Tunnel Heat Exchanger on the MH

Ausm7499 · May 13, 2013

I have decided to delete the radiators on my CR500 and will be using an Arctic Cat (07-08 M-series) heat exchanger and coolant bottle to handle my cooling. I am hoping that a heat exchanger will give me more consistent and better cooling over the radiators. I found that the radiators did not provide sufficient cooling on the trail and had to stop frequently to dowse them with snow. Lowering my center of gravity will also be a bonus but more than likely it won't be noticeable. I also can not keep from breaking radiator shrouds so I will be happy to delete those as well.

I am hoping that this is a pretty straight forward modification but have a few questions. Will my water pump be sufficient? Will my cooling improve and give me more consistent temps?

mnsnowhawk · May 13, 2013

Could you get radiator braces and not use the shrouds and add a fan to the radiators operated off a switch for the trail ride. Seems easier to me. Just throwing it out there. I don't know much about your bike.

up-high · May 13, 2013

If the heat exchanger has a greater surface area, it should provide more cooling but, where you mount it will be critical. on top of the MH framw seems like a good place but will that provide enough air flow when going slow through the trees. Is there enough room to put it under the tunnel?

Niskibum · May 14, 2013

Now I'm confused. I thought that people were covering up their radiators because they are running too cold in the winter, but you are looking for more cooling? Is this just during spring conditions?

Ausm7499 · May 14, 2013

adding a fan really isn't an option as power is not easy to come by on the cr500 and I really don't think that would solve my over heating problem on the trail. I will be mounting the heat exchanger under the rear of the tunnel just like a sled, air flow will have very little effect on cooling the snow will do the cooling. I an running a thermostat so that solved my problem with having to cold of temps while boondocking but I still get to hot when snow is not being kicked up on m my radiators.

PalousePoo · May 14, 2013

I think your on the right track. My yz will see 210 degrees in a long climb, and following goofey sleds on a tight, technical (for them) trail. The stock pump should circulate fine, how much it cools would depend on how much surface of heat exchanger you have. Prob would need a snowflap too so snow stays in the tunnel, like a sled.

I wanna hit freezeout with you next year.

off road rider · May 15, 2013

Ive done extensive testing and mods to the heat exchanger system on a Mod Hawk. Bigger motor, but the same Idea.
One thing you will run into is getting the snow to fly up under the tunnel enough to do much good. No issue in powder, but on marginal snow conditions or on the trail you will need a snow flap of some kind.
Another option might be to place the exchangers in or on the rails. Thats worked very well with the hawks.

What about doing both, retain your rads and use a heat exchanger?

Ausm7499 · May 15, 2013

I have snowchecked a 14' MH which comes with a flap so that should help a lot as for surface area this heat exchanger doesn't have a lot it's only about 8.5" wide by 12" long but provided about half of the cooling on my M1000 so it should work for an engine half the size. I think I may have to add ice scratchers for the trail if I can't kick up enough snow.

PalousePoo I would definitely like to ride with more people and Freezeout offers some of the best terrain for snobiking.

Ausm7499 · May 15, 2013

off road rider said:
Ive done extensive testing and mods to the heat exchanger system on a Mod Hawk. Bigger motor, but the same Idea.
One thing you will run into is getting the snow to fly up under the tunnel enough to do much good. No issue in powder, but on marginal snow conditions or on the trail you will need a snow flap of some kind.
Another option might be to place the exchangers in or on the rails. Thats worked very well with the hawks.

What about doing both, retain your rads and use a heat exchanger?

How would you run the coolant lines to the heat exchanger if it were mounted on the skid rails? Running both rads and heat exchanger is an option but not one that I want to pursue, I want my bike as light as possible.

Jon Mutiger · May 15, 2013

I've got a pair of KTM rads that have broken brackets, but could be used as additional air/water cooling if needed.

These aren't mountable on a bike the way you usually would without some welding.

Make an offer if interested.

Jon

Hawkster · May 15, 2013

A few of you guys know who this is , can't is not in his vocabulary . It gives you an idea on how an exchanger would go in , but in certain conditions an exchanger in the rails will cause excessive ice build up more than they normally do .

CATSLEDMAN1 · May 15, 2013

wow

thats quite a setup with heat exchanger in the rails !!!!

thinking about the same setup on my new build. sled experimenting though has always taken my back to : heat exchanger in the front of the track with snow flap in back.

off road rider · May 16, 2013

Hawkster said:
A few of you guys know who this is , can't is not in his vocabulary . It gives you an idea on how an exchanger would go in , but in certain conditions an exchanger in the rails will cause excessive ice build up more than they normally do .

Thanks Hawkster!!

