Top end big bore - compression not what it should be?
Seasoned HDF Member
Joined: Oct 2019
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From: OH
My interpretation of the DTT directions lead me to settings of 5 & 7
EDIT: I should add that my engine is similar to yours
570G`s / 3cc domes / .030 gaskets
Last edited by eighteight; May 25, 2022 at 03:42 AM.
Grand HDF Member
Joined: Sep 2017
Posts: 4,359
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From: Dubuque, IA
I can tell you from experience and Hammer Performance dyno tests you'll get the same torque curve but higher numbers on both ends running the Rush slip ons over those SEs or the old cycle shacks. In your case, the 1.75" baffle. 2" for better top end hp.
Those compression calculators are good for a general idea but aren't perfect p!us there's other factors that can affect final numbers the least of which is the tester.. Mine erred slightly the other direction. I should be 205 and got a strong 210 cold.
Rush dyno test
Note they're doing just short of 120hp on a sporty build. The test pipe, the patriot defender, is the fatcat of sporties. The 3" slashdowns are the exact same slip ons used on the softails and use to be widely used by dealerships til the EPA crackdown. You won't find a better slip on for that bike. I ran them on mine as a stage 2 with the 570s and still have them. I'm going to test them on my 127/126 build one of these days.
Yes the 570s are a 2800 to 5800 rpm cam. What you do below 2800rpm is more dependent on exhaust, compression, and head flow etc. for cylinder fill. I swear, while the tman 590s have a 3° later IVC and don't come on til more like 3200, there still stronger below that til it does come on the cam. But I'm also running heads that flow 310+ cfm. Better than most here will ever see.
Those compression calculators are good for a general idea but aren't perfect p!us there's other factors that can affect final numbers the least of which is the tester.. Mine erred slightly the other direction. I should be 205 and got a strong 210 cold.
Rush dyno test
Note they're doing just short of 120hp on a sporty build. The test pipe, the patriot defender, is the fatcat of sporties. The 3" slashdowns are the exact same slip ons used on the softails and use to be widely used by dealerships til the EPA crackdown. You won't find a better slip on for that bike. I ran them on mine as a stage 2 with the 570s and still have them. I'm going to test them on my 127/126 build one of these days.
Yes the 570s are a 2800 to 5800 rpm cam. What you do below 2800rpm is more dependent on exhaust, compression, and head flow etc. for cylinder fill. I swear, while the tman 590s have a 3° later IVC and don't come on til more like 3200, there still stronger below that til it does come on the cam. But I'm also running heads that flow 310+ cfm. Better than most here will ever see.
Last edited by 60Gunner; May 25, 2022 at 10:09 AM.
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From: poway
Wow, thats amazing... I removed carb from manifold, put jumper cables on my battery connected up to my little Toyota's car battery (not running of course) and re-did the compression test. Now the gauge is reading 200psi front and 200 psi rear! That's not cheating is it? 😁
So I guess the 570 cams are getting enough compression. The AFR has already been very quickly evaluated on the dyno up to 3500rpm (NO full throttle or heavy load) and with my 46 pilot, 195 main and 3.5 turns out on the mixture screw I was between 12 and 14 running through the gears. The Tuner would not do a full tune until 1000 miles, so that's all the tuning info I have. DTT settings now on 2 and 2.
What else would you suggest doing to get the most from the 570s? Feels like something is really holding them back. Or maybe they're just more of a 3000rpm - 6000rpm cam? If that's the case then I'm open to suggestions for a cam change that will give me more in the 2200 - 5000 range.
Thanks
BTW, very sorry to hear what's just happened in the town near San Antonio. My prayers go out to the Texas community.
So I guess the 570 cams are getting enough compression. The AFR has already been very quickly evaluated on the dyno up to 3500rpm (NO full throttle or heavy load) and with my 46 pilot, 195 main and 3.5 turns out on the mixture screw I was between 12 and 14 running through the gears. The Tuner would not do a full tune until 1000 miles, so that's all the tuning info I have. DTT settings now on 2 and 2.
What else would you suggest doing to get the most from the 570s? Feels like something is really holding them back. Or maybe they're just more of a 3000rpm - 6000rpm cam? If that's the case then I'm open to suggestions for a cam change that will give me more in the 2200 - 5000 range.
Thanks
BTW, very sorry to hear what's just happened in the town near San Antonio. My prayers go out to the Texas community.
At 10.5, cam like the Woods W6, W555 or W777. Maybe the andrews 54? My favorite was the crane H290 but they are noisy and work better with more intake flow. You might try adding some back pressure to the exhaust with the 570..
Grand HDF Member
Joined: Sep 2017
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From: Dubuque, IA
So you were trying to evaluate performance of the 570 by what it did between 2000 to 3000? They can be a bit flat in the lower RPM range.. Too much exhaust duration. They kind of bog down low on most builds. I tried one in a 96 / 103 and got rid of it.
At 10.5, cam like the Woods W6, W555 or W777. Maybe the andrews 54? My favorite was the crane H290 but they are noisy and work better with more intake flow. You might try adding some back pressure to the exhaust with the 570..
At 10.5, cam like the Woods W6, W555 or W777. Maybe the andrews 54? My favorite was the crane H290 but they are noisy and work better with more intake flow. You might try adding some back pressure to the exhaust with the 570..
Restricting the exhaust will most likely just hurt his peak torque and definitely his hp.
