1974 Honda CL360 barn find

[Untame]

I've heard of lost PLA casting but I've always wondered why people bother when there are filaments available that are made specifically for sand casting? Sure PLA is dirt cheap but if you're putting the time into designing the part to begin with, is $50 for filament really a big deal? For example:

https://machinablewax.com/wax-filament/

I've considered casting parts for a few vintage Ducatis but so far haven't taken the plunge. Mostly because I don't have the resources to do the actual casting, but the number of possible projects that could use it are growing. There is a makerspace type of place around here that could probably help but dag nab the membership is expensive. Those costs would go a long way towards buying the equipment needed to do it myself.

For now my 3D printed stuff has been limited to ASA and some PETG parts, but casting aluminum was one of the reasons I got a 3D printer to begin with. I really should get more serious about it. Especially since there's this tail light I've been working on that would be so much cooler cast than printed/painted...

In other news, as a retired development engineer (automotive exhaust mainly) I applaud your enthusiasm on the bikes you're working on, but as someone who's been riding for 30+ years I've been biting my tongue when I read your threads. Don't get too hung up on the theoretical part of what's "ideal". The details that make that intake runner ideal at 8650rpm will hurt it at 5800rpm or where ever. In your other thread, those angles you've calculated so precisely will change as soon as you sit on the bike or hit the brakes. I get the interest in it, and do not mean any of this as any type of flame, but keep the big picture in mind as you do all of this. Yeah you need a starting point so why not try to make it good, but the reality is a heck of a lot of engineering decisions in vehicle development are based on making it fit the space or using readily available parts, and the end result is perfectly fine for bikes that don't get judged by lap times in the hands of alien riders.

I know it's a cliche, but the idea of not letting perfect get in the way of good enough is SO true... don't fall into the trap that some engineering "ideal" is the best answer and you're somehow taking a short cut if you don't use it. A bike out there being ridden with less than ideal intake runners is a lot more impressive/fun than the one that has all the ideal numbers in it's CAD model but hasn't been built yet because you haven't quite worked out the ideal shape of the velocity stack or where to source 34.7mm diameter tubing or whatever.

Again, I don't mean any of this as a flame. These threads are much more refreshing than the typical "I got this Japanese cruiser free because it sat at the bottm of a lake for 20 years, where can I buy the kit to make it into a cafe racer OH LOOK A SQUIRREL!" threads.

A huge thank you for this! Great advice all around. It is in my nature to always believe something can be better, but I do understand the danger of becoming "paralyzed by perfection." For me, I will likely get more satisfaction from the journey of creating this bike than from riding it when it is done. I almost expect to feel a let down (disappointment?) when it is finished. Then I will need to start another project (would love to build a replica 1927 bobtail model T racer with a Mercruiser 3.7 liter 4-cylinder with Ford 460 head, four Stromberg pots, and a powerglide tranny).

As long as I'm going to take the time (and expense) to design/configure something I want to get as close to ideal as possible (within my mental and financial ability). That is why I have threads here, and that is why I am transparent with my thinking process. More than anything I need to learn what I don't know from you guys -- those with a lot of experience. I'm a huge believer in soliciting advice from as many sources as possible.

I've been deep into calculating the best jetting for the DCOE40, and I've realized that the new Spanish Weber DCOE 40 comes pretty close out of the box (maybe a little rich). The Keihin's have 28 venturis, and the Weber is 30 stock, but if I bore it to 69mm and use GS850 pistons it might be just right. At least I can just bolt it on and see how it works. Before going crazy buying jetting kits and chokes.

 

[Untame]

Great advice on using wax filament for investment casting, but just want to point out that it's not always so cut and dry. In many cases, print nozzles need to be altered or swapped out, so a little bit of research is necessary to determine compatibility for your printer. Personally, I would go with PolyCast. It's more compatible across the spectrum.

I will look into this. Saw I could use PLA, and didn't really investigate to see if there is a more ideal material compatible with my printer (Prusa i3 Mk3s+).

