Need new headbolt/is my piston burned?

thats genious!!! I stripped the top part of the rod where the top head nuts screw on because I tried to tighten one of the rods using the head nut. But thats very smart, the two nut thing. Im going to wait till the weather is a lot better before I start tweaking with my bike again. There are way too many things going wrong with it right now. Ill post some pictures hopefully tomorrow. Of the stud and the piston.

till then gents...
 
Anyone know where I can buy a new headbolt, just the headbolt? I stripped the top of one of them, and the nut wont screw on now. I figured that it wouldnt be safe to ride with one nut missing, so I didnt ride.

Also, once I get one, how do I tighten it as much as possible without stripping the threads?

And finally,
I checked my piston, and the top of it is mostly covered with oil/gunk. Some of it can be scratched away with a fingernail while most of it has hardened. Is this how the piston is supposed to be?
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Did you get that head bolt ??

FYI I have started making custom stainless steel engine studs
They are much stronger than the studs in the engine Kits, and you can get them in the length you need. If this is something you can use let me know. Im not trying to make a buck here I will only charge for shipping and material cost.
 
hey, if its not stripped too bad, you could try re-threading it. just a thought.
 
I haven't gotten to it yet, buisness has been really busy lately. But Ill get on it soon. Thanks for the offer, I might take it up, but do you mean the studs for frame mounting, or just the ones that hold the head onto the engine, the one that I stripped?
 
If you have never tightened head bolts before on a engine, my advise would be to actually tighten correctly with a tourque wrench first so you get to know the "feel" of ft/lbs.
If you say you have stripped the threads on a HT, it shows some have not progressed to that point of ever having used a torque wrench.
You'll be surprised that 15/20 ft/lbs on the HT head bolts may not seem tight as you think, no where near that tight to strip a thread.

I read somewhere here to, that it's not wise to use those dome shaped nuts as head bolts, because it's been known to screw up into the end of a closed off thread, and this will then turn the entire stud that holds the cylinder.
Use some other nuts to tourque the head and if enough space, use the domes last.

One other thing that is not mentioned,
when re-tightening the head bolts, it's probably best to loosen 1/4 turn so the "crack" of a stuck nut does not crack on the tightening side. Crack the nut on the loosening, or loosen right off, one at a time, spray some CRC between the bottom of the nut and the top of the alloy head where the nut sits.
Then re-tighten.
 
Actual "clamping force" or "pull down" varies greatly with:-

1 No lube on threaded parts

2 Kerosene or similar

3 Grease or good oil.

The clamping force difference between 1 through 3 can be over 50% when using the axial measurement from a torque wrench.

With rough or low quality parts the differences could be even greater.

In a dry state up to 90% of torque can be consumed by friction on the flanges and threads.

When lubricated this value decreases greatly.

There is much to know about the subject of force measurement, bolt tension ect.

Some manufacturers don't give torque values for fasteners but values in microns for the part pull down.
 
The clamping force difference between 1 through 3 can be over 50% when using the axial measurement from a torque wrench.

So, is recommended torque based on bone dry threads? I always wipe my threads with cloth but don't go to the trouble of using solvent or the like. Should I?
 
OK, this one may need to start from scratch.
Head studs and head bolts.
Engine expirience from cars.

Back when cars had caburtetors, in Australia, was the faithfull
"Red Motor".
These motors were often stripped and "done up".
The head bolts, go into the engine block and some go into the water jacket.
The recomnended sealant is called "Stag", it's brown/red in color and has a distinct odour about it.
One had to smear the threads with Stag, then tighten up the head.
When the car was initially started, it did not leave the workshop until the head was re-tensioned as soon as the water warmed up and ran for 20 minutes or so.
This was so everything had dried up, "settled" and during that warm up the timing and some carby adjustments were done so it's ready for the next run after the initial warm up.

After initial warm up of a HT, re-tension cos that lube/oil/kero-whatever would have dried up, caused some space, therefore a re-tension is warranted.

But,
if lets say an engine has been running for a month,by that time those head bolts have sealed firmly, "rusted" in, so if you try to undo them, they sound a "crack".
If one has this "crack" sound when they are tensioning the head, then you do risk breaking the bolts or stripping a thread.
Like I said before, loosen first, then re-tighten.
Warm it up, then check the tension again, but don't loosen the 2nd time.

To "visualize" what happens when you re-tighten a cylinder head in sequence, think of ironing a trouser leg, <<<>middle out->>>>>>|.
Same with a head, tension it outwards.
 
Who knows with these Chinese motors.

Would have to know what the design engineers had in mind when specifying the number 12.

Honda or BMW ect would be more specific.

I would use oil or grease though.
 
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