winter project - hybrid #2 2003 cr125/E-series

Discussion for swapping a KDX motor in a MX frame...
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winter project - hybrid #2 2003 cr125/E-series

Post by marrk_us »

This is my second, and probably my last hybrid build. After riding my first one for a couple of years and loving it (even sold my kdx220 with kx usd's, my hybrid is so much better) it's time to do it one more time. This is the last winter i'll have the luxury of a large garage to build things in, so it's now or never. It'll take all winter to finish as I work a ton of hours during Nov and Dec, which leaves little time for hobbies.

Basically I'll be taking the E series engine from my first hybrid Image

and putting it into this 2003 cr125 frame, just back from the powder coaters (welding is already done)

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I've already found a crf250x shock, swingarm and linkage for it and am waiting for a set of the showa twinchambers from a 250x or 450x to come down the ebay highway at a reasonable price, then i'll send them out for a revalve/respring.

I've decided to bite the bullet and go with new aftermarket wheels, but the Talons I have on the first hybrid won't be in the budget unless I stumble on a real deal. Going with an 18" rear with a trials tire for sure. Does anyone have any experience with other aftermarket wheels, good or bad? I'd like to keep the wheel budget around $750 if possible, but don't want stock hubs or junk. Any suggestions?

Other then that i'll post whenever some progress is made. Spent a few hours today cleaning the old engine before I pull it next week. It's been running fine but i'll probably do the top end while it's out. And maybe try the soda blasting to give it a little bit of a face lift. We'll see once it's out how the finish is holding up.
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The kx forks, scotts sharkfin and braided brake lines from the "old" hybrid will find new homes on my klx. And i'm hoping to reuse the carbon sparky on the new one as it has sliding, universal type clamps on the body (It's light and very stealthy, my friends say they can't hear me at all on their 4 strokes!) It may be a bit long but i'll find out when I get to putting the exhaust together. That'll be my contribution to recycling :grin:
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Last edited by marrk_us on 10:00 am Jan 19 2012, edited 1 time in total.
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2nd Build

Post by Bouillion »

Sweet. Do you know how much lighter the CR frame will be compared to the steel KX? I used a 2005 KX for my build and love it however, I just basically gave it to my daughter (lowered it for her) after selling her RM100 which she had long since out grown. I thinking hard about a second build but can't make up my mind. Might go for the KTM250XCW with that electric start?

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Re: 2nd Build

Post by marrk_us »

>|<>QBB<[quote="Bouillion"]Sweet. Do you know how much lighter the CR frame will be compared to the steel KX?

2005 kx125 frame,swingarm with bearings, and swingarm bolt = 38lb.
2003 cr125 frame, swingarm with bearings, and swingarm bolt = 30.8 lb.

Don't have a kx125 subframe on hand so weighed both minus the subframes.

Sweet hybrid! Loads better than getting a cellphone from your dad :supz:
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Post by marrk_us »

Just got these in the mail today. I remember spending a lot of time scrounging nuts and bolts for the last hybrid, a lot of time at the dealer, home depot, and trying to clean up old nasty fasteners.

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Seems pretty complete, high quality bolts, and packages are well marked. Should save me a few headaches and time on the build.
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Re: winter project - hybrid #2

Post by SS109 »

>|<>QBB<
marrk_us wrote: I've decided to bite the bullet and go with new aftermarket wheels, but the Talons I have on the first hybrid won't be in the budget unless I stumble on a real deal. Going with an 18" rear with a trials tire for sure. Does anyone have any experience with other aftermarket wheels, good or bad? I'd like to keep the wheel budget around $750 if possible, but don't want stock hubs or junk. Any suggestions?
What's wrong with the stock CR hubs?

