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Discussion Starter · #1 · (Edited)
I thought members who drilled holes in a perfectly good expensive exhaust system were crazy. I have to admit I was wrong. Today, based on all the information in this forum, I drilled holes in a perfectly good expensive exhaust system, and the bike sounds better. Since I had a little trouble digging up all the pictures showing what needs to be done, I have attached some of my own. Maybe they'll help others who want to do this modification.

If I had to do it all over again, I'd move the right-side hole up and forward to better match the location of the left-side hole.


Rune on lift



Left side stock




Right side stock




Underneath stock




Drill and bit




Left side drilled




Right side drilled




Underneath drilled

 

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Wow! :shock: I can't tell you how helpful this is! Thanks for taking the time to take and post all these pictures. You know what they say! A picture is worth a thousand words! Thanks Again!
 

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Welcome to the crazy side ! :a13:
Your bike is way to clean underneath and the rear tire looks brand new, get out there and ride the hell out of it! :biker:
 

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Hi Asacuta,
j refuse to consider the possibility to drill the exhaust. j wish the bike with the minimum possible noise. and the gorgling when j reduce the speed during a fast overpassing is fantastic.
anyway...
thanks for the pictures, j save them in the eventuality j could look for a different sound. you did a good job.
ciao from Italy
hannibal
 

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Discussion Starter · #5 ·
Hannibal:

You too may join the dark side. Carlo, an acquaintance of mine, resisted for years changing the exhaust on his 512TR. The last time I saw him, I could hear him coming from blocks away. He installed a tubi system that was little more than straight pipes on his flat 12. What a sound!

Regards,
Al
 

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hannibal

Be strong, hold your innocence and purity close to your breast, don’t let these hearing impaired demons of the decibel lure into the depths of the evil volume promoters.
 

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Asacuta

Or is it cutaasa!!!!! Your holes are located VERY close to where mine are.. Let me know if you notice much backfire.... I run very rich so maybe that is the biggest contributing factor...
 

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Thanks for the pictures.

Someone has some slider covers that you can install to close off the holes when you want. I don't remember who has them though.
 

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Backfires w/ Exhaust Mod ??

For those who have already done the exhaust modification, do you often have problems with backfires? Is there anything I can do to prevent this from happening, either before or after drilling the holes?
 

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Hi Sitedata & Asacuta

j told Fiore (my dear wife about your replies). she is replying that she will never have the courage for drilling exhaust in any rune and even if that could done should be a " cinghialata ", (wild pork action)
difficult to translate but similar to something done from an italian *******.
you know, people during the night driving with open windows and you may hear their music far 10 miles. :D
ok.
j drilled my motoguzzi Gt 850, j had some bikes where no necessary to drill exhaust (completely empty :roll: )
j wish high power and a swarm noice.
if j get an other Rune j will put the three exhaust in one, j like them.
ciao bross
hannibal
 

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Discussion Starter · #11 ·
Just got back from a 200-km ride. No backfires; just rumbles and burbles. I'm not sure if it makes a difference, but I live in the foothills of the Rocky Mountains, so I'm at a higher altitude than most.

Al
 

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asacuta

I’m at 4 feet above sea level and mine, most likely. sounds the same as yours.

However, during a Hurricane when I’m 2 feet below sea level I do notice a gurgling sound.
 

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Backfires

Rich Oas: the following is my opinion only:

You say you're running rich. Are you sure? A reduction in exhaust backpressure should result in greater airflow, resulting in a higher air to fuel mixture ratio. In other words, the exhaust mod should have you running leaner, which is the most common cause of backfires.

Any change in the air/fuel mixture (exhaust modification, freer-flowing air filter, altitude change, etc.) really requires a change in the fuel mapping logic in an EFI system. The Rune's ECU (Engine Control Unit, or Electronic Control Unit) is probably similar to most ECU's in that it can adjust its parameters to a certain degree. This is necessary because not everyone drives at sea level. However, the ability of any ECU to adapt is limited. If a change in mixture is outside the ability of the ECU to adapt, unwanted effects start to happen (i.e. too lean = the system backfires).

