final word for this mod.

[crisis123]

hello again> i really want to put some broom to my 2007 gz her milleage right now is 700. so i am still debating to myself if i will go thru with this mod, to put holes in my exhaust. any last word before i do this. i've been reading all your opinion and suggestions and seems everybody has thier own points. and i read so many information regarding about this. ok for the last time please let me know more about doing this.... d good and d bad/, i really appreciate any comments and suggestions. and lastly i really love this forum i learned so much. keep this forum alive, regards to everyone from northern california :rawk:

[alanmcorcoran]

Broom? or Vroom? If it is vroom, drilling the holes by itself isn't going to make it go faster. My understanding is you must also alter the carb to adjust for the increased airflow or it is going to run like crap. Pehaps you know this already.

If you really want comments, I think you are ruining a perfectly good machine. Without any tweaks at all I can get my 2008 up to 70, sometimes as high as 75. How much faster do you need to go? Try doubling your revs before shifting for a week (shift into second around 15, third at 30 and fourth at 45) and you will "feel" like the bike is faster.

Just my two cents. If the thing does 90 after you screw with it, I'll bring mine over and you can ruin it, too.

[Badbob]

Wasting your time.

Another thing to think about is resell value. Some people, myself included, consider any modification of this sort as damage. I've looked at lots of used motorcycles in the last two years. I skip everything that even hints that anything connected with the engine is not stock. Not that I really care if anyone does this but I'm not going to buy it if they do.

[zoned10x]

i really want to put some broom to my 2007 gz... put holes in my exhaust. any last word before i do this...

Putting holes in the muffler just makes a bike sound ratty because of the muffler's internal baffling. If you want to hear good thumper bark, you will need to fit a straight-through glasspak. That will involve sawing off the stock muffler from the header and fitting the new can. Reducing exhaust back-pressure will lean the fuel mix, so plan to tweak the jetting. It is very true that you will trash the value if you alter the machine, so I suggest buying a second OEM pipe from a motorcycle wrecking yard for your project and keeping your original for resale time.

[Easy Rider]

Putting holes in the muffler just makes a bike sound ratty because of the muffler's internal baffling.

OK, let's see if I can sumarize all the GOOD suggestions you got here (and add a little bit):

Don't screw with ANYTHING, muffler or air box unless you are going to do it ALL: Muffler, air filter AND the carb re-jetting. If you want just a little bit extra, do the carb mods first. That's where the most gain is and it still looks and sounds "stock".

Just drilling holes in the muffler endplate does NOTHING for the performance and just makes it sound wierd; I did it and then plugged up the holes with bolts.

Putting on a low restriction air filter is counter-productive as it make it run like CRAP without the carb mods. I tried that too.

So, the summary is: (which I think we have told you already at least once):
Unless you just get a lot of enjoyment out of screwing with it, don't change anything.
If the bike doesn't have enough power to suit you, sell it and get something else.

P.S. Depending on the type of riding you do, you might consider the 16T front sprocket. That's the ONE mod I think is worth while......for most people. It uses the low-end torque of the thumper to better advantage in the lower gears but you sacrifice a bit of top end speed.

[zoned10x]

...Don't screw with ANYTHING, muffler or air box unless you are going to do it ALL: Muffler, air filter AND the carb re-jetting. If you want just a little bit extra, do the carb mods first. ...Putting on a low restriction air filter is counter-productive as it make it run like CRAP without the carb mods. I tried that too....

The stock filter is less restrictive than many think it is. You should be able to just open the pipe and rejet the carb and feel some performance improvement. It's all about flow through the head, though, and these singles don't crank the kind of revs that 'require' a K&N, or similar. Tuners should also be aware that improving flow will make more muscle at high revs, but at the same time rob torque from low revs. Thumpers are all about tractor-like power down low, they don't particularly like to rev very high, so hot-rodding for high rpm horsepower is not the wisest move with these engines.

IMO, just tweak the airscrew and lift the needle. It will sweeten the mix and add a bit of power where you need it most in real world riding [low to mid-range rpm] and help to make acceleration seamless. The old rule applies here... "There is no substitute for cubic inches". Unless you run NOS, but that is another story.

