Topic: Gentleman's Express 550 engine build

[RAFster122s]

Could you machine the case halves and convert to roller bearings? Get rid of the ABBA bearing halves.

Likely doable......however, would require a new custom 'built-up' crank, along with all the specialized machining.  big,big $'s required!   The cost would make an APE crank with Carrillo's look very inexpensive.

There's a certain fellow who did the 750 top end for big bore cylinders I would imagine it would be a lot of CAD work to design a set of cases...and would they be billet or sandcast?     Or castings?

[HondaMan]

OK...those of you suffering from global warming...would you PLEASE send a little of it here, so I can work in the garage again?
 

[HondaMan]

OK, got back into the garage a little today!
 
First thing: modify the pistons (or, get them ready for the machine shop to modify) on the crowns. I made a paperdoll of the 500 piston crown, then traced that to the tops of the 750 pistons. It needs to be cut down 1.2mm (I'll probably go 1.5mm) to match the 500 height. The height is determined by inserting one piston pin into both types of pistons, and measuring the height difference to the 750 crown. Then I scribed it all around for the machine shop guys to cut it back for me.

[HondaMan]

Here's the heigh measurement pix...

[HondaMan]

Oh - and I weighed the 2 different pistons: the 500 piston weighs 4.5 oz., the 750 piston 6.1 oz. on my wife's bread-making scale.
 

[HondaMan]

I'm still trying to worry away the crank weights from the bottoms of the pistons, but I'm getting weightlifter arms from trying(!). My right arm hurts, too, from using someone's [short] tactical shotgun at a skeet-shooting contest 2 days ago - dang gun stock is so short that it ends up clobbering my arm instead of letting it be shouldered while sighting the bird!

I may have to take the crank to the shop for skimming these weights? So far I have only gained 0.5mm on the #3 piston bottom, which is the worst one in this bunch. The crank weights are all over the place with their shapes, which makes it tough!

 

[HondaMan]

Last step for tonight: the primary shaft is really stuck in this engine! It's probably rusty inside, like all the other parts have been, from sitting with wetted oil for 35+ years. I can't get the crank out! Gotta go make a puller, I guess?

[754]

Why not cut that 1.2 mm off the pistons in your lathe  ? Fairly easy to make a fixture.

[Stev-o]

Mark - will the stock 550 rods be used?

Thanks for posting this thread, there are many of us interested in doing this, ncludong me.
Already have a 650 cam on the shelf!

[Trad]

Glad to see you're back in action on this one! Happy New Year!

[scottly]

I'm still trying to worry away the crank weights from the bottoms of the pistons, but I'm getting weightlifter arms from trying(!).

I may have to take the crank to the shop for skimming these weights? So far I have only gained 0.5mm on the #3 piston bottom, which is the worst one in this bunch. The crank weights are all over the place with their shapes, which makes it tough!

 

Well, you're going to have to take the crank to the shop for re-balancing anyway, so you might as well have them do the heavy cutting and save the wear and tear on your body.

[HondaMan]

OK, I got a little collar and a 12x55x1.25mm thread bolt at Ace and made an adapter to fit my genuine Harbor Freight (free to me!) dent puller. Then I threaded it into the primary shaft and [gently] tapped it out. The oil in the spline inside the primary drive clutch assembly was "wet" and it slightly rusted those splines inside there, made it stick a little bit. Got all the other parts stripped from the bottom case to go into the other [bottom] case, still have to do the upper case, dowels, drains, caps, plugs...bearings.

The new crankcase has all "B" size crank holes where the old one was all "A" size, might or might not be a show stopper for parts, will check tomorrow. Sometimes the ID of the cases were borderline and if that's the situation, will install the "old" ones in the "new" crankcases, because they only have 2000 miles on them(!). It all depends on the crank journal actual sizes, will see tomorrow.

[HondaMan]

I also went ahead and clearanced the crank weights (huff, puff...) for all the pistons. The tightest one is #3, with just 1mm between the top of the flyweight and the reinforcement rib of the piston. Since this engine won't be compressing the rods with nitro and 12000 RPM runs all the time, I think that will be enough. I'll check with Axle and the other engine builders around here to see what they like for their minimum, but most of those guys are building engines with 3" and 4" pistons (V-Twins, etc.). Honda has like 5mm in the stock engines, so they didn't have to worry about it...

[HondaMan]

Mark - will the stock 550 rods be used?

Thanks for posting this thread, there are many of us interested in doing this, ncludong me.
Already have a 650 cam on the shelf!

Yep, they will. Except, I had to obtain a new (well, different used) set, as the originals in this engine had rust in the small ends which tore up both the wristpins and the ID of the rods, all 4. Very sad! They only have 2000 miles on them. The bottom-end bearings don't even look like they have seated yet. If I'd had the $$ available, I might have considered bushing the ends, although I don't have a local shop I trust enough to do these to 0.0002"-0.0005" tolerances: they all want to do .0010"-.0015" instead. Not for MY engines...and, another set of rods came to about $40, not bad!

