Stripped head bolt studs

OrionSphere

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I bought a bikeberry 48cc kit 2-3 years ago and have had it running off/on.

Recently I noticed that my head area is leaking alot of oil and compression is sucky. One of the head bolts is stripped. I don't know exactly what size I need.

Does anyone know, for sure, exactly what size bolt I need to replace it? Hopefully I can order the replacement on Amazon before I get home and won't have to open it up and measure. I'm riding my bike until I get it fixed.

It should look like this so everyone knows what I'm speaking of.
 

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Hand tighten the studs until they bottom out. It is highly advisable to use a high temp medium strength thread locker (243) to prevent movement of the studs in the case halves. In some cases you may need to use a wrench to drive the studs in until they bottom, but once they bottom out, don't go any further than a tiny snug (IE a 16th of a turn). Studs do not need to be torqued into the holes on the cases beyond a slight snug up after bottoming out, and doing so is a great way to break the case halves or strip the threading out again. I have built every engine this way and have never had an issue.

I also suggest not using the acorn nuts as the primary means to secure the head. I use them as a lock nut on top of a standard nut mainly for weather protection to the threads. I also use wide washers, bevel side down, and a lock washer on top of that to help prevent it backing off (combined with said lock nut is slightly overkill, but there is no kill like overkill.) I run the wide washers bevel side down to allow the head to expand and contract without greatly affecting the stud and other steel hardware. It's not really a necessary thing, I just do weird stuff because of my experience with working on and repairing other types of machinery.

Get an inch pound torque wrench if at all possible, but a light foot lb (say, up to 15-20ish) will also work. The standard torque is 12ft-lbs (dry). I go to 15 with upgraded hardware, but that's a me thing and not advice. I do mine in 2 stages, 10 in a criss cross, then 15. Again, not necessary really, but I always prefer to tighten most gasket sealed items in stages to allow better/more even compression of the gaskets and a more accurate torque bolt to bolt.

You can use loctite on the top nuts, but be aware that it acts as a lubricant to the threads which changes the torque applied to the fasteners. If you do, Loctite specifies that you reduce the torque on the fastener by 20% vs. the dry spec., which is 9.6ft-lbs or 115in-lbs. I use 243 on mine combined with said washer, lock washer, and the acorn acting as a lock nut (Trust me, I am nowhere near close to bottoming it out, so don't bother telling me I am wrong). You could probably skip the lock washer TBH, but again, there is no kill like over kill. :sneaky:
A 20v impact drill lightly on a fresh install never gave me issues. All my bolts are secure and never had to be seated again. No play, no thread lock. May not apply to stripped threads. Sound advise just don't understand why you or whoever deleted my post.
 
just don't understand why you or whoever deleted my post.
I can tell you exactly why.
don't listen to people claiming you need to replace acorn nuts with regulars. You will never pop the heads of the acorn nuts if you impact them correctly.
Wrong.
We have seen them still fail because all of those holes for those studs are not drilled to a precise depth that is consistant on all four holes, I have found that on my own motors when I took the time to measure depth as well as stud heights...This of course is one of the causes of why acorn nuts can top out on top of a stud and never have proper contact with the head of the engine to ensure proper torque to begin with.

Don't listen to people about having to retorque bolts multiple times. Their idiots, yes this is mandatory matienance but I dunno why people have to make this topic complex.
So now we are all idiots ???...Time to re-read the rules of the forum again @Deleted member 35519 of what NOT to say or do as regards others here on the forum that offer advice.

What is so COMPLEX about letting people know they will need to retorque during breakin because the threads themselves expand and contract causing the cylinder to not be torqued down properly to stop leakage ???

Watch Bike Berries videos their informative; regardless experience comes along either or.
Do you have any idea how many times forum members have found these videos to be grossly inaccurate over quite a few years now ???

Trust torque wrenches. It's in my opinion the most necessary tool needed for a motor.
Never trust them until you can prove that they are calibrated properly and haven't been dropped during shipping etc which can throw them off...I have seen shipments of brand new torque wrenchs to the Valvoline garages that were all off right from the manufacturer and all needed to be recalibrated.

Do I need to list anymore reasons why I deleted your posting ???...Hopefully not, and do not make the same mistake that other former forum members have made by deciding to duel it out in public with me either.
 
Do I need to list anymore reasons why I deleted your posting ???...Hopefully not, and do not make the same mistake that other former forum members have made by deciding to duel it out in public with me either.
I dont have time for that lol.

Not here to argue with anybody regarding this. Everyone has their methods if someone elses method fails then perhaps it was just the person. Even very experienced people make errrors, Humans are humans and not machines. It's like welders explaining whats the best method of welding, heat, speed, approach. People who typically think one way will make mistakes in welding. This is rather the same principle for assembly of a motor. I'm always up to hear methods for improvement or what has worked for others. Sometimes machines versus hands a percision vary. I'm not a mechinally inclined gifted genius by any means. My only point is that i have installed all my bolts straight and torqued very lightly with a 20v drill without thread lock material. I have tried thread lock on them in the past. Doesn't really make sense besides what the other moderator mentioned to use. All other mild applications of threadlocks allowed my hardware to vibrate out. My bolts are all equally portioned without, of course time will only tell if their a slight CM off over use and time. I only need to torque down my acorn nuts and cary a wrench often where i go just in case. This is typically only after driving for over 40 miles. Things vibrate, things need to be adjusted. It's normal matienance.

