Stripped Cylinder Studs

SpAsTicJaX · Mar 9, 2014

well after i did some basic port matching, and cleaning up of the ports i made my own head gasket out of a beer can (all nice and purdy

) and upon retightening i accidentally with my heavy handedness stripped the stud from the bottom crank housing (not the stud, the housing.) so today some stage im going to go to the shops and get some of this :
http://www.supercheapauto.com.au/on...High-Temp-Cold-Weld-45g.aspx?pid=346740#Cross

and hopefully that will hold the stud in until i can afford to get a HD freewheel from sick bike parts so that i can use my 66cc in my bike with shift kit.

so i suppose this is more of a tip lol, DO NOT OVERTIGHTEN STUDS AND HEAD NUTS!! OTHERWISE IT WILL CAUSE YOU GREAT GRIEF!!
fyi, in the future i will be investing in a torque wrench hah! xct2

Kioshk · Mar 9, 2014

I'm afraid you'll be disappointed with that; I highly recommend you invest in a helicoil kit. It'll last the life of your engine.

2door · Mar 9, 2014

Kioshk said:
I'm afraid you'll be disappointed with that; I highly recommend you invest in a helicoil kit. It'll last the life of your engine.

Ditto:
I'm not a fan of glue, in any form to repair critical threads. A true mechanical repair is the only way to make it permanent. Epoxy, JB Weld, ect. is a band aide. It will eventually fail and you'll be back to square one, or less.
Invest in a helicoil kit and a torque wrench.

Tom

maniac57 · Mar 9, 2014

I agree. Epoxy repair compounds will NOT hold a stripped head stud. The only repairs that work right are a HeliCoil kit, or replacing the case half.
Don't waste time and money on anything else.

SpAsTicJaX · Mar 9, 2014

maniac57 said:
I agree. Epoxy repair compounds will NOT hold a stripped head stud. The only repairs that work right are a HeliCoil kit, or replacing the case half.
Don't waste time and money on anything else.

well i have great news

turned out that it was just the stud that had stripped , and i luckily had a spare metre of the same thread stud in my shed.
if anyone is interested, i will upload photos later

also going to be trialing running a head gasket made of tin (beer can) and i am wondering if i should use head gasket maker aswell as the tin, or if i should just use the tin. cheers

maniac57 · Mar 10, 2014

Lucky break! I use thick aluminum roaster pans from the dollar store to make gaskets. It is nice and soft and seals well. Your beercan idea will probably require you to lap the head to prevent leaks. The metal is too thin to seal well compared to a real gasket.

SpAsTicJaX · Mar 10, 2014

maniac57 said:
Lucky break! I use thick aluminum roaster pans from the dollar store to make gaskets. It is nice and soft and seals well. Your beercan idea will probably require you to lap the head to prevent leaks. The metal is too thin to seal well compared to a real gasket.

i have cleaned up my head with sand paper and glass and then polished it up with the wire wheel on my rotary tool and i was just about to go do everything up but was just awaiting on a reply from someone for guidance whether i should use gasket goop or not as well as my home made gasket.
thanks for your replies!

i will upload some photos later tonight or tomorrow afternoon, as i have just finished my engineering course and i will be going back to do part time schooling as of tomorrow so this will be my daily ride 6kms there and 6kms back

Kioshk · Mar 10, 2014

Lapping is good, but avoid trying to polish with a wire-wheel; it may defeat the purpose of using glass: a flat mating surface. Don't use any goop on the head-gasket. I do prefer a thin coat of soft Permatex gasket goo on the case-gasket though. I also like using Blue LocTite on the studs in the case. On a related note: these studs have two different threads, make sure you don't force a stud into the case with the wrong end. hand tighten before torquing.

SpAsTicJaX · Mar 10, 2014

i think in the future i must invest in a quality torque wrench, helicoil kit and a few other tools if i am going to insist on working with these little chinese wonderd

they are such great fun to work with, and very simple.

2door · Mar 10, 2014

Kioshk said:
On a related note: these studs have two different threads, make sure you don't force a stud into the case with the wrong end. hand tighten before torquing.

This is a strange issue. Every engine I've had, Chinese 2 strokes, had studs with course and fine threads. The fine theads went into the block, the course threads went to the head nuts. However, some members have reported having studs with course threads top and bottom. From this I gather that there are both out there.

Nevertheless I've seen several engines returned to a supplier where the owner had tried to screw the course threads into the block and then tried to force course thread nuts onto the studs. It is really easy to compare the threads and see the difference but maybe it isn't as obvious to some folks.

Whatever, if you remove your cylinder studs for any reason take a good look and compare the threads on each end before trying to reassemble the cylinder/head.

Thanks for bringing this subject up again, Kioshk. Hopefully it will save some new builder a lot of grief.

Tom

MotorBicycleRacing · Mar 10, 2014

2door said:
This is a strange issue. Every engine I've had, Chinese 2 strokes, had studs with course and fine threads.

The fine theads went into the block, the course threads went to the head nuts. However, some members have reported having studs with course threads top and bottom. From this I gather that there are both out there.

Tom

You must not have got a motor off thatsdax recently because they have coarse threads in the block.

I get my motors from the same factory in China as dax and I prefer having coarse threads on both ends of the 8 mm studs.

2door · Mar 10, 2014

MotorBicycleRacing said:
You must not have got a motor off thatsdax recently because they have coarse threads in the block.

I get my motors from the same factory in China as dax and I prefer having coarse threads on both ends of the 8 mm studs.

As a matter of fact, Niel, I have one of Duane's recent customer returns on my workbench right now. It was returned and the customer said, "the head gasket leaked". He had disassembled the top end, removed the studs then got them in wrong and stripped threads in the case and the tops. It has fine threads, 8mmX1 in the block, course threads, 8mmX1.25 on the other end. I'm going to fix it and have a spare engine to play with.
I just feel that they come from the factory with whatever they were using that day.

"Monday? Let's use fine threads. Thursady? Go with the course threads today."

Tom

Theon · Mar 10, 2014

Probably right, two of my motors have fine thread both ends the other three have coarse both ends, not seen different threads on the same stud yet,
It seems to me that the coarse thread is better into the aluminum casings.
The fine thread is better for the head nuts.
In the automotive world it's usually coarse thread into aluminum, fine thread for head nuts.

paintgun · Apr 17, 2014

My engine has studs with different threads. Fine on bottom end, course on top. Had one strip out on the top end fortunately. I need to order one. Does anyone know who might have studs like this? The places I looked have either fine or course. Should I just order the fine threaded ones?

2door · Apr 17, 2014

paintgun said:
My engine has studs with different threads. Fine on bottom end, course on top. Had one strip out on the top end fortunately. I need to order one. Does anyone know who might have studs like this? The places I looked have either fine or course. Should I just order the fine threaded ones?

If your problem is only one stud then you could use a fine thread nut on it and course thread nuts on the other three. Otherwise, replace them all and buy four fine thread nuts.
Whatever, make sure you match the threads in the case to the studs. Fine or course. Then match the head nuts to the studs, fine or course.

Tom

paintgun · Apr 17, 2014

Thanks, Tom. I'm going to Lowes this weekend. I'll check and see if they have anything like that. Probably don't. So I'll see if the have hardened threaded rods and get one with fine threads. Do you know of anyone who sells the ones like I have? I can't seem to find any.

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Stripped Cylinder Studs

SpAsTicJaX

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Kioshk

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2door

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maniac57

Old, Fat, and still faster than you

SpAsTicJaX

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maniac57

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SpAsTicJaX

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Kioshk

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SpAsTicJaX

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2door

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MotorBicycleRacing

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Theon

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paintgun

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