The Fours (all the SOHC4) are seriously overbuilt, as Honda was very scared of their new flagships producing 'loss of face' in the world marketplace. This is one of the biggest reasons why others like Kawi and Suzy were able to challenge them so quickly with Fours of their own designs, as those other "brand X" engines are more cheaply built (to be blunt about it), with materials and parts pared to their minimums, and expectations for engine life being cut way back. As the result, you don't see hardly ANY old Suzuki DOHC4 bikes today, even their shaftie versions (which weren't bad bikes!) and, despite their enormous popularity with riders and Police, you don't see very many Kawis (Z1 or KZ Fours), either. My little bit of experience with Suzy Fours being built was limited to big-bore 10:1 pistons in the GS750 chain-drive bike, and in 5000 miles it munched the primary drive (which had then 12000 miles on it). It's things like this that make the bikes we still play with practical!

[Stev-o]

...despite their enormous popularity with riders and Police, you don't see very many Kawis (Z1 or KZ Fours)

Plz keep in mind that there were only approx 85,000 Z1's manufactured over a 3 year period compared to approx 600,000 CB750 SOHC's in 10 years.

But you are correct, the Kaw's were not known for there long engine life and many needed a top end rebuild after 25K miles. But...they sure are fast!

[HondaMan]

But...they sure are fast!

Roger THAT!
I have a friend here in Denver who collects them. He has one for each year they were KZ1000, and 2 of the LTD versions. I once designed a new fuel-injection thingie for one of those, about 12 years ago. The LTD didn't seem to be able to run with the KZ bikes, though.

Around this part of the country, the Police are still using the KZ1000 Police versions. They are traffic interceptors for their radar speed traps, quick and maneuverable.

[HondaMan]

OK, got the pistons into the hands of my machinist!
The crank will not have to be [re]balanced. I didn't think so: they build mostly racing engines where I have my work done and could balance it if needed, but it is not. Reason: since the mass of the crankweights is FAR in excess of the mass of these pistons, and since it is an inline engine that will not develop lateral harmonics (like V engines do) because they are already oppositely balanced laterally by 2 pistons at 180 degrees of rotation, no matter which set is at TDC. That's pretty much what I thought, based on machines that we build at work (many are cam-operated devices, with big masses), on which we swap out tooling weighing many pounds, but never have to change the dynamic weights. We actually balance the cams WITHOUT those weights.

[scottly]

OK, got the pistons into the hands of my machinist!
The crank will not have to be [re]balanced. I didn't think so: they build mostly racing engines where I have my work done and could balance it if needed, but it is not. Reason: since the mass of the crankweights is FAR in excess of the mass of these pistons, and since it is an inline engine that will not develop lateral harmonics (like V engines do) because they are already oppositely balanced laterally by 2 pistons at 180 degrees of rotation, no matter which set is at TDC.

That is correct as far as the pistons and rods are concerned, but you have removed material from the crank counterweights, which affects the factory balance of the crank. A couple of grams at a 3.5" radius is a LOT of inertia at 10,000 RPM.  

[HondaMan]

OK, got the pistons into the hands of my machinist!
The crank will not have to be [re]balanced. I didn't think so: they build mostly racing engines where I have my work done and could balance it if needed, but it is not. Reason: since the mass of the crankweights is FAR in excess of the mass of these pistons, and since it is an inline engine that will not develop lateral harmonics (like V engines do) because they are already oppositely balanced laterally by 2 pistons at 180 degrees of rotation, no matter which set is at TDC.

That is correct as far as the pistons and rods are concerned, but you have removed material from the crank counterweights, which affects the factory balance of the crank. A couple of grams at a 3.5" radius is a LOT of inertia at 10,000 RPM.  

In this case I doubt that I even removed 1 gram from all 8 weights combined. It wasn't even enough "file powder" to sweep into a pile: I picked it all up at the end by licking my fingers and dragging them along the floor to "sweep" it up. The main problem was flash from the mold edges for the weights: it was thin and just tall enough to touch the bottoms of 2 pistons of the 4. After I figured out how to file off the first one, the other 3 took 5 minutes to do (all 3), so it isn't much in weight. When I got done, I Scotchbrite-d the whole area to make it look nice and remove some of the surface rust the weights have from years of sitting in wet oil. I think more weight came off from the rust than from the filing! It completely clogged the Scotchbrite pad.

[flatlander]

I picked it all up at the end by licking my fingers and dragging them along the floor to "sweep" it up.

how did it taste? 

[HondaMan]

I picked it all up at the end by licking my fingers and dragging them along the floor to "sweep" it up.

how did it taste? 

Kinda gritty, and it made my fillings light up! 

[HondaMan]

OK, got the bottom end back together, now on to the top.
...after I get back from yet another business trip the next couple of days. 

The "all up" pic is a mockup, showing the paint scheme at this point. I'm probably going to polish the head's upper fin area. The non-black head will keep the cylinder temps down a bit, which will help with the high compression and thin cylinder walls. The rest of it is 'pinstriped' at this point.

[Camrector]

Hubba Hubba!

[hsas.69]

Looks great Mark! What kind of temperature difference do think you will you see with the non black head?

Sent from my SM-N900P using Tapatalk

[flatlander]

The "all up" pic is a mockup, showing the paint scheme at this point. I'm probably going to polish the head's upper fin area.

that looks nice together with a polished rocker cover. did the same on mine.