Topic: Custom Thermostat Sandwich Plate for CB750

[KickstandDan]

Hello,

I have an older unbranded sandwich plate on my 1971 CB750 that I use to connect an oil cooler. It has two 3/8 PT threads for the fittings, and I started wondering how much it would cost to have one custom-made. I modeled the plate in CAD and uploaded it to JLCCNC’s quoting tool. The estimate came back at around $60 before shipping for a 6061 aluminum part. I’d still need to tap the threads myself afterward, but it seems surprisingly affordable for a part like this.

Since I’m proficient in CAD and have my own 3D printer for prototyping, I’ve also been toying with the idea of designing a new version that incorporates a built-in thermostat. I don't want to worry about over cooling because I ride in most seasons, but in the hot summer my oil temp has jumped to 230+ degrees F on my modified engine (without the cooler installed). I’d like to make the sandwich plate as thin as realistically possible while including the thermostat. That way I wouldn’t need a separate bulky thermostat in the oil line, and it would keep the oil filter housing from being pushed too far away from the engine. Of course, it still needs to have enough thickness for proper oil flow and to leave enough material for the fittings to be securely threaded.

Obviously, there are some challenges to figure out making sure the oil passages flow properly, that the sealing surfaces are correct, and that there are no leaks. But as a concept, it seems like a neat way to create a custom plate that better suits my setup.

As a Engineer/Designer I think this is a perfect fun challenge for me to try out. What do you guys think about making a custom sandwich plate like this with an integrated thermostat? I am fairly confident that the roughly 100mm diameter needed for the sandwich plate doesn't exist right now with a built in thermostat but let me know if someone else already makes it!

Dan

[Don R]

 There was one made, I have it on the shelf of cool stuff in the shop. It pushed the filter out and didn't clear the RC header on my 836 so I haven't used it yet. (the header requires fin removal as is)
 I'll post a pic later when I go out to the shop.

[KickstandDan]

Oh very cool. Do you know if they are still in production or is it old tech? I think I will still take on this challenge to try and make a thinner one that doesn’t touch or get as close to the headers.

[Don R]

 I'm sure it is old technology but as they fit a lot of bikes, you never know. going out to grab a pic or two now. I had downed tree limbs to clean up.

[BenelliSEI]

I’ve used Mocal oil stats on a few bikes and many of my race cars. They are small, lightweight and can be had with push-on or AN style fittings. Cold oil by-passes the cooler and then goes there when HOT. They can also be dismantled and cleaned out if necessary. Very effective and reliable.

[Don R]

 Here are a couple, the thickness is only an issue because of the RC header, most other pipes would clear it easily. It's 1 3/4" thick, my non-thermostatic one is 1" thick.

[Don R]

One more, these are from google photos, downloaded to my desktop, hopefully they are visible to everyone.

 There's one on ebay but it doesn't show the adapter bolt. Way too many of these get separated from the cooler. TTR400 sells the bolt as well as the cooler plate but I'm not sure of the length.

[HondaMan]

The slickest thermostat I ever saw on the 750 was a 'bypass stopper' valve type that closed as it heated up. It was connected underneath the oil cooler, with 2 "tee" connectors on either side of the cooler forming a crossover tube just below it, in which was installed this temperature-operated 'bypass stopper' plug valve. When the oil was cool it ran mostly thru the 'stopper' valve because the hoses to it (from the tees) were larger ID than the route through the oil cooler with its restrictive smaller piping. As it heated up it then closed the 'stopper' valve and the thinned-out oil ran better through the cooler.

This was important in the kind of roadracing the bike was subjected to then, but would also be perfect for city riding, or even high-speed touring, as the oil flow to the oil filter was never restricted like it is when cold, in some other more common arrangements. It was a long time between heats and the bikes would cool way down, and they were races that started with the bikes off, sitting in their posted positions, and the riders ran to them, started, and then took off in the race, with [often] cold engines.

[BenelliSEI]

The slickest thermostat I ever saw on the 750 was a 'bypass stopper' valve type that closed as it heated up. It was connected underneath the oil cooler, with 2 "tee" connectors on either side of the cooler forming a crossover tube just below it, in which was installed this temperature-operated 'bypass stopper' plug valve. When the oil was cool it ran mostly thru the 'stopper' valve because the hoses to it (from the tees) were larger ID than the route through the oil cooler with its restrictive smaller piping. As it heated up it then closed the 'stopper' valve and the thinned-out oil ran better through the cooler.

This was important in the kind of roadracing the bike was subjected to then, but would also be perfect for city riding, or even high-speed touring, as the oil flow to the oil filter was never restricted like it is when cold, in some other more common arrangements. It was a long time between heats and the bikes would cool way down, and they were races that started with the bikes off, sitting in their posted positions, and the riders ran to them, started, and then took off in the race, with [often] cold engines.

As described, probably a MOCAL. They have been making them since the ‘50’s.

[KickstandDan]

The slickest thermostat I ever saw on the 750 was a 'bypass stopper' valve type that closed as it heated up. It was connected underneath the oil cooler, with 2 "tee" connectors on either side of the cooler forming a crossover tube just below it, in which was installed this temperature-operated 'bypass stopper' plug valve. When the oil was cool it ran mostly thru the 'stopper' valve because the hoses to it (from the tees) were larger ID than the route through the oil cooler with its restrictive smaller piping. As it heated up it then closed the 'stopper' valve and the thinned-out oil ran better through the cooler.

This was important in the kind of roadracing the bike was subjected to then, but would also be perfect for city riding, or even high-speed touring, as the oil flow to the oil filter was never restricted like it is when cold, in some other more common arrangements. It was a long time between heats and the bikes would cool way down, and they were races that started with the bikes off, sitting in their posted positions, and the riders ran to them, started, and then took off in the race, with [often] cold engines.

Interesting. I can totally picture the tee fittings and the single hose running below the oil cooler. It sounds like you are talking about an inline thermostat that closes when it gets hot. I haven't though of something like that but you are right it does seem pretty "slick." My goal is to make this sandwich plate thermostat even more slick so that it can become the slickest thermostat you ever saw. I am thinking matching fins and a low profile that doesn't even look like a sandwich plate is even there, but has plenty of flow, and obviously it will have the thermostat that will close at roughly 185F - 195F for optimum performance and cooling.

I will keep this forum updated as this project moves forward.