Yeti tunnel cooler

[portgrinder]

When you mount those things it’s a good idea to squeeze a whole tube of black rtv or the silicone of your choice between the cooler and the tunnel to hold it in placeThe little bolts at the back can rattle lose and it’s a real sob to check them. When I ran one in a kx5 I checked them after every ride and one was usually coming loose.

 

[chumbilly1]

I'm getting ready to install my c3 heat exchangers and this thread has been very informative. My plumbing is going to be tricky as I'm running carb heat, bar heat, and these. May end up getting rid of radiators and moving thermostats back to where airbox used to be. Almost wishing I would have used the 12" c3 coolers. One bike is a 300sx and one is Brc500. Think I'll be able to maintain constant temp?

 

[dooman92]

Chumbilly1, I'm assuming yours are both yeti kits. For the time being I gave up on my yeti kit due to limited space and cooler options in that tunnel. The 12" cooler from C3 is no longer available right? And Kevin said it required one rad to work. Plumbing can be tricky too. Regarding thermostat location, it should be as close as possible to the head/output and higher than output. If too far away the thermo will open late due to heat given up initially by the hose/piping getting to the thermo. The coolant in the head could be several degrees warmer than the coolant at the stat. Also want the stat above the output so warming coolant can rise to the stat. Also, don't want any dips in the coolant line that would trap cooler liquid which could further isolate the stat. That is less of an issue if running a bypass that continually circulates coolant, or there is a decent bleed hole in the stat.
I am currently working on my 450fx mototrax kit and removed both radiators. I want to eliminate the convection cooling from having the cold liquid above the engine with unimpeded drop from the rad into the block. In theory, consistant cooling should be easier without the rads as long as the engine is sealed up against snow intrusion.
Have you had that brc 500 on the snow? Really interested in how that is working out...

 

[chumbilly1]

Chumbilly1, I'm assuming yours are both yeti kits. For the time being I gave up on my yeti kit due to limited space and cooler options in that tunnel. The 12" cooler from C3 is no longer available right? And Kevin said it required one rad to work. Plumbing can be tricky too. Regarding thermostat location, it should be as close as possible to the head/output and higher than output. If too far away the thermo will open late due to heat given up initially by the hose/piping getting to the thermo. The coolant in the head could be several degrees warmer than the coolant at the stat. Also want the stat above the output so warming coolant can rise to the stat. Also, don't want any dips in the coolant line that would trap cooler liquid which could further isolate the stat. That is less of an issue if running a bypass that continually circulates coolant, or there is a decent bleed hole in the stat.
I am currently working on my 450fx mototrax kit and removed both radiators. I want to eliminate the convection cooling from having the cold liquid above the engine with unimpeded drop from the rad into the block. In theory, consistent cooling should be easier without the rads as long as the engine is sealed up against snow intrusion.
Have you had that brc 500 on the snow? Really interested in how that is working out...

I have not had the BRC on the snow. Lots of guys running them with good results though. Maybe I will run some sort of snowmobile catch/fill bottle in place of radiators, that will free up a bunch of space. Problem on my bikes, is that the hose from head to the t shaped tube KTM uses, is so short it makes it very tough to fit in a thermostat. Typically on 2 stroke applications the carb heat is the bypass, so will i just link my bar heat and carb heat together in the same bypass circuit? The Stats that I currently have are AVID and RAZE, not sure on the size of bleed holes.

 

[portgrinder]

I’ve plumbed a few ktm 2 strokes with coolers. Got it mostly figured out.

i drill/tap a second circuit in the head for the carb head. Do it right wherethe air screw on the top of the head is. Could use this for your bars too. I put a little valve on this circuit and then drill/tap a return hole in the water pump cover. Works real good. Then it’s always on and adjustable vs the bypass idea.

for the cooler routing, you want to do a hard 90 right out of the head and go back to the cooler. The avid tstat works good for this as you can put it immediately above the head and ‘clock’ it to turn 90 for you. Run the hose up high beside the voltage reg and then zip tie it onto your strut rod. Same path on the way back, but add some length to have it take a nice sweep back into the fitting that goes into the frame and up to the rads. That hose clamp is a real sob so make sure you know it’s on good. It really sucks when it leaks.
Can put some pics up if it would help anyone

 

[chumbilly1]

I’ve plumbed a few ktm 2 strokes with coolers. Got it mostly figured out.

i drill/tap a second circuit in the head for the carb head. Do it right wherethe air screw on the top of the head is. Could use this for your bars too. I put a little valve on this circuit and then drill/tap a return hole in the water pump cover. Works real good. Then it’s always on and adjustable vs the bypass idea.

