Topic: '78 CB550K named "Yuki" - Engine Build

[Nik-bot]

Hi All,

I'm building an engine (and if that goes well, a bike :-) )  and starting with a lot more enthusiasm than experience.

So I'm starting this thread to at least document the process for my own reference and hopefully to get help from the members here when I run into problems.   I'm also hoping that keeping a project thread will help me to devote more hours to this.

Here's what I'm working with:
   a) Cases, Cylinder, and Transmission from my '78 Honda CB550K
   b) Refurbished and Ported head from Cycle-X
      a. Kb guides and valves
   c) Crankshaft and rods from eBay
   d) Webcam 358a camshaft and hardweld rockers
   e) WiseCo 10:1 pistons, 1/2 oversized
   f) PowerArc ignition system (Cycle-X version)
   g) MotoWerks GP exhaust system
   h) APE HD Cyl Studs
   i) Adjustable cam sproket
   j) New o-rings, circlips, chains, seals, and any other consumable part I could find in the engine schematics
   k) etc….

I'm not decided on carbs yet and haven't purchased a head gasket.

For many months I've been acquiring and cataloging all of the needed parts, now all bagged and labeled.



And for the last several weeks have been working on assembly...

[Nik-bot]

The donor engine had suffered from oil starvation. I decided to replace the crank bearings and selected the bearing size using the markings on the case and crank (originally from different engines):



Using the case and crank markings to select bearing size worked out for me. Here are the clearances measured with Plastigage:

[Nik-bot]

Now for my first question.

When I removed the original cylinder studs, I measured the lengths extending from the top case.  The rear studs were all 122.2 - 123.4 mm. The front ranged from 105 - 106mm.

I installed the new HD studs from APE with a bit of light oil on the threads, torqueing them down to 8 foot lbs (double nut method).  Measuring them, they all extend from the case 0.25 - 1.6mm more than the originals. Should I be concerned about this? Is it possible the extra almost 2 mm length will interfere when assembling the top end?  What could I have done wrong?

Note that APE's instructions state torque no more than 12-15 ft/lbs max and I stuck with 8 ft/lbs due to broad consensus from other sources.

I took one original stud (front, shorter) and compared it by eye to an APE one and the length looks the same.

[Nik-bot]

Today I hope to button up the bottom end.

When unwrapping my NOS primary chain, I found it had rust spots. This is the worst of it:


The rust easily came off with a dremel and wire wheel so I am going to use it.  Any concerns?

Now I believe I'm ready to seal the cases, but found myself nervous, worried I overlooked something that would require splitting them again later.  That's when I decided to start this thread...

[Nik-bot]

I'm going to try to wait so see if anyone has any "don't forget to check X" type hints for me.  I know everyone is probably out riding on a Saturday 

But I will probably proceed after lunch. Will be using Locktite 518 for the case mating surfaces after seeing it successfully used in another project here (Patina Hyena)

[calj737]

APE studs are heavy duty and therefore can/shuold be torqued to 15#, in stages. Since you wound them to 8# already, step them up to 15# now. Any difference in length will probably get taken up, though your posted measurements won’t be an issue.

I hope you have had the cylinders decked flat and chosen a good head gasket?

In addition to new crank/rod bearings, how do the cam bearings look in the head and the cover? And did you replace any rocker arms?

[calj737]

Stock carbs if you are using the stock airbox are easily tuned to optimize the engine performance changes. Member Flatlander did a motor similar to yours, but with o/s intakes and uses stock carbs and gets pretty good HP from his.

[Nik-bot]

APE studs are heavy duty and therefore can/shuold be torqued to 15#, in stages. Since you wound them to 8# already, step them up to 15# now. Any difference in length will probably get taken up, though your posted measurements won’t be an issue.

Hi CalJ - thanks for your comments!  I was following the instructions from APE's site, below. I believe there were also some other threads about HD studs snapping on overtorque so want to be careful. Do you still recommend going up to 15#?