 

[irk miller]

I will look into this. Saw I could use PLA, and didn't really investigate to see if there is a more ideal material compatible with my printer (Prusa i3 Mk3s+).

PLA is a bioplastic made from corn starch and sugar cane, so don't get too worked up over any chemical issues with PLA. It's not putting out toxic fumes. It actually does a really good job casting very fine detail. Personally, I use it myself, but the advantage of using something like PolyCast is the machinability.

 

[Maritime]

We use PLA a lot because it works and the printer is in the living room so we don't want odors. other filaments can be finicky but PLA is pretty easy to get right. It's not the best for some applications but works for a lot of what we print. My son has also invested in an epoxy printer and that thing can produce some pretty fine prints. It stinks so lives in the basement shop.

 

[Untame]

PLA is a bioplastic made from corn starch and sugar cane, so don't get too worked up over any chemical issues with PLA. It's not putting out toxic fumes. It actually does a really good job casting very fine detail. Personally, I use it myself, but the advantage of using something like PolyCast is the machinability.

Watched this last night. For my application I think PLA will be fine. Bigger challenge I have is infill in my print as well as sprue placement. Sounds like investment casting is a better option because the PLA can be burned out before the casting. Also need to think about designing it so that ash can be adequately evacuated out of the mold.

I am also looking into prototype services that print in metal. Might be more cost effective.

 

[irk miller]

We use PLA a lot because it works and the printer is in the living room so we don't want odors. other filaments can be finicky but PLA is pretty easy to get right. It's not the best for some applications but works for a lot of what we print. My son has also invested in an epoxy printer and that thing can produce some pretty fine prints. It stinks so lives in the basement shop.

We’re talking about for investment casting, not prototyping.

 

[Maritime]

We’re talking about for investment casting, not prototyping.

I got ya, I was just saying if PLA works for it, might be the easiest to get the sacrificial mold for casting as its very forgiving print wise vs. other stuff.

 

[Untame]

Been thinking a lot about the carbs lately. Trying to mentally solve what direction to go. I know I don't want the factory Keihins -- they are on Ebay already.

The DCOE40 would be incredibly sexy, but could end up being a pain ($$$) to dial in. Also, there is the matter of the custom intake manifolds. (Found a local foundry who would make them for about $500... so I would be in well over $1000 on carburetion... is sexy worth it? I could make a 3D printed manifold from black polycarbonate, but not sure about how well it would handle the vibrations and weight of the carb. It would be a gamble.)

I like the idea of a single carb because you know the cylinders would be balanced. Also, the alternating intake cycles would even out the flow through a larger carb. So I looked at printing a PC manifold to mount up a single Mikuni TM36-68, But it is a little bit of a guess how this carb would work feeding two cylinders. Maybe it isn't the right size? Also the intake runners would be much longer. Again, more risk that I might be chasing a solution that is difficult to dial in.

This has me favoring a Mikuni TM32 two-carb kit from Niche Cycle. At $500 it costs the same as the Weber (but includes cables and extra jets) and comes pre-configured for a modified 350/360. If I do a Megacycle cam and bore it to 378cc for Suzuki GS850 pistons this would probably be just right. I know that VMs look more period correct, but from what I've read the TMs are more forgiving and offer more consistent performance and immediate throttle response (on and off). Putting this kit on would only require a new set of rubber flange mounts and port matching the head.

Honda CB350/CL350/CB360 Mikuni TM32 32mm Flat Slide Carburetor Kit

Brand new carburetor kit consisting of genuine Mikuni flat slide 32mm carburetors, pre-jetted with proven specs utilizing genuine Mikuni components. This kit is intended for hot street, or vintage race applications. This is intended

www.nichecycle.com

 

[Untame]

I talked to Megacycle today. $500 for cam regrind. Ouch. On top of GS800 pistons and cylinder boring... over $1,000 in performance upgrades. Is it worth it for how I plan to use this cycle? Yeah, it would be cool to know I squeezed a bunch more out of it, but.... $$$.