Ausm7499 · Dec 28, 2013

Ok so I have finally completed my MH heat exchanger and have rode it once setup this way. For a recap I have an 01 CR500 that I couldn't get consistant cooling out of (over heat on road, ice cold while boondocking) so I decided to delete the radiators and try a snowmobile type setup for my coolant system. First ride results look promising the bike maintained 120-160 degree temps all day long regardless of what I was doing. I am using a KTM 4 stroke thermostat and as you can see in the pictures it gets a little complicated at the front of the bike but seems to work really well.

dirtrebel · Dec 28, 2013

very nice! this looks like the way to go, as you said with rad's hot on trail cold in powder. Why not utilize the unlimited cooling available from the snow and also get rid of the vulnerable radiators to trees etc. good job! One thing to note, (as u said) a good working thermostat is key in this system or it will always run cold. worse case u might have to run scratchers on the super spring hardpack. Again, way to try something!

summitboy · Dec 28, 2013

Well done ! Nice to see thinking outside the box. I just cracked a rad boo hoo. They were 15 years old ha ha. Can you tell us more about your cooler ? Might be even easier with a single port out of the 500 head. Could eliminate some hose.

What size heater hose did you use ? Maybe a guy could fit a couple little bags where the rads used to sit. Neat !

Ausm7499 · Dec 30, 2013

summitboy said:
Well done ! Nice to see thinking outside the box. I just cracked a rad boo hoo. They were 15 years old ha ha. Can you tell us more about your cooler ? Might be even easier with a single port out of the 500 head. Could eliminate some hose.

What size heater hose did you use ? Maybe a guy could fit a couple little bags where the rads used to sit. Neat !

The heat exchanger and coolant bottle are off of a 07-08 Arctic Cat M-Series I think it cost me like $50 for both of them. The heat exchanger requires flattening which is easy to do with a press and some fab work to make it fit in the MH tunnel. I used some aluminum strap and had it welded to the heat exchanger and then aluminum angle was welded to the strap (see pic above) the heat exchanger mounts in the stock MH holes and will be easy to swap from kit to kit. The hose is all 3/4" ID heater hose except for the little bit of hose that comes off of the head which is 5/8" ID. It may be hard to see in the pictures but I have a KTM thermostat and trail tech coolant temp sensor plumed in.

A single 3/4" port coming out of the head would certainly simplify the pluming and probably improve efficiency, do you know anybody that makes a head like that?

Got my second ride in yesterday and the system worked flawlessly. I made an effort to pay more attention to temps throughout the day and have revised coolant temps and a couple questions. With this system the thermostat is getting a workout I can watch the temps climb to 155-170 depending on how hard I am working the bike and then when the T-stat opens the temp suddenly drops to 130-140 and it just plays that game all day long.

Here is my question does that instant 30-40 degree drop in temp cause any expansion contraction issues with the cylinder? I don't want to be in the middle of a hard pull with a hot piston and then have it get squeezed when that cold water hits the cylinder.

Another added benefit that I don't think I mentioned is the added coolant capacity that this system has I think it takes about 3/4 of a gallon to fill it which is probably about three times as much as the stock setup. This added capacity equals better cooling and my coolant temps stay pretty warm even after sitting and eating lunch.

Bigred1 · Dec 30, 2013

Great idea. Ive been using waterless coolant which eliminates the boiling water but not the higher temps. Is the coolant bottle necessary? seems like it would be an easier install and less to go wrong (Break).
Have you tried to drill a larger bleed hole in the stat so when the stat opens its not such a drastic change in temp?

Ausm7499 · Dec 30, 2013

Bigred1 said:
Great idea. Ive been using waterless coolant which eliminates the boiling water but not the higher temps. Is the coolant bottle necessary? seems like it would be an easier install and less to go wrong (Break).
Have you tried to drill a larger bleed hole in the stat so when the stat opens its not such a drastic change in temp?

If you didn't use a coolant bottle then the system would be completely closed (no where to add coolant or bleed off excess in a boil over situation) so I would say yes it's completely necessary but was really easy to mount. I used a 2.5" muffler clamp to mount it along with some aluminum strap and long nuts. If a guy is going to mount the bottle in the same place I did you will want the 07-08 maybe later years coolant bottle along with the hoses that go to the bottle.

I haven't tried drilling the bleed hole out but might do that, I think it could help keep the t-stat from cycling so much and would at the very least reduce the swing in temps.

Bigred1 · Dec 30, 2013

If you use the waterless coolant it doesn't boil until 375f and can be run at 0-psi so less stress on your hoses as well. but the bottle is nice so you can see your coolant level and makes filling easy. this is also a great solution to adding a stat to a KX500 since the head outlet is only 1/2 inch from the radiator inlet.

Tunnel Heat Exchanger on the MH

Well-known member

Well-known member

Well-known member

SnoWest Paid Sponsor

Well-known member

Well-known member

Well-known member

SnoWest Paid Sponsor

Well-known member

Well-known member

New member

New member

Similar threads