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

[RAFster122s]

Congratulations on getting the cases to separate.

[HondaMan]

What a job!!
The fin repair is amazing, I didn't know that was possible.
Following with great interest.

Yeah, this guy is amazing!

Good project and amazing cylinder repair, HM.  Curious why your not having all the fin damage repaired?

That was the owner's call: I think he's on a limited budget, and anticipating high costs.
I just pulled out and inspected the shifter drum: It has so little wear that I surmise the bike had REAL low miles on it before it was subjected to this big-bore build (and other unspeakable tortures). The 'Neutral bump" on the pre-[late]K3 shift drums always shows wear that is a reliable 'marker' for the bottom ends: this one looks nearly unused.

The primary chain roller, now kinda stiff from gunk inside its bearing, looks like it has about 1000 miles on it, barely shows any chain marks at all. I'm going to hand-polish the crank bearings as they are all stained, but I don't think they are harmed from the  rust. That's often the case: I often find these cranks to be real durable unless someone used too light oils and seldom changed it.

[MauiK3]

Wow, this is really a tough one, I'm watching with great interest.
Curious how the retainer was missing, why would anyone do that?
Terrible
The final product will be a triumph.

[CycleRanger]

Wow, this is really a tough one, I'm watching with great interest.
Curious how the retainer was missing, why would anyone do that?
Terrible
The final product will be a triumph.

No, it will be a Honda. 

[MauiK3]

😀😀

[MRieck]

Those aren't sandcast exhaust valve guides. What's up with that??

[HondaMan]

Those aren't sandcast exhaust valve guides. What's up with that??

It looked like they were changed before it got 'parked', and incorrectly sized to boot. One of the exhaust-side guides had too much clearance in it, the valve wiggle was over 0.008" already.
The intake guides had rust in all but one, interestingly enough that one was right on-spec.
All the guides had been replaced already, which makes me wonder what happened to it? The original Stellite guides were known to reach well into the 80K mile range, even with poor oil maintenance. In my own 750 they went to 135k+ miles and were just approaching the wear limits, none were over it yet.

[HondaMan]

Also....it makes no sense to me to repair the cylinder and not the head. I just...and will not....keep my mouth shut. I've done this stuff!!!

Well, me too, sometimes. But, it's also not my wallet!

[MRieck]

 Modified Yamiya guides are the answer....I stock them now. Much better than then the Cycle X Kibblewhite pieces......I have them here....they will take any lift and are so much better. The Cyclex pieces aren't as good......soft compared to the Japanese parts.

[Don R]

 I'm sitting on an early sandcast head, it also has had new guides installed. One had a stuck valve in it, so I replaced it. I was going to find it a home but it's way better than the thread challenged head I was going to use on my no number diecast motor so I think it can live there.

[HondaMan]

I'm sitting on an early sandcast head,...

Ow!

[BenelliSEI]

Another oil filter canister question:

This motor still had the smooth canister fitted? Does the canister have a tab cast on the outer edge to lock in the two tabs on the case? Does the engine case have the two tabs? Despite being a very early case, mine has the two tabs, suggesting Honda planned the finned and keyed oil filter housing, just didn’t quite get it done before production started? Thanks, J.

[HondaMan]

Another oil filter canister question:

This motor still had the smooth canister fitted? Does the canister have a tab cast on the outer edge to lock in the two tabs on the case? Does the engine case have the two tabs? Despite being a very early case, mine has the two tabs, suggesting Honda planned the finned and keyed oil filter housing, just didn’t quite get it done before production started? Thanks, J.

It does have those 2 tabs. The smooth housing doesn't.
It would seem Honda did have that in mind then?

[BenelliSEI]

Another oil filter canister question:

This motor still had the smooth canister fitted? Does the canister have a tab cast on the outer edge to lock in the two tabs on the case? Does the engine case have the two tabs? Despite being a very early case, mine has the two tabs, suggesting Honda planned the finned and keyed oil filter housing, just didn’t quite get it done before production started? Thanks, J.

It does have those 2 tabs. The smooth housing doesn't.
It would seem Honda did have that in mind then?

Thanks for this info! I have to guess that was the original design and the smooth “cans” were an interim solution. Another interesting piece of history......

[MauiK3]

They must have been scrambling to get the design and production stuff in lock step

[BenelliSEI]

They must have been scrambling to get the design and production stuff in lock step

I suspect you are correct!

[HondaMan]

I have no doubt of that! Their "K" (Kaizen) step-change system was more than a decade old by then, used on previous bikes. Honda didn't make a lot of the engine parts themselves: for example, the cam chain tensioner housings were made by several other companies, the last ones by TEC (Tokyo Electric Corp) and proudly labeled as so. I have a pristine example of that part from a K7. Hitachi, Nippon Denso, Sankyo and TEC all made the SOHC4 alternators at one time or another, and many of the 750 parts I have bought over the years that were not from Honda (like PartsNmore) were Mitsubishi pieces.

