KX/KDX hybrid pipe question. Any KDX'er with a pipe will know

[ebeck]

Does the PC2 pipe have more clearance between the pipe and the frame where it bends right out of the exhaust port? Maybe the FMF?

I am looking for a pipe that once installed is further away from the down tube. The reason is becasue with the KDX motor in the KX frame, the stock pipe is too tight and touches the downtube before it fully seats in th exhaust port.

The pipe comes out of the exhaust port and the bends to the left around a down tube. the stock KDX pipe touches teh KX frame that down tube and does not seat fully in the exhaust port. So I need a pipe with a longer section before it bends.

I can weld a section on I know but I figured aftermarket pipes may be a bit longer.

You will know if your aftermarket pipe on your KDX is further from the frame down tube than the stock pipe was. If you are not sure, post a pic of the area, I can compare it to the stock pipe down tube clearance.

[vinilla gorilla]

My FMF pipe doesn't touch

[155]

wow!!!

[vinilla gorilla]

wow!!!

[ebeck]

The KDX pipe does not touch the KDX frame either though. The KDX pipes does touch the KX frame though. I suspect I am not clear. Let me try it this way...

The question is, "does the aftermarket pipe offer more frame clearance than the stock pipe did"?

[155]

notch out the frame where the pipe hits!

[vinilla gorilla]

Yes if I put my KDX pipe next to my FMF pipe the FMF pipe looks smaller

[ebeck]

So the FMF pipe has less down tube clearance than the stock pipe did? That is the FMF pipe is closer to the frame?

That is the exact opposite of what I was hoping for.

[155]

just cut the freekin down tube of the frame and run the damn pipe already!

[ebeck]

I need another inch. I would literaly have to cut out the downtube all together. That is not feasable 155. It is a better solution to cut and weld on an extension to the pipe. That is easy and cheap too but I figured I'd ask first.

I want to use the PC2 pipe.

[don46]

adding to the pipe isn't necessarily the answer either, if you add an inch to it, you may end up running like a turd. You will want to try and maintain the lengths the same, The picture of the completed bike you posted earlier looked like it had a 125 pipe.

[ebeck]

Nope that was a KDX200 pipe.

[adam728]

Wednesday I'm going to yank my bike out of the trailer and do some work on it. I'll measure the clearance of the FMF in that area and then throw the stocker on and measure too. Should give you an idea if there is a little more clearance available there. You could extend the headpipe a little bit to help with clearance. 10 mm of extension will shift the powerband down approximatly 300 rpm from what I have read.

I could send you my stock pipe for the cost of shipping, but it would be next week before I get it out (just walked in the door from Phoenix, going to Nogales for the next 4 days). Why do you need another stock pipe?

[ebeck]

Yeah great thanks. I need another stock pipe to cut a section off mine and another pipe to cut a section off and weld it to my pipe. Lengthing the head pipe as you stated. Hmm if it shifts powerdown, I wonder if I should use the Rev pipe in the final form. I would need about 20mm worth of extension.

I want to test this with cheap pipes before I try it with shiny new expensive pipes. R&D on the cheap really helps me out and I'll put it back out in the community.

I assume the torque pipe has a shorter head pipe than the Rev pipe? Yours is a Torque Rev right?

I am not is a huge hurry. In the next 3 weeks would be fine Adam.

[adam728]

Torque rev? That's two different pipes.

The FMF gnarly comes in the woods (torque) and rev version. I don't have both to do a direct comparison, but the torque should have a longer headpipe and narrower/longer cone section. Both of these traits will mean a longer path for the pulse wave to travel, which means it will take longer to reverb back to the cylinder. This means it times up at a lower rpm. High reving pipes have shorter head pipes and steeper/shorter cone sections.

Denting the pipe isn't a deadly sin either. Some pipes for bikes come dented for clearance around imovable objects (such as frame rails). I would probably add a 10 mm head pipe spacer and dent the pipe 10 mm at the frame rail.

For reference, do you think there is enough material at the rear engine mount to offset bore it for the larger swing arm bolt and press in new steel spacers? If a few milimeters could be gained this way it could held with the lower most engine mount and the exhaust issue.

[ebeck]

yes, I typed torque and then remembered you said you have the Rev. Woods and Desert is the other terms. g-30 and G32 are the part numbers I think. OD is larger on the Rev pipe as well. Anyhow yeah I realize that it was a typing error not a knowlege gap.

Oh, I measured last night and I am 10mm too short not 20mm as I first stated. Now that is without the gasket or brass sealing ring which ever the KDX used so it is likley 8mm too short. If the Torque pipe is longer it may just clear.

The rear motor mount has lots of material. Going from 15 to 17mm doe afford some slop yeah. I wish I had thought of that before I had it machined out to 17mm.

In any event if the torque pipe and gaskets reduced the deficit to 2-3mm then I can dent the pipe.

Sure wish I could get a picture or measurment of a torque pipe mounted on a KDX.

[adam728]

I believe the Fredette torque ring is 10 mm, that may be all the answer you need right there. Need some one that has one to know for sure though!

[ebeck]

Wholy crap! That is it! That with the gasket and whalla! I never knew they made that. Thanks brotha!

[KDXGarage]

Check on www.frpoffroad.com. K-30 and K-35 are the 1995 and newer current FMF KDX pipe model numbers.

[ebeck]

Ahh yes the G models were the old Fatty and what not.

K(or KG)30 = rev, K(or KG)35 = torque.

Thanks for the correction. I plan on using the PC Plat 2 pipe.