[Easy Rider]

The stock filter is less restrictive than many think it is. You should be able to just open the pipe and rejet the carb and feel some performance improvement.

OK, the second part is true. It is also true that you will "feel some performance improvement" just by doing the carb mods. That basically yields a "European model".

If there isn't a siginificant amount of restriction in the stock air filter (and how do you know what "many think it is"?) how do you account for the fact that removing the filter altogether results in an engine that just barely runs ?? (without any other mods). :roll:

Overall though I agree that most people are better off NOT messing around with the intake.

[zoned10x]

> OK, the second part is true.

It's all true.


> It is also true that you will "feel some performance improvement"
> just by doing the carb mods. That basically yields a "European model".

Even the European models are lean these days. U.S. EPA and Euro EEB mandates restrict low rpm emissions resulting in fuel starvation and weak performance from internal combustion engines. The shim and airscrew 'mods' [tampering ;)] get you a few clicks closer to a pre-EPA machine, a motorcycle that runs like they did prior to 1980.


> If there isn't a siginificant amount of restriction in the stock
> air filter (and how do you know what "many think it is"?)

Time in grade. Experience with new riders has shown the first thing they want to do, not having a real clue why it could matter, is to rip out the stock air filter. The stock filter was designed by the Suzuki engineers to breathe well enough, even when dirty, to pass enough air to allow the engine to perform throughout the intended rev range.


> ... how do you account for the fact that removing the filter altogether results in an engine that just barely runs ?? (without any other mods).

All air filters restrict airflow, they are a wall of mesh in the doorway. A carburetor is simply a venturi tube with a reservoir [float bowl], fuel ports, and a metering device [slide needle]. As the piston moves down on the intake stroke it creates vacuum in the tube drawing air through the air filter. Resistance to flow from the air filter causes the vacuum in the tube to draw fuel through jet orifices. Removing the air filter allows the negative intake atmosphere to normalize almost completely through the end of the venturi tube bypassing the primary circuit jet which enters the flow earlier than the slide needle. Said another way, without the air filter the engine runs lean.

Suzuki's engineers are smart guys and way ahead of us consumers with our roll-aways and hand tools. Using EGAs, dynos, a myriad of sensors and other monitoring widgets, they calculate proper fuel flow into the combustion chamber with the given air filter and port resistance, and expansion flow out of the head with the given pipe and muffler resistance. Randomly removing or replacing parts of the flow system alters the equation.

[Easy Rider]

Said another way, without the air filter the engine runs lean.


So that means that the air filter offers signigicant restriction to the air flow. If it were not significant, it would not have so pronounced an affect.

Thanks for the refresher on the operation of a carb. It really MADE your point. :shocked:

Now tell us about that survey you took to substantiate "less restrictive than many think it is." :roll:

[zoned10x]

> So that means that the air filter offers signigicant restriction to the air flow.

'Significant' is your word. The stock air filter supplies adequate restriction in the airflow for the carburetion and draw. It is not too restrictive or inadequate, it does not hinder performance unless the exhaust backpressure is reduced.


> Now tell us about that survey you took to substantiate "less restrictive than many think it is."

Over 40 years working with wankers who don't get it.

[Water Warrior 2]

Just had a thought about the vacumn or lack there of. If the carb has less vacumn would the petcock be compromised and starve the engine for fuel. Take out the air filter, turn the petcock to PRIME and go riding. May or may not run like crap. And no, Lynda won't let me try that on her bike.

[Dupo]

> Now tell us about that survey you took to substantiate "less restrictive than many think it is."

Over 40 years working with wankers who don't get it.


Survey says.............. :lol:

[Easy Rider]

Just had a thought about the vacumn or lack there of. If the carb has less vacumn would the petcock be compromised and starve the engine for fuel.

That sounds logical, doesn't it, but it doesn't quite work that way.

