DK Custom, a platinum sponsor, has some advice on cooling a Twin Cam and M8 engines. There is a nice list of recommendations on his web site (List). I was wondering if anyone has tried the modifications he recommends of removing the left side thigh protector and using his Tank Lift with a Deluxe Option on a 2017 Ultra Limited? Any comments would be appreciated.

 

I got my M8 in Feb so at this point most of my warm days have been only upper 80s maybe 90, so at this point I have not hit the high 90s of a Mississippi summer but so far in the days that have been upper 80 maybe 90 I have not found any complaints about needing to make the M8 run cooler

 

Other than maybe some CAT heat. Not seeing it as a issue on the M8 RGU. maybe it is different with the Oil cooled versions.

 

A company recommending their own product? Amazing!

Seriously, mine hasn't gotten hot enough to make me uncomfortable yet. And I've ridden it in some slow/stop/go traffic in 90 degree heat.

 

M8's are melting down all over. So hot riders are passing out. You have not heard. You must right now buy an aftermarket fix. This story plays out time and time again.
While you are at order a new crank haven't you seen the pictures on the net of the blow up engines.
And don't forget new locks for you bags or someone will steal them.

 

I actually used some of their “inexpensive” tips (removed all wind deflectors - had three different sets installed and the left side thigh protector) last weekend and I must say, rode my 11 RGU for three hours on Sunday and the bike felt so much cooler.

 

The felt heat of the M8 is much less than a Twin Cam. However, the actual heat that the engine is seeing is very close to the same as a Twin Cam.

This is NOT good from a performance or longevity standpoint. See M8 Dyno Charts and heat documentation HERE.

Excerpt-

The M8 reacted very similar to the Twin Cam on the dyno in regards to heat.

When doing comparative Dyno pulls it is important to have the engine temperature the same with every pull.

On both the Twin Cams and the M8, when the cylinder head temp crosses the 250* line power drops off, significantly.

We always get the engines heat soaked, then use the dyno fans to try and keep the temperature stable. However, just like on the Twin Cams, the M8 will go past the 250* mark very easily, even with the fans on. So there are times when we have to wait for the engine to cool down to get to our 240-245 range for accurate comparative pulls.

The upshot of all this is that the M8, while have less felt heat, still seems to have the same overheating challenges that the Twin Cam does.

How to reduce heat Report HERE.

 

ok, just playing Devils Advocate...regarding not good for longevity perception..17 years of TC's...what, maybe 100,000 sold per year as a SWAG? X 17....now in reality what % of the ~1.7 million sold have experienced shortened engine lifespans due to excessivley hot engine temps? I don't have a clue, but I don't believe it's as bad as it's being made to sound...and what % of those that did have issues could be attributed to poor maintenance and fluid changes, hopped up, ridden abusively, etc. I mean, Harley has been building these a looooong time and must be doing something right over gazillions of real World miles..just my perspective..not saying heat ain't the enemy because we all know it is, which is the reason the fan assist oil cooler was the first thing I bought and agree with doing things to help manage oil temps..but ain't throwing the kitchen sink of mucho dinero at my bike because I'm afraid of it being a ticking time bomb

 

I don't know what the numbers are.

I do know we get at least one call a week from someone with a Twin Cam that has run their engine at "normal" operating temps of 300-320*, that has less than 50K miles (many times less than 20K miles) that is having their engine rebuilt because it has failed a leak down test due to cylinder and/or valve problems from heat.

I do know that every one of these bikes was still running. HD has done an amazing job at designing them to keep running, even after suffering heat damage.

Just because it is running, and just because the owner does not notice the loss of power, because it occurred over a period of time, does not mean it did not suffer damage due to running at the "normal" 300-320*.

Perhaps it would be better to describe it by saying that when the temps cross the 270* mark there is above normal wear occurring. Maybe that is more easily accepted/understood than saying longevity is being reduced.

I am coming to the realization that many interpret reduced longevity to mean that the engine is going to blow up sooner than it would normally.

This is not what I mean. All parts wear out, and as they wear out tolerances get looser and there is a corresponding reduction in power and efficiency.

When an engine is subjected to high heat, those parts wear out more quickly, resulting in a reduction in longevity of useful (within tolerance) life, and there is a significant drop in performance.

It is really easy for most anyone to see how heat affects a Twin Cam. Ride a known route, somewhat aggressively, while the temperature, as displayed on the PV by ET, is between 180* and 240*.

Ride the same route, the same way, while the temperature, as displayed on the PV by ET, is above 270*.

The bike will be markedly more sluggish when above 270*. This is because of two main reasons:

1. HD has the bike set to retard the timing when it gets that hot, to try and cool it down to protect it from damage.

2. The metal in the engine is expanding at different rates (and too much) loosening up tolerances resulting in lower performance.

Instead of riding, this same thing can be seen by putting the bike on the dyno. Do some pulls with the ET at 220*-240*, then let the temp go up to 270* or higher, and do the same pulls. You will see a significant drop in horsepower and torque.


Thank you for the DA post. It has helped me to realize that many have not understood the term "reduced longevity" as I have meant it, and I will be more clear in the future.

 

I don't have time for science.....felt heat, perceived heat, heat subtracted by wind divided by speed.................my ultra limited is just fine! Is it a lil warm on the right side.....yes, because of the CAT. I'm putting on a cool flow fan from Harley because I test rode a bike with one on and I could feel the difference. I don't doubt that the tips work........but I'm fine. I'll say this. I've been on this forum like 12 years......and here is what I notice. There is a forum opinion and then there is an opinion in your local town/city/state. And these opinions usually are no where close to each other. I haven't run into anyone having heat issues to where they need mods......except for on the forum. And I'm not removing wind deflectors! For real? Like the ones on my fairing? Man, those are the best things ever---direct them where I want and the wind from them is amazing.

I'm with mjwebb on this one. I loooooooove this forum. But sometimes we have to stop reading so much and just go ride and talk to ppl face to face about their opinions also. Truth be told, my local riders have never heard of LRS, C&C solo, Ohlins, Ward's Fans, etc.......these dudes buy their bikes and ride and have no complaints about their shocks, seats, shields, heat. I know guys who ride 50 states.....and they are just fine with their Harleys right out of the crate. But I do appreciate the forum costing me alot of money on companies like LRS, etc. It's been worth it. I do have the cooling wings from DK........but that was to stop the wind from coming up over my tank to fix some buffeting problems...at least that's what I bought them for and it worked a little.

There are more M8 problems on this forum than I've seen from the hundreds or close to 1,000 that I've heard of or seen riding in 4 or 5 different cities in NC to diff shops, hang out spots, etc.

OP, my rant wasn't directed at you bro!!!! Sorry if it sounded like it. I'm just speaking in general. Ride safe bro!