CR500 spring time overheat

[rhino89523]

O.K. title says most of it. I have a stack of parts coming and wondering best way to plumb it all. I am a big boy at around 270, I am hooked on this snowbike thing, the CR is the only way to go for me, partially because I love Cr500 and have many of them and partially because with my size this is the only thing I feel keeps me in the game with guys half my weight on 450's.

Spring hits in the Sierras and my bike is getting hot, my current answer is a router collection groove in my skid plate, stop and throw snow, collect water in bottle, refill radiator, keep eye on overflow steam pipe....not a great solution.

Parts I have coming, tunnel cooler, larger radiator, 2 avid thermostats.

original plan was run 1 radiator, route one coolant line off head to upper radiator inlet like stock with shutoff valve, run other line through thermostat to tunnel cooler then back into lower inlet of radiator, use bypass for carb heat off thermostat. problem with this set up would be if I ever open valve to radiator its just going to take that path of least resistance so really I don't need that valve I just need to plug that side permanent, then I wonder if one head pipe is enough flow to get the heat out of the head on hard springtime uphill pulls.

This led me to the second design. run both radiators, run both head outlets through 2 avid thermostats, T them together to the tunnel cooler which has a larger diameter of close to 1" run through the cooler back to another T back into the top of the radiators, tie both bypass portions to 1 and use for carb heat. Issues I see with this are running too cold when it's deep, handle that by blocking off radiators and run some kind of a jacket on the motor, which I also haven't figured out what you use that the pipe doesn't just burn the hell out of.

3rd design would be same as the last with 2 thermostats but only one radiator pipe the coolant out of the cooler into a single radiator, cap off one of the inlets.

4th design would be one radiator, use one thermostat going off the head to the upper radiator return second thermostat of other head pipe going to cooler, cooler return line back to lower radiator inlet that is originally the crossover pipe.

Man somebody help me here I am sure I am over thinking it, but I have looked at so many designs that I don't know what works for people. As I said I am a big boy, I have been riding 500's since 1988 and this is my first year in the snow. I would probably be considered an aggressive rider. We rarely get below 20 degrees here and this thing with bone stock radiators and no thermostat was running pretty good until this spring stuff hit. We get the Sierra cement going in the spring that is wet and heavy but if my bike would stay cool I think really fun. In this sprin stuff I can boil my bike out in probably 2 minutes pulling one big hill and I don't feel like walking so I would prefer to not blow her up.

The short version is I am worried with a tunnel cooler that I will run too cold when it is deep and when it is hot I am putting more stress to a 500 than I have put on one ever....makes dune pulls in 100 degree heat seam like nothing and I ride a 500 on single track barely moving and have never seen one steam out like what I have done with this snow bike.

 

[Grr]

I am thinking running from one head outlet through the tunnel cooler, and back into lower radiator crossover


2nd head outlet into a thermostat and into the radiator.
Use the bypass on therm for carb heat and tie into the upper radiator where the air hose crosses over. Just make sure to not shut the carb heat completely off. The tunnel cooler will do more than 2 radiators can even dream of. Will likely have to run a restrictor in the line to the rad though so it doesn't take the path of least resistance like you say. Main advantage of the tunnel cooler is the volume of liquid more than anything


Anyway this is what I have drawn up for mine

 

[dhdey]

I removed the rads completely and put a bump/resivoir bottle from an F7 in the place of the right hand side rad. 3 seasons ago and never had an issue since always perfect temps. one outlet goes to thermostat then tunnel cooler. other outlet goes through temp guage then carb heater then back to bottle.

 

[M5-]

Pressure is pressure so I'm not sure ALL the coolant will take the path of least resistance, if anything the cooler may offer less resistance because of the volume of rad hose. The first thing I would do and this is how I have mine setup is to tap the flat boss on the back of the cylinder for the carb heater and forget about the bypass. This is how I have mine set up and it results in about a 4" line coming from the cylinder to the heater which provides hot coolant no matter what. Return that line wherever is handy. I have a shutoff but I have never turned off my carb heat. Eliminate the left hand rad and replace it with the tunnel cooler. Plumb the cooler from the left side outlet on the head. Install a simple thermostat in that line with a bypass. 120 degrees or whatever they are. Return the line to the bottom of the right rad. I think for spring it will be fine, for the deep it may run too cool depending on the bypass system and how much it flows. Use a 1.7 Bar rad cap and install an overflow bottle. Before I switched caps mine used to boil now its good but I'm only a buck eighty, 205 geared up.

In the deep my temps drop more from snow hitting the block I'm not sure the rads do dick all.

M5

 

[rhino89523]

I have the boss on the back of the cylinder tapped, and that is where I am currently running the carb heater, I return it currently into a T on the left radiator return from the top of the head. I also have a valve on it I turned off for spring time and this set up worked perfect in the Deep. I don't have a temp gauge and maybe it was a little cool with snow packed everywhere but it ran great and started easy enough and never overheated in waist deep snow.

Come spring I can't keep water in this thing!!!

 

[needpowder]

Eliminate the left hand rad and replace it with the tunnel cooler. Plumb the cooler from the left side outlet on the head. Install a simple thermostat in that line with a bypass. 120 degrees or whatever they are. Return the line to the bottom of the right rad. I think for spring it will be fine, for the deep it may run too cool depending on the bypass system and how much it flows. Use a 1.7 Bar rad cap and install an overflow bottle. Before I switched caps mine used to boil now its good but I'm only a buck eighty, 205 geared up.

In the deep my temps drop more from snow hitting the block I'm not sure the rads do dick all.

M5

This is how I had mine set up as well and it worked perfect. I ran carb heat from the bypass though. My bike never once overheated. I ran scratchers for the rare moments on the hard pack trail. In powder I had to run a full plastic shroud around my pipe and engine. That was the only way I could keep temps where I needed them.

 

[rhino89523]

Hey Need power,
How did you build the plastic to keep it from burning up the pipe? did you wrap your pipe?

 

[M5-]

I forgot to mention that, I run shrouds in the deep as well. I only have the left side fully shrouded as well as the rear of the engine. By the time you look at the right side there is so little that you can actually shroud that isn't pipe that I didn't bother with it. Seems to work fine. I think with a tunnel cooler some type shrouds are a must.

M5

 

[needpowder]

Hey Need power,
How did you build the plastic to keep it from burning up the pipe? did you wrap your pipe?

I made more of a faring type of plastic shield that didn't touch the pipe. Of course after riding and crashing, and rubbing trees, I burned a few holes in it which I just patched up and got used to the smell of burning plastic. Not ideal, but it kept my temperatures up. I ran it clear up over the radiators as well and taped up any gaps that I could using gorilla tape. With my bike I found, that I needed to have it as enclosed is possible to run warm in the deep and light. I didn't have my pipe wrapped but that probably would've solved my problems.
I used plastic from an auto parts store. I'll try to find my pictures of it and post them when I have More time today.

 

[HalfBrit]

To limit boil over. Try evans waterless coolant much higher boiling point. Drawback is you won't know if your running way too hot If you ve boil over unless you look at your temp gauge