Topic: Need help from someone with their top end off, CB750k!

[brazwell]

I recently posted a topic regarding my APE studs seemingly being too short once torqued in the cases. Im hoping that someone who has their top end off can measure the depths of the threaded holes in the cases that the studs thread into. Please help.

[HondaMan]

I recently posted a topic regarding my APE studs seemingly being too short once torqued in the cases. Im hoping that someone who has their top end off can measure the depths of the threaded holes in the cases that the studs thread into. Please help.

The long end of those studs goes into the cases, if that helps? Other than that, they should be a drop-in fit. Be sure to torque them into the cases, per their online instructions.

[brazwell]

Ive got the long threads in the cases. Torqued to 8 ft. lbs. The studs all look nice and even. Once the cylinder and heads are on, the studs are too short. Once nuts are torqued, I have several threads still in nuts. Im at a loss.

[BPellerine]

are all of the dowels the right height ,could they be holding the head or barrels up,in your other thread the height for studs is there did you measure the installed height?bill

[brazwell]

I dont know what the installed stud height should be. Everything is sitting nice and flush, studs just barely stick out.

[MCRider]

I recently posted a topic regarding my APE studs seemingly being too short once torqued in the cases. I'm hoping that someone who has their top end off can measure the depths of the threaded holes in the cases that the studs thread into. Please help.

I have a set of K2 cases with no studs. I can measure the holes tomorrow. Don't know if it will help. I think I've got one with oem studs in it, I can measure them too.

I read your other thread as well.

The comment about the dowels has merit. We need to cross that out. Are the cyls drawing down to the cases and the head drawing down to the cyls. OR can you see or feel daylight at the gasket levels.

My engine has APE studs in it with xtratall HD nuts with washers from CycleX. They torque down flush to the top of the studs. AS it should be.

[brazwell]

That would be super helpful MCRider. Yeah, cylinders are seated nicely as are the heads.

[JohnN]

I have K2 cases with studs removed; the holes vary from 31-32mm in depth.
John

[mrbreeze]

I don't have one opened up to compare but I noticed the nut has that flange on it . Are those the correct nuts? I'm sure one of the other posters would have noticed that but ya never know. There has to be some explanation for this problem.

[Garage_guy_chris]

I have the studs out on my K4 #2351600 and the stud holes range from 1.175" to 1.250" deep.

My Kibble white studs spec out at
long   = 195mm / 7.675"
short  =  160mm / 6.300"

also the case end of the studs the threads are only .750" long so they are .425" to .500" from bottoming meaning a ball in the stud hole as suggested wouldn't be enough to take up the gap on my kibblewhite ones anyways < wrong... read lower....

The other thing that crosses my mind is the thread fits if the case threads have been chased with the wrong tap (kibblewhite specifies a M8 x 1.25 D5)  or tapped to deep or the studs threads are undersized and out of spec they may be going in deeper than they should somewhere i even saw what the thread fits are but i can't remember where?

maybe consider another set of studs? another set of the APE or maybe the Kibblewhite studs?

[mystic_1]

Chris, those figures seem to jibe with what Mick posted in the other thread.  Your short studs seem to be 10mm shorter but your long stud measurement was the same.

I don't know if everyone noticed this from the other thread, but in the first picture you can see a stock long stud and a stock short stud laying against the package of the APE studs and they appear to be the same lengths.

mystic_1

For your reference mate, the stock stud lengths are
Long Stud - 195mm OAL
Short stud - 170mm OAL

Installed height
Long Stud - 170mm
Short Stud - 130mm

Below are stock studs on APE HD studs for comparison



Below are installed (stock studs) - 170mm and 130mm height from top of case.



The best thing to do now is to Loctite the studs into the case and set the heights (above) as evenly as you can.
It doesn't have to be a micro measurement, just get them as close as you can by eye with a steel ruler.
The warning here is, don't flood the stud threads with Loctite.
Lightly coat the threads in the case with a toothpick and then screw the studs into the case.