Maybe the woods tw5-6 would suit you better tho if you're interested in a cam change. They'd come on a little sooner but die a little sooner too making for a little less hp.
Last edited by 60Gunner; May 25, 2022 at 10:33 AM.
Seasoned HDF Member
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From: poway
He's running a good exhaust for those cams tho. I did 93ft.lbs @ 2200rpm in my stage 2 103 with the stock head pipes/crossover and Rush slip ons with 2" baffles. But yeah, they're not going to be real strong til closer to 3000rpm.
Restricting the exhaust will most likely just hurt his peak torque and definitely his hp.
Restricting the exhaust will most likely just hurt his peak torque and definitely his hp.
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Road Master
Joined: Apr 2017
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From: out there
So you were trying to evaluate performance of the 570 by what it did between 2000 to 3000? They can be a bit flat in the lower RPM range.. Too much exhaust duration. They kind of bog down low on most builds. I tried one in a 96 / 103 and got rid of it.
At 10.5, cam like the Woods W6, W555 or W777. Maybe the andrews 54? My favorite was the crane H290 but they are noisy and work better with more intake flow. You might try adding some back pressure to the exhaust with the 570..
At 10.5, cam like the Woods W6, W555 or W777. Maybe the andrews 54? My favorite was the crane H290 but they are noisy and work better with more intake flow. You might try adding some back pressure to the exhaust with the 570..
I am looking for more of a low and mid range torque curve. The Woods cams are popular.
I can get a good deal on Andrews cams from my local Indy. What do you think of running the 54 cams in a 10.5 95" build? My understanding was that they really only shine in bigger cubic inch motors?
Thanks
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Road Master
Joined: Apr 2017
Posts: 1,050
Likes: 92
From: out there
He's running a good exhaust for those cams tho. I did 93ft.lbs @ 2200rpm in my stage 2 103 with the stock head pipes/crossover and Rush slip ons with 2" baffles. But yeah, they're not going to be real strong til closer to 3000rpm.
Restricting the exhaust will most likely just hurt his peak torque and definitely his hp.
Maybe the woods tw5-6 would suit you better tho if you're interested in a cam change. They'd come on a little sooner but die a little sooner too making for a little less hp.
Restricting the exhaust will most likely just hurt his peak torque and definitely his hp.
Maybe the woods tw5-6 would suit you better tho if you're interested in a cam change. They'd come on a little sooner but die a little sooner too making for a little less hp.
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Joined: Dec 2005
Posts: 19,929
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From: poway
No, I wasn't trying to evaluate the 570's by what it did between 2000rpm and 3000rpm.... I'm just saying it's a bit soft below 3000rpm. It just doesn't suit my riding style.
I am looking for more of a low and mid range torque curve. The Woods cams are popular.
I can get a good deal on Andrews cams from my local Indy. What do you think of running the 54 cams in a 10.5 95" build? My understanding was that they really only shine in bigger cubic inch motors?
Thanks
I am looking for more of a low and mid range torque curve. The Woods cams are popular.
I can get a good deal on Andrews cams from my local Indy. What do you think of running the 54 cams in a 10.5 95" build? My understanding was that they really only shine in bigger cubic inch motors?
Thanks
You could bump the CR to 10.8 and run the 55s. Those made pretty good power in my 02 RKC. They will be a little soft down low but not as bad as the 570s. You could probably hit 100/100 with the 06 heads.
I'll agree with you on the 570s. For me, they were way soft down low. Open the throttle up all the way and they'd go but what was between on the throttle positions was pretty soft.
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Road Master
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From: out there
I've not tried 54s but at 10.5 to 1, I'd think that they'd do well. I suspect that the reason they don't do too well stem from the compression being too low in the smaller motors, You may not hit real high numbers but I'd suspect that you'd have a nice power curve.
You could bump the CR to 10.8 and run the 55s. Those made pretty good power in my 02 RKC. They will be a little soft down low but not as bad as the 570s. You could probably hit 100/100 with the 06 heads.
I'll agree with you on the 570s. For me, they were way soft down low. Open the throttle up all the way and they'd go but what was between on the throttle positions was pretty soft.
You could bump the CR to 10.8 and run the 55s. Those made pretty good power in my 02 RKC. They will be a little soft down low but not as bad as the 570s. You could probably hit 100/100 with the 06 heads.
I'll agree with you on the 570s. For me, they were way soft down low. Open the throttle up all the way and they'd go but what was between on the throttle positions was pretty soft.
Can't afford to increase compression.
I'm limited to a cam change and the cam specs off the Andrews 54 seem a good for on paper, but never seen or heard of one used in my application... might have to be the guinea pig and try it out? 🤔
Otherwise, the Redshift 575 cams also could be really good? Again, I have not seen them used in a stout 95" build.
Seasoned HDF Member
Joined: Dec 2005
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From: poway
Thanks.
Can't afford to increase compression.
I'm limited to a cam change and the cam specs off the Andrews 54 seem a good for on paper, but never seen or heard of one used in my application... might have to be the guinea pig and try it out? 🤔
Otherwise, the Redshift 575 cams also could be really good? Again, I have not seen them used in a stout 95" build.
Can't afford to increase compression.
I'm limited to a cam change and the cam specs off the Andrews 54 seem a good for on paper, but never seen or heard of one used in my application... might have to be the guinea pig and try it out? 🤔
Otherwise, the Redshift 575 cams also could be really good? Again, I have not seen them used in a stout 95" build.