Author Topic: My CB755 Project - COMPLETED!!!! (Read 34506 times)

Tews19 · « **Reply #25 on:** January 04, 2013, 06:12:44 PM »

Damn MW, you have nerves of steel. I would have lost it. 3 engines with this project. Yikes. Keep up the work. Can't wait to see the work of cool headed person. I'm a hot head and that would have had me thinkin bout every bump in the build.

mwvachon · « **Reply #26 on:** January 12, 2013, 06:28:41 AM »

This TOTALLY SUX! I've been working on the engine bottom end for the better part of two weeks now and am beyond frustration. Totally dis-assembled, I prepared to do the plasti-guage thing. But I have a mental problem with trying to do .000x size measurements just by eyeballing a piece of cardboard. I made the decision to just take the cases, crank, con-rods and bearings to my local machine shop. The guy there has always been awesome and he's quite meticulous as well. The first bad news was the crank pins came in under spec - no saving that. Measurements were such that there wasn't enough left to grind down to the next bearing size. Fortunately I still have the 3 salvage engines to pick parts from, so I wasn't too worried. The REAL bad news came when he tried to measure all the case bearing seats. The first one (next to alternator/starter) was badly deformed, it's out by .004! Not even enough meat left to re-bore! I do have one more useable (K3) salvage engine, so I may be going back to square one. I just can't believe this!

mwvachon · « **Reply #27 on:** January 16, 2013, 03:39:35 AM »

Postmortem on the latest engine:
The RTV should've been the tip-off! Trying to find a virginal 40+ year old engine is like trying to find... well... a 40+ yr old virgin! After many measurements and re-measurements and a a few beers to dull the pain, we've determined that in addition to the out-of-round #1 crank bearing seat, it looks like the entire crank had been previously re-ground. All the crank pin measurements are well under the minimal Honda spec, but are all within .0002" of each other. I need verify, but it also looks like all the crank bearings are over-sized - even beyond the thickness of the Honda 'black' bearing specs, but I need to wait for my more-micrometer-savy brother-in-law to come by and confirm this to make sure I'm looking at this correctly. Went ahead and did the plasti-guage thing anyway and found the connecting rod clearances were not bad, but the crank bearings are at the high end of the limit. Not acceptable.

Now to determine next step(s)...
Option #1 - Tear down the remaining K1 salvage engine and see if it's worth it to have the front sprocket patch properly repaired (AFTER confirming the crank is at least close to spec). This is slightly attractive in that it again gives me a K1 motor in a K1 bike, making the resto more correct...

Option #2 - Tear down the K3 Salvage engine and start all over again with that. Again, I'm saddened that it takes away from the 'correctness' of the project, but is still a viable option...

Option #3 - Go hunt for another K1 motor (but they don't grow on trees...)

Tell me again why I started this project in the first place?

Toxic · « **Reply #28 on:** January 16, 2013, 03:58:12 AM »

Go back to the K1 motor, if everything is in spec, and it has to be better than what you are finding with your other motors, get that patch done right.

It's not that big of a repair.

best of luck

iron_worker · « **Reply #29 on:** January 16, 2013, 06:16:23 AM »

I'm going to have to agree with that. Get the correct engine back in that bike. I think you'll be glad you did in the long run.

Take it to a competent shop and they should be able to handle it I'm sure.

IW

Vinhead1957 · « **Reply #30 on:** January 16, 2013, 09:52:49 AM »

Sometimes we have good days sometimes not. I had a frustrating day last week. I had to walk away to think about it for a while. My motto is, " it's gonna be a long winter and I have plenty of time". Trying to accomplish one positive step every day no matter how little. The beauty of the project is I am the boss and take a day away anytime.

mwvachon · « **Reply #31 on:** January 17, 2013, 05:58:14 PM »

Thanks guys. I had a long talk with my machinist and he had similar sentiments. The patch on the original motor was a mess. The crankshaft pins from crankshaft in that engine measured in really well, so that was a small plus. I started tearing down the other K1 salvage motor, which appears (from the outside anyway) to have a bit better patch job. There is a fabricator located right around the corner from the local machine shop that was recommended to me. Plan now is to finish tearing down this other K1 engine, have the machine shop do a quick measurement on the bearing seats to make sure the cases are usable, then have the fab shop guy see if he can fix the cases properly. Trying to feel optimistic here... The best part is I'll be able to cherry-pick from the three assemblies any of the components I think are best.

iron_worker · « **Reply #32 on:** January 17, 2013, 06:13:20 PM »

The key will be in cleaning the cases very well before welding. Preheating and holding the preheat for a while may help to bake out any oil left in the porosity of the cast aluminum as well. For dirty cast aluminum you'll need a TIG machine that has adjustable A/C balance so you can really crank up the cleaning affect to bring up any impurities. Using a copper back-plate to to hold in weld metal may be a useful tool as well.

