Ideal 4 stroke engine temperature?

[needpowder]

Just wondering what's ideal. I am running Thermo Bob, full PST engine jacket including extra piece, and foam between my engine and skid plate. When I got off the trail into some pretty deep snow I was consistently seeing in the 130s. I thought I would be able to keep temperatures up a little higher than that. On the trail it would run between 150 and 170, but as soon as I would jump off to the side they would drop again. I'm thinking my next step is to somehow cover the back of my engine so the track is not throwing so much snow on it. I'm concerned because there are definitely many days
(I hope) which I will be riding in deeper snow and colder temps all day long.

 

[RACINSTATION]

That is a bit on the cool side, but not bad. It also depends on the outside temps. In deep powder on a 0-20 degree day you should be 155-190. On warmer days it will get up to 200.

 

[ges]

same temps for us we also made some plastic radiator cover that we slide up and down to cover the radiators i think it should be running at least 160 to 185 fan kids on at around 200 on ours anyways

 

[HalfBrit]

Two of us were running in the upper 130s to 155ish yesterday in 28 to 30 degree powder/trail. Thermo bobs. one with jacket one without.

 

[AKdragon700]

rear engine shield

If you look closely you can see the shield I put up behind my engine. Keeps snow off the back of the engine and more importantly the starter.

I used a flexible kitchen cutting board. Super cheap and just about the right size. I was looking for kids sled roll up material but couldn't find any. Walmart had my answer in the kitchen section lol

 

[needpowder]

Akdragon, that is exactly what I'm thinking. I was in the garage last night cutting up some plastic trying to fab up something similar. I'm going to work on it a little more tonight, I think it will help.

I used one of my wife's plastic cutting boards one time to replace a chunk in my side panel that had blown out when I blew a belt. worked awesome!

 

[WingNutRacing]

Ok

NeedPowder, I have the same setup and was looking at that, let me know what u come up with....


Also, what kind of foam is everyone using, and where to get it, for between bottom of engine and skid plate?

 

[n16ht5]

Has anyone here ruined their motor from over fueling? I have jacket and tstat still runs cold in the deep Husky 501

 

[dooman92]

Ref the original question, lots of research supporting engine coolant temps of 200F +/- few degrees as optimal for efficiency and longevity in the modern 4stroke.

I've had great luck with temp control over the past couple years on my '10 husky. I have a thermobob with 190 stat, temp gauge, insulation around crankcase, tall skid/snow deflector, fan and most important a canvas radiator cover that I could employ while riding and adjust as conditions changed. 80-90% of all my riding the coolant temp was 190-200. When jumping into powder I completely covered the radiators. Periodical I would see 150-60 when bathed in snow and 225 on a slow climb. Never a hint of fuel or moisture in the oil.

 

[needpowder]

Tried my best to block off the back of the engine. Didn't work great. Still lots of gaps for snow to get in but should keep the constant spray of snow off the back of the engine. Also tightened up my engine jacket with a couple more grommets and zip ties. I'll know soon how much this helps (assuming the forecast is correct).

 

[needpowder]

Ref the original question, lots of research supporting engine coolant temps of 200F +/- few degrees as optimal for efficiency and longevity in the modern 4stroke.

I've had great luck with temp control over the past couple years on my '10 husky. I have a thermobob with 190 stat, temp gauge, insulation around crankcase, tall skid/snow deflector, fan and most important a canvas radiator cover that I could employ while riding and adjust as conditions changed. 80-90% of all my riding the coolant temp was 190-200. When jumping into powder I completely covered the radiators. Periodical I would see 150-60 when bathed in snow and 225 on a slow climb. Never a hint of fuel or moisture in the oil.

Why do do you need radiator covers if your t-stat doesnn't open until 190 degrees? I made some up out of plastic then figured they wouldn't do any good because of the t-stat. i'll bring em with me this weekend.

 

[dooman92]

Why do do you need radiator covers if your t-stat doesnn't open until 190 degrees? I made some up out of plastic then figured they wouldn't do any good because of the t-stat. i'll bring em sith me this weekend.

Good question. I also thought the stat alone would have resulted in more consistent temps but, it was not as effective without the rad cover. First the stat is not a complete block and the biggest reason is the the transfer of heat via convection in the coolant lines from the case to the bottom of the rads. The rise and fall of the warmed coolant in these lines will warm the rads and cool the case well before 190. When the rads are cooled down by snow the stat will close and the temps will drop quickly. I found covering the rads allowed temps in the rads to stay warmer and rise quickly back to stat temp when bathed in snow. I also had the void between the skid and case filled with a closed cell insulation which helped a bit. But, covering the rads was necessary in deep powder. Oh yeah, I removed the rad shrouds as well but, that was prior to riding in snow so don't know the impact of shroud removal... Hope this helps.

