more power, no pipe?

[PolarisRider]

I have to get rid of my hmf because the neighbors dont like it. What can i do to increase performance and have a stock pipe?

[2004exrider]

You can always bore it out, or bore and stroke it. But the stock pipe is still really restrictive im not sure if it will make that much of a difference:confused: .

Jimmy

[PolarisRider]

I was thinking a higher performance cam and an 11:1 piston, but like you said the stock pipe is REALLY restrictive. The header is pueny.

[n811]

No quiet core?

[Blue250X]

Does anyone know how it would do with a WB head pipe and stock silencer?

[redrideronly]

I've been messing around with different configurations with just intake and exhaust. First to debunk a frequent misnomer. Unrestricted exhaust doesn't mean more power. Nor does unrestricted intake. For example, I removed my Uni airfilter competely and took off my T-4 Slipon pipel Holy S---! it was loud as heck, but I lost tons of high end. Sure it was punchy, but but it acheived high RPM quickly and because there was no backpressure on the pipe, I was loosing power. It may have sounded like i was going faster, but all that sound was where my power was going (straight out the pipe). When I checked my sparkplug it was WHITE!!! way to rich and hot!!! This is not good for anything in the motor. Then I Put my filter back in with no muffler. This took care of the white sparkplug problem, but still loosing some top end. Next I REPACKED my T-4 Pipe with (4-stroke) packing (yeah.... 2 stroke doesn't work... will catch on fire!!!). I wrapped the honeycomb pipe frame as tight as i possible could. THEN took Fiberglass mesh tape (from the home depot) and wrapped that (this is just to hold everything tight so you can slip the pipe cover on...it will burn off) I put everything back together, and wow what a differnce. Uni Airfilter, T-4 tighpack slip on is the way to go. The packing in the muffler, actually has a lot to do with not just the sound but the back pressure in the exhaust system. Unrestricted exhaust no good for the motor. Remember PACK THAT honeycomb as TIGHT AS POSSIBLE

Ride it like you stole it!

[Blue250X]

^^ Don't you mean too lean and hot? Rich shows a black and wet plug tip.

[2004exrider]

Originally posted by redrideronly
I've been messing around with different configurations with just intake and exhaust. First to debunk a frequent misnomer. Unrestricted exhaust doesn't mean more power. Nor does unrestricted intake. For example, I removed my Uni airfilter competely and took off my T-4 Slipon pipel Holy S---! it was loud as heck, but I lost tons of high end. Sure it was punchy, but but it acheived high RPM quickly and because there was no backpressure on the pipe, I was loosing power. It may have sounded like i was going faster, but all that sound was where my power was going (straight out the pipe). When I checked my sparkplug it was WHITE!!! way to rich and hot!!! This is not good for anything in the motor. Then I Put my filter back in with no muffler. This took care of the white sparkplug problem, but still loosing some top end. Next I REPACKED my T-4 Pipe with (4-stroke) packing (yeah.... 2 stroke doesn't work... will catch on fire!!!). I wrapped the honeycomb pipe frame as tight as i possible could. THEN took Fiberglass mesh tape (from the home depot) and wrapped that (this is just to hold everything tight so you can slip the pipe cover on...it will burn off) I put everything back together, and wow what a differnce. Uni Airfilter, T-4 tighpack slip on is the way to go. The packing in the muffler, actually has a lot to do with not just the sound but the back pressure in the exhaust system. Unrestricted exhaust no good for the motor. Remember PACK THAT honeycomb as TIGHT AS POSSIBLE

Ride it like you stole it!

That was the worse suggestion/statement i have ever read:ermm:

[95300exrida]

why dont you just insert a quiet core? or else just keep the noise when you are riding around your home?

[underpowered]

redrideronly-all i can say is wow, yeah. all that info you stated was pretty much well, wrong. of course you lost power when you removed the air filter and pipe. there is alot of R&D that goes into making a pipe to engineer it for power. engines need back pressure to operate, and no one ever said anything about plain out opening up a motor with no pipe or filter. however you can make more power without a filter if you jet it correctly, but i would not suggest it because you will suck all kinds of dirt and crud into you motor.

your plug was white because you were lean, not rich. you were simply pulling in to much air without your filter. gettin power is not simply about opening up the intake and exhaust. companies spend alot of time and money making their parts perform as good as possible.

[PolarisRider]

the quiet core just makes it more high pitched and gay sounding. its pretty much the same sound level.

