exhaust threads in cylinder stripped out

[MotorNut123]

I'm not sure what to do whether try to re-tap the threads the same size, or re-tap it a hair size bigger and then just go with a bigger stud.

I noticed it was stripped out after i came back from a ride and saw the exhaust nut loose, and when i went to tighten it the stud pulled out. And the threads from inside came with it.

Has this happened to anyone before? is it easiest to just re-tap it?

I screwed the stud in there with some thread lock because there still is threads deep in, but not enough to hold the stud in there permanently because it eventually rattles out after a few rides.

Not sure what to do, thinking its just the best solution to re-tap it.

 

[Al.Fisherman]

I'm not sure what to do whether try to re-tap the threads the same size, or re-tap it a hair size bigger and then just go with a bigger stud.

I noticed it was stripped out after i came back from a ride and saw the exhaust nut loose, and when i went to tighten it the stud pulled out. And the threads from inside came with it.

Has this happened to anyone before? is it easiest to just re-tap it?

I screwed the stud in there with some thread lock because there still is threads deep in, but not enough to hold the stud in there permanently because it eventually rattles out after a few rides.

Not sure what to do, thinking its just the best solution to re-tap it.

Has this happened to anyone before? Yea yes, that is one reason I preach "change hardware", and mount the engine correctly. I doubt that taping it to a 7mm will work, but many have done it with a 5/16 18/24.. Remember if you go the 5/16" route (6 mm = 0.236220) (5/16 = .3125), use the proper drill. 1/4" is only .242"
I'm sure that some have just threaded a 1/4" stud/bolt into the whole, But I wouldn't, but that's me.
http://www.efunda.com/designstandards/screws/tapdrill.cfm

https://docs.google.com/document/d/1GcesQihc7-mm3hJGf7UPiqOaRXZ8ekUT99QUZq2qXXE/edit

 

[mapbike]

I've heard of some retapping with a 1/4 20 tap, you may or may not have enough material left in the 6mm holes for it, but if there is enough for the 1/4 20 to hold good and snug I would just make myself up some 1/4 20 studs double nut them on one end with the two nuts being good and tight against each other and then on the end of the stud that will screw into the cylinder/jug just put a healthy dose of RED Loctite on the threads and screw them in nice and snug, let them alone for an hour or so and then file the holes out a tad if need be on your exhaust pipe flange so it will fit correctly over the studs and BAM.... you gott-ur patched up real nice.

Some people run from RED Loctite because it is so hard to remove a bolt that has been doped up with it, but in your case you have nothing to loose and it just might be something that will help get your little China Girl up and going again.

Best Wishes....

Peace, map

 

[MotorNut123]

I don't think it had to do with the hardware or the way it was mounted cause all that is perfect. its just the cheap pressed in threads.

Is the 5/16 the next size up? And what size are the studs? I would like to go just a hair size bigger if possible without having to do any major drilling and all that. I've used tap/die sets before and its pretty so i don't have any problems there.

 

[Texhun]

Hey Motornut before you go resizing your studholes go to your nearest parts store and just get a thread repair kit, they work great and are very durable. Plus it's very simple to do. I don't know if you've seen them before, they look like springs in a pack with a insertion tool and drillbit.

 

[mapbike]

The most common brand of the thread repair inserts are called Heli Coils and yes they do work great, used them myself, most parts store I've check in don't always carry the metric sizes, but they can be had.

I mentioned the 1/4 20 size because the holes can be tapped to this size without having to drill the holes out, a 1/4 20 tappered tap will start and tap those 6mm holes in that Alum. and then if a bottoming tap is used as well threads will reach very bottom of hole and that would make it even better that will cost much less than a Heli Coil Kit, considering taps can be bought for a couple bucks at the hardware store, some places charge $30 for the Heli Coil kits and that is about what he can get a New Jug, piston & rings from BGF for, I was thinking quick, easy, inexpensive fix, but as you said Heli Coil Inserts do work great and that would for sure be a permanent fix.

Any of the things mentioned so far will fix the problem, all depends on what your willing to do and what your willing to spend MotorNut123.

Peace, map






[QUOTE="go to your nearest parts store and just get a thread repair kit," [/QUOTE]

 

[biknut]

Since I know it, and it all, according to my wife just do what I say.

What you need to do is helicoil it. I had to do it on the exhaust stud on Bruce's bike. It took like 5 minutes, and it's better than stock. I used size M6x1. You can buy them at most auto supply stores. get the kit, and some extras for next time.

I make my own studs, but you're probably rich enough to buy them. I use # 5 or 8 bolts and cut the heads off.

Keep a close eye on the exhaust bolts, but don't over tighten them.

 

[Al.Fisherman]

Once repaired, if you didn't already have the muffler hanger strapped to the frame ...do it. That's what I was referring to when I mentioned "mount engine correctly".

 

[MotorNut123]

I was thinking of the heli coil because I've heard they work very well but I'm trying to spend less than what a new jug would cost. I thought of just getting a new jug since they're cheap but there are a lot more easier options.

There's a hardware store right down the street so I'm gonna see if they have a 1/4 20 tap and also the thread repair kit. The thread repair kit sounds kinda like how the threads are put in from the factory so I may just go with the tap. It'll thread new threads right into the aluminum and then I can get a new stud (bolt) from the store for a few cents and cut it to length. I'm gonna go down in a bit and see what they got.

