2003-1990 KX-DX Hybrid Build

Discussion for swapping a KDX motor in a MX frame...
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zz3gmc
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Post by zz3gmc »

dfeckel, will you be riding enduros with this bike next season? I think we live near each other. Do you belong to SJER? Im in Meteor and my girlfriend is in CDR. Im also building a hybrid right now, just a little bigger. 04 KX250/500. Should be fun in the woods! Good luck with the project!
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Post by BobbyZ »

I'm out of the country at the moment but i can make arrangements to have it picked up if you're in a hurry to get rid of it.I'm not too worried about the hoops as if need be I'd just take the subframe and have it welded to my bent one.
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Post by dfeckel »

zz3gmc,

Yes, I'm in SJER. I ran five or six runs this year in C Vet, and I'm graduating to B next year. I plan on running all the enduros (except Scrub Pine--travel conflict) in B 200. My Husky CR 125 in the sand, and the KX-DX in the rocks. That 500 you're building is going to be crazy! I'd need a nice built-in throttle stop, right around 1/16.

BobbyZ, there's no big rush on picking up the frame. I want to get the frame loops welded at the same time as the motor mounts (fewer trips to the welder), and I certainly won't get to that point before New Year's.

Would you rather I cut the loops off my frame and give you a loopless frame? It's up to you. Let me know.

I did make some progress this weekend. The KX is down to the frame, so hopefully tomorrow I'll introduce myself to the machinist and get the rear mount bored and swingarm modified. Then I can get to work lining things up.
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Post by canyncarvr »

Re: 'I've never split cases, and the last thing I need is to buy a bunch of new, specialized tools. How much is a basic bottom-end rebuild at a dealer?'

I didn't follow the link Inda put up..maybe it applies to this.

Tusk makes a couple of tools that make the job pretty easy. Besides the splitter, the crank removal/install tool is nice, too!

I've never heard of a bottom end done by a 'shop' that didn't cost a LOT of $$.

Consider getting the tools you'll need. RMMC has some videos that are helpful..using those tools.

A rhetorical question...but what is anyone thinking to run a bike (or any motor for that matter) without an air filter.

Ooops. I ran my Duster at the dragstrip without a filter. Not QUITE a dirtbike..still......

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Post by Julien D »

I might have zipped my mustang up and down the street without a filter once or twice. My bike? Nahh....
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Post by Colorado Mike »

For the helicoil question, my son stripped his oil plug too :evil: . I did some reading and some folks said heli coils were a bad idea for fluid plugs since they're a piece of spring. Not sure how big a deal that is if you use a gasket under the plug, but I went with a TimeSert. Pretty expensive for the kit, but it worked well. I did not split the cases to repair it. I just flushed the case a few times after.
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canyncarvr
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Post by canyncarvr »

You're gonna make me lookup 'TimeSert'? That's not nice.


What's the 'spring' part about? Spring steel is too hard to have an effective thread seal?

It's already broke..so it's not like causing more damage to the engine case is a problem, so how 'bout one of those oversized self-tapping plugs?

I'm a fan of doing things right the first time..but sometimes that just isn't a reasonable approach.

A local quick-lube place stripped the drain plug hole on the company van when it was brand new. They replaced it with a 'toggle'..one of those drywall looking things? I knocked that out running in some too deep snow, realized it when the van was sitting in a pool of oil the next morning. Anyway..a couple trips to the NAPA store to get the right assortment of self-tapping plugs and washers later..it was all better!

Another useless anecdote for your perusal.................but it worked just fine.

Good luck!

