yortz

Member
May 16, 2004
35
0
first i would like to say , this is a outstanding web site , as a newbie I really am impressed with the incredible amount of info. ,seems to be alot nice people with know-how. any way me thinks me ordered the wrong pipe. gnarly woods pipe for my 220. i ride only tight woods, so i thought low end would be the answer. but after reading a recent thread it seems that its a torque pipe for the 200, and somthing a bit different for the 220 . O well whats $ 300 .ouch. fast learning curve!!.any how looking foward to my first post break-in ride. i have had several XRs through the years, and am totally impressed with power and weight of these greene machines. Enough yappin.its taken 25 min. to peck this memo out !!!
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KAY DEE EXER

~SPONSOR~
Mar 3, 2003
629
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I may be wrong but Im sure I read if you add a torque ring from FRP it makes it close to the rev pipe. I am probably wrong though and Im sure someone will correct this if Im wrong. It could be a cheap way out if they wont exchange it for you.
 

canyncarvr

~SPONSOR~
Oct 14, 1999
4,005
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You didn't say...if that's a US$ figure, you got bit pretty bad.

Not to worry. From what you say, you have the right pipe.

There is a lot of confusion over only two choices (from FmF) that really doesn't need to exist.

They make two pipes for the KDX (referring to the newer 'H' series). They are called lots of different things, but still.....there are only two. One is a high-rpm profile, a rev or desert pipe, one is a low/mid rpm profile, a torque or woods pipe.

The letters may vary (and sometimes pipes are labled incorrectly!) but a rev will have a -30 designation and a torque will have a -35 designation.....these numbers usually stamped on one of the mounting tabs.

Part of the confusion comes courtesy of FmF themselves. They mix the 'names' of their pipes from the 200 to the 220, calling it one thing for a 200, something else for a 220.

Both pipes have the same profile impacts on both kdx displacements. The rev is 'upper', the torque is 'lower.'

Yes, the port timing and carb differences between the two bikes would make the same pipe act differently if put on the two different kdxs, but that's because the bikes are different from the git-go. Most any pipe will make those differences stand out.

The torque (woods) is the choice of more than a few 220 riders. If it's bottom end you are after, you picked the correct pipe.

If you end up buying a 'rev' pipe to compare....try to find a better price! ;) $189/US is usually easy to find.
 

yortz

Member
May 16, 2004
35
0
Thanks for the info. guys, I should clairify,I paid $ 179 for the pipe, and $ 124 for the silencer, and did not know if i pissed $ 300 away on a totally wrong set up. but it sounds like it will work fine! again thanks for the help:
 

canyncarvr

~SPONSOR~
Oct 14, 1999
4,005
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The same silencer (a spark arrestor I hope) will fit either pipe. So, when you buy your new -30 to compare your -35 to, you will use the same S/A.
 

dougjc

Member
Mar 23, 2003
65
0
I've got a 220 and added the fmf woods (torque) pipe and turbine core II Q silencer. I definitly noticed more kick in the lower to mid range. If you ride tight woods and narrow trails, you will be happy with your choice.
 

motorpsycho

Member
Jun 8, 2003
20
0
I ride pretty tight single track 90% of the time, and wanted a tractor. I went with the desert pipe Boyesen(sp) reeds a new Weisco piston and dropped the front sprocket to a 12 tooth.
The bike absolutetly rips! :) Anyway.........I am sure that you'll have a noticable improvement over stock.
RIDE ON!!!!!!!! :aj:
 

Aflica

Member
May 23, 2004
66
0
Hey there...i got an 03 KDX 220 , with the Gnarly woods pipe , and i do tight trail riding and love it. You'll be ok with your choice , take care and stay in between the TREES !! :cool:
 

skipro3

Mod Ban
Dec 14, 2002
902
0
One more thing: The woods pipe you got is not as fat as the rev pipe and less likely to be smashed when out in the forest. In either case, protect it with a good aftermarket pipe guard.
 

