When I installed my Thundermax about 7 years ago, I was getting 280-300km (around 180 miles) out of a tank of gas. Since then, the only thing I've done to the motor is added cams (Wood TW-555). I was told that since it was basically still stock and had the stock throttle body, to just let the T-Max do it's auto tune thing it should be good, but now I'm lucky if I get 180km (110 miles) out of a tank, which is less than 25mpg like, less than HALF of what everybody else reports getting! Something's not right here! BUT it runs great, spark plugs look fine, and no fuel leaks. You are supposed to be able to adjust this thing for good fuel economy AND power. Last year, I adjusted the AFR a few degrees lower to to try and nip this in the bud, but all I did was lose a bit of power. As you can see from the maps I've attached below, my offsets say I need more gas. This issue actually started before I added cams and has sort of been a gradual loss of fuel economy over time. Can anybody tell me what gives? Do I need to look at ignition timing or other factors as well? Anyone have any thoughts on this? I'd be glad to attach more maps if anyone wants to have a look or to send someone my whole mapping file to look at.

I'm going to post this over at Harley Tech Talk forums as well and see if I can get some answers. I need to either get this fixed or I need to start saving for a Power Vision.

@1280-1792RPM


@2048-3840RPM


@4096-5120RPM


@5376RPM onward

 

Somebody bum doped you. You most definitely need a new base map to go with new cams. Your lucky your bike runs at all considering how far off the you need was from the one you stated with....

 

Aside from the terrible gas mileage, it actually runs great! I did modify the timing a bit to get rid of some decel pop I was getting, too.

So, new base map based on my cam and let 'er auto tune? Run Auto IAC as well, with the map change, correct?

I notice you have a similar motor build to mine (.555 lift cam, 2-1 exhaust), only you have the 103ci motor. Do you think I should be running the same or similar base map to yours? Which are you running?

 

You can lean it out a little more but with the cam change, your CCP likely dropped.. It could probably use a little more timing. Have you tried a newer map that matches closer to your build?? Your current map says N/A which typically means it's been superseded to a newer map..

 

No, I haven't tried a new map. Just been working with the old one. But as I scan the database of available base maps, nothing there really seems to match. Closest thing seems to be for 95ci build with Redshift 557 cams and Thunderheader or D&D 2:1 exhaust (map 619 or thereabouts). Am I missing something? Is there a more abundant database elsewhere? And yes, I do get a message that comes up whenever I go into the database which looks like this:

 

Whats your build?

 

96B
Stock TB
Wood TW-555 cam
SE stage 1 intake kit
Ness-Comp by Magnaflow 2:1 exhaust

 

Well. Going from a 30 deg intake close to 41 deg is going to kill your CCP by about 10 psi.. Like you are going from about 170 psi down to 160.. Low cranking compression is not good for mileage but yours is really in the dumps. I would try Map 894 as it is about the closest to your build.. Don't use 95 ci builds as their stoke is different and it plays a big roll in ignition timing as does compression ratio..

Feed the info to Q1SVT over on HTT and see what map he suggests.. He's pretty good at picking starter maps.. When choosing maps, it's almost always better to use maps that are higher numerically as the guys building the maps are finding ways to improve on things like mileage and cold starting.

 

Dude! You're in my head! I'm already working with that guy over there and 894 is indeed one of the maps he suggested! Fate?

 

No not really.. We both know how to pick maps.. For me the important parts are basically a stage 2 96.. Any cam that is within a few degrees of what you want will work.. Not sure who told you you could get away with the cam change and let the Tmax do it's thing but they are wrong when the cam change is drastic with stock to a 555.. Way different cams..