Marble mod stops backfiring? Not so much

[andyw8705]

took the stock cans off the busa just to see what it would sound like with just the midpipes(2000 model year) took it out for a spin and man! Pop popoppopopop!!! Stuck a bolt in the tube and tried again...POPOPOPOPOP! what gives? any thoughts?

[Acehole]

uhmmm the marble mod will help with aftermarket slip-on's, but with no can at all i don't think it does much good.

[GIXERHP]

Is there a power commander on the bike?

[andyw8705]

no power commander, the more and more i tear into the bike, the more i think it has been wrecked and just put back to stock, for example...different bolts holding the headers on...starting to think maybe the bike has a map on it for a different setup than stock

[rashad]

if the header bolts are different it probably just means it was previously modded and put back to stock so they could sell it. No worries.

[Busa1166]

no power commander, the more and more i tear into the bike, the more i think it has been wrecked and just put back to stock, for example...different bolts holding the headers on...starting to think maybe the bike has a map on it for a different setup than stock

Stock bike stock map with no cans should backfire imo not a tech guy though

[ogre]

just get the block off plates, you'll be good to roll.

[Vonderbach]

I have shorties which are virtually straight with little baffle and the marble mod (bolt mod for me) works great. Just an FYI.

[nabusa]

I think I'm the only one that likes the backfiring. I didn't do the pair valve mod.

[smithabusa]

put an exhaust on it, they run pretty crappy with stock header no cans

[Acehole]

I think I'm the only one that likes the backfiring. I didn't do the pair valve mod.

Would wear out your can packing pretty quit, no?

[jdsbusa]

Would wear out your can packing pretty quit, no?

It would if he was running cans.

Frankly, if you like the sound so much of just the midpipes just put a compressor and dumps on it. No more backfires, you've got the noise....what am I missing.......OH YEAH, gobs more horsepower!!

[LILGSXR]

i like when mine back fires sounds cool sounds even sweeter on my buddies 08 with the brocks full system and he did the marble mod didn't help at all puts down 183 to the ground and back fires all the way back down from redline as you can watch tons of packing particals fly out of the exhaust lol

[andyw8705]

thanks for the info guys, this is just a temp solution till I can save up more money to get a full...times are rough

[ogre]

don't be a sissy, get a snail

[b16sleeper]

running open header is bad because you run the risk of burning a valve...u need some back pressure on an n/a motor..

[Commuta_Busa]

the marble mod was never intended for a open mid-pipe exhaust.

[Wayneovich]

running open header is bad because you run the risk of burning a valve...u need some back pressure on an n/a motor..

+1 to that any exhaust tht just runs straight out is going to sound bad back pressure is a good thing

[pontnewynyddboy]

took the stock cans off the busa just to see what it would sound like with just the midpipes(2000 model year) took it out for a spin and man! Pop popoppopopop!!! Stuck a bolt in the tube and tried again...POPOPOPOPOP! what gives? any thoughts?

Actualy what you are describing is called after-fire. Back-fire is when the explosion would come "back" through the carbs and scare the crap out of you,espiecialy when you would be working on it and have yer nose hairs and eyebrows vaporized, ah! the good old days. All engines after-fire. It is caused by unburned fuel re-igniting when it comes into contact with the headers.I believe valve timing overlap is the cause. Performance engines open the intake valve just before the exhaust valve closes. The out-going exhaust gas produces a drawing effect in the combustion chamber which pulls the intake fuel-air mixture into the cylinder, but because the exhaust valve is still slightly open some of the mixture goes out through there and causes the explosion your hearing. Its perfectly normal.The reason you don't hear it is because of the design of the mufflers which makes it almost undetectable Hope this helps. Bob T