Imathorp

Member
Dec 29, 2003
71
0
I run what i consider to be the best of both worlds. i have a "rev" pipe but retarded my timing way back to keep the torque i was used to having with my "woods" pipe. I now have a bit more of a peaky hard hitter in the mid-top end but can still keep it under the pipe and use the retarded timing to tractor up the tuff stuff.
 

canyncarvr

~SPONSOR~
Oct 14, 1999
4,005
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Please take a read at THIS for a good explanation of timing and engine response (from Rhodester).

It works backwards of what you said...pretty much. Yes, retarding the ignition will give you a '..peaky hard hitter..' but that is at the expense of the bottom end.

Advanced ignition timing will (relatively) increase bottom end response, smooth out the 'hit' and take a toll on the top-end/upper rpm response.

You can find the same explanation in a number of different venues if you take exception to that post.

**edit**
This is in error. Facts and errors are mixed together to make a goober. Read this (same thing found many other places) to get it straight.
 
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yortz

Member
May 16, 2004
35
0
gentlemen thanks for the advice I think i will try the pipe first,[ it should be here today] and see if it is suffiiciant. I also orderd a set of carbon fibre reeds, and a 12 toothe sprocket.How ever i do have a question? Do you think it is alright to just let the CDI unit [ i think that is what it is ] hang down inside the air box. I took the lid off , and removed the unit, it seems to have heavy wiring ,and is well epoxed. so i just tucked it inside the air box. see any major problems with that set up?
 

KelvinKDX

LIFETIME SPONSOR
Aug 25, 2000
1,622
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yortz said:
Do you think it is alright to just let the CDI unit [ i think that is what it is ] hang down inside the air box. I took the lid off , and removed the unit, it seems to have heavy wiring ,and is well epoxed. so i just tucked it inside the air box. see any major problems with that set up?

I afix mine to the inside of the airbox with industrial strength velcro. I do not want anything loose to bounce around.
 

Junkyard Dog

Member
Mar 31, 2004
63
0
I used a dremel tool to cut the top out of the air box lid (where the snorkel used to be) except for the lip around the outer edge of the air box, and also left the part that the cdi sits on. So the lid and the cdi unit remain in the same place as stock.
 

Imathorp

Member
Dec 29, 2003
71
0
Like i said i RETARDED my timing giving me MORE bottom end and then gained the top end i lost back with the rev pipe.

to advance timing brings the spark further away (sooner) from top dead center thus allowing it to rev higher and still produce power effeciently into the higher RPMs. retarding the timing brings the spark in closer to top dead center producing better power at slower RPMs and taking away RPMs from the top end. turn the stator plate counter-clockwise to retard and clockwise to advance.

still dont believe me? go try it and report back your findings!

the more peaky hit i spoke of is from the rev pipe as well as the picked up higher RPMs.
 

canyncarvr

~SPONSOR~
Oct 14, 1999
4,005
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You are only making the point all over again.

You are incorrect. Not altogether in every aspect...but in several.

re: 'to advance timing brings the spark further away (sooner) from top dead center thus allowing it to rev higher '

Uh..in a word, no.

re: 'retarding the timing brings the spark in closer to top dead center producing better power at slower RPMs and taking away RPMs from the top end'

Uh...same word.

re:'go try it and report back your findings'

I have. Many times. My findings are coincident with the facts of the matter....just not your facts. ;)

Apology accepted.

Oh...and you're most certainly welcome!
 

Imathorp

Member
Dec 29, 2003
71
0
well you basically turned into a huge hardy and sure-footed animal smaller and with longer ears than the horse right there and didnt correct or explain anything.

reading it again I could try to better explain my use of the word "sooner". by the use of "sooner" i mean the spark is earlier or farther away from TDC in the revolution.

So wise-guy! lets hear your version of timing and YOUR explanation of the effects to torque by advancing and retarding timing. And make it YOUR version not just a URL for us to read other's comments from.

here's a few tidbits you can use to elaberate on:

The time that the fuel takes to burn is roughly constant. But the speed of the pistons increases as the engine speed increases. This means that the faster the engine goes, the earlier the spark has to occur. This is called spark advance: The faster the engine speed, the more advance is required.

Force causes acceleration, torque=force x distance

There is a small delay from the time of the spark to the time when the fuel/air mixture is all burning and the pressure in the cylinder reaches its maximum. If the spark occurs right when the piston reaches the top of the compression stroke, the piston will have already moved down part of the way into its power stroke before the gases in the cylinder have reached their highest pressures.

To make the best use of the fuel, the spark should occur before the piston reaches the top of the compression stroke, so by the time the piston starts down into its power stroke the pressures are high enough to start producing useful torque.


Uh...OK?
 

Imathorp

Member
Dec 29, 2003
71
0
You see... at slower speeds and with less advance you bring that fine line (last post) closer to TDC and the power stroke is at its strongest at the slower engine speeds. So with retarded (base) timing you cant free it up enough to run into the higher RPMs. Reads: not advanced enough causing efficiency to fall off and thus power falls off.

However, we’re dealing with 2 strokes here and the vacuum and sonic waves from the pipe have a huge role here too. That is were by changing pipes you can effectively increase intake charges and change timing at the exhaust port. So a combination of retarded ignition timing and a larger and longer expansion chamber can work together to broaden the power band.

In reverse: Advance the timing with a lager and longer expansion chamber and you shorten the power band but increase the power output (bigger hit). Usually the shortened power band is raised to a higher RPM range too. Or just the lower end of it is chopped off. This all depends on the pipe design of course.
 
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Rhodester

Member
May 17, 2003
549
0
Sorry, but CC is 100% right. So was Eric Gorr when he suggested I advance my timing to enhance the power and snap off of the bottom end. I understand this trick from my ATK406 days of playing with the compression ratio and observing the results. Advancing the timing gives the "effect" of increasing the compression. The flame front reaches its max pressure sooner increasing the compression effect as the piston approaches TDC. I don't fully know all the technical science behind it but I've observed its effects in enough different situations to know how it practically works and have used it to manipulate the power characteristics of more than one engine. Advance the timing on a 2 stroke and it will enhance bottom end performance but tend to choke off the available maximum RPMs the engine can achieve. Retard the timing and it will soften the bottom end power and snap and allow the engine to rev more freely and reach higher RPMs. More effective compression = more bottom end and less top end revs. Less effective compression = softer bottom end and more available revs.
 

Imathorp

Member
Dec 29, 2003
71
0
I still disagree. you're like half right. we're talking about the fine line between too much advance and taking away torque and not enough and losing performance too in regards to bottom end power. if you play with the timing you will feel the power band move up (effect of advancing) and down (effect of retarding) with the timing. there is such a thing as too much of either and all depending on where prefer your power band.

This fella (original poster) was worried about losing bottom end or better yet keeping what he had with the supposed wrong pipe (rev or dessert). my original advise was to retard his timing to keep or recoupe his bottom end.

once again, its basic engine dynamics. If the burn cycle starts too early in the rotation ( due to advanced timing) the torque will fall off because the peak cylinder pressure is being achieved too early (wasted energy). the piston has to complete the rotation past TDC under the pressure of the expanding gases missing the peak cylinder pressure and not forcing the piston down as hard.

torque=force (pressure) X distance(stroke).

retard the timing and the peak pressure hits at that magic moment when the piston is juuust traveling down the stroke and utilize the maximum amount of energy to force the piston down (increasing the torque)

Is there not someone out here that can shed some light on this....I'm starting to think I'm nuts and bike is running bass-ackwards LOL
 
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trsrdr

~SPONSOR~
Jul 12, 2001
66
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Uh, about the pipes issue . . . Fredette told me that on a 220, the Rev pipe was the way to go, there is almost no difference in performance from a stock pipe to a Woods pipe, but there is a weight savings. He also said that without porting and carb work, the stock silencer was fine, just a bit heavy. After porting and enlarging the carb bore, an aftermarket silencer can be added to "tweak" performance. A good idea might be to call Jeff Fredette and get his take on pipes for the different bikes, riding styles, etc. He probably could help with timing questions as well.
 

Knobbyjake

~SPONSOR~
Jan 29, 2000
203
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"well you basically turned into a huge hardy and sure-footed animal smaller and with longer ears than the horse right there " LMAO! :laugh: I like that! Mind if I use it in MY next argument?
 
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