Lackluster Cooling System Performance

[Wattsthematter]

Does anyone know the id/od of the rubber coolant hoses being used on the EX? Looking to do a complete cooling system relocation with two front radiators like a traditional dirtbike. I ride my Varg only as a supermoto and although i haven’t had any Powertrain overheating issues just yet after i ride on average my motor side plate/case is seeing 140 degrees. that temp is measured immediately after i get off from a spirited 10-15 mile ride.

Being in central Florida with such high average humidity percentages and overall temps, to really be able to push the bike and have the kind of fun with it I want to have i have no choice but to completely rework the cooling system as well as have an engineer design me some motor plate/ gearbox plate heatsinks. I bought spare motor and gearbox plates that I’ve been taking with me to get quotes from engineers/machinist to take measurements from for the basic bolt pattern/ part outline. I want to get at least 25mm tall fins and 5-6mm in thickness of the fins themselves. Both side plates as well as the inverter case get on average 130-140 degrees Fahrenheit. I also want to see if it’s possible to remove the inverter from its metal case to put it in a heat sink engineered like case or possibly gluing some heatsinks on the exposed areas on the outside of the frames on each side.

I can’t help but think that when they were testing these EX prototypes they must have not tested in very heat saturated climates like Florida’s brutal but very common 85-95% humidity as a daily average throughout a majority of times through the year. I’m going to be doing everything in my power to aid this thing in the cooling department. I will update the thread with pics and mod details, followed by real world results.

I love my Stark and think it’s an incredible machine but it is far far far from being a fully problem free, well thought out design for all climates world wide. In my opinion there’s to much “Fluff” from too many fanboys out there. Like i said though “no doubt“ i love my ex for so many cool reasons but there are massive oversights in the cooling performance department and for the people who truly intend to street this bike as the primary mode of use It’s causing legitimate daily usability issues.

 

[markhamr]

I am not sure if you are chasing something that is not there.
I would be asking some motard riders what they do to beat the heat,
they put a lot of heat stress on there bikes.
How hard are you riding it / what gearing / settings and more all matter
The retro fit idea does not seem good to me.
Make sure everything you have is in order first.
I have a mx1 but do not run it on full noise,
The first time i did it only went 900mtrs.(thermal shutdown)
on 60 its fine.On steep fast uphills up to 130kph
multiple hard pulls on the drivetrain hot humid too.
I am no fanboy read my posts.
Most issues can be solved just don't beat yourself up going down the wrong road with it though.

 

[vic321]

You are on the wrong path. The air humidity has a very little effect on cooling properties. Q=m*cp*Delta (t). Where cp ist the specific heat capacity. It is 1,005 for absolute dry air, and 1,030 for 100% humidity. So a difference of 2.5 %.

 

[vic321]

The Stark was build in Spain, where high temperatures are common. And 140 Fahrenheit is just 60deg Celsius. That is nothing for an engine. Sure a cooler engine could drive more efficient, but if you could decrease the temperature from 60 to 40 dec C, you would not feel any effect. Especially that nobody rides with the full 80HP.

 

[Erwin P]

I see that 60C as well on my powertrain and it does not bother. Has done that for almost 2 years, also with cold weather in the sand.

I would first try to find if it overheats, it won't explode or something, it will just loose some power or if you ignore that might go into limb mode. And even then, it's the battery 99% of the time, not the powertrain. The battery isn't watercooled so whatever you do about the liquid cooling won't affect it.

Edit: The way i see it you're going after the most expensive way to not solve the problem.
You need to get more cooling around the battery. Let us know if you solve that. If you're just streetriding or SM you could consider removing the skidplate. That's very thick and around a significant part of the battery.

 

[markhamr]

kool problem solved then.
There isn't one.

 

[Erwin P]

Well it does have cooling problems in SM. However that have little to do with the powertrain, but more the battery.
Especially when 30min moto, 30min charging... repeat 5 times. We use fans during charging to cool the battery a bit and that does seem to work a bit to stretch how many laps we can do before power is going down.

 

[markhamr]

Mine was a battery issue.Maybe the sensor or even firmware.
I have sprayed water on inverters to lower temps shed system cheap chinese inverter.
It helped a lot.

 

[Erwin P]

In the beginning overheating issues were a lott more common. Some updates later we see way less overheating issues. Also in the beginning we saw are lott more acute shutting down due to heat. Now it's more reduced power.

Edit: But we do love a good build, so do proceed, just know the result might be more of a cool gimmick than the result you wanted.

