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Author Topic: A one of a kind KX200.  (Read 818 times)
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Jr. Member
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Posts: 10

« on: February 25, 2019, 09:36:10 AM »

Well guess it is time to show you guys my monster.

It's a 1991 Kx125 that I picked up for almost nothing from the dealership I work at. Someone traded it in in pieces. Literally the engine was in a home depot bucket and the top end was missing. I have no idea what the dealership gave the guy for it but they let me have it for a pizza. I had no desire for an MX bike so my original plan was to sell off most of it and keep the suspension and swap those parts over to something a little more trail oriented, CRF/TTR230, something newer 4 stroke lacking in the suspension department, and then I got to thinking.

I had a Quad sitting in the back that hadn't been ridden in a very long time partly because I didn't have a title for it and didn't want to go thru the hassle of doing lost title paperwork, but mostly because it was a bit too small for me. Engine wise it was fine, I had some work done to the engine a while back so it had good power. No power valve so it isn't peaky and gearing was well suited for the trails. Anyway the more I got to looking the more I started to think that the engine would fit in the frame with minimal modification, so I pulled the engine from the quad and test fit it in the KX. Surprisingly it fit pretty darn well. There was a small mounting lug on the bottom of the engine that needed to be removed. Once that was off All that needed to be done was to oval out the front mount tabs a bit to bolt the engine in. It fit but was sitting up at a strange angle so to get it down to more where it looked happy I had to move the front mounts down about 3/4 of an inch and make a small indent in the frame on the right side to clear one of the clutch cover bolt lugs.

As the bike sits, the engine in on its way back in for hopefully the second to the last time. The frame has been painted black mostly to keep it from rusting after welding so there wasn't a lot of concern in making it look good right now. after it is together and running maybe even ridden a bit, it will come apart again and the frame stripped and powder coated. I am waiting on a swingarm bearing kit to come in so I can mount it and get it mack on it own to feet. Then I can start working on the next big part, the pipe.

So here it is, my KX125/Blaster combo. Sorry the pictures are a bit small and this is the first time I have used Google picture storage over photo bucket so they are hyper links rather than pictures themselves.



Here you can see the notch in the frame to clear the engine. In the picture it looks like the engine is sitting on the frame but it doesn't once the swing arm bolt is in.

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James Stewart DID NOT invent the scrub!!..JoJo

« Reply #1 on: February 25, 2019, 10:15:38 AM »

curious how it'll ride.

Excuse me, ma'am...but you've got extremely nice legs!!!...what time do they open???                                                                                                               https://www.youtube.com/watch?v=n8tCgN3aryQ
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« Reply #2 on: February 27, 2019, 10:27:24 PM »

Just want to throw a few pics up real quick. It might be a bit before the next update. I have a couple of things to do on the house and I need to clean off the lathe to make a couple of spacers. With all the other projects going on right now making parts for this is a little low on the priority. I might get to it this week...

Chain alignment looks pretty good from here. It is a tad to the left but not by much based off of the existing marks on the chain guide.


There is still a small gap in the washers I am using for the engine spacers so when I take measurements for the spacers I will compensate for the chain alignment also.


So I have a couple of options when it comes to pipes. This is the pipe from my blaster, It is a right hand bend which it pretty unusual for this quad, so if I can help it I would rather not cut this pipe. But I was thinking a pipe set up like this will give the bike kind of an old school KDX look with the air cooled engine. I would have to make a custom or loose the right side rad shroud.


The KX125 pipe actually lines up pretty well also. It is more than likely going to be on the small side for the engine so I dont plan on actually using it but just to get an idea of what it would look like with a newer style 2 stroke pipe on it.


And the KX pipe in the other orientation. Just to see what it would look like.


Somethings make me question the engineers... The more I play with this project the more I wonder it it was intentionally done with this swap in mind. So I turned the KX pipe up like in this position like the blaster pipe would be just to see what it would look like and after taking the last pic. I noticed that there is a manufactured dent in the pipe to clear the engine cases (or frame possibly, I dont remember which) and I found that the dent aligned pretty well with the shape of the blaster head... Kind of weird... Just saying...

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« Reply #3 on: April 04, 2019, 10:17:24 PM »

Quick little update. Got a bunch done in the last couple of weeks. Once the engine spacers were made and in it all went together very quick for what will be the last mock up build. Spacers came out nice and pretty much put the engine right where it needed to be. It might still be just a tad to the left, but that is something that I can change a little later if need be. I think I have even figured out what I am going to do for a pipe.

A friend of mine races moto as well as he and his dad own a small machine shop dealing with motorcycle and ATV/UTV engine work. The last time I spoke with him he told me that he knows someone that builds expansion chambers for two strokes, so at some point I will be getting in contact with him for a proper pipe for this beast. In the mean time I have purchased some 2-stroke pipe software and ran a few numbers... The 125 pipe is a bit on the fat side surprisingly for the power output I am looking for, but the biggest problem with it is that it it too short both in the head pipe and stinger. I managed to get my hands on another pipe, one that has the same size head pipe KX. So I used it to lengthen out the KX125's pipe on the head side. The stinger on the other hand is a tad bigger in diameter but it should work well enough for now. So what I am ending up with is something a tad shorter and a bit fatter than it should be. I think a re-tune on the carb should do well enough to get me a few miles down the road so I can see if i like riding this monstrosity.




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