Pulled case bolts?

Assembling Son's 600 engine.. To fix an unexpected Heat Siezure.. Which thanx to Messages here was best Diagnosed as a Head/cam seize..Unheard of in my 35 yrs of DIY engine work.. At least that was the only area evidencing any damage at all.
Stud/bolt 'pulled' out during Torquing.. yes to 20 nms on a decent Beam type wrench. WTF?
Very upsetting. Obviously another hidden issue. .. removed stud and sure enough the thing had stripped out it's case threads. Took a peek at my 'spare' engine and retrieved a fresh Stud... then noticed that the threaded portion of these studs is an inch long. !? Similar stud threads in my Yama 350(s) are approx 2" long . Go! yamaha. :evil:
Gonna try JB weld and and pray I give this 'repair' a 50% chance of working.
Any better ideas?
No I'm not Eager to take the cases out AGAIN to helicoil/insert them .
My 'appreciation' for this particular Model/Engine design could not be lower at this point

 

The best news I can give you is do it right or your just throwing money away. Pull the case, the long term success of this rebuild is pretty slim if you don't.

 

take a look around on kzriders.com ,that seems to be kind of common on some old kows
they will usually tap for the next size up or heli-coil it
good luck

 

You have a limited number of options.
Weld-it-up, drill-it-out and tap new threads.

Drill the oversize and stick-in the HeliCoil.

Swap-out the whole damn engine.

Personally, I have never encountered a Cam seizure on any engine I have put my hands on -- in my life.
Now, you've got to admit that ... that, right-there ... is one spooky situation.

Having a bolt strip-out the casings threads while being torqued to 20 nms
(20 Newton Meters = 4 FtLbs -- for practical purposes ... "Hand tight") is scary.

So, ... with this engine racking-up both a "Spooky" and a "Scary" ... I would have to take pause.

The Motorcycle God's are seemingly not looking-down upon that engine project, favorably, now.

Are they???
....................

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Get that bike fixed right.
Good luck.

 

Just an FYI, 20nm is closer to 15 foot pounds, a little more than hand tight.

Jim 8)

 

Absolutely Right on several counts. Also Never Seen nor even heard of a head /cam sieze.. it was someone here's suggestion and barring ANY evidence of siezure anywhere in the engine ( I have 2 strokes.. there is ..never .any ambiguity with those I only parroted the claim.
Have 'replaced' the Cyl block, rods, pistons and the Cyl head in it's entirety.. even did a port job/valvework & grind on it Utter waste of many hours in retrospect.
Recently had a case stud issue on my YVPS 350 .. had the stud extracted using an EDM (search beyond all expectations result , seriously recommended... IF the object is deemed worth the effort.
But do that? on this POS? utter waste of time, money and technology IMO.
I used the JB weld ...and apparently it does indeed hold the correct TQ .. my 2 stroke site mates claim this is definitely a "poor practice" (bodge repair but suggest that it ..will ...likely outlast the rest of the engine in Real life use.
True ? dunno, We are not planning to have it around to find out though
Just putting the thing back together now
. In all candor this thing has both disgusted and frustrated... it specs out 'jes fine'.. yet it fails.
Hopefully the thing will be up and running soon.. the 'Kid' is intending to lose it.. an End to a V expensive experience for him (have you priced Genuine Yama FZ parts?) and unprecedented frustration on my part.
Still really pissed.. but starting to get over it

 

I have a friend who stripped a bolt on his case, but it was one in a "tab" and a longer bolt through with a nut on the back solved it witout having to drill/tap/helicoil. I'd suggest this method if possible, or simply try a longer bolt. You may have only stripped out the end of the threads, and going a little deeper you might get to an undamaged portion. Or not.