Topic: Sandcast Engine #1770 rebuild - it made it!

[1080]

Looks Great 

  Hondaman  can you give more details on the method your welder uses when fixing the fins on the cb750. Boy, a video him welding a 750 head, barrels, or cases would be a excellent thing to see.

[1080]

Will your aluminum welder build those fins back out ? Tig welding ? That's a 'skill'.

[HondaMan]

I don't think anyone has watched him? He said he just "builds them up" as he goes, and uses an air die grinder with a flat sander disc to make them tapered and to the same thickness as the others.

[MauiK3]

Sounds like a patient welder!

[HondaMan]

Sounds like a patient welder!

No kidding!
Once when I was picking up a part from him, someone (a semi-reputable local used-car dealer we know) dropped off a car transmission with about 12 square inches of bell housing broken out of it. The guy told the welder, "I know you can JUST BUILD THAT BACK UP..." which I thought was pretty brassy, since there was obviously a missing bolt bolster somewhere in the 8"-wide broken-out section of the bell housing. When the welder asked for the broken-out piece, the response was that it was in a 'hundred pieces', given that his mechanic had forgotten to remove one last bolt before 'dropping' the transmission. Well, sir, I watched that transmission grow a new bell shell, slowly over the next 4 weeks, without a bolt boss: when I asked the welder how much he was going to charge the used-car dealer for the work he just said, "enough that next time he can use the same $$ to buy another transmission instead".

I think that was a weld bead too far?

[MauiK3]

Wow, quite a story.
Amazing what some clueless folks will do.
That welder is a treasure.

[HondaMan]

I've almost finished a recalcitrant K2 engine that has soaked up most of my time lately, then will be determining the new crankshaft bearings for this one next.

[HondaMan]

Now I could use some help, if someone out there might have a starter clutch set from a dead crank?
The moisture etching is so deep in the starter clutch's grip face that it will destroy any new rollers.
Not that the rest of it is in great shape: the mixed red dust and moisture has wiped out the springs and rollers (probably the little followers, too) inside their cubbyholes. They still move, but their surfaces are too pitted to be useful.

Does anyone happen to have a dead crankshaft that could lose its starter gear-and-clutch housing? I have some new roller-and-spring sets for it, if yours are pooched.

[grcamna2]

Wow 

From here.. the rollers still look ok?

[newday777]

Hey Mark
I might have both.
I just looked at the CMS fiche for the K0-K8 for compatibility with the K0 and all are the same numbers.
I will check their condition after church this afternoon.
There is a NOS starter clutch available at Honda Restoration here in NH if you'd rather get a new one.

https://www.hondarestoration.com/photodetail.asp?hrPart=28120-300-000

BTW
I got your package when I got back home yesterday from spending the week with my mom while my sis was away camping with family. Everything looks great. How much was shipping and the parts?(did I get an email/pm on those costs and shipping??)

[RAFster122s]

Dang Mark, that's some pretty ugly photos of the damage... Amazing how bad the little rust monster can wreck things. It is amazing how much damage can happen inside a motor.  Especially when it has not been flooded.

[MauiK3]

I wonder if chrome plating would work
Hope you get the parts, looks bad.
It's a shame what happens to these noble engines.

[HondaMan]

I'll tear down the starter clutch today to see how it looks inside: Stu suggested the Evaporust for that, it might work?
I'd like to try to keep the original parts as much as possible, for cost reasons mostly, but this poor starter gear isn't going to make the cut. The bumps and grooves will quickly damage new starter clutch rollers, so it would become a 'kickstart or replace rollers [again]' engine, don't want that.

I'm thinking there might be an old spun crankshaft in the pile(s) in the shed, now that the flooding here has receded and I don't need rubber boots to step in there. Chances are it will be sitting rotor-down, which is about 3" tall, and I had 2" of water where those parts are stored ("piled" is a better description?) so maybe the clutch survived.

[HondaMan]

I got the crank/rod bearings figured. The sandcast engines don't have the [in]famous journal size marks on them, so you have to measure every journal and every hole with the cases bolts together (middle one is hard to do), and the rods too, similarly. Honda showed the case holes as "AAABB", but they measured out to be "ABBBB". I've noticed similar discrepancies in other engines, too, when measuring everything from scratch: such is the life of the machinists who have differing tools. The crank got all BLACK bearings, yielding 0.0012"-0.0015" final fit-up per Plastigage (screw the discrepancies, Plastigage rules!), and the rods had all 4 the same crank journal size, but oval like most have become, by 0.0002" or so. They all got BROWN bearings to give 0.0014" load-side and 0.0012" wide-side clearances. That should last a long, long time.