 

[Rush44]

If I could keep my motor above 160F all day in the pow I would be a super happy camper. That seems to be the temp where the motor starts to have pretty much no cold issues anymore. I remember before shielding and stats that my temps would drop to 90F in the deep powder sometimes.... caused a little overfueling and condensation to say the least lol

 

[dooman92]

If I could keep my motor above 160F all day in the pow I would be a super happy camper. That seems to be the temp where the motor starts to have pretty much no cold issues anymore. I remember before shielding and stats that my temps would drop to 90F in the deep powder sometimes.... caused a little overfueling and condensation to say the least lol

Yeah, 160 better than 90 but, I submit still to cold. Few things are as important to longevity and reliability as proper engine coolant temps. I'm sure many old wrenches have experienced the same but, I recall rebuilding my first prematurely failed 4s gas engine more than 40 yrs ago and seeing the devastating effect of a 160 stat and short trips. Temp control was the thing I focused on most when setting up my snowbike 3 yrs ago. It's a pita to cover and uncover the complete or partial rad but, without the covering the temps were unacceptable to me. The oil has to get hot in order to flash off any fuel or moisture that has made it to the oil. And it has to be a vapor in order to be carried out the vent tube by the hot crankcase air mixture. I like to see 200 coolant temps.

 

[needpowder]

175° to 185° all day long in deep snow--stoked!!

I knew I was in business as soon as I left the truck and watched the temperature slowly climb from 150 to 180 on the trail with 6 to 8 inches of snow on it. After about a quarter to a half mile I hopped off the trail climbing uphill through pretty deep snow--second gear pinned, and watched my temperature climb all the way to 200 as I was doing it--turned out and blasted downhill in deep powder and my temp stayed at 200 degrees. Turned uphill and my temperature started rising even more. Another couple hundred yards and i was at 210°. I turned around and shut my bike off. Pulled off my plastic radiater covers and started again. Temperature instantly dropped to about 180 then 175° going downhill. After that 175° to 185° give or take all day long. Thermostat opens at 177(so says thermobob, seems about right). Fan kicks on at 180--heard it pretty much every time i stopped.
I spent alot of time this week making a cover for the rear of the engine, packing foam around as much of the engine as I could, and tightening up my PST engine jacket by adding some grommets and zip ties.
The snow wasn't as light and blower as it can be and temperatures weren't very cold, but it was definitely deep, covering my entire bike and face shots going downhill. I think it's a pretty good indication and i am stoked! Heading up tomorrow morning for some more good times.
First pic is the radiater covers-slide up between my rads and enduro engineering rad guards.

 

[needpowder]

Different conditions slightly different results.

Wow. Today was epic! The snow was much lighter and dryer and temperatures a little colder. I was seeing cooler temperatures on my bike 150 sometimes 140 even. Put in one radiator cover and I started running in the 160s to 170s. Started to get a little hot on the trail on the way out. So I had to pull it. Overall very stoked and feel like I have a good handle on things for changing conditions. Really, really good conditions today. People were getting stuck on the flats.

 

[Dirtnut67]

So I have to ask. What is the material that everyone is using for the motor blanket or cover.

 

[Pedec]

So my 250 sx 2 stroke today was 105 to 119 and my thermbob is 130 so is it ok to run at 105 TO 119 on a 2 stroke or should I also look at covering radiators. It was cold today -28 and deep snow. The other day when it was -15 and not as deep of snow engine was running 137-150. Bike ran good all day just like when engine temps where higher. I am running avid carb heater and Lectron carb. Thanks for any help also wondering can 2 stroke run up to 200 with no problems this is first time I have had a temp gauge on dirt bike and was not sure what temperature bike was running before.

 

[wwillf01]

With a 2 stroke that's good I would not worry..

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[Chadx]

So I have to ask. What is the material that everyone is using for the motor blanket or cover.

Anymore, I'd go with one of the many prefabbed for sale, but if you want to do your own or need material for radiator covers, see post below...

http://www.snowest.com/forum/showpost.php?p=3552318&postcount=43

Radiator covers make all the difference. More me, they were off when on the trail and one or both were on when in the powder. My belief is you want your bike running at a temp where your thermostat is opening pretty often. If it is rarely getting up to where your thermostat opens, you need to keep working on your setup until it does.