Topic: 1977 CB750 K7 Resto-mod, Knoxville

[AintNoEasyWay]

Cool, thanks enwri. Just to confirm, you also believe that those 4 cam tower studs should be removed & retightened with thread sealer?

Hope you're doing well. It's good to hear from you again.

[enwri]

Yep, I'm going ok thanks, how about you? Still helping the bloke with the old bike collection?
    I really don't know about the stud thing. Someone may know that all of them run through, or only some, or if you can only tell by taking them out and looking.
Does happen if people have mentioned it, and a way to stop it. How do you feel about Murphys' Law? If you don't, it will leak, if you do, what are the chances of the studs breaking off or threads coming out with them? probably come out easy, (the studs, not the threads) they've been in a nice oily environment their whole lives so far, but wait,,,, now that I've said it...

[AintNoEasyWay]

Went through everything last night to make sure I had all my parts ready before I put the cylinders over the pistons. I'm missing one o-ring that goes on top in the back of the jugs, there are two that go over the studs on the top back of the crankcase & two that go on the top back of the jugs. Unfortunately I only bought three so I'm gonna call the local honda shop today to see if they have one I can run by & grab. Hopefully they'll have some Hondabond as well?

In brandEn's leak free thread, he tells you to check to make sure the four dowels, all the #3s in the diagram below, sit flush with the head surface. Mine do not, as I've tried to show in the photos below. Is this an issue? The head gasket I bought seems to fit perfectly around the dowels despite them sticking up IF I remove the rubber rings that fit around them (I can try to measure how many millimeters that may be if that'd help). I've also attached a photo of the case where I leave the rubber rings around the dowels. There's a significant rise in the head gasket off the surface because the head gasket isn't cut on the two front center holes to accommodate for the rubber rings. Any answers you guess can provide would be great!

Just to summarize the photos below, 1st & 2nd photos show the dowels sticking up WITH the rubber rings also in place around them. The 3rd photo shows the head gasket sitting nicely against the cylinder because the dowels do not have the rubber rings in place.

[enwri]

The gasket I have has big holes there. the O rings have to stick up higher than the gasket through the big holes, but the short dowels mustn't be able to touch the head when its torqued down, flush is best. It can hold the head up off the gasket otherwise. make sure the long dowels have enough room to never bottom out their holes in the head either.

[AintNoEasyWay]

Ok, maybe I will try mocking up the head with the cylinders tonight & see what type of feeler gauge I can fit in between? I guess it wouldn't be a true reading though since nothing would be torqued down. Damn. Not sure if I'll need a new gasket now or what to do. I ordered this one: https://www.davidsilverspares.com/CB750K7-FOUR-1977/part_8011/

Which in the photo appears to have the same size holes for each of the for inner dowels. I still have the receipt from last fall. Maybe they sent the wrong gasket??

Also, what fix is there if the short dowels stick up to far into the head? Do you just shave the dowels down somehow? Haha, so much confusion.

[enwri]

Without O rings and gasket, head should ideally sit flat, no gap. over the no.8s poking up.

The no.3s in the diagram are there to stop the no.2s, (O rings) squeezing out.

 The short dowels, no.3s, cannot stick up more than a torqued down gasket thickness, (flush with block is best) the O rings must stick up MORE than a torqued down gasket thickness. (To seal against head.)

The no.8s are the ones that slip into the head to locate it and stop it moving around.  These long dowels stick up into the head, and must not bottom out in the holes in the head.(front corners)

The no.7s are the oil supply O rings, also sticking up higher than the gasket to seal against the head. none of the O rings sit ON the gasket, must be through a hole.

That diagram doesn't show the no.8 in the left front. both front corners should have one.

have you had them all out and compared lengths, you would have used some under the cylinders too if you're missing shorter ones. can't remember how different, if at all.

If they machined the surface of the cylinders they might be too long now.

And yes you may have to trim then, they all came out of there before though, they should go back in.

Bike bandit shows the no.8s as 18mm long x 12 diam.  The no.3s just show as 12mm, could be length or diameter.

[AintNoEasyWay]

have you had them all out and compared lengths, you would have used some under the cylinders too if you're missing shorter ones. can't remember how different, if at all.

If they machined the surface of the cylinders they might be too long now.

And yes you may have to trim then, they all came out of there before though, they should go back in.