I could just slap a set of TM28 carbs on it and call it good. Probably get a little performance bump out of that. Then money could be put toward other things.... or would I regret not "doing it right" and making the engine special?

 

[ridesolo]

I talked to Megacycle today. $500 for cam regrind. Ouch. On top of GS800 pistons and cylinder boring... over $1,000 in performance upgrades. Is it worth it for how I plan to use this cycle? Yeah, it would be cool to know I squeezed a bunch more out of it, but.... $$$.

I could just slap a set of TM28 carbs on it and call it good. Probably get a little performance bump out of that. Then money could be put toward other things.... or would I regret not "doing it right" and making the engine special?

Tough decisions for sure. I didn't go w/ different carbs on my CL378, though I did have @crazypj do his mods to the stockers. The first time the thing was started after doing the GS850 pistons I was shocked at how much deeper the sound of the engine was. It ran well and very strong. I'm not sure about a special cam and haven't heard much about cam work on a 360. I think that if you did the 378 and carbs you'd be happy and could always open it back up for a different cam later on. As others have said, don't forget the oil mod and get a set of CB350 "racing" clutch springs, not expensive and worth the trouble.

These old bikes aren't an investment just put in what ever you're comfortable with.

And I haven't seen anyone mention it here: Be careful when you take the left side cover off, the one over the drive sprocket. There is a ball bearing inside the clutch control mechanism that's easy to lose and you'll never get the clutch to work right w/o it!

 

[Untame]

Tough decisions for sure. I didn't go w/ different carbs on my CL378, though I did have @crazypj do his mods to the stockers. The first time the thing was started after doing the GS850 pistons I was shocked at how much deeper the sound of the engine was. It ran well and very strong. I'm not sure about a special cam and haven't heard much about cam work on a 360. I think that if you did the 378 and carbs you'd be happy and could always open it back up for a different cam later on. As others have said, don't forget the oil mod and get a set of CB350 "racing" clutch springs, not expensive and worth the trouble.

These old bikes aren't an investment just put in what ever you're comfortable with.

And I haven't seen anyone mention it here: Be careful when you take the left side cover off, the one over the drive sprocket. There is a ball bearing inside the clutch control mechanism that's easy to lose and you'll never get the clutch to work right w/o it!

Right on about the "investment" part. My numbers are coming together at about $3,000 for this build without the engine modifications. I'm quite sure I couldn't sell it for $3,000 when I am finished.

I found Suzy pistons in stock at a couple dealers. $150 for the pair plus $65 for the rings. Not sure about the machining cost -- will need to check into that. Not many local shops do engine machining nowadays. I think my local parts store has a location about an hour from here that they send parts to. Could check with them for a quote.

It might be that I could port the head and go to the TM32 carbs if I increase the displacement to 378. I know Niche sells the TM32 set configured for CB350/360 so it can run on a hopped up 350.

I got the clutch cover off (bugger was quite stuck) and there was so much gunk in there that the ball bearing wasn't about to fall out. I have the parts all cleaned up and cataloged now. I had to remove it to get the chain off -- it was an endless chain.

 

[ridesolo]

Right on about the "investment" part. My numbers are coming together at about $3,000 for this build without the engine modifications. I'm quite sure I couldn't sell it for $3,000 when I am finished.

I found Suzy pistons in stock at a couple dealers. $150 for the pair plus $65 for the rings. Not sure about the machining cost -- will need to check into that. Not many local shops do engine machining nowadays. I think my local parts store has a location about an hour from here that they send parts to. Could check with them for a quote.

If I recall... I think I got $3500 for mine when I sold it. Sad part about that is I'm about 90% sure that it's sitting in the corner of a barn in the Pittsburgh area and hasn't been started and ridden since it left here. It would never have passed PA inspection to be licensed there. She wanted to take it to Sturgis with her and ride it around there.