for the cooler routing, you want to do a hard 90 right out of the head and go back to the cooler. The avid tstat works good for this as you can put it immediately above the head and ‘clock’ it to turn 90 for you. Run the hose up high beside the voltage reg and then zip tie it onto your strut rod. Same path on the way back, but add some length to have it take a nice sweep back into the fitting that goes into the frame and up to the rads. That hose clamp is a real sob so make sure you know it’s on good. It really sucks when it leaks.
Can put some pics up if it would help anyone

So, would you suggest leaving both rads if running a 30" yeti cooler? I like the idea of tapping the head for the aux circuits! I was trying to figure out how I would control temp to carb and bars and your idea seems to solve it. Thanks

 

[portgrinder]

I made a little kit to drop the left rad, just haven’t done it yet. Don’t see why you couldn’t. I’ve got mine consistently running around 100-130F with some homemade blankets and the cooler, so I don’t want to mess with it too much. If anything I want it a little colder.

 

[chumbilly1]

I made a little kit to drop the left rad, just haven’t done it yet. Don’t see why you couldn’t. I’ve got mine consistently running around 100-130F with some homemade blankets and the cooler, so I don’t want to mess with it too much. If anything I want it a little colder.

Would you mind posting a couple pics? Ive got an SXS snowshield here (wont do much for temps) and ive got a CF guard on my PC2 platinum pipe. Think Im gonna use race car plastic and cover the motor and exhaust a little more thoroughly though. Planning on sending pipe to be ceramic coated at some point. Do you have the NPP snowbike pipe?

 

[portgrinder]

I wouldn’t waste money putting ceramic on your pipe.

Ya I run the NPP snowbike pipe. Been developing it with him since around 2012. 80+ hr a season on the snow.

my blankets are just some junky vinyl from a fabric shop. These contraptions with the tunnel cooler keep the temps very consistent.

the Tstat on this build is just an inline ktm with a tight silicone 90 down to the head

 

[chumbilly1]

Do you cover the lower part of motor as well? Why cover the cylinder and electronics if you are trying to keep temps low? The NPP pipe is tuned for lower temp correct? Thats why you dont need to wrap or coat? Did you guys develop a 2016 and earlier 300 snow pipe as well? What EGT system do you recomend? KOSO? Sorry for all the questions. This bike project has been in corner of shop for too long. Yesterday It got started for the first time and after a little jetting work it sounds and feels really strong.

 

[wwillf01]

I use a koso they have worked very well...

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[portgrinder]

getting a little off the original topic but here’s my answers.

on any two stroke I’ve done I never cover the case/bottom. A cold case makes more power and you don’t have any ice buildup.

Ide like to be a little cooler but not very much. the name of the game is consistent temps. I find a bit of a blanket + a cooler gets you there. If you don’t have a blanket, your system cools off ice cold when you stop for lunch etc. And if you aren’t careful and take off like you’re riding a sled you can smear a piston. Same when in deep snow. Basically I want my coolant to do all the cooling so it’s regulated by the tstat.

If you get it right you can stop watching your temp gauge and focus on chirping your 4 stroke buddies temp-talking every time they stop.

the NPP is tuned for a very flat tq curve. So you have lots more in the low/mid and it revs out farther. Wrapjust makes a bunch of mess. The pipe was build to run in the snow. Was originally developed on a kx5. Works good on the 16 and oldermotors as well. Kinda explained all that in another spot on here.

the koso is ok. I’m gonna run it for a few mote rides then pull it off. Once you’re tuned you don’t need one.

 

[chumbilly1]

I use a koso they have worked very well...

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[chumbilly1]

Thats a sweet YZinger! Thats the guage I was looking at . What do you set your warning light at on initial rides if you dont mind?

 

[wwillf01]

1100 is what I aim for... but you have to check plugs at first.... I have had bikes that like 1250 to 1350 (cr500) then the yz likes 1100... make sure your getting that without the pipe submerged.

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[Chadx]

Revival of old thread, that I participated in previously, but I'm now tackling tunnel cooler install on my 2020 Yeti 129/2020 YZ450F. Can anyone confirm if the C3 thermostat outlet nipple and the Yamaha top radiator inlet nipple are both 3/4" I.D.?

When I ordered the tunnel cooler from C3 I also bought the C3 silicone double tunnel cooler hoses (5/8" I.D.) and plan to route my coolant lines like Snowscooter5 did in the above images. It looks like the C3 thermostat nipple is 3/4". Also looks like the radiators upper inlet is 3/4". I could pull the hose and check, but hoping to not pull it until I start the project. If both are 3/4", I'll use 3/4inch "HPS Silicone 180 Degree Elbow Coupler Hose" coming off the C3 thermostat to redirect hose backwards, then a 3/4" to 5/8" adapter into my 5/8" I.D. tunnel cooler line. On the 5/8" tunnel cooler return line, I'd use a 5/8" to 3/4" adapter to go into the cut, stock 3/4" upper radiator hose (or better yet, likely save and not cut the factory hose and just get a scrap of 3/4" I.D. coolant line to use). Mainly want to confirm that both the C3 thermostat nipple and the Yamaha upper radiator inlet nipple are both 3/4" so I order the right hoses and adapters the first time.