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Colorado Mike
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Post by Colorado Mike »

It wasn't the hardness, some said the oil oozes along the winds of the spring. I'm not saying it won't work, I just didn't want to screw with it vs. use a system designed specifically for through holes that have fluid behind them. The repair is stronger than the original and might better survive a young man that can't quite get a handle on the whole counter clockwise is loosen thing, especially when the bolt is upside down.

and for those without Google....

http://www.timesert.com/
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Post by dfeckel »

Dropped the motor and swingarm with bearings at a machine shop not too far from me--hopefully I'll soon be lining up exhausts and airboxes and gas tanks...
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Post by Tedh98 »

>|<>QBB<
dfeckel wrote:Dropped the motor and swingarm with bearings at a machine shop not too far from me--hopefully I'll soon be lining up exhausts and airboxes and gas tanks...
You didn't mention leaving the frame, are you going to cut down the swingarm sleeves? I'd like to find a better way of doing it.
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Post by skythrasher »

>|<>QBB<
Colorado Mike wrote:It wasn't the hardness, some said the oil oozes along the winds of the spring. I'm not saying it won't work, I just didn't want to screw with it vs. use a system designed specifically for through holes that have fluid behind them. The repair is stronger than the original and might better survive a young man that can't quite get a handle on the whole counter clockwise is loosen thing, especially when the bolt is upside down.
HeliCoil makes inserts that are not the spring type. They sell kits that come with a hand reamer and inserts and a tool to swage them once they are installed. Work like a champ. Never seen one leak that was installed per directions.
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Post by dfeckel »

I didn't leave the frame, but I left the swingarm pivot bolt. That should be enough for him to verify that the bored out rear mounts line up with the swingarm. And he's going to cut down the swingarm for me, as well as two sets of pivot inner races (the originals and a new set for spares). He's also going to repair the stripped drain hole--I belive he's just going to tap a slightly larger hole and use a bigger plug. This is okay with me, since when looking into the drain hole, I realized that there is a relief/galley on the side of the threads to allow a total drain of the trans. A helicoil or timesert would likely block this and I'd always have half a cup of trans oil in the bottom of the cases whenever I drained it.
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Post by Colorado Mike »

they make short inserts that work fine, but whatever works for you.
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Post by SAPPER »

make sure you put up sum pics of the build
real men measure with inches not centimeters

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Post by dfeckel »

As soon as I start building, the pics will commence!

So far, I have only bare frames and a pile of parts.
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Post by dfeckel »

The parts accumulation is almost complete. Just about ready to get back to work on the project. I'm picking up the motor and swingarm tomorrow, and I have just about all the things I need to design motor mounts. The only missing puzzle piece is an IMS 3.2 gallon tank. I bought a used tank from a guy who had several tanks left over from his previous racebikes, for a song ($50!!!). I just need to pick it up. I also got from him an 18" rim which should lace up to the KX hub.

Speaking of the 18" wheel, what spokes should I order to lace the two together? Should I specify a particular model bike, and order through the dealer, or call up one of the aftermarket wheel manufacturers?
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Post by canuckhybrid125 »

>|<>QBB<
dfeckel wrote:The parts accumulation is almost complete. Just about ready to get back to work on the project. I'm picking up the motor and swingarm tomorrow, and I have just about all the things I need to design motor mounts. The only missing puzzle piece is an IMS 3.2 gallon tank. I bought a used tank from a guy who had several tanks left over from his previous racebikes, for a song ($50!!!). I just need to pick it up. I also got from him an 18" rim which should lace up to the KX hub.

Speaking of the 18" wheel, what spokes should I order to lace the two together? Should I specify a particular model bike, and order through the dealer, or call up one of the aftermarket wheel manufacturers?
Depends on the rim,aftermarket or oem and how many holes.Some aftermarket rims you can use a oem spokeset.But I would go with aftermarket SS,tell them what rim and hub you have.
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Post by dfeckel »

Good info. I'll definitely go with stainless steel. I have a stock DID KLX 300 rim, I think, and of course I'm going to use the KX hub. I'll report back exactly what spokes work.
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Post by zz3gmc »

My girlfriend converted her 03 KX250 to a 18"(should be the same hub) using a Excel rim and a Excel Spline Drive spoke kit.
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Post by dfeckel »

I likely will buy a ss spoke/nipple set from Moose--they have a set right on their website for converting KXs to 18" wheels--$69.95. I just need to find someone local to build up the wheel. I've tried before, and it's a total PITA. I can get a lot of other work done on the project in the three hours I would spend trying to true up the wheel...
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