I have 4 longer dowels & 8 shorter dowels, the 4 longer dowels go out on front corners, on the top & bottom of the cylinders (the two that go beneath the cylinders are the ones that were rusted into the head & were culprits for me not being able to get the jugs off).

I've compared the old 8 shorter dowels to the new 8 & it does seems like the old are ever so slightly shorter than the new. I can take a picture later on, but when I put those old dowels in the cylinders to test, they still sat slightly above the surface. I'm wondering if they machined too much off my cylinders?

[enwri]

Grinder, belt sander, file, concrete floor.
Listed in order of efficiency.
Shouldn't really use the side of a bench grinder stone but it's a flat surface, may be a bit aggressive though, I don't think the short dowels are a hard steel anyway.
 Drag them up A nice sharp file, should cut them pretty easily.         

[AintNoEasyWay]

Thanks, enwri. I'm going to leave out those 4 center rubber rings that go around the short dowels. The popular brandEn's leak free top end thread shows him leaving out those 4 inner rubber rings & just using some non-hardening gasket sealant around the short dowels instead. I guess I may try that. He says it's common to get gaskets that don't have holes large enough to accommodate the 4 inner rings.

I started getting my cylinders down over the pistons last night. I got #2 & #3 in, but then it got late & pistons #1 & #4 weren't cooperating. So instead of letting my frustration get to me, I went on in to bed. I will play with it more tonight & hopefully get the remaining two pistons up in the cylinders.

[AintNoEasyWay]

Not much luck getting #1 & #4 pistons up into their cylinders. Seems like it's a tough job to do alone. I can't be on both side of the cylinders at once to make sure everything is matching up properly.

The main issue is that I was able to put blocks under #2 & #3 to keep them from moving around while I got them in, but even after turning the crankshaft up, #1 & #4 pistons don't go high enough to put anything under them to keep them steady. I will try again tomorrow, but for now is giving me a fit.

[Restoration Fan]

It's definitely easier as a two person job.  But the key thing is that you just need to get it so the pistons aren't moving.  You may be able to put something beneath pistons 2 and 3 still that keep them from moving.  Potentially even something as thin as a pencil.  But you just need to lock the pistons from being able to move up & down.  If you can lock down 2 & 3, it might keep 1 & 4 from moving as well.

[AintNoEasyWay]

Cool, thanks, Ron. I may be able to get some extra help come Sunday when my dad gets back in town. I'm waiting on 1 more o-ring to put at the top of the cylinders anyway before I can move on to the cylinder head.

[AintNoEasyWay]

Got my pistons in but I've got a significant gap between my cylinder head & the cylinder block. I can get a .65 mm feeler gauge in between them if I have the dowels in but leave the rubbers inserts out. I'm going home at lunch to re-check, but I've started another thread for the time being to get more input about it: http://forums.sohc4.net/index.php/topic,148540.msg1693109.html#msg1693109.

Here's a short video of me explaining the issue:

I'm also going to call the local bike shop that did my head work & sublet my cylinder head out to a machine shop for work. I'm not sure exactly what type of work the machine shop did & hopefully they'll be able to let me know.

[Restoration Fan]

Here's a short video of me explaining the issue:

Yeah, that's not good.  The head should mate flat against the top of the cylinder jugs.
First thing I would do is have them contact the machine shop and get them to tell you the exact thickness that was removed when the head was decked.
If they give you a number that doesn't explain the gap, then the only other thing I can think of is that you may have the wrong sized dowel pins.  But weren't these the ones that used to be in the engine back when it was running?

[AintNoEasyWay]

Here's a short video of me explaining the issue:

Yeah, that's not good.  The head should mate flat against the top of the cylinder jugs.
First thing I would do is have them contact the machine shop and get them to tell you the exact thickness that was removed when the head was decked.
If they give you a number that doesn't explain the gap, then the only other thing I can think of is that you may have the wrong sized dowel pins.  But weren't these the ones that used to be in the engine back when it was running?

Unfortunately I had this work done way back in early November. Ah!!!

I've checked to make sure I have the correct dowels. I bought new dowels, but they're the same size as the old. Yesterday I tried putting the old dowels in to see if it made any difference, but I still have the same gap, whether I use the new or old dowels.

[Restoration Fan]

Well, worst case, I know Bill Benton has other heads so you could always get a replacement head if they truly did screw the pooch on that one.  Of course, that would mean cleaning, replacing the valve springs, etc and would absolutely suck.  But that beats putting an engine back in that you know for a fact is going to leak. 

