Thanks so much for the replies and helpful information. Unfortunately it rained pretty much all day yesterday (Sunday) here in Charlotte, so I didn't get a chance to work on the scooter and today has been no better. Hopefully Tuesday the weather will be better and I'll have a chance to get under there and give the "Tapping" a try. It's kinda a pain in the arse as I have to work on her out in my apartment complexes parking lot, since I don't have a garage...and none of my friends do either...the asphalts hard and rough, plus its either hotter than heel or cold as sheeot or rainy or one of my neighbors about runs over me...tough gig....lol I have attached a pic of what I bought to "tap" the threads with, and a package of the 7 mm bolts I found, but they are not self tapping, just flange bolts. s24.postimg.org/rj01jvzet/GEDC0142.jpgAgain guys thanks for the advice and I will let you know what I get done (with a pic or 2). |
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Post by cyborg55 on Jan 23, 2017 14:56:50 GMT -5
Fortuna filium meum
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Post by brainpup on Jan 23, 2017 15:32:13 GMT -5
LOL...thanks
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Post by tvnacman on Jan 23, 2017 16:04:43 GMT -5
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Post by rockynv on Jan 24, 2017 4:47:56 GMT -5
If you go with a bolt just remember that you will be wearing out the threads in the aluminum with every turn under pressure which is why they put studs on. With studs the forces of tightening the exhaust flange will be a fairly static pull on the aluminum and the wear of turning the threads under pressure while securing the exhaust will be between the hard steel nut and the threads on the stud.
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