Kawasaki Motorcycle Forums banner

1 - 17 of 17 Posts

·
Registered
Joined
·
625 Posts
Discussion Starter · #1 ·
I have been reading and searching for days to come up with no definite answer. I plan on running the stock header for now until i order an aftermarket. and a side cutout but just a straight pipe no baffle or anything inside it. now my question is will this set up be safe to run without a power commander for a while. i dont want the bike to run to rich or to lean. ive been reading post's about back pressure and "burning the valves" but i have mixed answers. so do you exhaust guru's think this will be safe to do?

and thanks in advance, Ryan
 

·
Registered
Joined
·
2,438 Posts
Can it be done yes. A friend ran his zx10 for a few months without a pc. It is going to run like crap though. So get a pc as soon as you can. Also after doing a few dyno tunes he lost about 8 whp when put on his side cut out. [the exhaust finished right after the footpeg.] So he ended up selling it and just getting a yoshi full system. So just be aware that the short exhuast is going to lose some power.
 

·
Registered
Joined
·
171 Posts
I ran my bike for about 3 months with the exhaust running right out the lower right side. I bought a pipe at advanced with a bend in it and ran it out right behind the right rear set. I went to the dealer ship and asked what it would hurt. they said nothing. then i asked my drag buddy who is the head mechanic at the HD dealer here and he said the only way it would hurt it is if you were running lean already. My bike runs really rich. Black soot on the inside of the tip of the muffler. and the strong smell of gas when you first crank it up after it cooling off. he said with it running rich the most you could possibly do is file the spark plugs out. as long as you leave the cat on you should be good he said. well he ran my bike in the 1/4 (with pipe) and pulled a 10.97 then ran it with the jumper mod and pulled 10.79 then with no pipe and jumper he pulled a 10.94. i have my pipe back on now because i have been practicing wheelies alot and well being loud makes the cops look. :p

side note. i raced 2 guys on stunt bikes in like 1/8 mile and they have like 54 tooth rear sprockets. well they got me but the people at the line said all they will remember is what my bike sounded like when it went by :D
 

·
Registered
Joined
·
885 Posts
I know this will not be popular but:

Why do you want to create an exhaust system that is so loud that all it does is give all of us a worse view in the eyes of the public?

Besides, it will initially at the least hurt not help performance and you can't ever come close to getting even 3/4 of the performance capabilities out of the bike on the street and wouldn't be allowed at most tracks.
 

·
Registered
Joined
·
625 Posts
Discussion Starter · #6 ·
Why not wait for the PC3??
Because i had some spare time on monday and all the parts wanted to get the ball rolling, but it seems like it will do more bad then good, so im thinking just stick with my two bro's slip on and buy a header pipe in the future then a power commander, thanks for the input
 

·
Registered
Joined
·
171 Posts
Because i had some spare time on monday and all the parts wanted to get the ball rolling, but it seems like it will do more bad then good, so im thinking just stick with my two bro's slip on and buy a header pipe in the future then a power commander, thanks for the input

or you could just get the motowerkz pipe.. loud and so said to gain power.
 

·
Registered
Joined
·
625 Posts
Discussion Starter · #8 ·
or you could just get the motowerkz pipe.. loud and so said to gain power.

I dont see what the difference between the motowerkz pipe and mine besides the baffle... plus i want to wait for a dyno sheet and the new undertail...
 

·
Registered
Joined
·
204 Posts
Im no exhaust Guru.. in fact im new to the bike scene all together... but my boss.. drives a Harley Road King... and he told me it was all about back pressure.... and different size pipes with different baffles create different back pressure..

He took like 8 different shower drain plugs that had different hole patterns on the end and had them welded around the inside edge of the exhaust and made a bracket to try out different ones to give different back pressure.. and he found ones that worked great for his bike.. and he had it checked out by a Harley certified Specialist.. and the guy said that the bike had a lot more hp than stock just from that and a few other little tweaks he had done...

and when I had my full yoshi exhuast on my 08 250 installed without the silence tip it was loud... and I did notice a lil bit of improvement from stock but not much.. but then I decided to stick the little quiet tip on the end.. and it created a lil more back pressure and the difference in perfromance was very obvious that it was even better...

