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  • walka Posts: 3365
    MELBOURNE
    Forum Legend walka
    30 Jan 2019 09:11 PM
    The rear cyl of my bike has been weeping at the base over the last year , the bike has done about 45,000 k’s 
    After a lot of research I desided to rebuild the top end a fit cams. S&S do a 106 hot up kit that comes with 106 barrels , forged pistons, 585 easy start cams, lifters, adjustable push rods and gaskets.  
    All fitted up great , with the stock heads it ups the comp to 10;0 

    just got the bike back from Dyno, it made 110 hp with stock header pipes and Vance & hinze monster ovals ,,, with the stock header pipes the exhaust was holding the bike back, 

    The bike did make 96 hp as a 103 so Riding back from the Dyno the extra 14 hp didn’t feel like much and honestly I felt a bit disappointed .

    So tonight I cut out the cat,,,, boy what a difference , it’s like I’ve got a 100 extra hp now ,, the thing is a weapon ... I have it booked back in for another Dyno run next week and any adjustment. so I will post up the results then 

     if you still got a catalytic converter on your bike and want a easy power increase, I highly recommend cutting it out asap
  • paulybronco Posts: 11157
    Forum Legend paulybronco
    30 Jan 2019 10:06 PM
    Good to hear, should have read my tip back in 2012..LOL  The boys at Sunny coast claim that the cat delete is only 1 hp off a dedicated performance header system. Will run cooler and easier to tune not to mention a deeper exhaust note
  • walka Posts: 3365
    MELBOURNE
    Forum Legend walka
    08 Feb 2019 03:53 PM
    Back to the Dyno today , lost 6hp but gained 10 ft pounds of torque ,,, going to do a rest set and see if we can get back so hp 
  • Ratbob Posts: 794
    Adelaide Hills
    Performance Poster Ratbob
    08 Feb 2019 04:43 PM
    Hi Walka, was the cat in each muffler or in the collector point of the header?
    It’s interesting (am I reading correctly) you said it felt like a weapon with the cat out but you had lost 6hp ?
    I have two header systems for my 110 Dyna, 1 cat in, 1 cat out and the two pipes isolated internally. When riding, I feel the cat in gives  better performance but in your experience are you saying the cat out felt way better but actually dropped a few hp?
    Should we be looking more at the tourque figures?
  • walka Posts: 3365
    MELBOURNE
    Forum Legend walka
    08 Feb 2019 06:35 PM
    The bike was dyno and tuned with the cat still fitted ,, today has just a recheck ,, my dyno guy didn’t have time today to remap it so I will have it back there as soon as I can . I guss it was the extra torque that I was feeling , my dyno guy is very confident that he can get the power back and find some more.

    The cat on a street glide is on the right hand side just past where the header pipes meet
  • paulybronco Posts: 11157
    Forum Legend paulybronco
    08 Feb 2019 09:14 PM
    Quoting Ratbob on 08 Feb 2019 04:43 PMedited: 08 Feb 2019 04:44 PM
    Hi Walka, was the cat in each muffler or in the collector point of the header?
    It’s interesting (am I reading correctly) you said it felt like a weapon with the cat out but you had lost 6hp ?
    I have two header systems for my 110 Dyna, 1 cat in, 1 cat out and the two pipes isolated internally. When riding, I feel the cat in gives  better performance but in your experience are you saying the cat out felt way better but actually dropped a few hp?
    Should we be looking more at the tourque figures?
    The cats are in the header
  • Ratbob Posts: 794
    Adelaide Hills
    Performance Poster Ratbob
    09 Feb 2019 10:00 PM
    Quoting Ratbob on 08 Feb 2019 04:43 PMedited: 08 Feb 2019 04:44 PM
    Hi Walka, was the cat in each muffler or in the collector point of the header?
    It’s interesting (am I reading correctly) you said it felt like a weapon with the cat out but you had lost 6hp ?
    I have two header systems for my 110 Dyna, 1 cat in, 1 cat out and the two pipes isolated internally. When riding, I feel the cat in gives  better performance but in your experience are you saying the cat out felt way better but actually dropped a few hp?
    Should we be looking more at the tourque figures?
    Quoting paulybronco on 08 Feb 2019 09:14 PM
    The cats are in the header
    Yeah, I’ve not had one of these bikes but I do have a shed full of chopped up exhaust systems, so I’m thinking removing the cat turns the system from a 2 into 2 to an untuned 2 into 1. Hence the loss of 6 hp. The cat being like a tight handful of straws, effectively maintains the working of a 2 into 2. Removing the cat creates an empty chamber that works as a damper (creating more back pressure) wherein the exhaust gases slow down and get pressurised again to exit through both mufflers. While it takes a bit of surgery, after removing the cat, I found it best to weld in a divider that maintains the 2 into 2 (true dual) system which maintains the speed of the exhaust gas to the extent possible. This seems to drop the tourque but ups the horse power so again I’m thinking, don’t cut the cat if you prefer tourque over power.
    Any thoughts guys ?
  • Nutty Posts: 256
    Stage 1 Poster Nutty
    10 Feb 2019 12:18 PM
    Quoting Ratbob on 08 Feb 2019 04:43 PMedited: 08 Feb 2019 04:44 PM
    Hi Walka, was the cat in each muffler or in the collector point of the header?
    It’s interesting (am I reading correctly) you said it felt like a weapon with the cat out but you had lost 6hp ?
    I have two header systems for my 110 Dyna, 1 cat in, 1 cat out and the two pipes isolated internally. When riding, I feel the cat in gives  better performance but in your experience are you saying the cat out felt way better but actually dropped a few hp?
    Should we be looking more at the tourque figures?
    Quoting paulybronco on 08 Feb 2019 09:14 PM
    The cats are in the header
    Quoting Ratbob on 09 Feb 2019 10:00 PM
    Yeah, I’ve not had one of these bikes but I do have a shed full of chopped up exhaust systems, so I’m thinking removing the cat turns the system from a 2 into 2 to an untuned 2 into 1. Hence the loss of 6 hp. The cat being like a tight handful of straws, effectively maintains the working of a 2 into 2. Removing the cat creates an empty chamber that works as a damper (creating more back pressure) wherein the exhaust gases slow down and get pressurised again to exit through both mufflers. While it takes a bit of surgery, after removing the cat, I found it best to weld in a divider that maintains the 2 into 2 (true dual) system which maintains the speed of the exhaust gas to the extent possible. This seems to drop the tourque but ups the horse power so again I’m thinking, don’t cut the cat if you prefer tourque over power.
    Any thoughts guys ?
    I've only been playing with HDs on the dyno for two years but nearly every power-up kit loses torque on the stocker up to 3000rpm. Since Tourers spent 99% of their time under 3K, unless the rider wants HP above 3K I'm keeping the M8 header stock. The M8 header runs heaps colder than a TwinCam and isn't anywhere near as restrictive. I did a tune last week on a 107 M8, SE stage 1 conversion of the OEM air filter and a powertuner with a complete OEM exhaust. It flies and has a quiet but nice note. Also it LOOKS stock to the Popo. 4.7l/100km.
  • Baloffski Posts: 1588
    Victoria
    Motor Head Baloffski
    10 Feb 2019 06:42 PM
    Aye Crew, the cat is an arsole, like mant cats, not all, but most. 
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