 

[markhamr]

My bike is a early edition
I ran it out of the box stock that's when I had most of the issues
I have my stark going pretty good now but still firmware problems,
I can get around most of them .just annoying and something I do not need on race days,
by the end of the year I am hoping to be on a 1.2 and from what I have learnt
smoothing sailing ahead besides it is the only real mx e bike out there.
I even thought of just building my own from scratch but getting it certified is another problem
and i wouldn't be selling them so
If anything maybe a bespoke battery would be the way to go.Same case leave the cells out on top
oops that is cheating But i doubt there going to weigh it.Or even do that run some ballast.
Steel skidplate ?Besides it is all fun to me.
Watts bike doesn't need anything maybe just a coolvest for him when hes out riding it.
I am not sure if you are chasing something that is not there. quote.

 

[vic321]

How about spraying water on the battery from a bottle?

 

[vic321]

Of course demineralized water.

 

[Erwin P]

Spraying water with a bottle is rather inconvenient during riding. You could however having perforated tubes spraying a mist over it. The evaporation heat would cool the battery, if not everything is blown away directly. And why demi water? That little bit of deposit you get during a riding day is easily sprayed of with normal cleaning.

I however think that normal riding in the heat will give you problems worth working with tubes etc. I think the most effective thing you can do is remove the bashplate or at least the damping under it.

 

[vic321]

Not during riding, during charging.

 

[Erwin P]

That sure would help some. Best would be a constant supply of a thin layer of water. Best handheld option is something like this to apply a thin layer that then can evaporate. Only very little heat is transmitted through normal conduction that's why it will cool more with an ever maintained thin layer of water then when you would actually ride it into the water.
The latter might also be possible in Florida although i heard some issues with aligators.

 

[Wattsthematter]

I very much appreciate all the comments/suggestion. Yes, i do agree with all of you guys that are saying by aiding the motor/controller/inverter/gearbox I’m not going to see any performance benefits. However I’m not really looking to gain any performance rather just keep the power system at a healthier and more sustainable constant temperature. Also, as crazy as it may sound i do ride around 85% of the time in 80hp and may switch to 65hp for a smoother throttle application when I’m in traffic and have no choice but to just cruise so to speak.

My gearing setup I finally settled on and am most happy with is 15t/45t, and so far to date as of my ride home this evening Im sitting right at 892 miles total on the clock.

So far i have tried 12-13-14-15t front sprockets in combination with 48-46-45-42t rear sprockets.

My average speed throughout 85% of my joy rides/commutes is between 45-55mph and with my 15/45 gearing wide open throttle will allow me to hit 103mph before reaching the motors max rpm cutout.

At the 80hp power setting the bike can still pull up the front end from 45-55mph which again is where i find myself at a majority of the time. Having the freedom and ability to still be able to power wheelie up to about 85mph definitely makes all my rides so incredibly enjoyable and addictive. My EX got swapped to my warp 9 supermoto wheels/tires while i was finishing up the paperwork at the dealer. The off-road wheels/tires don’t have 20ft on them from pushing it out of the showroom and into there shop to switch them before i loaded it up to take it home. If I’m completely honest my EX will probably never see a single blade of grass or any kind of off-road adventure. I live in a pretty urban area and really enjoy my asphalt jungle riding. I have 3 supermoto bikes all of which I have done the same with and never have taken them off-road not even once. I have a 2024 Beta 430 Race Edition and a 2024 KTM XC300 and now the 25 Varg EX, i just rotate through them all throughout the week to always keep all my rides fresh and fun. And yes both the Beta and KTM are registered, have plates and are all fully insured.

So back to my Varg EX cooling system desires. Throughout all of those almost 900 miles thus far the one component on my Varg EX that hasn’t gotten really much above ambient has been the battery. By far the single hottest component is the motor. I’m seeing 140 Fahrenheit as kind of my normal average for every ride. I’d love to just keep it possibly 10-20 degrees cooler if it all possible. Not for any gains per say but more so for peace of mind that I’m not over working the components and all the bearings.

I value all feedback and apprecite all the suggestion/input. I will update the thread as i start to make changes after i have made all of my bone stock temp. logs that I’m creating over the next few weeks trying to establish a bulletproof set of baseline numbers/temps so that when i am ready to start modifying and making changes i can verify that I’m actually making improvements or if i am heading in the wrong direction I can immediately be able to change course and try to point myself in the correct direction towards better efficiency.