[PolarisRider]

Originally posted by Blue250X
Does anyone know how it would do with a WB head pipe and stock silencer?

i would also like to know

[-copyguy-]

Originally posted by PolarisRider
the quiet core just makes it more high pitched and gay sounding. its pretty much the same sound level.

umm..nope. quiet core just quiets the HMF pipe down...a lot. spend the $20 to get one. Don't try modifying a stock exhaust either...been there, done that, not worth the time.

As far as having an aftermarket headpipe with the stock silencer, I don't think it would help as flow is still way more restricted in the stock silencer than in an aftermarket one.

[PolarisRider]

Originally posted by -copyguy-
umm..nope. quiet core just quiets the HMF pipe down...a lot. spend the $20 to get one. Don't try modifying a stock exhaust either...been there, done that, not worth the time.

i have one lol, i notice a tiny difference. but all in all, its still loud.

[ATC_KING]

F the people that live next to you . the people that live next to my dont like the ATVs AND ATCs that i ride around on but they dont have the balls to say that ot my face they have to tell the cops and then they tell me but they cant do anything about it. so if you dont like the people that live next to you just keep it on:devil:

[PolarisRider]

Originally posted by ATC_KING
F the people that live next to you . the people that live next to my dont like the ATVs AND ATCs that i ride around on but they dont have the balls to say that ot my face they have to tell the cops and then they tell me but they cant do anything about it. so if you dont like the people that live next to you just keep it on:devil:

Ones my grandma, ones my great grandma, and ones my great aunt. oh and a cops one of my neighbors too ;)

[Blue250X]

Originally posted by PolarisRider
Ones my grandma, ones my great grandma, and ones my great aunt. oh and a cops one of my neighbors too ;)

hahahaha Plan B:p

[-copyguy-]

PolarisRider, sorry man, I missed the fact that you already had a quiet core. I know it helps my 400ex out quite a bit... anyhow, maybe you should look at getting one of these...

http://www.rockymountainatv.com/productDetail.do?navType=type&webTypeId=57&navTitle=Exhaust&webCatId=18&prodFamilyId=5439

:p

[2004exrider]

Ear plugs always make a great christmas present:p

Jimmy

[wilkin250r]

I don't know exactly about the stock header being restrictive, but I imagine you are correct. Old technology, high RPM power never really entered into the equation. The stock valves and ports are definitely restrictive, it only follows that the pipe would be also.

However, even with the stock pipe, you can still see power gains with a larger bore, higher compression, and cam. Granted, you would see even more with a higher-flow exhaust, but those mods will still add power even with the stock pipe.

[PolarisRider]

Well i think itd be nice to drop a 330 in this summer. but i like being able to walk out in my garage and know it will start. I think a cam, new valves, rockers, port and polish, and a high rev box, along with a stock bore 11:1 would be decent. wilkin250r how will all that run with a wb header into a stock silencer? will the silencer still slow it down?

[wilkin250r]

I would forget the WB header, unless you already own it. It's not going to hurt anything, but it also isn't going to help. The silencer is your restrictive point. It's like driving with the brakes on, greasing your wheel bearings doesn't really improve anything.

I would also forget the high rev box. More than anything, the restrictive exhaust will kill the high-rev power. If you had head porting, oversized valves, and a free-flowing exhaust, then a high-rev box would be a great addition, because you could rev the motor out further and build good power. But with the stock exhaust, your power dies off right about the stock rev limit. If the power dies off, why would you need the ability to rev higher?

[pats2007450er]

Buy HMF Q series and put the Quiet core in it.The Q series is not that loud so when you put the core in it that will make it even quieter.

[PolarisRider]

Originally posted by pats2007450er
Buy HMF Q series and put the Quiet core in it.The Q series is not that loud so when you put the core in it that will make it even quieter.

thats a decent idea

[Old Head]

The new dirtwheels that just came tested a new exhaust on a 450 along with other mods and it runs at 93db

[PolarisRider]

Originally posted by Old Head
The new dirtwheels that just came tested a new exhaust on a 450 along with other mods and it runs at 93db

what kind?

[I wanna go FAST]

If you want somthing quite sell it and buy a Recon ! You cant be scared of your neighbors, And you cant get rid of your HMF. I'm really impressed with mine and would recomend it to anyone! You cant sheltor a sport fourwheeler by keeping the stock exhaust on it........

[Old Head]

Originally posted by PolarisRider
what kind?
FMF Q-4

[yotacrawler4]

Originally posted by ATC_KING
F the people that live next to you . the people that live next to my dont like the ATVs AND ATCs that i ride around on but they dont have the balls to say that ot my face they have to tell the cops and then they tell me but they cant do anything about it. so if you dont like the people that live next to you just keep it on:devil:

X2 :p :devil: