M8 Engine Temps
Road Captain
Joined: Sep 2014
Posts: 718
Likes: 210
From: IL
The common crankpin keeps the cylinders closer together than dedicated journals on Japanese V-Twins, so Harley cylinders are less exposed to airflow. Looked at my son's Yamaha Cruiser and there's a big difference in cooling wind exposure. I just installed Love Jug fans for a pretty penny and called it a day. Should help cylinder life, oil life, and retain performance during heat waves.
Check this out, you can do fast forwarding, but interesting findings, especially towards the end:
Grand HDF Member
Joined: Aug 2020
Posts: 4,798
Likes: 5,889
From: Knoxville
My M8 runs well in temperatures of 35 degrees and up, especially for the controller.
Temperature is key for that part of the system. Its located midway, up top behind the fuel tank.
Too cold and the bike literally doesnt start. Sometimes the controller gets hot, but a shut down outside an eatery or bar usually suffices to reengage the warmer temperatures in about an hour.
Temperature is key for that part of the system. Its located midway, up top behind the fuel tank.
Too cold and the bike literally doesnt start. Sometimes the controller gets hot, but a shut down outside an eatery or bar usually suffices to reengage the warmer temperatures in about an hour.
Road Warrior
Joined: Nov 2022
Posts: 1,541
Likes: 543
From: MN
I had the love jugs. Personally for me, I wasn't impressed.
Check this out, you can do fast forwarding, but interesting findings, especially towards the end: https://www.youtube.com/watch?v=KnJcJwA6c_k
Check this out, you can do fast forwarding, but interesting findings, especially towards the end: https://www.youtube.com/watch?v=KnJcJwA6c_k
Say more why you weren't impressed. Did you measure pre & post temperatures? Oil? Rear cylinder head?
As long as there are interweb claims, here's the OEM's claims ---> https://love-jugs.com/the-debate-abo...owess-is-over/
Last edited by Old New Rider; Aug 1, 2023 at 02:01 PM.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,925
Likes: 8,027
From: poway
Say more why you weren't impressed. Did you measure pre & post temperatures? Oil? Rear cylinder head?
As long as there are interweb claims, here's the OEM's claims ---> https://love-jugs.com/the-debate-abo...owess-is-over/
As long as there are interweb claims, here's the OEM's claims ---> https://love-jugs.com/the-debate-abo...owess-is-over/
I'm not to hot on the checking temps video either. Pun intended...
Nether is of any value running down the road.
Road Warrior
Joined: Nov 2022
Posts: 1,541
Likes: 543
From: MN
Maybe I'll borrow an IR gun and see the diff with jug fans on and off. The video guy is right about cooling all the engine oil through his oil cooler, though, while Harley just does the heads without fans. Better than nothing, but still not much.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,925
Likes: 8,027
From: poway
What is funny about the vid is that if you watch him point the temp sensor at some point, the number bounces around and he seems to pick a high temp at times and a low temp the others.. He night have picked some in the middle to.. To get any kind of decent reading you need to pick a black spot and make it consistent between measurements.. Still there are other factors also involved.
Road Warrior
Joined: Nov 2022
Posts: 1,541
Likes: 543
From: MN
I give the guy credit for effort, but that's not an accurate reading of air cooled cylinder head temp. Need a thermocouple for that - embedded in the rear head if you can tie into the ECM readout.
Otherwise we use bulk oil temp as a general indicator. I can't find an oil temp gauge dipstick to fit the Heritage M8 107, though.
It's not a bad idea to run a 2nd oil cooler with fans that cools all the oil, not only the heads like the stock oil cooler does. And does not with the bike sitting still.
But I know adding fans to cool the cylinder fins helps a lot when sitting still. Forced convection heat transfer basic experiments from textbooks prove it.
Which cools more? Significantly more? Don't know, don't care. At least I've got something cooling when stopped.
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HDF Community Team
Joined: Oct 2018
Posts: 4,347
Likes: 3,392
From: Seattle
I'm not really all that concerned about temps myself, but when DK Customs comes out with their Softail radiator fan I'm gonna grab one.
I'm pretty sure the golden radiator mesh that I got on my bike atm, is not very good for air flow at low/mid range speeds, especially when I'm out carving up twistie roads.
Engine temp can get really hot riding twisty roads, and I'm hoping the fan assist helps.
I'm pretty sure the golden radiator mesh that I got on my bike atm, is not very good for air flow at low/mid range speeds, especially when I'm out carving up twistie roads.
Engine temp can get really hot riding twisty roads, and I'm hoping the fan assist helps.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,925
Likes: 8,027
From: poway
I'm not really all that concerned about temps myself, but when DK Customs comes out with their Softail radiator fan I'm gonna grab one.
I'm pretty sure the golden radiator mesh that I got on my bike atm, is not very good for air flow at low/mid range speeds, especially when I'm out carving up twistie roads.
Engine temp can get really hot riding twisty roads, and I'm hoping the fan assist helps.
I'm pretty sure the golden radiator mesh that I got on my bike atm, is not very good for air flow at low/mid range speeds, especially when I'm out carving up twistie roads.
Engine temp can get really hot riding twisty roads, and I'm hoping the fan assist helps.