Reasons being that too much liquid runs the risk of "hydraulicing" the stud in the threaded hole and secondly and most importantly, there's every chance that the oil galleries that let oil feed the top end will be blocked solid.
If that happens, you'll be pissed off big time. 

[Garage_guy_chris]

Chris, those figures seem to jibe with what Mick posted in the other thread.  Your short studs seem to be 10mm shorter but your long stud measurement was the same.

I don't know if everyone noticed this from the other thread, but in the first picture you can see a stock long stud and a stock short stud laying against the package of the APE studs and they appear to be the same lengths.

You got me worried for a sec there i just pulled out some old studs and they are the same length as the Kibblewhites so someone has mis-measured at 170mm??? mine are infact 160mm

[mystic_1]

Quite possible.  If we do some math comparing the overall lengths to the installed heights that Mick posted, we get:

Long = 195mm - 170mm = 25mm depth into cases
Short = 170mm - 130mm = 40mm depth into cases??

But if we take your measurement for the short studs, and his installed height, we get:

160mm - 130mm = 30mm depth into cases

This seems to be more reasonable when compared to figure we got with the long studs, and corresponds well to the figures that JohnN posted above (31-32mm hole depth)

mystic_1

[mick7504]

My apologies gents.
The short stud is 160mm OAL.
The installed height of the long stud is 170mm.

I'll edit the early post to reflect the above.

[Garage_guy_chris]

mathematically this makes sense but the long threads are only just under 20mm long so a 20mm thread in a 30mm deep hole so the studs are not meant to bottom in the cases to achive the torque. I just messed with mine for a sec and the top end threads into the cases by hand easily to the end of the threads while the bottom interference threads or longer end will only go 2-3 threads then gets too tight to do by hand

its got to be the threads are cut too long and going into the cases too deep, or the thread fits are off and going too deep.

now i just realized something the threads are recessed 5mm into the case holes so heres what i figure:

long studs 195mm - 20mm of thread - 5mm for the recessed threads = 170mm height from base gasket surface stick out < matches mick7504's measurement
Short studs 160mm - 20mm of thread - 5mm for the recessed threads = 135mm height from base gasket surface stick out

taking the fact that the holes are 31mm to 32mm deep

31mm - 20mm of thread - 5mm for the recessed threads = 6mm under the studs to bottom of hole
32mm - 20mm of thread - 5mm for the recessed threads = 7mm under the studs to bottom of hole

so technically a 6mm or 7mm ball bearing could work but doesnt sound right.... threads should be binding @ 20mm of engagement to achieve the torque figure. 

 

Quite possible.  If we do some math comparing the overall lengths to the installed heights that Mick posted, we get:

Long = 195mm - 170mm = 25mm depth into cases
Short = 170mm - 150mm = 40mm depth into cases??

But if we take your measurement for the short studs, and his installed height, we get:

160mm - 130mm = 30mm depth into cases

This seems to be more reasonable when compared to figure we got with the long studs, and corresponds well to the figures that JohnN posted above (31-32mm hole depth)

mystic_1

[MCRider]

That would be super helpful MCRider. Yeah, cylinders are seated nicely as are the heads.

Sounds like others have provided you with measurements, so I won't be.

[Phinn]

The threaded ends aren't meant to bottom out. Installing the studs deeper than the top of the threaded hole would add no additional strength (especially since the factory studs are cut away in between the threaded ends, so the shafts wouldn't touch the sidewall of the hole anyway).

I just pulled my factory studs out a few days ago. Several of them still had a pressurized air pocket that went "pfft" as I removed the stud. There's no way those studs could have been installed all the way down.

[brazwell]

It sounds like I need to try new studs. Any reccomendations between the Kibblewhite and Cycle X studs?

[Retro Rocket]

It sounds like I need to try new studs. Any reccomendations between the Kibblewhite and Cycle X studs?

