Modifying stock late model pipe

kmccune · Feb 6, 2005

There was a post here I think in the last year from a guy who modified his post ’97 model KDX pipe by cutting a hole out of the inside wall of the pipe. I found a stock pipe for five bucks and I’d like to see how it goes.
If no one remembers the post has anyone done this and how well does it work compared to new pipe?

PS I searched and came up goose eggs.

Thanks

bigpa · Feb 6, 2005

Check the current thread (actually a revived old thread) "KDX new owner by GRAHAMSYMCOX...By the way do not proceed untill you read the last post by me! :think: :rotfl:

BRYDEN1 · Feb 6, 2005

Gutting your pipe isn't as bad as Crossryder makes it sound. When I did mine it took about two hours to pull it off, gut it and reinstall. I have since installed a torque pipe (FMF). I found that gutting the pipe made the hit more noticable and helped slightly with bottom end power. (I also went up 2 or 3 main jet sizes after gutting). The torque pipe improved the bottom end even more and spread the mid range pull out a little farther. The first thing I noticed after gutting the pipe was the ability to pick up and carry the front end by just rolling on the throttle in third gear. Before the mod it used to take a hard yank or a seat bounce to lift the front end in 3rd.

Go to the JUST KDX home site and read the tech tip article on gutting pipes. Plan your initial cut to go through all the spot welds and you should have no problems. I brazed mine back together and ran it for a couple of years with no problems. If your unsure about your fabrication abilities, just go buy a pipe. Either way, it's all good. :cool:

kmccune · Feb 6, 2005

It was Crossryders thread that got me thinking about it, I have read the Just KDX tech tip on older model pipes many times, but I thought that the newer pipes are made differently? Anyway what I wanted to know was the improvement over stock and how much better an after market pipe would be.
If the guy is still willing it will only cost me 5 bucks to find out! Thanks

Oh I almost forgot, BRYDEN1 do you have a 200 or a 220?

BRYDEN1 · Feb 6, 2005

I have an 01 220. If cost is an issue, gut the pipe. It's cheap and gives you a good performance gain although not quite as much as an aftermarket pipe. Although the stock pipe is heavy, it is very tough. The aftermarket pipes ding easily and NEEDS a pipe guard. Make sure you rejet when your done.
Good luck.

kmccune · Feb 7, 2005

Sorry Crossryder, when I looked at the thread that you were talking about, I realized it was the one I wanted. Price is a bit of an issue for the next year or so, guess I'll be gutting a pipe!

Thanks again

bigpa · Feb 7, 2005

Glad I could help. All kiddind aside it's not as bad as I made it sound. It's worse! :yikes: Seriously, I finally got all the mesh out and getting it welded. It's not that hard, just a no fun, messy job. And Bryden, come now... you took the pipe out, cut, gutted, cleaned, welded, repainted and reinstalled in 2 hours?? :yikes: :rotfl: Kawa needs you to work on Bubba's race bike! ;)
I'll post performance impressions soon!

BRYDEN1 · Feb 7, 2005

I used to work in a welding and fabrication shop. It's way easier and faster when you have the right skills and equipment. It always takes longer when you do anything the first time. Do yourself a favour and don't make the cutout too small. Take the time to find all the spot welds and plan your cut accordingly. :)

bigpa · Feb 7, 2005

Ok, now I believe yuo Bryden! I forgot and you touched a key point. Do make sure you cut a big enough plate. GRAHAMSYMCOX recomended a 5x5 inch cut but a little bigger will make things easier as Bryden pointed out! Good luck, you're gonna need it! :rotfl:

DirtRoller · Feb 23, 2005

Well you guys got me tinkering. To much rain around here, and no after-market pipe in stock = cut-out and remove baffel like innards.
It took about 1hr to cut and gut. Will weld tomorrow... should look untouched when done.
Don't exspect to see much from this mod because it is pretty far along in the expansion chamber.
Going on a long distance ride this wkend with a guy on a KTM 525. I'll need all the help I can get :ugg: :coocoo:
I have pictures of this project if anyone wants them.

MY KDX 220 R · Feb 23, 2005

Pic's would be great - alot of rain here too.

DirtRoller · Feb 24, 2005

I could post them here or e-mail them to you.
If I post here it would only be one or two. If you want I have about seven pictures from start to finish.
I'm sure the picture you want is where to make the cut,right?

DirtRoller · Feb 24, 2005

Here are the pictures click here first then the link below.

http://www.freeridesouth.com/pics/pictures/4596.jpg

MY KDX 220 R · Feb 24, 2005

Nice pic's, please e-mail to rodneychaplin @ aol .com, let us know on the performance and the overall effect

Dirt Bike Dan · Feb 25, 2005

If you're feeling really ambitious, why not make your own pipe? I'm going to try to make a couple this summer. Google hydroformed expansion chamber, and expansion chamber design. Only problem is if you don't have a MIG.

DirtRoller · Feb 25, 2005

Tried to e-mail you but it kick back.
Some details added; The trick is to use a 35 thous. cutting wheel.
Clean all the spooge out of the pipe.
Sand along all the cuts before welding.
I also cleaned up the front weld on my pipe.
Oh, I used magnets to hold the plate in place for tacking.

Amazingly there is a difference in perfomance.
Low seemed smoother, mid felt snapier, and the top end seem to have the biggest improvement.
Now all this might be just from all the spooge removed from the whole pipe, and the front weld cleaned up... I don't know. But it's all good.
Need to play with the jetting maybe to see if I can squeeeeze a little more out.
This mod gets a thumbs up tinkering rating. (look up tinker in the dictionary) :laugh:

MY KDX 220 R · Feb 25, 2005

Nice one with the magnets.
Must apologize forgot the 8. rodneychaplin8 @ aol .com

Will definately be giving this a go, thanks again for the info'. I'll let u know when I have done mine. Want to get a few more hours on it ( only has 6) and then will do the fluids and hopefully the Wiseco all at the same time.

kmccune · Mar 6, 2005

Hi thanks for the info, pics would be great as well

kmccune@somtel.net

Sorry for the late reply, I was in Fl all week spending my kids inheritance... well at least I was spending it on them :)

Thanks again

DirtRoller · Mar 7, 2005

kmccune, did you see the pics in the post above?

UP-date on this mod....... DO IT!
Like I said, I don't know for sure what made the improvement, every bit of spooge removed,or front weld sanded smooth, or the cut and gut. So do all three.
This bike was tested hard this wkend... and it is bigger improvement then I thought from the test ride around the block.
I need to pull the plug and make sure it is not to lean... 148m/j
If I have time I'll post a link showing the finished pipe on the bike. The only way to tell is the pipe is black (not dark grey) and if you look on the back side (motor side) there is a weld seem.
Now lets see where can I spend that 170 bucks that I saved on a pipe. :nener:

kmccune · Mar 7, 2005

Not sure how but I did miss them. Maybe you should send then to cdave for the Just KDX website tech tips? Thanks

Modifying stock late model pipe

kmccune

2-Strokes forever

bigpa

BRYDEN1

kmccune

2-Strokes forever

BRYDEN1

kmccune

2-Strokes forever

bigpa

BRYDEN1

bigpa

DirtRoller

MY KDX 220 R

DirtRoller

DirtRoller

MY KDX 220 R

Dirt Bike Dan

DirtRoller

MY KDX 220 R

kmccune

2-Strokes forever

DirtRoller

kmccune

2-Strokes forever

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Modifying stock late model pipe

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