This is why, IMHO, we need a replacement ECU, so we can change our intake/exhaust bits, and then optimize the fuel system.

I think the Rune powerplant is capable of WAY more power than it has stock; we just need someone to take enough interest in it to design us the parts.

The problem is, of course, that there's just not enough of us out there to make the R&D worth it.

Of course, our small numbers is a good thing too, right?

john
 

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Yes, the rune out of the box runs a little on the rich side, of course this is better than a little lean.
I was the first to do this mod and mine has never backfired, a little gurgling during deacceleration. A backfire is a loud, sharp, firecracker sound, is that what you guys are hearing?
Backfiring is most commonly caused by incorrect ignition timing, and can also be caused by vacuum lines that might have a leak or collapse a little during deacceleration.
This mod we did doesn't greatly reduce the backpressure, it's not like we went to straight pipes. I'm thinkin that the ECU has no problem adjusting to this small change. IMHO
 

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WhataMarune and Hogslayer

Thanks for the info WhataMarune... I didn't realize backfire was more likely the result of running lean..I thought the opposite....course that is why I don't do bike repair for a living... I thought it might be a "running rich" thing because I actually SEEM to have more soot since I drilled my holes..that's definitely when the backfire started also... When I first noticed the extra soot I thought it might be attibuted to my Big Black Smoke (BBS @ 7,500mi) problem and was blowing off some extra residue which was trapped in the pipe but suddenly able to exit due to the holes.... and maybe that is still part of my issue altho I have around 12,000 miles since BBS and around 8,000 miles since drilling the holes. I am trying to put my finger on the culprit and am beginning to think the gas octane and/or brand might have something to do with it. I have noticed a couple times that I am running fine and after a fill up I suddenly feel the bike is "loading up" or running rich thing and I would notice a bit more soot... Can the bike be so temperamental to slight changes in gas octane and brand.. I say octane because sometimes the only premium at the pump is 93 octane while I most often use 92... And does anyone know if the gas hose drains back so no residue 89 octane is in the hose when the fill begins. Perhaps causing some issues... Anyway...I am trying to be more observant of exact events preceeding some of my "added soot" issues..

Hogslayer...it is inded a backfire ...sometimes a ladyfinger crack....sometimes a blackcat firecracker crack...but occassionally an M-80 boom...occasionally scares the crap out of me even if I know its coming if I am between buildings and get the full affect of the noise... Thanks again for clarification... and any additional feedback is appreciated...
 

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Hogslayer

I meant to add...but got carried away on other topics that I will ask the dealer to check the timing on my next visit...thanks...It is weird tho...how this bike can run so perfect and so clean at times and so dirty at others....
 

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The backfiring you hear with the drilled pipes while decelerating is the major reason why I like it. Nothing bad is happening to the engine. You are simply mixing more oxygen in the exhaust downwind of the air injection system.

I have noticed that changing the coolant to propylene glycol, and the resulting slight increase in engine temperature has improved both fuel economy and the 'clean burn' for the exhaust soot deposition. Stopping at long lights in 98 degree weather sucks more however. I cant wait for cooler weather!

Ken (34,250 miles)
 
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drilled mine out this morn. All I can say is thank you, Thank ypu Thank you. went for a qiuck ride to check it out an got home 2&1 half hrs. later. AT 104 degrees. at 70 yrs. old. Hogslayer, YOU ARE THE MAN !!! Chet 67 rune :twisted:
 

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Chet...

Hogslayer is a man of superb vision and guts...as are the other wrenchheads on this board............. but you my friend ...at 70 years old ARE THE MAN:bow1: ....You gotta come to Irwin,TN for the rally over Labor Day weekend... I want to meet the man I want to be when I enter my second childhood at 70 :bow1:
 
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