Anyways, I recommend Warp 9. http://www.warp9racing.com/mx_wheels_honda.html Their customer service is absolutely top notch, the quality seems great to me, and it is right in your price range. Buy them straight from Warp 9 (call Kevin, don't email) and they can set you up with just about any color combo you could want. They also come with a new sprocket and brake rotors.
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Post by marrk_us »

Nothing wrong with Honda hubs at all in my experience. I've had several xr's and an xl600 and never a problem. I've also had a few Yamahas that i'm now conviced that Yamaha sold some of them with missing spokes, or built them out of straw. :sad: It seems that all the cr wheels I see advertised are either beat to death, repaired, or overpriced. There's a pair of very nice crf450x wheels on ebay taken off a nearly new bike i'm considering, but at $700 i'm still thinking. The speedo drive would be nice and the crfx's already have an 18" instead of the 19". We'll see. Where we ride in Colorado it's all red dirt that tends to stain the factory finishes over time. I keep my bike at a friends place in the mountains all summer and we sometimes ride into the night so the bikes don't get properly cleaned after each ride, but the aftermarket hubs always clean up nice. That's also one reason I went with powder coating instead of painting or polishing the frame. I have a klx that's been coated for 10 years and still cleans up like new.

Thanks for the advice on the Warp 9's. I'll check them out.
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Re: 2nd Build

Post by Bouillion »

Sweet hybrid! Loads better than getting a cellphone from your dad :supz:[/quote]

Well I'll find out next weekend if she is willing to race it or simply "ride in the race" as she was doing on the RM. He is a pretty talented rider but not very aggressive. She will follow right behind me on the trails at a very decent pace but when she is racing in the women's class basically refuses to pass anyone unless they fall. Either case I'm still proud of the fact that at nearly 19 she still enjoys a weekend in the woods with the old man!

Good luck with the hybrid. I'm keeping my eye open. If the right KX comes along I just might have to build another.
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Post by marrk_us »

Had the day off so I decided to work on getting the engine out of the "old" hybrid and do a quick check on the condition of the power valves, piston, and cylinder wall. Only took about 20 min. to get it out.
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Back when I first bought the 90 kdx I had Joe Shedron at what use to be Moose Racing (before the moose was sold to the clothing company) do my suspension, back then Moose Racing and Mr. Freddette were the big kdx specialty shops. At the time people were having problems with Honda CR's breaking power valves and the systems getting coked up by people using lowgrade premix oil. When I went to test ride and bring my kdx back home I got to talking to Joe and he told me the about the problems "everyone else" was having with power valves. He recommended using BG Products 2 stroke oil and promised I wouldn't have any top end problems with my new toy. Well that was over 20 years ago and I've used nothing but BG premix at 50:1 in this engine from that day forward. I think I had about 50 miles on the bike when I took it up to have the suspension done. I've never had a problem with the engine all these years (except for a bad stator) and it's always run fine. But at 20 years I figured I'd pull the top end and replace the original piston with a new one and see how the power valves looked. I've never pulled them to check them as they always seemed to be working, but after reading so much about problems and broken parts I was a little nervous about what I'd find.
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Looking pretty good so far.
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a little oil and build up but I've seen a lot worse.
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The head looks good, a little build up on the top of the piston but looking good so far.
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The cylinder looks great too, barely feel a tiny build up at the top, I'll measure it once I clean it up, but i'm thinking maybe a stock bore wiseco will work. Now for the power valves. They move smoothly and there's no up or down play in the rack.

More good news! This is the way everything looked when I pulled it apart. No missing metal, chipped or broken teeth.
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And after wiping them off with a dry shop rag.
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I guess old Joe knew what he was talking about! I'm thinking new gaskets, a new piston, rings, and new o rings for the valves and i'll be good! I have a head for it in the garage (had to cut the head stay off this one, but need it for the cr frame) Now is probably the time to try out RB head and carb mods as I won't be sinking much money into engine parts. Everyone seems to have good luck with Ron's work.

Hopefully in the next few weeks I'll be able to drill out the pivot hole and get the engine into the frame. No luck yet on front suspension parts. CR125 forks are pretty easy to find, but since i'll be apart for a few months i'm hoping some crf250/450 showas show up on ebay. Wait and watch for now.
Last edited by marrk_us on 08:24 pm Oct 28 2011, edited 2 times in total.
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Post by Julien D »

Nice! :)
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Post by scheckaet »

dang! that's the 1st pic of an unbroken kips subvalve from E serie I have ever seen!
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Post by dfeckel »

Exactly what deal with the devil did you have to make to keep you KIPS valves that pristine??
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Post by marrk_us »

>|QBB<[/url]
dfeckel wrote:Exactly what deal with the devil did you have to make to keep you KIPS valves that pristine??
You might be on to something. All this is true.