Did you check out eBay for the pistons? Can't remember for sure but it seems like I paid about $35 each and while used, they were in beautiful shape. I think maybe I have one set of new GS650 rings you can have if you want them... if I can find them. We've got a guy in this area who is a great machinist. I know he's done several 360/378 jobs and Levi (@Hurco550) and I as well as some of the other DTT guys have used his services; fast and reasonably priced. Levi has his contact info.

 

[irk miller]

The stock carbs, with PJ's mods, work extremely well. I'm running VM28s on my last build nearly complete, which has a stock bore. I've built them with VMs and with stock carbs. I've been trying to get Murray to do a 2-into-1 intake for the 360s for years. Not enough on the road to make it worth his while, I suppose. I would like to mess with printing them out of TPU.

 

[Maritime]

The stock carbs, with PJ's mods, work extremely well. I'm running VM28s on my last build nearly complete, which has a stock bore. I've built them with VMs and with stock carbs. I've been trying to get Murray to do a 2-into-1 intake for the 360s for years. Not enough on the road to make it worth his while, I suppose. I would like to mess with printing them out of TPU.

IF Murray did make a kit it would be the go to. I am actually looking for a basket case bike that he makes carbs for as my next project.

 

[Untame]

The stock carbs, with PJ's mods, work extremely well. I'm running VM28s on my last build nearly complete, which has a stock bore. I've built them with VMs and with stock carbs. I've been trying to get Murray to do a 2-into-1 intake for the 360s for years. Not enough on the road to make it worth his while, I suppose. I would like to mess with printing them out of TPU.

What carb would you use?

Here is what I came up with for a manifold printed from black polycarbonate. This material can handle the temps, shocks, and fuel vapors, but it is somewhat hard to print (and long -- this would be a 2-day print for one piece... if it doesn't fail mid-print).

On the engine side it is designed to slip into and around the stock flange adapters and be clamped around the outside of the manifold On the carb end a Mikuni flange adapter is mounted for the carb. Probably a good idea to fabricate some sort of carb hanger/support so that the manifold is not stressed too much.

There is a recess in the manifold for an o-ring gasket between the manifold and carb adapter. Also, there is 4.5 degrees of downward tilt after the clamps for the engine flanges. This is to level the manifold and carb.

 

[ex119x]

I talked to Megacycle today. $500 for cam regrind. Ouch. On top of GS800 pistons and cylinder boring... over $1,000 in performance upgrades. Is it worth it for how I plan to use this cycle? Yeah, it would be cool to know I squeezed a bunch more out of it, but.... $$$.

I could just slap a set of TM28 carbs on it and call it good. Probably get a little performance bump out of that. Then money could be put toward other things.... or would I regret not "doing it right" and making the engine special?

I think you are seeing the light. Engine performance upgrades are not going to be worth it for the kind of riding you will be doing. Putting in a set of used GS850 pistons with new rings makes sense since you will already have the engine apart and more displacement will give a power increase where you will use it most, bottom end and midrange. Matching the ports while you have it apart also makes sense since it is free and optimizes what you have. I think that stock carbs with the PJ mods will give you the best drivability over any of the other carb options, other than perhaps a single carb. A single carb will never give more HP, but with a stock head and bigger displacement might improve bottom end and midrange so will be a better bike for riding on back country roads. Bill Bune, in the Cities , billbune.com, is a top motorcycle machine shop.
I would spend the time and money on suspension and brakes.
BTW, I used to work with a M/C mechanic that swore by using used pistons for his best motor builds as he claimed thay had all the high spots worn off and were heat cycled and stable. He then bored them tight and ran them hard. I don't know if that is true, but I have followed that principle in the past and had good success. I just check that the ring lands are in good shape and that the piston skirts aren't cracked.