A carb works on the petri effect (or is that venturi effect ?) as much as it does on vacume, that is, it depends on air FLOW. The vacume is kind of a side effect and is always present downstream from the throttle plate.......unless you are turbo/super charged........or for that instant right after you whip it WFO. The difference in vacume when changing styles of air filter depends on carb. design but usually is VERY small, if any.

The fuel in the bowl is more than enough to make up for a momentary loss of vacume......if you have one.

OK, zoned, your turn. Surely there are several "nits" in there that you can expand into a couple of pages of "corrections". :biggrin: :poked:

[Dupo]

Ok, this along with several other threads in this forum have been taking a turn for the worst and this needs to stop. Posting from new members has really decreased over the past few weeks and i can see why.

I know we all are starved for information here but this is getting out of hand. Nit picking words in sentences then wanting numbers, percentages, surveys, pie charts is just absurd. "...than many think it is" is obviously just a general statement that did not need a graph to back it up.

Seriously, what the F happened to THIS thread in particular? A member asked what the +/- is to the holesaw mod and it turns into a pissing match of knowledge and i honestly do not see any answers. Only a battle of wits and attitude problems. How about answering the guy and not just tell him NO, then turn the thread into shit.

You guys need to realize that these are machines .... and since the first firing of an engine people have wanted to modify them. These are bikes, extensions of our personality. Our bikes are what we make them, stock or custom. I, for one, will always support someone who wants to modify or change something to make it to their liking or personal taste. We, as a group, should encourage someone or give them help/direction in what they want to do and not knock them for wanting to change something that might involve rejetting or taking something apart and modifying it. I mean, really, every time someone wants to either mod something beyond what you guys think is normal .. or <gasp> upgrade to another bike they are whacked across the knuckles with a ruler and basically degraded/told not to do it.

This was the same crap that happened on the shadow forum i once belonged to. Buncha old farts on there that jumped on anyone who wanted to modify their bikes past new pipes and a windshield. I left that group very quickly due to the close mindedness of the members there. Luckily i found another forum that bitches at you for not removing the reflectors on the radiator cover lol. They support and guide anyone who wants to change something on their machine without getting on their ass for wanting to do so.

Lately, this forum has been showing the following:

1. You do not need a loud pipe or pipe modification. Stock is good enough.
2. No air box mods are necessary. Stock is good enough.
3. My bike does not go past 70 mph, even in wind with a truck pushing me down a hill, neither does yours.
4. No upgrade to a bigger more powerful bike is necessary. You are a noob and can't handle one. They are too heavy, you'll drop it. The GZ is the only thing you'll ever need.
5. If you say anything remotely close to "they say" "its been said" "people have said" you will need a pie chart, signed affidavits, notarized letters or any other legal document to back up your claim. Otherwise your argument is mute.
6. If you ask a question and need help on modifications, make sure you are only talking about the needle shim, windshield or 16 tooth sprocket. Otherwise you will be told its beyond your knowledge and discouraged into doing it. Then the thread will take a wrong turn and never answer your question.
7. You're 6'9" 280lbs? sure, you'll fit on this bike perfectly.


Sound familiar?

If this kind of support keeps up i will have no choice but to lock threads that go south.

[Easy Rider]

Seriously, what the F happened to THIS thread in particular? A member asked what the +/- is to the holesaw mod and it turns into a pissing match of knowledge and i honestly do not see any answers.

OK this is what I meant by over-reaction.

His question WAS answered, nicely and calmly, by several people BEFORE the thread took a bad turn.

We deserve to catch hell for the bad turn but NOT for ignoring his question. :skull:

Doesn't sound to me like he is unhappy: "lastly i really love this forum i learned so much. keep this forum alive"

Has he since changed his mind ??

Chris: If I have said anything that offended you, I am sorry.
Did you get the information you need.......even if it wasn't quite what you expected ??
If not, what else can we do to help ??

[Dupo]

It wasn't chris that emailed me and it was also an ongoing thing for a while now. Not singling anyone out or saying who has emailed me in the past, but today was the last straw. Hence this big post.

Anyone wanting to comment go to this thread and we'll discuss viewtopic.php?f=3&t=1964 (http://www.gz250bike.com/forum/viewtopic.php?f=3&t=1964)