I was married at the time we bought 2 white kdx's from the same dealer. Like 3 months later the dealer goes out of business, rumors were the IRS were coming down hard on him.

This engine was in "her" kdx. The next spring we are out climbing some hills, the bike throws her off, catching her wrist in the bark buster, breaking it.

Not long after that we get divorced and I move out taking "my" kdx with me. Within a month it gets stolen. My ex offers to sell me hers so I snatch it up. All is well. The next year things are fine, we're still friends, she buys a new crf and asks if it's ok to ride with me. I'm fine with it, but that day we're taking a break, laughing, and admiring her new bike. We get on the bikes, take off across a field and my throttle sticks WFO. I manage to get it shut down before we head back into the woods. My ex says "wow, you were flying when you passed me!" I explain to her that my throttle stuck open. So we inspect it, and clean everything when I got home but didn't find anything. Now i'm thinking could my, (formerly her) kdx be jealous of my EX?? Nah. Jokingly I think about naming her Christine.

A couple years ago I put the engine into the first kx frame. I'm testing it out behind the house, all is well. My ex comes by to check it out. I ask if she wants to take it for a spin. She says sure! She makes 3 or 4 loops around the yards, pops a wheelie, and yep, the kdx comes down on her breaking her leg! I hear her yell, and go running over (to check if the bike is ok!) pick the bike up, get her to the ER. By this time she's drugged up and joking that the kdx motor tried to kill her again! We laugh, she says she hopes she didn't damaged the hybrid to badly, but i go home that night, go out to the garage and you guessed it. I can't find a single scratch. Now I take apart the kips and they look like new and the cylinder also?? Could it be?

I calling these guys just in case before anyone else gets hurt.
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Post by Julien D »

HAHAHAHA!!!!

Epic post :mrgreen:
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Post by dfeckel »

Did the KDX odometer happen to run backwards by any chance?
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Post by 80elkster »

Yeah Christine is a fitting moniker for that evil engine. She really has it out for your Ex. Happy Halloween :twisted:
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Post by marrk_us »

So long as she treats me nice :prayer:
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Post by marrk_us »

Did some reading on how others went from the stock 15mm rear engine/swingarm hole to 17mm. Some just drilled, some reamed, and at least one had a problem with the swingarm binding up. I didn't want to chance having a problem with misaligned or oval shaped holes, so I called a retired former machinist friend to have a look and offer advice. He showed up, micrometer and calipers in hand, checked the stock hole / swingarm bolt fit and found "a ton of play" by machinists standards. Meaning a few thousanths. While just taking a 17mm bit and going for broke freehand would be "barbaric" and "could cause problems" according to Ray, he also doesn't think a machine shop is needed either.

He gave me this website, http://www.wttool.com/ and had me order the following

16mm drill bit, 16.8mm bit, 17mm bit, and an 16.75-18.25mm adjustable hand reamer. Total cost around $35

The plan is to go up in small increments to keep the holes straight and then hand ream to get the hole "round" again. Also reaming the whole way through from one side to the other, instead of from "one side and then the other" will help keep the holes "aligned enough for our purposes" Having been a mechanic and not a "machinist" I always thought drill bits made round holes, apparantly not. Since drill bits only cut with the tip, there is always some "hunting" going on and thus the holes are not round (again... by his standards), a reamer cuts along its length so the holes are rounder, and the length will help keep everything straighter. (Hanging out with Ray is a learning experience but sometimes makes my head hurt :? ) Bottom line is he says it'll be a piece of cake, we'll see.

Anyway, finally got the bits/reamer in the mail and am going to try to get the engine mounted by the weekend. Then i'll pull the FMF off the 220 for a test fit to see if it'll be easier to modify an e-series or h-series pipe.

I also nabbed a set of front forks, and front and rear brake systems off a 2007 CRF250X that someone managed to blow up with less than 1000 miles on it. Still no luck on wheels in good shape. I'll probably just end up going with Warp 9's.
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Post by kawabunga »

marrk_us wrote:Did some reading on how others went from the stock 15mm rear engine/swingarm hole to 17mm. Some just drilled, some reamed, and at least one had a problem with the swingarm binding up. I didn't want to chance having a problem with misaligned or oval shaped holes, so I called a retired former machinist friend to have a look and offer advice. He showed up, micrometer and calipers in hand, checked the stock hole / swingarm bolt fit and found "a ton of play" by machinists standards. Meaning a few thousanths. While just taking a 17mm bit and going for broke freehand would be "barbaric" and "could cause problems" according to Ray, he also doesn't think a machine shop is needed either.

