Tyl3r's 05/04 KX/DX Hybrid Build - DONE!

[Tedh98]

I'll have to get a complete breakdown of everything...and figure out a polite way to say I feel like being raked through the coals.

If it were me, I would just get the suspension back either way. If he is being dishonest or gouging you, enough said. And if the components are in that bad of shape, then I personally wouldn't put that much money into them. I would hope that a good tuner and decent person would have said that the components are shot and not worth dumping a bunch of money into.

I see it like repairing a rusted out panel on a car. You can spend a lot of hours and $$ trying to make a bad panel good. Or you can just start with a new or better shape used panel and save a lot of time and $$ in the end.

[Tyl3r]

Yea, I am going to pick them up today. Guess I learned a lesson the hard way! Didn't think of it like fixing a car lol brings things more into perspective.

Still waiting on one last freaking drill bit to come in the mail so I can drill the case... dying to start fitting the motor in the frame

[Tyl3r]

Parts are starting to pile up, got the suspension back, and powder coated the trees and rims


Drilled and reamed the case


Cut the old motor mounts out of the KX frame, put the motor in, and got it almost ready for the new motor mounts. I want to try and use the FMF Fatty pipe. I'm going to get a KX250 silencer and see how everything lines up before I go any further. Since the KX is an 05, I would want a silencer that fit a 05 KX250, correct?


Its moving along, slowly but surely! I know I don't know how far up the motor is going to be clocked, but it doesn't like there will be too much issue with having enough room for the carb to mount. I want to run the V-Force 3 reed block, and I know it is "taller" than the stock reed block. Does anyone think it is tall enough that I should get one on there before I finalize the motor mounts? Just to make sure the carb will still fit in there alright...

[Tedh98]

Since the KX is an 05, I would want a silencer that fit a 05 KX250, correct?

2003-2005 are the same p/n.

[Tyl3r]

Since the KX is an 05, I would want a silencer that fit a 05 KX250, correct?

2003-2005 are the same p/n.

Ok thanks, I was just making sure that was the year range that I wanted and not an earlier one. I got a Powercore II on order, as well as some 08 KXF shrouds, V-Force 3's, and an IMS tank (which just arrived).

Anyone have any trouble installing their IMS tank? I was having some trouble installing the L-bracket on the right side, its almost as if I need to elongate the slot in the bracket. I don't know, its been cold out, so maybe the rubber piece on the bracket is hard and won't compress. I don't want to go modifying anything on it just yet. Also, it looks like the tank comes quite close to the coolant hose on top of the head. I haven't started on the motor mounts yet to know for sure, but I hope I don't run into clearance issues with the tank...

[Tedh98]

Scroll down to the bottom of this page, that is how I addressed the clearance with my IMS tank. It also cleaned up the hose splicing.

hybrid build

[Tyl3r]

Nice, I really like that solution. I remember reading that before, but couldn't remember where I saw it.

I am going to still try and see if I can make everything fit as is. If I can't, I think I am going to take the route that you did.

[Tedh98]

Are the KXF shrouds you bought for the 250 or 450?

[Tyl3r]

...250 ....i messed up and didnt pay enough attention to realize the 250 and 450 shrouds are different. Sending them back and exchanging for some 450 ones. I wanted to try and make them work, but I think I would have to trim the crap of them to get them tight enough to the tank, and I would have to make more brackets.

[Tedh98]

You definitely will make life easier with the 450 shrouds.

[Tyl3r]

I got the spacers turned down on the lathe, ended up with 1.811" (drive side) and 1.771" overall widths on them. Then I took .35" and .31" off the swingarm. I rough cut it with a cut off wheel then ground it nice with a file, turned out pretty nice! Chain seems to line up nice and straight too. (I noticed everyone uses the metric system when measuring for their builds... why? A decent bit of us are in America! The metric system is based off of a scale of 10...and that makes too much sense lol j/k I deal with the imperial system all day at work, so just more natural to me)




I am hoping to address the motor mounts next weekend. As it is sitting right now, the motor is rotated up as far as it can go hitting the coolant line into the head. I plan to make a plate to clock forwards for more room for the bigger tank; like Tedh98 did (thanks for the good idea!).

As it sits though, it looks like the Gnarly pipe is going to work out, I'll keep my fingers crossed.


Did anyone have an issue with the front head stay interfering with the coolant line? was thinking about making a mount for it on the frame, but I think its going to interfere and need cut off.

