Will a KX pipe work on KDX Hybrid?

Discussion for swapping a KDX motor in a MX frame...

Will a KX pipe work on KDX Hybrid?

Postby morganid » 10:28 am Sep 11 2018

I'm weighing pros and cons of tearing apart my complete 2003 KDX 220 and building a hybrid in a 2001 KX125 frame I have. I'm trying to mentally gauge the difficulty of the fitment issues and if it's worth doing.

As I've researched various builds, it looks like there will be a gap between the motor and pipe header. As far as I can tell, all the builds have the KDX pipe. Will a KX125 or KX250 pipe fit better? Do any of you have experience with this?
morganid
Supporting Member
 
Posts: 154
Joined: 05:38 pm Jan 24 2014
Has thanked: 0 time
Been thanked: 6 times

Re: Will a KX pipe work on KDX Hybrid?

Postby Jason » 11:46 am Sep 11 2018

A KX125 pipe will not be tuned for a KDX engine, so even if it fit likea glove, it would suck.

A KX250 pipe won't fit a KDX200 / KDX220R. It also would not be tuned.
Thank you, Julien D for all your hard work!

PLEASE! Do not "dip" PWK Keihin carbs in Berryman's to clean them! It will damage the internal o-ring (jet block gasket).
User avatar
Jason
KDXRider.net
KDXRider.net
 
Posts: 8580
Images: 12
Joined: 06:45 am Nov 01 2004
Location: AL, USA
Has thanked: 145 times
Been thanked: 347 times

Re: Will a KX pipe work on KDX Hybrid?

Postby morganid » 01:15 pm Sep 11 2018

Yeah. I know they won't be tuned for the KDX engine. But adding an inch or two the header detunes the pipe also.

Baised on internet pictures, the 125 pipe looks to be a similar size of expansion chamber. However the KDX pipe looks to have more of a curl in it before the large part of the expansion chamber. It more resembles the shape of the 250 pipe. I'd assume the 125 pipe is a closer tune than the 250. But I could be wrong.

I'd also assume that the 250 pipe has a larger diameter on the header than the 125 pipe. Not sure if either match the KDX header diameter.
morganid
Supporting Member
 
Posts: 154
Joined: 05:38 pm Jan 24 2014
Has thanked: 0 time
Been thanked: 6 times

Re: Will a KX pipe work on KDX Hybrid?

Postby Timtee » 03:17 pm Sep 11 2018

If you are going to do a hybrid, just get the KDX pipe. It fits perfect and will match the engine.

Using a KX pipe is a lot of work for sub-par performance.
Timtee
Member
 
Posts: 129
Joined: 10:02 am Mar 08 2014
Has thanked: 0 time
Been thanked: 7 times

Re: Will a KX pipe work on KDX Hybrid?

Postby morganid » 07:52 pm Sep 11 2018

I'm fairly sure a KDX pipe has to be extended for the 99-02 frame. (Which is what I have). I think it fits for the 03+ frame.

The only reason I would consider a KX pipe is so I don't have to make/modify a pipe.

Can anyone validate or deny this from experience?
morganid
Supporting Member
 
Posts: 154
Joined: 05:38 pm Jan 24 2014
Has thanked: 0 time
Been thanked: 6 times

Re: Will a KX pipe work on KDX Hybrid?

Postby bufftester » 11:17 pm Sep 11 2018

I have the stock 2001 KDX pipe on my hybrid built on a 2001 KX125 frame. No modification was needed, no extension, not even a torque ring. It comes close to the frame but doesn't touch. The key is to mock up the exhaust with the engine before making the engine mounts so that you get it all lined up correctly.
849
847
822
User avatar
bufftester
Platinum Member
Platinum Member
 
Posts: 2135
Images: 168
Joined: 06:03 pm Oct 31 2012
Location: University Place, WA
Has thanked: 3 times
Been thanked: 143 times

Re: Will a KX pipe work on KDX Hybrid?

Postby Timtee » 05:45 am Sep 12 2018

bufftester wrote: The key is to mock up the exhaust with the engine before making the engine mounts so that you get it all lined up correctly.


But you do have to step back and make sure that the engine isn't rotated too far forward or backward, otherwise you'll wind up with issues of the chain and swingarm.

When I have done my hybrids, I position the engine where it needs to be and then deal with the fitment of everything else. Never a problem with a KDX pipe.
Timtee
Member
 
Posts: 129
Joined: 10:02 am Mar 08 2014
Has thanked: 0 time
Been thanked: 7 times

Will a KX pipe work on KDX Hybrid?

Postby Artstoy » 10:20 am Sep 12 2018

The kdx pipe will work in the 03 frame without mods, beyond welding new mount tabs to the frame to fit kdx pipe. the tricks the silencer. pro circuit and fmf change up things a little as well
Artstoy
Member
 
Posts: 11
Joined: 03:20 am Sep 04 2018
Has thanked: 0 time
Been thanked: 0 time

Re: Will a KX pipe work on KDX Hybrid?

Postby bike4500 » 04:45 pm Sep 14 2018

I had to add about a 1\2 to the header on my 2002 hybrid to get it to clear the frame rails. fmf gnarly with a 2001 kdx 200 motor.
bike4500
Member
 
Posts: 21
Joined: 03:43 pm Jun 13 2013
Has thanked: 0 time
Been thanked: 0 time


Return to KDX-MX Hybrid

Who is online

Users browsing this forum: No registered users and 2 guests