He gave me this website, http://www.wttool.com/ and had me order the following

16mm drill bit, 16.8mm bit, 17mm bit, and an 16.75-18.25mm adjustable hand reamer. Total cost around $35

The plan is to go up in small increments to keep the holes straight and then hand ream to get the hole "round" again. Also reaming the whole way through from one side to the other, instead of from "one side and then the other" will help keep the holes "aligned enough for our purposes" Having been a mechanic and not a "machinist" I always thought drill bits made round holes, apparantly not. Since drill bits only cut with the tip, there is always some "hunting" going on and thus the holes are not round (again... by his standards), a reamer cuts along its length so the holes are rounder, and the length will help keep everything straighter. (Hanging out with Ray is a learning experience but sometimes makes my head hurt :? ) Bottom line is he says it'll be a piece of cake, we'll see.

Anyway, finally got the bits/reamer in the mail and am going to try to get the engine mounted by the weekend. Then i'll pull the FMF off the 220 for a test fit to see if it'll be easier to modify an e-series or h-series pipe.

I also nabbed a set of front forks, and front and rear brake systems off a 2007 CRF250X that someone managed to blow up with less than 1000 miles on it. Still no luck on wheels in good shape. I'll probably just end up going with Warp 9's.
16mm drill bit, 16.8mm bit, 17mm bit, and an 16.75-18.25mm adjustable hand reamer. Total cost around $35

Bingo! That's the reason I'm here. Hopefully I'll be able to contribute

something useful in the future.

You've piqued my interest in BG oils.Do you order online?
reviving old war-horse.
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Post by MadMax »

I have a question. Why did you powder coat the aluminum frame?
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Post by marrk_us »

>|<>QBB<
kawabunga wrote:
marrk_us wrote:Did some reading on how others went from the stock 15mm rear engine/swingarm hole to 17mm. Some just drilled, some reamed, and at least one had a problem with the swingarm binding up. I didn't want to chance having a problem with misaligned or oval shaped holes, so I called a retired former machinist friend to have a look and offer advice. He showed up, micrometer and calipers in hand, checked the stock hole / swingarm bolt fit and found "a ton of play" by machinists standards. Meaning a few thousanths. While just taking a 17mm bit and going for broke freehand would be "barbaric" and "could cause problems" according to Ray, he also doesn't think a machine shop is needed either.

He gave me this website, http://www.wttool.com/ and had me order the following

16mm drill bit, 16.8mm bit, 17mm bit, and an 16.75-18.25mm adjustable hand reamer. Total cost around $35

The plan is to go up in small increments to keep the holes straight and then hand ream to get the hole "round" again. Also reaming the whole way through from one side to the other, instead of from "one side and then the other" will help keep the holes "aligned enough for our purposes" Having been a mechanic and not a "machinist" I always thought drill bits made round holes, apparantly not. Since drill bits only cut with the tip, there is always some "hunting" going on and thus the holes are not round (again... by his standards), a reamer cuts along its length so the holes are rounder, and the length will help keep everything straighter. (Hanging out with Ray is a learning experience but sometimes makes my head hurt :? ) Bottom line is he says it'll be a piece of cake, we'll see.

Anyway, finally got the bits/reamer in the mail and am going to try to get the engine mounted by the weekend. Then i'll pull the FMF off the 220 for a test fit to see if it'll be easier to modify an e-series or h-series pipe.

I also nabbed a set of front forks, and front and rear brake systems off a 2007 CRF250X that someone managed to blow up with less than 1000 miles on it. Still no luck on wheels in good shape. I'll probably just end up going with Warp 9's.
16mm drill bit, 16.8mm bit, 17mm bit, and an 16.75-18.25mm adjustable hand reamer. Total cost around $35

Bingo! That's the reason I'm here. Hopefully I'll be able to contribute

something useful in the future.

You've piqued my interest in BG oils.Do you order online?
I get it from my local dealer. Some dealers carry their snowmobile 2-stroke oil (same stuff). Or you can get it from this site http://www.nowearracing.com/bghome1.HTML
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