I am not sure if there is more to this... or not.. I know it has a lot to do with timing of the valves and other things like that.. but maybe that will help a lil bit.. with what the difference may be with your pipe versus the motorwerkz gp exhaust..
 

·
Registered
Joined
·
1,664 Posts
I dont see what the difference between the motowerkz pipe and mine besides the baffle... plus i want to wait for a dyno sheet and the new undertail...
Enter...The Exhaust Guru. Lol.

Can you run your stock bike with a short straight pipe without damaging parts, Yes. As long as the pipe is tuned to the engine. Bigger is not always better when you start building an exhaust; The tube diameter, length, number of bends and baffling makes a big difference in the final product's performance and sound. Just slapping on an autozone unit will not do.
 

·
Registered
Joined
·
625 Posts
Discussion Starter · #12 ·
Enter...The Exhaust Guru. Lol.

Can you run your stock bike with a short straight pipe without damaging parts, Yes. As long as the pipe is tuned to the engine. Bigger is not always better when you start building an exhaust; The tube diameter, length, number of bends and baffling makes a big difference in the final product's performance and sound. Just slapping on an autozone unit will not do.
I'm using the stock mid pipe from the bike with the stock bend, if you turn it out instead of up where its supposed to be it angles perfect out of the side then you just cut it at a desired length, so its stock diameter with one 45 degree bend.
 

·
Registered
Joined
·
1,136 Posts
Im no exhaust Guru.. in fact im new to the bike scene all together... but my boss.. drives a Harley Road King... and he told me it was all about back pressure.... and different size pipes with different baffles create different back pressure..

He took like 8 different shower drain plugs that had different hole patterns on the end and had them welded around the inside edge of the exhaust and made a bracket to try out different ones to give different back pressure.. and he found ones that worked great for his bike.. and he had it checked out by a Harley certified Specialist.. and the guy said that the bike had a lot more hp than stock just from that and a few other little tweaks he had done...
That is becuase, frankly, harley guys are not the brightest gearheads in the automotive world. Ever had one try to say they can take your crotch rocket in the 1/8th or from a dig because they have more torque?! I have :Laughing rolling:.

No offense but thats one of the dumbest things I have ever heard, and sounds like something a 16 year old would do to their neon.

I can absolutely promise with 100% certainty that his little mod is costing him power. Restriction in the exhaust is bad for low end hp, top end hp, low end tq, top end tq, EVERYTHING. It is a restriction, and the engine has to overcome it!!!! The ideal exhaust system for a bike would be something like the pinebox or motowerkz pipe with the cat deleted and a proper dyno tune. Noise(and costs) makes that not an option for some people though.

What a combustion engine needs is scavenging, not "backpressure" - and scavenging is due to the shape, length, and diameter of the header primaries - not some random crap blocking your exhaust flow. Exhaust gas does not come out in a stream like a hair drier, it is a series of rapid back to back pulses, and each pulse literally sucks the next pulse of air out from the engine. Scavenging will increase the force of this "in-between each pulse vaccum", literally sucking the exhaust out of the engine and helping it make more power.

Anything after the collector, where the headers scavenging is not tuned to take affect, is a restriction and will therefore cost hp. That includes the cat, baffles, valves, any rough pipe transitions, and especially shower drain covers(wtf?!?).

Backpressure is one the the most widespread engine myths, and I have seen so many misconceptions over the years that it is not even funny. Sure, you get some backpressure from a properly tuned header system, but that is not the goal - just a side affect of the exhaust design needed to create scavenging.

A lot of the misconception comes from the fact that sometimes an ECU cannot compensate the A/F ratio after eliminating a lot of backpressure, so the engine ends up running lean or overcompensating and running rich. That is why you get the people who run open headers without a tune on their bike/camaro/civic complaining that it runs like garbage now...and automatically assume it is because of not enough "backpressure". No, it is becuase your injector pulse width and timing have not been tuned to take advantage of the free flowing exhaust!!!