CS500H CYLINDER STUD INSTALLATION INSTRUCTIONS

1. Long threaded end must be installed in the case.
2. Note stock stud length location before removing. There are two different stud lengths.
3. After removal of stock studs (removal tool #SP-100 available from APE) thoroughly clean holes with solvent and blow out.
4. Use APE stud installation tool #08-151 or two 8x1.25mm nuts on the noted location, bottoming out, then using a torque wrench torque to 8 ft. lbs. maximum.
5. Install head, and following manufacturer's torque pattern, torque nuts to 20-22 ft. lbs.

I hope you have had the cylinders decked flat and chosen a good head gasket?

Yes, when I had the cylinders bored, I also asked the shop to ensure the surfaces were flat. They said they did this (and I can see light marks showing this). Is that what you mean by "decked"? If so, should be good here. 

As for the head gasket, there are different thicknesses available so I understood I should wait to see how the pistons clear the deck before deciding?

In addition to new crank/rod bearings, how do the cam bearings look in the head and the cover? And did you replace any rocker arms?

The cam bearing surfaces on the original head were damaged (photo below) after the oil starvation. For the refurb head I bought, it was difficult to tell the condition by appearance since the normal shiny surface appears to be gone by whatever blasting treatment was done (second pic below).  But Kenny @ Cycle-X (who sold the head to me) said it was OK and the shop that bored my cylinders said the same. 

I played it safe and got hard-weld rockers as recommended by Web-Cam (supplier of new camshaft)

[Nik-bot]

Stock carbs if you are using the stock airbox are easily tuned to optimize the engine performance changes. Member Flatlander did a motor similar to yours, but with o/s intakes and uses stock carbs and gets pretty good HP from his.

I am glad to hear this!  I would really like to use the stock carbs that I have and I will be keeping the stock airbox. An expert told me that even with the other mods (ported head, cam, etc.) the engine wouldn't REALLY wake up unless I improved the carbs, such as with CR-26s.  So I've been keeping that possibility in back of mind...

I will try to find Flatlander's thread and see what's involved in oversized intakes - there's still time for that...

[calj737]

For OS valves, you’d need to recur the seats. Not really worth it in the need unless you are determined to wring every bit of HP out of the beast.

Stick with 8# on the studs then, but do get the kits to 20#, then sit overnight, release torque in reverse sequence, then torque once more. This takes the stretch out of the bolts and compressed the gasket fully to achieve proper, final head torque. And do step the head torque in 3 stages. 8#, 15#, then 22#. Follow the sequence and do all once, then repeat twice more. Really important to do it properly.

[Nik-bot]

I've encountered what seems to be a big problem.

I put the case halves together and everything went so well. Down to the very last bolt, an 8x145 mm top case bolt (left rear corner, position pic attached).  The bolt bottoms out hitting the top of the bottom case. 

I cleaned and chased every threaded hole many times in prepping the parts. I thought, could the top and bottom holes be misaligned somehow?  So I used this little bore scope to take a look. Picture attached.

It looks like the bottom case hole is not even threaded? Could this be possible?

I reviewed my disassembly notes and found that this bolt was missing when I tore it down.

It looks like I will be splitting them apart again to investigate and resolve this problem.

Has anyone seen this before?

[calj737]

That is definitely where that bolt belongs. Only thing that makes sense is the PO sheared the original bolt or stripped the threads in the bottom of the case? Going to have to split them I’m afraid... 

[flatlander]

I will try to find Flatlander's thread and see what's involved in oversized intakes - there's still time for that...

right, i'll make it easy for you: click on the link under this message.

your motor will be pretty neat. i actually switched from the 126-00 cam to the 358a which you now have. it gives better torque while reaching the same top hp.
using stock carbs with stock airbox at the moment. mind you, i found out on the dyno that after about 10k km it's time to replace the paper filter as it starts to flow significantly less at high rpms.

and yeah, i'm afraid those cases have to come apart again.

[Nik-bot]

right, i'll make it easy for you: click on the link under this message.