[BenelliSEI]

Curious how you measure the centre journal? I have a set of “T” shaped snap gauges that I set, then measure. Not great.

[MauiK3]

Snap gauges are fairly good but fiddly to use, up close. The center of the crank case would be tough.
Plastigage rules, does not lie.

[HondaMan]

Curious how you measure the centre journal? I have a set of “T” shaped snap gauges that I set them measure. Not great.

I used bore gages, and YEAH, that center one is a bi#ch to get! I finally did it in what the machinists I worked with called the "cheater's way", where I held the compressed bore gage in place with [rubber-wrapped] pliers with one hand, releasing the twistgrip using some fuel hose on it to 'extend' the handle out past the alternator side. This made it really hard to snug it back down enough to hold the measurement, so it took about 8-9 times, then I picked the number that was closest to the other 4 holes.

In the end, the Plastigage confirmed I was pretty close: I was still off by about 0.0003" on my measured number for it. I can live with that.

[BenelliSEI]

Curious how you measure the centre journal? I have a set of “T” shaped snap gauges that I set them measure. Not great.

I used bore gages, and YEAH, that center one is a bi#ch to get! I finally did it in what the machinists I worked with called the "cheater's way", where I held the compressed bore gage in place with [rubber-wrapped] pliers with one hand, releasing the twistgrip using some fuel hose on it to 'extend' the handle out past the alternator side. This made it really hard to snug it back down enough to hold the measurement, so it took about 8-9 times, then I picked the number that was closest to the other 4 holes.

In the end, the Plastigage confirmed I was pretty close: I was still off by about 0.0003" on my measured number for it. I can live with that.

That’s a picture. Sounds like a circus act!

[MauiK3]

That takes patience!!

[MRieck]

Do you still need that starter clutch gear?

[newday777]

Do you still need that starter clutch gear?

He should have gotten the one from me yesterday

[HondaMan]

Do you still need that starter clutch gear?

Nope, but thanks for remembering! Stu sent me one.

[BenelliSEI]

Do you still need that starter clutch gear?

Nope, but thanks for remembering! Stu sent me one.

Curious what you decided for a head gasket?

[HondaMan]

Do you still need that starter clutch gear?

Nope, but thanks for remembering! Stu sent me one.

Curious what you decided for a head gasket?

I'm still looking for an old part number for the non-holey one. CMSNL suggests that if they have that number, their [unique] sub-to/sub-to-superceded-by/superceded-by system might be able to find one, or at least if one can be determined to exist. My oldest K0 parts listing has the K0 diecast head gasket number on it, which ends in -020 (already), suggesting Honda was already on Vendor#2 for these gasket by the beginning of the diecast engines.

Normally, Honda would start with -001 for the original last 3-digits of any given part number, and up until the [in]famous 2007 rearrangement of their parts numbering system this number would increment to the next "010" value for a new vendor of the same part Most of the actual production parts started with -003 endings, suggesting some reworking of many of them before actual builds began. One example of this is the oddball 6x32mm crosspoint screw used by the shifter on the 750 cases: it was a 6x35mm, ending number -001 in the earliest fiche I remember, with -003 happening in the first K-model parts lists when it became 6x32mm so it would not stick out inside the sprocket area. The sandcast engines often have 6x35 screws there, with their tips sticking thru the engine boss by a few mm.

So, until I can figure out the original, actual, no-hole gasket number, I'm not sure how to help them proceed?

Arcane as this may sound: when I was in NASA training to be an engineer on Apollo 18 (which LBJ cancelled, grrr...) we were required to memorize all part numbers used on any [electronic] design(s) we did, in case of urgent need of the information in situations like that of Apollo 13: there was no quick-retrieval system by computers in those days, so if you were going to get a 'call' on some subsystem in the middle of the night, you'd have to spew out the particulars from memory. So for a long time, I used to memorize this stuff for habit-training (and OCD-ish tendencies), and some of those pieces of trash still show up in the sewer-pot that is my present brain, 60+ years later.

[BenelliSEI]

Mark….. amazing story, must have been a fascinating time! I went through all my old head gaskets and found one (made in the USA, “Best Gasket”, no less) that lined up with all the holes perfectly and had really nice crimped copper rings around each bore hole. I think there’s a photo of it in my project thread. It fit so well, I snipped off the tab from the extra hole and used it. Fingers crossed!