 

[Erwin P]

Why do you want that temperature to be so low and have you compared it to your Beta 430? I think you will be shocker by how hot that engine cases get. What i want to say is, what are you basing the lower numbers you want on?
That powertrain has a temperature alarm wich is set there for a reason, and since you're not hitting it you're in operating temperatures.
Is the cooling fan running constantly during all of your rides? If not even the system thinks it's well within operating temperatures.
Have you tried reaching out to Stark about what are the acceptable temperatures?

This kind of reminds me of people removing the thermostats from their ICE bikes so they constantly have more cooling. Wich in turn makes the cylinder too small for their piston, leading to extra wear. Combustion temperatures go down wich leads to more carbon deposits wich is leading to more wear.
It won't be as dramatic on your Stark, but bearings are chosen with a specific freeplay for specific temperature in mind. Running below that will actually have the motor have too much freeplay.

The power level also doesn't directly leads to overheating. Even if you wheelie part of the time, streetriding still is pretty relaxt. SM is fighting for every single bit of speed you can get and gives not a second for the battery to ''rest''. That's why you will probably not run into problems in your setup.

 

[Wattsthematter]

That sure would help some. Best would be a constant supply of a thin layer of water. Best handheld option is something like this to apply a thin layer that then can evaporate. Only very little heat is transmitted through normal conduction that's why it will cool more with an ever maintained thin layer of water then when you would actually ride it into the water.
The latter might also be possible in Florida although i heard some issues with aligators.

View attachment 14644

Why do you want that temperature to be so low and have you compared it to your Beta 430? I think you will be shocker by how hot that engine cases get. What i want to say is, what are you basing the lower numbers you want on?
That powertrain has a temperature alarm wich is set there for a reason, and since you're not hitting it you're in operating temperatures.
Is the cooling fan running constantly during all of your rides? If not even the system thinks it's well within operating temperatures.
Have you tried reaching out to Stark about what are the acceptable temperatures?

This kind of reminds me of people removing the thermostats from their ICE bikes so they constantly have more cooling. Wich in turn makes the cylinder too small for their piston, leading to extra wear. Combustion temperatures go down wich leads to more carbon deposits wich is leading to more wear.
It won't be as dramatic on your Stark, but bearings are chosen with a specific freeplay for specific temperature in mind. Running below that will actually have the motor have too much freeplay.

The power level also doesn't directly leads to overheating. Even if you wheelie part of the time, streetriding still is pretty relaxt. SM is fighting for every single bit of speed you can get and gives not a second for the battery to ''rest''. That's why you will probably not run into problems in your setup.

I appreciate all your input! Some good points in there for sure.

I really cant compare my beta‘s 4t or the KTM’s 2t engine temps as obviously any IC powerplant is surely going to run hotter for all the more than obvious reasons. However I’m just spitballing saying i want to get the temps down 10-20 degrees as at the 130-140 im currently seeing I can barely even touch the outside cases without burning myself. I’d just like to be able to keep it within a range to where its more along the lines of being warm-hot but not to the point to where it actually can burn my leg when wearing shorts or whatever. I plan to install 4-5 different temp probes all around the bike that will give me real time (as I’m riding with air moving/flowing) temperature data from all the components i have the probes temporarily attached to. Those numbers will be my baseline to truly know if all my future plans truly do make a difference and or maybe even in some cases i could definitely possibly cause something to heat up even more as I’m not claiming to be an electrical engineer or aerodynamicist. I fully expect to probably do a bit of both throughout my journey of trying to reach more acceptable operating temperatures. I will certainly be completely transparent on both my success and failures along the journey.

I can totally say i would agree with you that the I’m very sure Stark engineers selected the appropriate bearings/bushings and accessories etc to be able to handle and support whatever the bikes set operating temps are aimed to be within as well as whatever margins all there testing revealed to be the best range. I actually did email Stark in what those temps are and what temps are within there optimum operating range for the best overall performance as well as what should be the highest temp that can be sustained before you start possibly contributing to shortening the power systems multiple components life in terms of looking in the long term data. But of course even though i sent that email repeatedly 3 times i got zero response, which i definitely was expecting.

Also, I am just making the assumption that reduced heat within the motor/controller/powertrain/gearbox etc “should” make for any overall happier and longer lasting electric operating system as a whole. It’s my understanding that the main enemy of sustainably long lasting electrical components is the ability to have a very good handle on how much heat they are constantly having to work within as well as limiting the amount of time spent above what are considered to be the maximum safe continuous temperatures. Obviously lowering it to an extreme would be even possibly detrimental due to there needing to be like a base operating temperature that all the grease/oil/lubricants need to see in order to even begin to work as they are designed to and to provide the friction reducing action they were created to combat. However i don’t see 10-20 degrees as being out of that range of normal operation.