Honda did make rings, heads, cylinder castings and some of their bottom-end parts for the 750 at first, but used trans components, oil pumps, chains and pistons made for them by other vendors who did that sort of thing, to Honda's specs. The industrial espionage in Japan back then was incredible, too, but not really against their laws.

By the end of the SOHC4 series, though, Honda was mostly an assembly company, and a monster-sized one of which many smaller operations wanted to be a part. Some of the people involved spun off into their own companies, like CruisinImage's founder (the present owner's grandfather) of Thailand and M/C Rings. I've also heard (not verified, though) that the RIK ring maker's head today is a grandson of one of the piston ring designers at Honda when the CB450 twin was king. I sometimes wonder if that's why they still offer the 1-piece oil ring sets that I use in the pre-K2 (3/72) 750: they are identical to the Honda parts in every measure I've used, and act the same. (Yes, they are heavier and can flutter above 8k RPM to make smoke, but they outlast the 3-piece rings by 2x or more.)

[HondaMan]

While I thought the wristpins were the pressed-in type...nope! 
They were the rusted-in type. 
Here's just some pix of how I had to remove the clips. The wristpins were the tapered-end type, but were also a mite too long, so the builder had to stake the circlips into place. Instead, he should have flat-ground off the ends of the wristpins, but maybe they weren't intended for this set of pistons? Hard to tell at this point.

So, to remove the circlips, they had to be cut out in little pieces, as they were both staked in and rusted tightly against the ends of the wristpins. Nasty stuff...

[grcamna2]

Those pistons look like they were quality(Yosh)made back then  Would be nice to find another set of them as good a quality as them today.

[HondaMan]

...then there is the [sad] story about the oil leak under the engine, and the troubles he surely had with the shifting of the tranny!
As was common with the sandcasts and K0 bikes, the O-ring around the Neutral Switch (or rather, the hole in the case FOR the O-ring) was a tiny bit too big, so most of them leaked. The switches often got changed, suspecting they were the leaker, and this one looks like that happened, too.
But...the wrong O-ring was used to install the switch afterward, so the Neutral Detent feeling was all but gone in this one, probably leading to Neutral being near impossible to find when the engine was running. This points to the wear on the clutch plates and why they were changed already on such a low-mileage engine: mis-disagnosis of the trouble.

In the post-K0 engines the hole in the case around the Neutral Switch shrank a bit, making the 18x3 O-ring hard to stuff in, but that worked to seal the hole better, since it sits underneath hot oil all the time and can use all the help it can get. If you [get to/have to] work on one of these early engines and the bottom around the Neutral Switch is REAL greasy while the Switch and O-ring slide in easily, consider using a 3.1x18 or 3.2x18 O-ring in the hole to dry it up: this was what Honda supplied as their "fix it" part (aka "Delta" part) for years - but which is REAL hard to install.

The 3.2mm thickness version was #91311-044-000 (now superceded to the 3.0mm part if you buy one) while the 3.0mm part is 91307-035-000.

[Don R]

 The industrial espionage in Japan back then was incredible, too, but not really against their laws.
 My brother was in Japan in 59/60 or so and said he was surprised by the Japanese made clone bikes. Lilacs that looked like little Beemers, Harleys that said Kawasaki on them, etc.

[BenelliSEI]

Phew! Those wrists pin clips look brutal! Will you be able to reuse the rods?

[HondaMan]

Phew! Those wrists pin clips look brutal! Will you be able to reuse the rods?

Yep, the rods were well-oiled at their pins, so the piston's death grip on the too-long wristpins was the only real trouble. Once I got the pieces of circlips out of the staked-down grooves and drove the pins out of the corroded piston holes, the rods cleaned right up. I've been musing on where I saw this staked-in circlip thing before and I remembered: it was on the 16k RPM CB750 midget-car engine in IL. There was a club of midget-car racers there, some which had hacked off the trannies of several 750 engines (one also had a similar Kawi Blue Streak triple he'd made that way, and was building a 750 version when I left there) to compete with the typical Offenhauser engines the other club members had. Two (or it might have been 3) of the 750 guys were running 12k-14k RPM, but this one guy had a REAL trick spark advancer he had made that would retard the spark mechanically at about 14.5K RPM a couple of degrees, which then let it "rip" up to 16K on the straightaways, then advancing another 6 (my guess) degrees after it passed 'the wall' at 14k RPM that everyone else talked about. He had the cylinders off at the time and I noticed the punch marks around the wristpin holes: one of the other shop guys asked him if he ever planned to remove the pistons, but he just smiled.

[BenelliSEI]

Years ago, I rode down to a VJMC meet in Gettysburg. On a quiet afternoon we visited a SPRINT car Museum in the area. Amazing place, with literally 100’s of oval track cars. They had one of those Honda Powered Midgets on display. It took me a few seconds to even recognize what I was looking at! It had a the transmission hacked off, just as you described.

There was another one that was BMW powered and FWD. Fantastic place, we actually went back a second time, too bad I had no camera!

[newday777]

Dang! 16K RPM...... that would be something to get out of these motors.
I thought the valves floated after 10.5K with the Action Fours cam and springs I had in my 76 811 back in the day. Maybe it was the points floating?