I thought they measured the correct length..?  Ape already told you what to do, they have built more bikes than you've had hot dinners, these studs only torque to 8 foot pounds anyway, once you torque the head that torque is reduced as its important at the top of the engine to keep the head torqued down, which puts upward pressure on the studs. It seems that you just keep posting this in different threads trying to convince yourself that they are wrong, there are thousands of these studs on the forum and i think Jay makes these in house. Seriously, stop over thinking it and use them... What are you going to do when the Kibblewhite ones measure the exact same length..?  If anything, it sounds like someone has gotten a little over zealous when cleaning out the case threads and opened them up a bit, making the studs want to sit deeper.......

[mystic_1]

It is interesting that the math we did above corresponds EXACTLY to the original suggestion from APE.

31mm - 20mm of thread - 5mm for the recessed threads = 6mm under the studs to bottom of hole
32mm - 20mm of thread - 5mm for the recessed threads = 7mm under the studs to bottom of hole

They have suggested that I "drop a 3/16 or 1/4"  steel ball in the hole and screw the stud down onto it and tighten."

1/4" = 6.35 mm


To be fair it sounded like a kludge when I first read the suggestion, but based on the above discussion, this is the way I would go* if it were mine.

mystic_1







*  Actually not quite.  What I would do if it were mine would be to take some aluminum rod stock of the appropriate diameter and slice off some 6.35mm slugs, and use those instead of bearings.  That way, the force of the initial torque on the studs isn't concentrated in a single point.  I'd be worried about collapsing the bottom of the hole, not knowing how thick it is there off-hand.

This also assumes that the threads themselves aren't completely trashed.  Got any close-up pics of the threaded holes, brazwell?
-m

[Brantley]

Brazwell,
I've been lurking on both threads.
Have you actually disassembled the top end and done the detective work to be absolutely sure you didn't miss something or a PO hasn't buggered the threads in the cases? I'm sure the most experienced engine builders here (of which I ain't, but I've done a few) will own up to overlooking something minor once or twice that has stymied progress and required backtracking. I've used APE studs (and other parts and machining services) on two builds without issue and haven't seen a post here concerning an issue like yours. Not trying to sound like their cheerleader, but they kinda know their binness. A bunch of numbers have been thrown at ya- whip out the measuring devices and use them. I've also read nothing about your build that may provide clues, as you likely didn't tear yr engine down just to replace the studs... What thickness base and head gaskets are you running? Dowel pins have been mentioned. Pistons too tall and at TDC (had it happen, but only .013")? Tensioner hung up? Cam chain guide mislocated?  Just throwing ideas out...  I have bare K3 cases and'll be happy to throw a depth gage in the case threads, if you want to compare. As far as Cycle X or Kibblewhite studs- I'd throw my brain at this problem before throwing more dough at it.

[Brantley]

If anything, it sounds like someone has gotten a little over zealous when cleaning out the case threads and opened them up a bit, making the studs want to sit deeper.......

And/ or, lest we forget our machines were made by PEOPLE. Bad day at the office? 

[brazwell]

Yeah, I know nothing about the bike or the PO. I tore the top end off due to a leaky head gasket. The engine had been apart before, their were very deep pry marks on the cylinder surfaces that required decking. Im using an Athena gasket set and my cylinders and heads are sitting perfectly flush. Ive never used APE studs before which is why Im assessing every avenue possible. Im not quite comfortable with the hole ball bearing idea yet so ill still explore other avenues and hopefully find why im having this problem. My first mistake was tossing the stock studs (or whatever studs I removed), they would have been nice to have for comparison.

[evanphi]

Yeah, I know nothing about the bike or the PO. I tore the top end off due to a leaky head gasket. The engine had been apart before, their were very deep pry marks on the cylinder surfaces that required decking. Im using an Athena gasket set and my cylinders and heads are sitting perfectly flush. Ive never used APE studs before which is why Im assessing every avenue possible. Im not quite comfortable with the hole ball bearing idea yet so ill still explore other avenues and hopefully find why im having this problem. My first mistake was tossing the stock studs (or whatever studs I removed), they would have been nice to have for comparison.