Yes, got it. I now recognize yours as one of the builds I referenced while researching ways to improve the performance of this engine. Maybe why we ended up with similar components

and yeah, i'm afraid those cases have to come apart again.

Yeah, just dropped them at a local shop. Looks like Cal was right and someone in the past had broken the bolt and just left it like that.

I guess my lesson here is to always dry fit with ALL hardware before final assembly. My bad there.

[Nik-bot]

Cleaning, removing sealant, and prepping the cases for reassembly.

I am using bolts kits from AlloyBoltz. Each allen head bolt also uses a washer. One side of the washer has rounded edges, the other has sharp edges. It seems like this is an artifact of the washers being stamped from a sheet?

Anyway, I originally installed the washers with the sharp side towards the case, round side facing the bolt head. I used this orientation because I thought the flat side would have more contact with the case surface than the rounded side. Also, the round side out looks better.

I noticed that the sharp lip of each washer has left its mark on the case.

It looks like this sharp lip is preventing the full face of the washer from contacting the case. I'm not sure, but it seems that maybe the bolts could lose torque over time as the washer fully seats.

Should I try to grind the roughness off the flat side of each washer? Should I just flip them and install the rounded side towards the case face?  Is there an intended orientation of these washers?   Am I worrying for nothing?

[calj737]

Why not use a flangehead bolt instead?

[Nik-bot]

Because I've got these nice shiny new kits 

[jus4selling]

Looking like you'll end up with a tidy motor, good job.

[Nik-bot]

Update:

I reassembled the bottom end. To avoid further rework, this time i dry assembled everything including the shift mechanisms to ensure it all works.

Since the case bolts are stainless steel into aluminum, I used an anti-seize paste. I understand that I should reduce torque values by ~25% for dry install vs. wet. So here is what I used:

      ○ 8mm bolts (including crank bolts): reduced from 17 ftlbs to 12.75
      ○ 6mm case bolts: reduced from 8 ftlbs to 6 ftlbs

It felt kind of wrong to only tighten to 6 ft/lbs so asking for a check there - are these values OK for wet torque?

I ran into another snag - I'd decided to install the primary shaft after the cases are together, but I did not first put into place the starter clutch and large gear. I could not get it into the primary chain at all. Thinking I would need to again split the cases, I was very upset and went for a long walk...

Later I found this thread:  http://forums.sohc4.net/index.php/topic,122084.0.html

What would I do without the knowledge and experience collected on this forum?!?

Anyhow, I was able to install the starter clutch using the method described by xsmooth69x and Dave500 in the above thread. With a tight, brand new primary chain, it was VERY difficult to do - it took me a few hours trying different angles and approaches. BUT it is in now and I'm very pleased 

Whiskey Time and studying for the Top End...

[Nik-bot]

took some time away in an RV to go see lots of live music in Southern California.  Now need to get back on track here.  To get things going and buy some time, here's a photo of the bike this beautiful engine will eventually live in.   

that seat!  those mirrors! 

What would you do with it?

[flatlander]

hmmmm... your pics are not showing for me.

[Little_Phil]

Up to reply 10 pics and then on just blanks.

[Marissa]

Nik bot,

What are you using to host your images? Unfortunately they aren't loading for me but this build sounds interesting. Would love to see your progress!

[Nik-bot]

Thanks, All, for letting me know that my inline pics are not visible. I'm gonna say that's why this thread has been kind of a dud :-) I have been trying to link them directly to my Google Photos - has anyone done this?  Anyhow, I went back to the last several posts and replaced the inline pics with attachments.

Now I have installed the gear shift mechanisms and am able to shift into all gears - albeit with some difficulty. I have to try several times to get into the higher gears. I think this is OK and normal but someone please tell me if the shifts should be clean while spinning the motor manually...

Now I have to plan my next steps. I guess to keep the weight down while it's still on the bench I will proceed with the top end now with engine as it is in the attached photo. And later install the clutch, rotor, oil pump...   

[wolf550]

Keep up the Good Work!
I always find alot of 550 parts up in Central CA on Craigslist
Alot of good music down here in Orange County