Proper prep work is key.

IW

mwvachon · « **Reply #33 on:** January 26, 2013, 11:17:43 AM »

Still dead in the water. Met with both the machinist and the fabricator this AM.

Machinist says all the crankcase bearing seats measure at or within spec, but even this case has a bit of distortion on the #1 and #5 bearing seat. It's only in one spot and is around 0.01 for each - middles look good. Where this isn't exactly going to be a race bike, he thinks that it would be useable - far better than salvage engine #2. Not great news, but then not necessarily bad.

Fabricator was appalled by the existing patch. I then explained the one in the original engine was much worse. His diagnosis was to cut out all of the existing patch back to virgin metal and rebuild from there. Do-able, but pricey. To do both top and bottom case, he said it would be $250 minimum and probably more because he also has to rebuild the mating surfaces. He wondered if I'd have better luck just finding a motor for probably less than that.

The problem with sourcing yet another motor (even without a patch) is the bearing seats will be yet another crap shoot. I'm putting out calls to local scrap yards (anyone got any suggestions on N.E. bone-yards other than Cooper's?) and maybe I'll finally have a sliver of luck on this build. It's been a dismal affair thus far... $:-\$

Tews19 · « **Reply #34 on:** January 26, 2013, 04:30:55 PM »

There is an early k1 engine lower case on eBay right now for like 55 bucks plus 60 shipping.

mwvachon · « **Reply #35 on:** January 27, 2013, 04:58:11 AM »

Thanks Tews. From what I've read, cases are matched, so best to score a top & bottom from the same engine. I'm eyeing another K1 case set on eBay right now...

mwvachon · « **Reply #36 on:** January 28, 2013, 05:33:46 PM »

Still dead in the water. Prospective set of K1 cases listed on eBay turned out to be a bust. Spoke with the guy at the salvage yard and we went over them carefully while on the phone. Turns out, these are not matched cases - normal numbers look like a grease pencil marking, usually found just inside the clutch housing and is typically a letter and 1 or 2 numbers, something like J27, or M14, and is duplicated on both top and bottom half of case. Too bad, other than being painted black (and poorly done), they looked to be perfect. Chasing a number of other leads...

thrutheframe · « **Reply #37 on:** January 29, 2013, 08:12:29 AM »

Way to hang in there. I feel your pain, it's always that one peice that holds up the whole project. Unfortuantely for you it was the engine cases.

Thanks for the great work on the parts fiches.

Scott

mwvachon · « **Reply #38 on:** January 29, 2013, 05:56:02 PM »

Dare I hope? Just scored a set of low serial # (confirmed matched) set of cases... It's gonna be a loooooong 7-10 days waiting for this package!

mwvachon · « **Reply #39 on:** February 02, 2013, 06:00:37 AM »

Lets hear it for crazy-fast shipping! Cases are here! Initial inspection looks good. Now to run these over to the machine shop for the final 'blessing'. Hopefully I can get going again with these...

brandEn · « **Reply #40 on:** February 02, 2013, 08:34:09 AM »

This looks like it going to be a great project, good luck with those new cases!

Tews19 · « **Reply #41 on:** February 02, 2013, 08:35:13 AM »

Congrats! How low of a vin? If that falls through, pm stev-o. I think he may have a few k1 cases.

mwvachon · « **Reply #42 on:** February 02, 2013, 05:22:10 PM »

OK - This just keeps getting weirder all the time. I'm not 100% sure, but think I may have scored a set of sand-cast cases. In cleaning these up and prepping for the machine shop I noted a number of things. First is the serial # 1007826. Most of the documentation I've seen puts the highest sand cast # at 1007500 - which is a good reason to doubt that these are... EXCEPT - Look at the serial # base, the rough castings (part of where the term 'sand-cast' actually came from), and the way the serial # was stamped (number is a bit uneven). The good news is that these are in excellent condition - all bosses and threaded holes in great shape, nothing broken, just a few minor abrasion marks around the lower engine mounts (case was probably dragged across a floor at one point). Cases are at the machine shop, awaiting Master Kevin's blessing... Threw in some close up shots and a snap of me executing the infamous double-nut method for removing cylinder studs... (Note the MAP torch in the background - sometimes heat is your friend ;-) )

kmb69 · « **Reply #43 on:** February 02, 2013, 06:01:36 PM »

