2003-1990 KX-DX Hybrid Build

Post by **dfeckel** » 02:52 pm Jan 19 2010

I took the motor back to the shop and they opened it up perfectly--he used some kind of hone. He spent a while getting it to just the right size, then he had me hold the motor down while he spun it with a hand-held hammer drill (!). The thing was waggling all over the place, and I was wondering why I just didn't let the guy take a sledgehammer to the motor. But a few seconds later, we had a perfect slip fit, exactly the same as with the 125 cases. Crisis averted. Now I just need to get my swingarm inner races the right length, and I'll be in business.

skythrasher · Post by **skythrasher** » 03:34 pm Jan 19 2010

Take them to him and let him face them off in a lathe. The will be able to do it a just a few minutes.

Post by **dfeckel** » 05:45 pm Jan 19 2010

"face them off in a lathe"

Man, I should have taken some shop classes...stupid science degree!
I really appreciate all the expert advice I'm getting from this site.

BobbyZ · Post by **BobbyZ** » 03:31 pm Jan 22 2010

Glad to see you got the swing arm worked out.I can't wait to see some pics or even better yet for me to get back to the states and do some riding

I'm counting the days till march.

edit:I just noticed your name in your sig,by chance are you of any relation to the Eckel's of Eckels diesel in Cape May??

Post by **dfeckel** » 05:51 pm Jan 22 2010

Eckel's Diesel in Cape May? Not related to my knowledge, but Cape May is nice--maybe I'll drop in and claim to be a long lost nephew and eat some clams...

Yeah, a little update on the swingarm--9mm seemed to work alright. I thought that the clearance between the swingarm and cases had to be pretty much flush, and 9mm per side yielded a pretty good gap. The critical dimension is the swingarm bearing inner races. When it's all torqued down, the frame sides butt up to the outer busings, which butt up onto the bearing races, and the collars of the bearing races butt up to the case sides--the whole assembly clamps down into a rigid, strong pile of clamped together pieces. Too much clearance btween the cases and races, and it won't cinch together tight. The first set of races were cut too short, so I'm using the races from a second swingarm I bought in a panic when I thought I trashed my first one. When I'm convinced the fit is perfect, I'll finally have my Pivotworks races cut and install the new bearings.

Post by **dfeckel** » 09:50 pm Jan 25 2010

Some progress!

I hacked off the mounts and ground off all remnants of the previous welds.

The swingarm mounted beautifully using the properly cut inner races.

I played a bit with the stock 125's headstay brackets just to get an idea of vertical positioning.

Stock 125 airboot and airbox lines right up. The KDX boot clamp allows enough compression of the too-large boot to seal up with the KDX carb.

Looking good so far. Time to try the exhaust.

Post by **dfeckel** » 10:02 pm Jan 25 2010

Here's where I have run into a snag with my master plan.

After reading all the hybrid build threads i could, I decided a PC Platinum 2 pipe and KX 250 silencer would work best, likely requiring no mods. The flaw with my plan is that this pipe won't fit an E series engine!!

Looks okay here...

And it's actually okay here, too...

D'Oh!!

It's going to require a heckuva dent to clear that big ol KIPS thingee.

It's here that I must mention that I don't think anyone has actually done an E series hybrid in a 99-later frame! I'm blazing new territory

So, anyone have pipe mod suggestions?

Post by **Indawoods** » 10:07 pm Jan 25 2010

Break out the BFH! Unless you can return it and get a E pipe.

Post by **dfeckel** » 11:39 pm Jan 25 2010

Not sure, but i think an E pipe sweeps up too high to work with the KX chassis.

KarlP · Post by **KarlP** » 04:21 pm Jan 26 2010

I think a dent is called for.

It won't hurt!

Tedh98 · Post by **Tedh98** » 04:51 pm Jan 26 2010

KarlP wrote:I think a dent is called for.

It won't hurt!

Agree.

Another pipe might clear that cover, but I'd bet it would hit somewhere else. That PC2 pipe fits the frame too well. I think I saw a build where an FMF pipe was used, but it didn't clear the downtube and had to be cut and extended.

Pretty easy to fabricate a dent.

Brian · Post by **Brian** » 05:25 pm Jan 26 2010

Shoot, come riding where I ride and dents magically appear.

Post by **fuzzy** » 10:57 am Jan 27 2010

Saw some old dyno results where the dented up pipe won.

Tedh98 · Post by **Tedh98** » 11:05 am Jan 27 2010

fuzzy wrote:Saw some old dyno results where the dented up pipe won.

Hope some of the people on eBay don't see that info, otherwise they'll start charging more for their 'performance enhanced' pipes.

Post by **dfeckel** » 04:18 pm Feb 10 2010

Mo' updatin'...

I fabbed up some headstay brackets out of aluminum I bought at Tractor Supply. Initially, I tried to make offset, angled brackets like the KX had originally, but it was beyond my 8th-grade metal shop skills. So, I just made up some flat ones and spacers.

Unfortunately, it looks as if I'll have to get those angled brackets made to clear my IMS tank.

The flat headstay brackets were useful for suspending the motor so I could fab up the other mounts.

I'm moving the lower pipe mount further back on the frame to match up with the PC mount. However, I'm still not happy with the pipe alignment. I may cut the mounts off the PC pipe so I can optimize the alignment to the stinger and silencer. As you can see, I had to cut the stinger off the pipe because it was coming into hard contact with the airbox. I'll add it to the list of things I need the welder to address.

Here's the expansion chamber post-BFG treatment to clear the KIPS machinery.

If I haven't mentioned it already, I suggest using an H series engine so the pipe fitment is easier!!!

Post by **dfeckel** » 04:46 pm Feb 10 2010

Um...I meant BFH treatment. Not BFG treatment. Pipe would probably look worse after being run over by a BFG...

Post by **fuzzy** » 05:50 pm Feb 10 2010

Nice 'mod' ;)

red-eye-righley · Post by **red-eye-righley** » 09:41 am Feb 12 2010

Forgive me if I'm wrong - aint this the later frame with the earlier engine?

The pipe is pretty low though (maybe for this reason)....

Post by **dfeckel** » 05:43 pm Feb 15 2010

Red-eye,

This is the later frame with the earlier engine--but there's just no way that the earlier E-series pipe would fit the KX frame--it sweeps up way too high.

Post by **dfeckel** » 05:47 pm Feb 15 2010

Here's a question--I'm lacing up the 18" wheel to the KX hub, and I don't know which spokes go where. Specifically, the set comes with 27 "inner" spokes and 9 "outer" spokes. The 9 outer spokes are about 2mm longer than the 27 inner spokes. Anyone know where to put those 9 "outer" spokes? Do they all go on the sprocket side or the disc side or some combination?

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2003-1990 KX-DX Hybrid Build