I would like to ask for a little assistance with setting the motor mounts. What am I looking for in regards to sprocket position relative to the swingarm/chain slider as the bike is sitting? Horizontal with the pivot point? Or higher? I guess I don't know how to judge what a good amount of contact would be with the chain slider while the suspension is at fool droop and not on its wheels. Any photos would be helpful if anyone had any handy. I was looking at my buddy's YZ450F yesterday and his sprocket center line looked like it was directly in line with the swingarm with the bike at fool droop. Imagine if you drew a straight line through the center line of the rear axle, thru the centerline of the pivot point; it would pass through the center line of the sprocket. Is that what I want? Just thinking about it, I would have thought that would be too high while riding it.

[B737driver]

On my '04 I had issues with the front head stay contacting the coolant line that goes between the radiators. My solution......cut it off the head. No issue with that anymore.

With the sprocket position....I took a lot of measurements while the 125 motor was still in the frame and did my best to get it back in that position. As others have said, this is probably the primary thing driving your motor mount positioning. I took all other things into consideration as well and mounted the motor where the pipe, sprocket, and air boot to carb connection agreed the most. Haven't ridden a bunch (yet), but I do not notice any premature wear of the slider.

Not the best pic but here is where my sprocket ended up. I'll try to get a closeup in the next few days.

[B737driver]

You may also have fitment issues with the right side radiator line that goes to the water pump contacting the kips governer cover. At least I did. I simply used a really thick hose clamp ( not the worm gear type, a pre-formed clamp I had laying around) and placed it over the hose and resting against the governer cover. This basically added strength at "the bend" and kept the hose from pinching.

That was my solution, not sure what others have done.

[B737driver]

While I'm on a roll here....

Here is an idea for the inevitable splice that you'll make on the left side radiator hose to head connection.

1. It might actually work.
2. It looks cool.
https://www.rockymountainatvmc.com/p/91 ... ter-Cooler

[Tedh98]

Imagine if you drew a straight line through the center line of the rear axle, thru the centerline of the pivot point; it would pass through the center line of the sprocket. Is that what I want? Just thinking about it, I would have thought that would be too high while riding it.

I've gotten my KX's as rollers, so I wasn't able to see how the motors were positioned from the factory.

So I positioned the swingarm to be at 1/2 travel. Then I rotated the engine so the C/S, swingarm and rear axle were in a line.

That approach is a compromise, but it made sense to me.

The PC pipes fit no problems with only the airboxes to deal with.

[kenpowell]

Here are pictures of my build. You can see the relationship of the coutershaft sprocket to the swingarm pivot on page 3.
http://s34.photobucket.com/user/ken-pow ... ent&page=3

[Ffryno13]

Take this with a grain of salt since I haven't built a kx hybrid... But if your not binding on your chain roller at full droop then you should be fine otherwise.

[Tyl3r]

Awesome, thanks for all of the great info guys! Much appreciated. I will definitely check into the coolant line issue, I was kind of thinking there may be issues there... Ted, that sounds like a good plan for setting the sprocket position. What type of airbox issue did you have with the pipe? I also appreciate the photos. Hopefully I will have those mounts banged out over the up coming weekend!

[Tedh98]

Ted, that sounds like a good plan for setting the sprocket position. What type of airbox issue did you have with the pipe?

The pipe didnt create any problems with the pipe. The pipe fit with no modifications. I have aligned the air boot a couple of different ways. hybrid airbox options

[Tyl3r]

Ted, that sounds like a good plan for setting the sprocket position. What type of airbox issue did you have with the pipe?

The pipe didnt create any problems with the pipe. The pipe fit with no modifications. I have aligned the air boot a couple of different ways. hybrid airbox options

O ok, I misunderstood, thought you meant they were related. Since I saw your second method on that page, I planned to go that route, with the sandwiched plates. I was going to use a dremel to cut out the aluminum and mill the pocket for the boot to sit in. If I actually had a router or a ban saw, I like the first method better; I like how you got the edges rounded off as nicely as you did.

I'll cross that bridge when I come to it though. Still trying to find the time to get the motor mounts done! Its hard when you work a normal 50 hour a week job that requires the occasional travel and have a small business on the side that requires a few hours after work every day and all day during every weekend. I feel like I work extra hard to get things done to have time to work on the bike, then when I do go to work on it, I'm too exhausted haha. O well, enough complaining.... this is just taking wayy too long , I'm dying to finish it!