 

[Untame]

I think you are seeing the light. Engine performance upgrades are not going to be worth it for the kind of riding you will be doing. Putting in a set of used GS850 pistons with new rings makes sense since you will already have the engine apart and more displacement will give a power increase where you will use it most, bottom end and midrange. Matching the ports while you have it apart also makes sense since it is free and optimizes what you have. I think that stock carbs with the PJ mods will give you the best drivability over any of the other carb options, other than perhaps a single carb. A single carb will never give more HP, but with a stock head and bigger displacement might improve bottom end and midrange so will be a better bike for riding on back country roads. Bill Bune, in the Cities , billbune.com, is a top motorcycle machine shop.
I would spend the time and money on suspension and brakes.
BTW, I used to work with a M/C mechanic that swore by using used pistons for his best motor builds as he claimed thay had all the high spots worn off and were heat cycled and stable. He then bored them tight and ran them hard. I don't know if that is true, but I have followed that principle in the past and had good success. I just check that the ring lands are in good shape and that the piston skirts aren't cracked.

What are PJ's mods, or does PJ actually do the rebuilding?

CV carbs have a bit of throttle lag. Wouldn't it be a reasonable compromise to go with a set of VM30s? (SpeedMotoCo has a set for about $400 with carb boots and velocity stacks.) I was under the impression that CV carbs were designed as an emissions device to take away some of the fun of riding in order reduce unburned hydrocarbons in the exhaust.

 

[ex119x]

What are PJ's mods, or does PJ actually do the rebuilding?

CV carbs have a bit of throttle lag. Wouldn't it be a reasonable compromise to go with a set of VM30s? (SpeedMotoCo has a set for about $400 with carb boots and velocity stacks.) I was under the impression that CV carbs were designed as an emissions device to take away some of the fun of riding in order reduce unburned hydrocarbons in the exhaust.

PJ, here on this site, modifies your carbs to give the proper jetting and improve throttle response. CV carbs can work very well and have excellent throttle response. The poor performance of emission era cv carbs was more due to lean jetting and people putting poorly designed pod filters on them. I have found that the stock CV carbs with appropriate jetting, the stock rubber velocity stacks and foam filters to work great on my CB350 race bike. I would not spend $400 on a set of kit carbs. If I wanted to go that direction (and I have) I would get a pair of the cheap chinesium knock off carbs for $30 a piece, a generic 2-1 throttle cable and get them to work. I put a set of 32mm on an XS650. With the richest jets they came with and raising the needle all the way, it was very drivable. I probably could have gotten it a little better, but didn't bother. I probaly had about $100 in the whole setup and had some fun and gained knowledge making it all work.

 

[Untame]

I think you are seeing the light. Engine performance upgrades are not going to be worth it for the kind of riding you will be doing. Putting in a set of used GS850 pistons with new rings makes sense since you will already have the engine apart and more displacement will give a power increase where you will use it most, bottom end and midrange. Matching the ports while you have it apart also makes sense since it is free and optimizes what you have. I think that stock carbs with the PJ mods will give you the best drivability over any of the other carb options, other than perhaps a single carb. A single carb will never give more HP, but with a stock head and bigger displacement might improve bottom end and midrange so will be a better bike for riding on back country roads. Bill Bune, in the Cities , billbune.com, is a top motorcycle machine shop.
I would spend the time and money on suspension and brakes.
BTW, I used to work with a M/C mechanic that swore by using used pistons for his best motor builds as he claimed thay had all the high spots worn off and were heat cycled and stable. He then bored them tight and ran them hard. I don't know if that is true, but I have followed that principle in the past and had good success. I just check that the ring lands are in good shape and that the piston skirts aren't cracked.

$150 for boring at Bill Bune. $130 at my local automotive machine shop. Not much of a difference for the experience and reputation of a motorcycle specialty shop. The bigger issue is shipping or delivery. BB is about 2.5 hours from me and the local shop is 3 miles.

 

[ridesolo]

Hmmm, dat's kinna cool. (the 1 into 2 above)