Definitely diecast cases. 10 hole clutch cover pattern and diecast oil pan pattern. Appears someone milled the original engine number pad off and restamped them. Doesn't appear to be the Honda stamp font. Very useable and no big deal if they are solid cases.

mwvachon · « **Reply #44 on:** February 04, 2013, 04:03:52 PM »

A bit more info. According to one restorer, these are definitely NOT sand-cast cases, but they are cases Honda provided to dealers who were doing warranty work for the broken chain/cases problem. The serial # area was left blank on these cases and the repair shop was responsible for punching the required serial number into the top case. With these, it looks like they weren't all that fussy with the stamping and 'Doug' couldn't resist putting his own mark on 'em. If the engine # is anywhere near correct (to the one it replaced originally), this means that this engine was in a mid-to-late K0 model. As it stands right now, if they pass muster with the machine shop, I will clean them up and refinish them to look like new. I still have leads on at least two other engines as well, so this part isn't quite over yet... 'Patience, gotta have patience...'

David B · « **Reply #45 on:** February 11, 2013, 09:15:36 AM »

Glad to see it's finally moving forward again.

mwvachon · « **Reply #46 on:** February 24, 2013, 05:13:58 AM »

Still sitting in engine limbo-land. The latest set of cases are still at the machine shop. An initial measure of the crank bearing bores showed some weird measurements (in by a thousandths at 10 O'Clock, out by a thousandths at 2 O'clock, etc.) I've been patient with the machinist because he hasn't charged me for checking the last 3 cases, but I did tell him yesterday that I needed to get going on this and wanted to know if I needed to seek out another engine at this point. He said that he thought the seats looked very good in general and wanted to split the cases again to see what might be causing the strange readings he's seeing.
In the mean time, I've ordered/received new primary chains and new cam chain. Going to go ahead and order the rollers and rings while I'm waiting. At some point there WILL be an engine!

mwvachon · « **Reply #47 on:** March 10, 2013, 07:10:14 PM »

Finally back at it! Got the cases back Friday morning (after a month-long delay at the machine shop). Strange measurements from the machinist be damned! I did a bunch of surface prep - these castings were rougher than most I've seen (perhaps because they were warranty replacements?) I knocked down a lot of the casting irregularities and cleaned up a lot of the flash and parting lines before giving them a final sanding. Next was 2 coats of high-temp primer and two coats of the 1615 Aluminum silver. Finished off with a 200F degree bake for a couple hours. I then pulled out the crank that was 'blessed by the machine shop and proceeded to Plastigage all of the crank and connecting rod bearings. Everything was under .002 and most were probably .0018 or so. I can live with that. Going to put together a little cradle for holding the upside-down top case to allow the connecting rods and cam chain to hang down while I complete the lower-end assembly. Will probably doing some of that during this coming week.

mwvachon · « **Reply #48 on:** March 17, 2013, 06:05:09 AM »

OK, some more progress... if only incrementally...
I began 'dry' fitting the internals for the lower engine cases. The good news here is I now have three complete engine assemblies to pick and choose parts from! I noted that some bearings were decidedly more worn than others, and I'm making sure ALL of the bearings I use show no signs of wear. I also found that one engine had a pristine primary chain tension roller - yet another thing I don't have to buy! I haven't installed the new primary or cam chains just yet, I'm thinking those will drop right in without an issue. A few things I did note however:
- Complete gasket sets aren't always... well... er... complete! I ended up having to order a handful of 'O' rings (see attached image).
- My cases pre-date some running changes in the K0-K1 motors. Specifically, the K1 uses a full 360 deg clip to secure the outer bearing on the final drive shaft. My cases are not 'cut' for this. Instead, Honda used the same one-side bearing stay for both bearing on this shaft. None of my K1 and newer engines had the required bearings. I ended up ordering the outer bearing, but discovered that there is an identical bearing on the clutch shaft that matches the other required bearing for the final drive shaft. Now if I can just persuade this bearing off of that shaft (seems to be pressed fit!)
- I popped out the access disc in the lower case so I could better examine the transmission assembly once I do bolt up the two case halves. I can't seem to find a listing for the 'O' ring that goes on this!
Hopefully once I have the above issues addressed, I can do a 'test' assembly and then apply assembly lube to all the proper places, put the HondaBond on the mating surfaces and close this sucker up!

edhaeuser · « **Reply #49 on:** March 17, 2013, 12:04:26 PM »

Wow, that had to be a frustrating wait on the cases. I'm expecting to see plenty of updates now :-)

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Author Topic: My CB755 Project - COMPLETED!!!! (Read 34506 times)