M8 Heat

Jack Klarich

Gold Member
Oct 11, 2016
18,135
15,215
Jacksonville, FL
Name
Jack
Over the next month I am going to reinstall a stock air cleaner

I want to see what this change will make in over all engine heat

With the Power Vision I will track it on the same road with and with out the change

If I am right there will be very little change

Why? The M8 runs not nearly as lean out of the box as does the Twin Cam

I am seeing temps @ 288 degrees when the Engine Management kicks on

This is with the Love Juggs on and the air deflectors from D K Customs

I have put my stock (gutted ) mufflers back on ditching my modified Fishtails for now

My mileage did go down .3 mpg

Not a big deal, how ever this also shows me the M8 can be tweaked very easy

The M8 also cools down much faster, dropping About 1 degree per minute after shut down

The Twin Cam holds the heat much longer

Ever heard of a heat soaked Twin Cam having trouble starting?

If not you probably will

With the DK Customs Outlaw air cleaner, PV Tuner, heads vented to a catch can with a drain and modified fish tails I was seeing 44.7 mpg with Engine Temperatures of 300 degrees

After installing the D K Customs air deflectors and Love Juggs Mighty Mites the temp dropped a good solid 25 degrees this past summer

I will post my results in a couple of weeks, good or bad;) ( The M8 has bigger and full circle) cooling fins compared to engines in the past

I am sure the engineers @ HD know with the bigger 107, higher compression the M 8 would run hotter

Yet the metals in the engine seem to take this heat pretty good

Time will tell

I have 15,200 miles on now ( 9,000) since the new parts were added

I have maxed out the mpg IMO @ 44.7 I was hoping for more;)
 
Let me get this straight Jack, are you reinstalling the OEM breather tubes & routing them back to venting into the throttle body like stock?
 
Let me get this straight Jack, are you reinstalling the OEM breather tubes & routing them back to venting into the throttle body like stock?

Just the stock air cleaner

I would NEVER run that mix thru the throttle;)

I just want to see the engine temp and performance or lack there of so I can document it

I already know with the fishtails and air cleaner it ran a bit hotter and leaner

But it was NOT as lean as a stock Twin Cam so I know the M8 has tons of tuning potential
 
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My unofficial test results so far

Mileage has gone down .75

Temperature went up by 15 degrees

The sound level went down

The stock air cleaner is pretty restrictive IMO

I will be swapping back to the DK Customs outlaw air cleaner

I will keep the stocker in case of needed warranty work

This way in hopes the MOCO cannot void my power train warranty:p
 
My unofficial test results so far

Mileage has gone down .75

Temperature went up by 15 degrees

The sound level went down

The stock air cleaner is pretty restrictive IMO

I will be swapping back to the DK Customs outlaw air cleaner

I will keep the stocker in case of needed warranty work

This way in hopes the MOCO cannot void my power train warranty:p

Jack, in your opinion, would installation of an external breather give them cause to void the warranty?
 
Jack, in your opinion, would installation of an external breather give them cause to void the warranty?

Just ''Asking'' a dealer if such and such will void the warranty....

Will void the warranty.......:laugh:
 
Jack, in your opinion, would installation of an external breather give them cause to void the warranty?

I dunno

I do know there is a lot of fear mongering over the EPA fines that HD had to pay

Some are saying ANY changes made to 17 and newer bikes HD must void there power train warranty

I aint taking chances

The breather could be among those changes

The breathers are like your pcv set up on a car

The oily vapors with water mist is supposed to be sucked back thru the induction modules to be re burned in the engine

That may work fine for a 4 cylinder or bigger auto engine, NOT in a 2 cylinder air coole motor cycle engine JMO
 
I dunno

I do know there is a lot of fear mongering over the EPA fines that HD had to pay

Some are saying ANY changes made to 17 and newer bikes HD must void there power train warranty

I aint taking chances

The breather could be among those changes

The breathers are like your pcv set up on a car

The oily vapors with water mist is supposed to be sucked back thru the induction modules to be re burned in the engine

That may work fine for a 4 cylinder or bigger auto engine, NOT in a 2 cylinder air coole motor cycle engine JMO

Any changers to the engine intake that is NOT EPA Approved is considered tampering with smog/pollution controls... A federal offense...Very few dealers would touch that with a ten foot pole....Especially after Harley got hit with a 15 million +dollar fine last year....
 
Any changers to the engine intake that is NOT EPA Approved is considered tampering with smog/pollution controls... A federal offense...Very few dealers would touch that with a ten foot pole....Especially after Harley got hit with a 15 million +dollar fine last year....

While this is true

Harley burned itself by installing tuners they knew were NOT EPA OK

This is going to be ugly in the end IMO

Said dealer will be fined and maybe lose its franchise

Even if some dealers step up to warranty work THIS TOO is ILLEGAL

Lets see how this plays out in a court JMO

I will return my intake to stock and take my tuner ioff before any warranty work is done to my bike;)
 
I dunno

I do know there is a lot of fear mongering over the EPA fines that HD had to pay

Some are saying ANY changes made to 17 and newer bikes HD must void there power train warranty

I aint taking chances

The breather could be among those changes

The breathers are like your pcv set up on a car

The oily vapors with water mist is supposed to be sucked back thru the induction modules to be re burned in the engine

That may work fine for a 4 cylinder or bigger auto engine, NOT in a 2 cylinder air coole motor cycle engine JMO

So if you have to visit the dealer for warranty work, I guess you need to remove any mods they may find questionable, like an external breather.
 
So if you have to visit the dealer for warranty work, I guess you need to remove any mods they may find questionable, like an external breather.

Most dealers won't care, The problem might arise if your out of town and a major part goes south, And the dealer has to call in a Harley rep to ok the warranty work..Theres where it could get touchy, :Shrug:
 
So if you have to visit the dealer for warranty work, I guess you need to remove any mods they may find questionable, like an external breather.

Most dealers won't care, The problem might arise if your out of town and a major part goes south, And the dealer has to call in a Harley rep to ok the warranty work..Theres where it could get touchy, :Shrug:

Yes

What Bob said
 
My final take on the M8

It does fine with an air cleaner change and exhaust change

It does not run TOO lean in fact Kevin has the read ots that prove even in stock form these engines run closer to 14.6 than any other HD engine

That said, I can change back to my D K Customs air cleaner and pick up the lost mpg at a price of a bit higher engine temps

IMO this is not a big deal with the M8 to date

I have over 9k miles on now with this set up and still running strong

I wanted to see what the changes may be

Now I know, but I am keeping a stock air box just in case

I am not too worried about the knocked out exhaust

The tuner would come off the bike before warranty work

'To date I do not think the dealer scanner can detect how many times the ECM has been re written

I hope I am wrong, I have 2 copies of a stock tune any wa

I dunno why the P A catalog says with a K N air filter you need to have a new download in your ECM

I doubt the bike would ever run out side of EPA parameters with just an air filter change while still using the stock air box and head breather tubes in place JMO
 

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