 

[biknut]

From my experience when you try to cheap out, it always ends up costing more. Don't ask me how I know.

 

[MotorNut123]

Yea biknut, I guess in most cases that is ccorrect, but I dnt wanna go off and get a helicoil kit if tapping it will do just as good. I'm debating that if the tapping doesn't work I may just get a new jug. Its easy to put on and I have a torgue wrench and thread lock to put the 4 head bolts on to correct torque. But I am definitely going to check out the tap first, cause that would b the quickest option instead of having to order and wait for the jug to come. The only good part is if I get the jug I can tear into the motor and see how its holding up in there!

 

[bairdco]

i've tapped the M6x1.0 exhaust studs to 1/4-20 before, after stripping them out.

you don't need to drill out the holes. after stripping them, it's pretty much the right sized holes.

you can also take your cheap 1/4-20 harbor frieght tap and grind the pointy tip off of it so it bottoms out in the hole.

just go slow, use some cutting oil, (or 3-1 or something. not wd40) and make it nice and straight.

also, stay way from stainless steel bolts. they have sharp threads that bite into the aluminum, causing seizures and stripping.

 

[biknut]

Yea biknut, I guess in most cases that is ccorrect, but I dnt wanna go off and get a helicoil kit if tapping it will do just as good. I'm debating that if the tapping doesn't work I may just get a new jug. Its easy to put on and I have a torgue wrench and thread lock to put the 4 head bolts on to correct torque. But I am definitely going to check out the tap first, cause that would b the quickest option instead of having to order and wait for the jug to come. The only good part is if I get the jug I can tear into the motor and see how its holding up in there!

I've bought new cylinder and piston on eBay for $35 shipped.

 

[Ibedayank]

much better then helicoils

 

[mapbike]

MotorNut123,

Baird is 100% correct here on all points, follow these directions and you'll be good to go.

Best wishes, map

i've tapped the M6x1.0 exhaust studs to 1/4-20 before, after stripping them out.

you don't need to drill out the holes. after stripping them, it's pretty much the right sized holes.

you can also take your cheap 1/4-20 harbor frieght tap and grind the pointy tip off of it so it bottoms out in the hole.

just go slow, use some cutting oil, (or 3-1 or something. not wd40) and make it nice and straight.

also, stay way from stainless steel bolts. they have sharp threads that bite into the aluminum, causing seizures and stripping.

 

[MotorNut123]

i've tapped the M6x1.0 exhaust studs to 1/4-20 before, after stripping them out.

you don't need to drill out the holes. after stripping them, it's pretty much the right sized holes.

you can also take your cheap 1/4-20 harbor frieght tap and grind the pointy tip off of it so it bottoms out in the hole.

just go slow, use some cutting oil, (or 3-1 or something. not wd40) and make it nice and straight.

also, stay way from stainless steel bolts. they have sharp threads that bite into the aluminum, causing seizures and stripping.

I am very likely to go with this plan. I went down to the hardware store today and found a 1/4-20 tap for a few bucks not including the handle for it. And they have a 5 inch long 1/4-20 bolt that i can get a few studs out of if this happens again. I'm sure harbor freight i can get a tap that includes the handle for it along with extra sizes for cheap, but they're about 15 minutes away so it may be worth it to go right to hardware store to get it

 

[mapbike]

If you pay close attention to alignment, you don't need a tap handle, I've used a small Cresent wrench many times for tapping a hole or just cleaning up threads, just remember that no matter what you use, only run tap in about 3/16'' to 1/4'' at a time and then back it all the way out, clean the chips off it add a bit more oil to it and run it in again, continue until it hits bottom of the hole, what ever you do, don't get rough with it or you may break the tap off in the hole and that can be a chore to get out sometimes.

again, best wishes

Peace, map

I am very likely to go with this plan. I went down to the hardware store today and found a 1/4-20 tap for a few bucks not including the handle for it. And they have a 5 inch long 1/4-20 bolt that i can get a few studs out of if this happens again. I'm sure harbor freight i can get a tap that includes the handle for it along with extra sizes for cheap, but they're about 15 minutes away so it may be worth it to go right to hardware store to get it

 

[2door]

Why worry about making studs? Just use 1/4 20 Allen head cap screws. I've never understood this allure to using studs and nuts when one piece will do it better. Same for the stock fasteners. If you're concerned about the quality of the kit supplied hardware, especially the intake and exhaust fasteners, why not just replace them with cap screws?
Doing it that way you only have one set of threads to worry about as opposed to two.
Tom

 

[mapbike]

AMEN to that Tom

Grade 5 cap screws and some blue loctite and she's good to go.

Why worry about making studs? Just use 1/4 20 Allen head cap screws. I've never understood this allure to using studs and nuts when one piece will do it better. Same for the stock fasteners. If you're concerned about the quality of the kit supplied hardware, especially the intake and exhaust fasteners, why not just replace them with cap screws?
Doing it that way you only have one set of threads to worry about as opposed to two.
Tom

 

[MotorNut123]

That never crossed my mind 2door and I think I'll do that. Because the billet intake does come with a one piece allen head bolt.

I haven't done anything with it yet because it's been a bit chilly to ride anyway and the loctite I put on is holding it pretty well. I'm gonna end up re-tapping it to 1/4 20 and then getting the Allen head bolts