Lesson learned: never throw anything away! I have a growing stack of small boxes and bags that contain all the original parts for my bike.

[Garage_guy_chris]

Just because someone has been in the engine before doesn't mean much concerning the studs. if they were the thin original studs like the top one in the photo then its highly unlikely anyone has ever taken them out before you. thus no ones messed with it but you. If i were you id pull the head and pull the cylinders up a 1/2" and compare where your dowels and o-rings are, i would bet you have doubled up somewhere or something is hung up. If after this you still cant figure it out then pull the head and cylinders completely off and check your stud lengths from the gasket surface..

long studs 195mm - 20mm of thread - 5mm for the recessed threads = 170mm height from base gasket surface stick out < matches mick7504's measurement
Short studs 160mm - 20mm of thread - 5mm for the recessed threads = 135mm height from base gasket surface stick out

this also concerns me from one of your other threads... if these are too long they can hold the cylinders or head from seating properly leaving a gap and will translate into the problem your having with short studs..

Re: Engine Dowel Pins Source
« Reply #1 on: August 28, 2008, 05:08:59 PM »

    Quote

I am having the same problem currently with my 750 k3 rebuild. Need one of the corner dowels between cylinder and head. Absolutely unavailable. My next attempt will be measuring said dowel ( think its 14x22mm), and trying to match it up. Lots of online sources for random dowels.

[Retro Rocket]

Yeah, I know nothing about the bike or the PO. I tore the top end off due to a leaky head gasket. The engine had been apart before, their were very deep pry marks on the cylinder surfaces that required decking. Im using an Athena gasket set and my cylinders and heads are sitting perfectly flush. Ive never used APE studs before which is why Im assessing every avenue possible. Im not quite comfortable with the hole ball bearing idea yet so ill still explore other avenues and hopefully find why im having this problem. My first mistake was tossing the stock studs (or whatever studs I removed), they would have been nice to have for comparison.

Tossing the stock studs really means nothing, you've been given the measurements, looking at more stock studs won't make anything any different. As i've repeated 3 times now, APE have built literally thousands of engines since the 70's, there are about as expert as you'll ever get anywhere, Measure the depth of the holes first to eliminate any  PO stuff up then, if Jay {APE owner} said put bearings under them then, put bearings under them, or, cut a small piece of the same sized thread off a bolt, or bolts in this case, , any cheap bolt with the same thread will do, or even a length of threaded rod in the appropriate thread size, cut a slot in the top and screw it into the case holes, then screw in the studs. Hundreds of current members have APE studs in their engines and thousands of people world wide, I have a 35 years old set in one of mine...

[mystic_1]

The APE studs that I installed in my engine a few years back were almost the only components to NOT give me any complications at all.

Would Recommend.

Good Seller.

mystic_1

[BPellerine]

Yeah, I know nothing about the bike or the PO. I tore the top end off due to a leaky head gasket. The engine had been apart before, their were very deep pry marks on the cylinder surfaces that required decking. Im using an Athena gasket set and my cylinders and heads are sitting perfectly flush. Ive never used APE studs before which is why Im assessing every avenue possible. Im not quite comfortable with the hole ball bearing idea yet so ill still explore other avenues and hopefully find why im having this problem. My first mistake was tossing the stock studs (or whatever studs I removed), they would have been nice to have for comparison.

Tossing the stock studs really means nothing, you've been given the measurements, looking at more stock studs won't make anything any different. As i've repeated 3 times now, APE have built literally thousands of engines since the 70's, there are about as expert as you'll ever get anywhere, Measure the depth of the holes first to eliminate any  PO stuff up then, if Jay {APE owner} said put bearings under them then, put bearings under them, or, cut a small piece of the same sized thread off a bolt, or bolts in this case, any cheap bolt with the same thread will do, cut a slot in the top and screw it into the case holes, then screw in the studs. Hundreds of current members have APE studs in their engines and thousands of people world wide, I have a 35 years old set in one of mine...

nuff said +1 on solution.bill