If backpressure was a good thing, dragsters would run exhaust valves and 1" moped pipes instead of massive open headers. Do a search for exhaust cutout dyno gains if you do not believe me - companies like QTP make electric Y-shaped pieces for exhaust tubing that opens a cutout on one side, essentially turning a tame street car exhaust into open headers. Back to back dyno gains, with a proper performance tune, show increases in both horsepower and torque with an essentially "0" backpressure exhaust system. Popular belief would lead you to think that hp will increase but tq will plummit, but that is just not true. That is why almost every performance exhaust part for any combustion engine from snow mobiles to diesel trucks always advertise with claims like "low backpressure!", "free flowing!", and "no restriction!".

Sorry for that rant, but If I can prevent just one person from cramming crap up their ninjas pipe to create "backpressure" for more torque, this long rant would be well worth it!!!
 

·
Registered
Joined
·
1,136 Posts
Breathe Puck Breathe! Lol.
Hahaha sorry! :Laughing rolling:

It just gets kind of tiring after reading the same type of posts whenever exhaust topics come up :violent:.

:D
 

·
Registered
Joined
·
297 Posts
'Backpressure' is never a good thing, that's true..... From what I've learned and researched, it's all about scavenging for sure but also exhaust VELOCITY is a big point. Hotter exhaust has a higher velocity.

And feel free to correct me if I'm wrong here......but from what I understand, the more efficient you make an engine, the higher its operating range becomes. Sort of like putting a bigger cam in a motor, and it shifts the powerband higher. There comes a point where the powerband is shifted so high that the engine never actually gets to operate long enough in its peak efficient range.

Like.....you could bolt a huge intake and huge exhaust onto a stock car and tune the AFR and timing dead on and it's still going to run like garbage, until you run it up to 9,000 rpms that is. But oh wait, the bottom-end can't handle 9000 rpms. Oh and the head flow gives up the ghost at 7,000. Know what I mean?
 

·
Registered
Joined
·
1,664 Posts
'Backpressure' is never a good thing, that's true..... From what I've learned and researched, it's all about scavenging for sure but also exhaust VELOCITY is a big point. Hotter exhaust has a higher velocity.

And feel free to correct me if I'm wrong here......but from what I understand, the more efficient you make an engine, the higher its operating range becomes. Sort of like putting a bigger cam in a motor, and it shifts the powerband higher. There comes a point where the powerband is shifted so high that the engine never actually gets to operate long enough in its peak efficient range.

Like.....you could bolt a huge intake and huge exhaust onto a stock car and tune the AFR and timing dead on and it's still going to run like garbage, until you run it up to 9,000 rpms that is. But oh wait, the bottom-end can't handle 9000 rpms. Oh and the head flow gives up the ghost at 7,000. Know what I mean?
Just a few things to point out:

'backpressure' in a four stroke engine, is when exhaust air/fuel mixture build up during the completion of the exhaust stroke. Stock engines run with a certain amount of backpressure; the amount is determined by several factors: Valve overlap, Valve Duration and Exhaust Restriction. To fully understand what is actually happening refer to the pics below


The red or orange color is the burnt fuel/air mixture(on it's way out in this pic) as the piston moves upward.


Above is at the end of the exhaust stroke and the start of the intake stroke(note overlap). The build up of pressure on the exhaust side, will force burnt air/fuel mixture to come back through, into the combustion chamber and even sometimes out the intake side(depending on overlap).
The purple/blue color is a product of 'backpressure' and a contamination to the upcoming cycle, which reduces the maximum possible power.

Here's a cool video of the complete four stroke process. http://www.youtube.com/watch?v=2QB7XPMeLnA



Pic References:
http://www.kruse-ltc.com/Diesel/diesel_cycle.php
 
1 - 17 of 17 Posts
Top