My method to torquing them down is pretty simular to what impulse rocket is explaining. Just to be fair on that matter simply cross tigthing as a goto method should be a mandatory safe practice for all.

"Get an inch pound torque wrench if at all possible, but a light foot lb (say, up to 15-20ish) will also work. The standard torque is 12ft-lbs (dry). I go to 15 with upgraded hardware, but that's a me thing and not advice. I do mine in 2 stages, 10 in a criss cross, then 15. Again, not necessary really, but I always prefer to tighten most gasket sealed items in stages to allow better/more even compression of the gaskets and a more accurate torque bolt to bolt."
 
A 20v impact drill lightly on a fresh install never gave me issues. All my bolts are secure and never had to be seated again. No play, no thread lock.
You can use power tools to your hearts content. If it works for you, great, but it's completely unnecessary and potentially dangerous advice for people who don't understand what "lightly" could possibly mean since that is a subjective metric. Spin down until seated and maybe give it a little tiny extra 16th of a turn to snug it in place is something that everyone of every skill level can understand and follow. Given the quality of the metal, castings, and machining that goes into these engines (aka, none and crappy) I ALWAYS lean to the cautious side. I have seen stud holes drilled so deep into case halves that the stud broke through into the crankcase and caused an air leak, and that was caused by a tiny little snug up.

You have to understand that there are many people that come to this site for resources that have very little knowledge of mechanical and electrical stuff and equal levels of skills, tools, and experience. We will always police any advice that can potentially cause damage/harm to those person's engines/bikes or or bodies. It's nothing against you, so don't take it that way.

Thread locking compound isn't strictly necessary, but it is great insurance. Especially insurance when using helicoils as it will seep through the coil and help to also secure them in place. It's insurance against vibration, shields dissimilar metals from each other to reduce galvanic corrosion, and thermal cycling with dissimilar metals that can cause looseness - very prevalent when using steel hardware in aluminum during warm up periods. Think of it like fool proofing and protection against the what-ifs. Don't want to use it, that's fine. Nobody here is telling you that you are wrong, we are just saying our idea is the better/safer way.
 
You can use power tools to your hearts content. If it works for you, great, but it's completely unnecessary and potentially dangerous advice for people who don't understand what "lightly" could possibly mean since that is a subjective metric. Spin down until seated and maybe give it a little tiny extra 16th of a turn to snug it in place is something that everyone of every skill level can understand and follow. Given the quality of the metal, castings, and machining that goes into these engines (aka, none and crappy) I ALWAYS lean to the cautious side. I have seen stud holes drilled so deep into case halves that the stud broke through into the crankcase and caused an air leak, and that was caused by a tiny little snug up.

You have to understand that there are many people that come to this site for resources that have very little knowledge of mechanical and electrical stuff and equal levels of skills, tools, and experience. We will always police any advice that can potentially case damage/harm to those person's engines/bikes or or bodies. It's nothing against you, so don't take it that way.

Thread locking compound isn't strictly necessary, but it is great insurance. Especially insurance when using helicoils as it will seep through the coil and help to also secure them in place. It's insurance against vibration, shields dissimilar metals from each other to reduce galvanic corrosion, and thermal cycling with dissimilar metals that can cause looseness - very prevalent when using steel hardware in aluminum during warm up periods. Think of it like fool proofing and protection against the what-ifs. Don't want to use it, that's fine. Nobody here is telling you that you are wrong, we are just saying our idea is the better/safer way.
Yeah that's proper advice honestly. As I mentioned above it only takes one slight error to ruin this application.
 

Note something. Those are head bolts, not studs. You don't really toque studs, and if you do it's usually not very much.

The benefit of studs is that the resistance of the threads in the block are not engaged in the clamping torque of the fastener, something that causes inconsistent clamping force, even if the torque wrench tells you it reached that value. By putting the resistnce on the threads of the nut, which has a much smaller thread engagement area, you reduce that effect greatly, and end up with more consistent and accurate clamping force from the fasteners.

 
Note something. Those are head bolts, not studs. You don't really toque studs, and if you do it's usually not very much.

The benefit of studs is that the resistance of the threads in the block are not engaged in the clamping torque of the fastener, something that causes inconsistent clamping force, even if the torque wrench tells you it reached that value. By putting the resistnce on the threads of the nut, which has a much smaller thread engagement area, you reduce that effect greatly, and end up with more consistent and accurate clamping force from the fasteners.


Great...lol...Now I got to teach the Giphy people how to spell now too...The "Mo" you know???...lol...lol.
 
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