Thundermax
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Tourer
Joined: Jul 2007
Posts: 351
Likes: 18
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Thundermax
Installed a Thundermax 50 on 2011 CVO SG with 2:1 D&D Fatcat. With 4" Rhineharts and PCV was getting about 40 mpg. Only put about 200 miles on bike since the new install, but now getting 33 mpg. Hope it will get better after riding it more. Am I living in fantasy land? Runs and sounds great though.
Road Master
Joined: Aug 2007
Posts: 837
Likes: 35
From: Northern California
It makes sense that the mpg dropped when going from stock ECM to T-Max. Stock H-D runs lean of peak and wicked hot. T-Max is going to significantly enrichen the mixture to rich of peak. My gas mileage dropped as well. On m Dyna, around town is 33, highway is closer to 40.
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Tourer
Joined: Jul 2007
Posts: 351
Likes: 18
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Bet your are correct. When I did the math riding 12,000 miles per year and the difference in fuel cost of 40mpg vs 33mpg, it comes out to about $250 a year or just over $20 per month. I feel stupid for even worrying about it now. Runs too good to even consider going back to PCV. Thanks.
Cruiser
Joined: Jun 2007
Posts: 189
Likes: 1
From: Alberta Canada
Quick question guys, if you adjust the A/F ratio to lean out the 20% throttle to give a little better MPG at cruising speeds, wouldn't the auto tune feature over right them again??
Still trying to learn as much as I can on the tmax.
Both my 09 Street glides run awesome, just found a massive drop in MPG's.
Thanx in advance
Still trying to learn as much as I can on the tmax.
Both my 09 Street glides run awesome, just found a massive drop in MPG's.
Thanx in advance
Road Warrior
Joined: Sep 2009
Posts: 1,267
Likes: 6
From: Northern Michigan
Quick question guys, if you adjust the A/F ratio to lean out the 20% throttle to give a little better MPG at cruising speeds, wouldn't the auto tune feature over right them again??
Still trying to learn as much as I can on the tmax.
Both my 09 Street glides run awesome, just found a massive drop in MPG's.
Thanx in advance
Still trying to learn as much as I can on the tmax.
Both my 09 Street glides run awesome, just found a massive drop in MPG's.
Thanx in advance
The autotune will adjust to your new AFR values not the old ones.
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Cruiser
Joined: Jun 2007
Posts: 189
Likes: 1
From: Alberta Canada
Thanx, but it seems like they are dialing themselves in now.
Power is still very good and MPG's have come back up as well.
Getting between 250 - 300 KMS to a tank of fuel.
Power is still very good and MPG's have come back up as well.
Getting between 250 - 300 KMS to a tank of fuel.
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Tourer
Joined: Nov 2010
Posts: 305
Likes: 1
From: Fairmont West Virginia
I've ran a tmax for over a year now and my mileage always seems to get better after it auto tunes for a while. Might be that once I've gotten used to it I don't twist it hard as often as I do when I try a new map or make changes. 
Stellar HDF Member
Joined: Jun 2009
Posts: 3,423
Likes: 421
From: Northern, Ohio (Yuck!)
Only problem i had with my TM was low mpg. Was around 35. Just got done updating the firmware to 2012 version and I adjusted the map. Raised the cruising AFR from about 2400 rpm to about 3400 rpm to around 13.8.
I only have about 150 miles on this new setup, but I think the mileage has increased dramatically.
Time will tell...
Also if you had the miles to empty problem, the newest firmware fixes that.
I only have about 150 miles on this new setup, but I think the mileage has increased dramatically.
Time will tell...
Also if you had the miles to empty problem, the newest firmware fixes that.
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