And, just my own personal opinion, but there's no way I would try to make up that much of a difference with a built-up head gasket.  Even a copper one isn't really intended to cover up a gap that large.

[AintNoEasyWay]

I just went home for lunch to check things. The two longer dowels that sit at the corners of the cylinder block aren't causing any trouble. I just put them in & the head is able to sit flush with the block.

So, it's the 8 center dowels that are causing the issue. The holes in the head aren't large enough to go over them, so the dowels have to sit completely down into the holes on the cylinder block, otherwise there's a gap. Like enwri said, I am wondering if I can just shave these dowels down & not have any consequences?

[AintNoEasyWay]

Powderman & madmtnmotors confirmed that I can just shave the dowels and be ok. I'm going to practice with the old dowels I have first to make sure everything looks good. If things seems ok I'll operate on the new dowels I bought & move right along.

[AintNoEasyWay]

Just finished shaving the dowels down & now the head sits flush against the block. Awesome. Thanks enwri & others who suggested I go this route.

Hondaman & madmtnmotors suggested I go ahead & punch out the holes in my head gasket that aren't cut to accommodate the rubber inserts, just as security. I'll see about doing this tomorrow. Then I hope to move on to the head.

[Restoration Fan]

Great news, Nate!  Looking forward to hearing her sing.

[AintNoEasyWay]

Cut new holes for the inner four rubber inserts/dowels. I used a 3/4″ punch to cut out the gasket, then sanded them down with a sanding drum on the Dremel (Thanks for the suggestion, Ron!). Time to torque & move on to reassembly of the cylinder head.

[AintNoEasyWay]

Well, guess I got too excited about getting to assemble the head & unfortunately am going to have to take a step back. I just broke off one of the bolts that goes near spark plug #1 in the head. It broke off down in the cylinder block.

I am using heavy duty APE studs, so I followed the torque sequence in Hondaman's book & torqued first to 7 ft-lbs, then to 14, then to 21.

I then moved to the spark plug bolts tightening from #4, then over #1. My Clymer manual said to tighten these bolts 6-9 ft lbs. I only tried to tighten to 6 ft-lbs at first. As I first tightened #4, I realized the torque wrench never seemed to click, so I stopped tightening & figured I'd move to tighten #1. Had the same issue with #1, & I heard it click, but not the torque wrench, it was the bolt. The bolt popped loose.

First picture just has the broken bolt matched up against a good bolt to show how much it broke off. Second photo shows bolt #4 that I almost broke off as well. Pretty obvious from the warp.

What the hell am I supposed to do now?  I guess I have to remove the cylinder block completely to have the bolt removed? Can't believe I did this.

[madmtnmotors]

Maybe not.

>First of all, move the head gasket out of the way to a safe place to prevent damage to it.
>COMPLETELY cover the top of the cylinders to prevent contaminating the combustion chamber.
>Cut away a small circle around the offending bolt and tape the cut edge to the top of the cylinder block to prevent contamination of the cylinders/combustion chamber.
>Now go to work on it.

A small pick might turn it out. Looks like you've got a little nub to work with. If that won't budge it, then I recommend left hand drill bit. I usually take a diamond stone in my Dremel to make my center "divot" before drilling. Start with an 1/8" left hand bit first. Usually the heat and force will turn them right out without having to step up to the next bit. If the bolt were seized then I would suggest removal of the cylinders, but since you merely over torqued, there is no longer stress or tension on the threads. You might luck out as long as the threads weren't galled as a result.

Oh yeah, most in-lb torque wrenches won't "click" unless you lock them after adjustment. For small fasteners I usually go to the vise and test for the "click" first. I know, hindsight is 20/20...

[AintNoEasyWay]

Thanks so much, Wilbur. I plan to give it a go tonight & will report back hopefully with good results.

[AintNoEasyWay]

Success. Thank you, Wilbur. I got the remainder of the bolt out with an extractor. No threads seem to be stripped, although the bolts do not appear to use all of the thread they have? Not sure how to state this correctly. Maybe a photo will be of help. I also still have the original bolts from when I took apart the top end. The old bolts appear to be much more durable than the new honda bolts I purchased. Is this a surprise to anyone? Has Honda started having cheaper bolts made? Or is this just entirely my fault (I'm okay with that if it is, haha).