Regarding the two small bolts, that are part of the gas can/rack bracket, that will hold up the rear of the tunnel cooler, are the factory ones long enough or do I need to source longer ones? I saw one recommendation to use some type of sealant between the cooler and tunnel, but seems unnecessary if the two small rear bolts are loctited in place. How many have used sealant? How many have only used the bolts (with loctite) and had or not had bolts back out?

Also, how best to determine where the holes are drilled? Spacing between the holes I can get from measuring the tunnel cooler, but for placement top to bottom, looks like a guy just wants to drill below, but as close as possible to, the external cross brace, correct?

I'm gathering as much info as I can beforehand and hopefully make this go smoother and get it done in mostly one sitting rather than having to stop mid project and drive for parts or order parts.

I really thought about getting rid of the radiators all together, but having trouble finding an appropriate "coolant filler neck and cap" for the project. The ones from the late 90s Artic cats look perfect (picture attached), but can't find new versions and don't like the idea of 20+ year old plastic. There are some universal ones that seem reasonable (pictured) but not finding anything ideal. Any ideas there would be appreciated as I still might do radiator delete. Only reservation there is if I ever get into a situation where the tunnel cooler isn't enough (boiler plate trails in the spring where I can't dip off to the edge of the trail to cool). Or, if I ever damaged the tunnel cooler mid season and needed to temporarily have another form of cooling while I wait on parts or to finish out the season). In both cases, having left the radiators in place would give me options. I'm really drawn to the notion of removing them and all the associate plumbing, though. Lighter, simpler, cleaner, less failure points. I have radiator guards in place that would stay to support the bikes plastic shrouds and the filler neck, etc. I also have a radiator bib that covers them completely and could then stay in place full time, once I install the tunnel cooler, whether I delete the radiators or not.

I'm also using Evans waterless engine coolant, so don't need a pressurized system since it will never boil.

Example of old Arctic cat filler neck that are around, but old plastic. I can't find this part newly manufactured rather than old used or old stock, but maybe the plastic they used ages well and there is no issues with using 20+ year old plastic? Just makes me a bit nervous.


Universal filler:


Another (though this one has its drawbacks with nipple orientation and not much neck, but the the 3/4" barbed fittings are removable in case you need to install your own fittings in the 1/2" NPT Female threads so one could put in 5/8" 90degree elbow to more easily tie into the 5/8" tunnel cooler hose and then the 5/8" hose that drops down to the water pump.

 

[Dr._Z]

I have the plastic one on mine and deleted the rads. Works good but it's 1" hose size if I remember correctly. Had to use adapters. I'd like to go with another option this year with my new kit and I just bought an exchanger made for the ARO someone sells on here. The only time it ever got a little more warm was on solid ice back to the truck. a good set of scratchers keeps it cool on the trail.
Here's a link to the guy's filler bottle he makes. https://xrtengineered.com/shop/snowbike-coolant-bottle/

 

[Chadx]

Really like the looks of that filler bottle! Interesting that they want you to plumb the thermostat-bypass-circuit through it rather than the thermostat-open circuit. Hadn't considered that. I'd intended to run the thermostat-open circuit (tunnel cooler circuit) through the filler neck/bottle but maybe that is simply because that is how the radiator is plumbed so what my mind is familiar with (and also because that is how most people seem to plumb the radiator-deletes). But I guess I can see how any air in that circuit would eventually push out the thermostat bypass circuit. I might see if they can make the 1/2" side inlet be 5/8" like the outlet, then one could leave your bypass circuit as it and plump the thermostat-open/tunnel cooler circuit through this.

Anyone have any thoughts on reasons why one should only place the filler neck/bottle on the thermostat-open/tunnel cooler circuit rather than bypass circuit? I do have coolant heated handlebars an they are my bypass circuit, so when I turn that circuit completely off, nothing would run through this filler bottle, but once air is pushed out, that should really matter. and with my C3 thermostat having internal bypass hole, dumping ice cold/ non-bypass-circuit mixed coolant all of a sudden isn't an issue because the thermostat bypass keeps the thermostat-open circuit from being ice cold. Also of consideration is it would make tunnel cooler plumbing much easier, on my YZ450F, to run the return line from the tunnel cooler back to a coolant bottle up where the radiator was rather than the return line going down to the water pump at the base of the engine.