St1100 stock exhaust Mod

[viclava]

Has anyone ever done the exhaust mod I read about on the .org web site? I would be very hesitant to drill a hole in my stock exhaust and run the risk of having to re-jet. I would be curious to know if anyone has done it, and if so did you get better sound and low end power increase.

Thanks,

Scott

 

[John OoSTerhuis]

Has anyone ever done the exhaust mod I read about on the .org web site? I would be very hesitant to drill a hole in my stock exhaust and run the risk of having to re-jet. I would be curious to know if anyone has done it, and if so did you get better sound and low end power increase.
Thanks,
Scott

Don't do it, Scott! This is really one of the silliest ideas ever dreamed up for an ST1100. Almost as bad as drilling 1" holes in the air cleaner box. I don't know why STeinar even allows this dumb idea to stay up on his fine site. TTBOMK over the many years I've been on The ST1100 (and now ST1300 also) LiST, I've only heard of a few stupid enough to drill out their OEM exhausts.

Simply put, there is no easy, homespun way to increase power (low or high end) or sound (sadly, I assume you mean 'louder' - I'd be happy if I couldn't hear my ST at all but FWIW, I like its very unique, techno-industrial sound) on an ST1100 without spending big bucks at a professional tuner/shop, and even then Honda got it right to start with so there really isn't much of an increase even possible. If you're looking for more, maybe you picked the wrong bike.

Just MHO of course,

Regards, John

 

[st1300.56]

well call me stupid but i have done it to my st 1300 not drilled. but i just used a poggy bar the size off the holes in the exhaust and knock a hole throught the baffle and the gause plate and have had no problems.its just an easy way to get a note at no cost try it. u have got nothing to loose

 

[tarfin]

Its a fairly popular mod on the concours.org board for the old Connie. People seem happy with the exhaust note and it isn't severe enough to require re-jetting. YMMV

 

[st1300.56]

thats why i did it. staintunes are to dear .i would sooner be riding than paying for something that dosent give u much gain.i run mobil 1 racing 4t in the engine and 75-90 syn in diff with exhaust mod makes it rev better. not a big beliver in k/n filters as they let to much dust in over the long term.

 

[John OoSTerhuis]

<snippage>
its just an easy way to get a note at no cost try it.
u have got nothing to loose

I think there is a cost, and something to lose by permanently damaging the mufflers on your ST: resale value.

JMHO, again.

Regards, John

 

[viclava]

Well, I am more inclined to think as John does, because I tend to look at it like Honda has their power plant + exhaust to give optimal power as is stock. It seemed to me to be a pretty big gamble drilling in a perfectly good stock exhaust system. I was looking to also obtain a little louder exhaust note, but not at the risk of screwing up how the bike runs and performs. I'm still undecided however.
Scott

 

[wjbertrand]

Can't speak for the 1300, but I think John Parker did a before and after dyno run with drilled pipes on his ST1100 as per the .org site. IIRC correctly there was a 2 - 3 horsepower loss as a result of doing this. If you are after more sound, drilling the OEM pipes didn't make any difference to my ear when I heard John's bike.

He went deeper than that too. He tried the drilled air box, re-jetting, after market pipes, etc. I think he was finally able to show a slight HP gain on the top end, but the mid and low range losses in power and driveability (not to mention fuel efficiency) motivated him to return the bike back to stock.

I've yet to see objective evidence (i.e. B&A back-to-back dyno runs) that drilling the OEM pipes, or even installing aftermarket mufflers adds any power at all to an ST1100.

Bottom line - don't waste your time.

 

[saaz]

I don't know about the exhuast mod, but a set of Staintunes I put on recently (cheap!) definitely has an effect down low, add more tractability, but no affect in midrange or higher up. The bike was/is running rich in the area of improvement (according to a dyno run, with standard pipes). If I get around to changing the mixture I will post before and after runs.

 

[wjbertrand]

I don't know about the exhuast mod, but a set of Staintunes I put on recently (cheap!) definitely has an effect down low, add more tractability, but no affect in midrange or higher up. The bike was/is running rich in the area of improvement (according to a dyno run, with standard pipes). If I get around to changing the mixture I will post before and after runs.

Got a dyno chart to prove it?

 

[John OoSTerhuis]

I don't know about the exhuast mod, but a set of Staintunes I put on recently (cheap!) definitely has an effect down low, add more tractability, but no affect in midrange or higher up. The bike was/is running rich in the area of improvement (according to a dyno run, with standard pipes). If I get around to changing the mixture I will post before and after runs.

Are we STill talking about CV carburated ST1100s, or fuel injected ST1300s that Power Commanders don't work on?

Regards, John

 

[saaz]

I am only talking about ST11s, as that was what started this. PCs only work on earlier models of the ST13, so I hear.

I will get another dyno run done after I look at the carbs to check out the rich running. It has a very rich spike in the lower end, so something is amiss (running as rich as 10:1 afr low down, and 12:1 up top). No jetting changes are need with the mufflers, so I stiil have to address that problem reagardless of which mufflers are on it. Dyno runs do not tell all, as you would know, as throttle responsiveness etc does not necessarily show up. I am only talking about top gear roll on from 2000 to 3500rpm, so don't know what a dyno would tell you about that. Too much stock is placed on absolute dyno numbers, which tell you nothing much about throttle responsiveness and what a bike is like to ride. It is not a dramatic improvement, just a comment on pulling a bit cleaner down in the area identified as running way too rich with the standard pipes. Thats why I said it felt more tractable, not necessarily more powerful etc. If you had ridden the bike before and after it would have been on the noticeable side if you have any sensitivity for these things, but again not a dramatic change. An yes, I don't have a dyno run to show it does not run any better up top! I have tuned my older bike with slide carbs and gone through all sorts of adjustments to get it running properly in road conditions, from pilot jets, needles jets, slide cutouts. Establishing maximum power settings is the easy bit, diveability is much harder to achieve.

But overall, I agree with Jeff that putting an aftermarket system mostly leads to just noise and no or a loss in performance. I would presume the ST13 is similar, altough I have seem claims about improvements on the intake side.

The ST11 design does not lend itself to any dramatic improvements as the power delivery is designed from start to finish to give a flat power delivery with a broad torque curve. Getting the tuning right with the standard system is more important I think. If the mufflers I bought were not 1/4 new price I would have just fixed the bracket on the side that broke. If you check out http://www.mcnews.com.au/ and look for 'muffler comparison' all you see is performance loss, or just noise for little or no gain.

 

[Yeti7072]

Don't do it, Scott! This is really one of the silliest ideas ever dreamed up for an ST1100. Almost as bad as drilling 1" holes in the air cleaner box. I don't know why STeinar even allows this dumb idea to stay up on his fine site. TTBOMK over the many years I've been on The ST1100 (and now ST1300 also) LiST, I've only heard of a few stupid enough to drill out their OEM exhausts.

Simply put, there is no easy, homespun way to increase power (low or high end) or sound (sadly, I assume you mean 'louder' - I'd be happy if I couldn't hear my ST at all but FWIW, I like its very unique, techno-industrial sound) on an ST1100 without spending big bucks at a professional tuner/shop, and even then Honda got it right to start with so there really isn't much of an increase even possible. If you're looking for more, maybe you picked the wrong bike.

Just MHO of course,

Regards, John

Honda, Yamaha, Slozuki and even Harley’s are all severely limited by smog rules and emissions standards. I am not sure when the EPA first started regulating motorcycles but here In wonderful overbearing and highly controlling California you can find smog equipment on motorcycles from the 80’s. That being said the 4 major things manufacturers start restricting/detuning are: Air Intake, Exhaust (restrictive manifolds, mufflers and catalytic converters), Compression and Timing. So any sane rational mind would naturally conclude that anything you can do to improve these area’s it should improve performance. Go ahead cut and drill the air box and mufflers. Always remember it’s a lot easier to remove more material than it is to put it back so start small. If some guy hadn’t started fiddling with the carburetor on his little jalopy Ford and another guy wouldn’t have done the same on his pos Chevy probation would have been a lot more successful, nascar would have never been born and automobile aftermarket which provides 10,000’s of jobs and makes 100’s of Billions of dollars every year. Never be afraid to Fail without failure you will never know success!!

 

[Al st1100]

Honda, Yamaha, Slozuki and even Harley’s are all severely limited by smog rules and emissions standards. I am not sure when the EPA first started regulating motorcycles but here In wonderful overbearing and highly controlling California you can find smog equipment on motorcycles from the 80’s. That being said the 4 major things manufacturers start restricting/detuning are: Air Intake, Exhaust (restrictive manifolds, mufflers and catalytic converters), Compression and Timing. So any sane rational mind would naturally conclude that anything you can do to improve these area’s it should improve performance. Go ahead cut and drill the air box and mufflers. Always remember it’s a lot easier to remove more material than it is to put it back so start small. If some guy hadn’t started fiddling with the carburetor on his little jalopy Ford and another guy wouldn’t have done the same on his pos Chevy probation would have been a lot more successful, nascar would have never been born and automobile aftermarket which provides 10,000’s of jobs and makes 100’s of Billions of dollars every year. Never be afraid to Fail without failure you will never know success!!

What do they say about doing the same thing over and over but expecting different results? There is nothing new here it's been tried and tested.

 

[Oilpond]

I was feeling inadequate about a year ago and so out with the grinder and at the end of the pipes where the chrome meets the blak end bit i cut all the way around not cutting the inner pipe cause the disc wasnt long nuff and i love it Produced a notible grumble but not tee bag juss mint i use my 11 every day to tear around this shet town and drag back munchies and haul meh fat ass for runs out of a night now n then on suicide rides about25k year. was searching now cause am thinkin of choppin the exhausts completely