KX Riders
Maintenance & Technical => KX500 Steel Frame Conversion (SFC) => Topic started by: BigGreenMachine on March 15, 2007, 07:37:16 AM
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Hey guys, what would it take to put a KX500 motor in a KX250 chassis? Does it fit at all? Can you use the airbox and not have to mod the tank?
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I Can't speak for all years of 250, but, the 99-02 is quite easy to do. My avatra is a 05 250f chassis, its a pain in the a$$. The 250 conversion will require the swingarm to be narrowed about 8mm on each side, the swingarm motor mount to be drilled to 17mm, the head stay cut off the back of the motor and a new one fabricated on the front of the head, the 250 fron motor mount will be removed and repositioned, the bottom mount will fit, The pipe has to be modified, some guys are using a CR500 pipe and denting it around the water manifold and kick starter. The air box works as is, either use a short ceramic plug or warm the gas tank a bit and push up the bottom to gain clearance for the plug. This makes an awesome bike that handles night and day better than the stocker, the 250 has better suspension than the k5 and is much narrower.
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got me hurtin on that one...got the stuff, but scared of the mods.
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Don,
I take it that you mean the 99-02 2-stroke 250 is the easiest frame to convert to 500 power. Can you give me a rough list of things that you had to mod. Thanks. Cam.
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You are correct, 99-02 250 2t. Front motor mount needs to be re-positioned, swing arm spacers and the actual swingarm need to be narrowed to accomodate the k5 motor. bottom motor mount should be OK, motor needs to have the swingarm bolt mount drilled to 17mm, pipe needs to be modified to fit the 250 chassis, head stay cut off and new one fabricated. Pretty much what I'd said in my first post. I bought all the parts off ebay for 600-700 bucks and then rebuilt everything. I can take some pictures and show you the mod to the swingarm. It is truly an easy swap if you have a modest amount of mechanical ability, at most 1 weekend. I would say the pipe is the most time consuming part.
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Here do you have some pic?s!
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Here do you have some pic?s!
If your asking me for pic's, look up a couple of replies. Is your first picture of a KDX chassis? In the states, when the KX250 went perimeter they also went upside down forks.
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don46 could you post some pics of the swingarm mod and some close ups of the head stay and front motor mount?
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Anyone know about the earlier KX like a 96 or thereabouts?
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What about the 05 KX250? I've found one for $200 almost complete.
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I did a 97 KX250 conversion. If I had to do it again I'd look for a 2003 or newer 125 or 250. Personally for me steel is easier to work with than aluminum, and the 03 and newer KX's have the head mount to the rear like the 500. I don't know if the tank clears but if it does the head mount would be much easier to build.
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I would stay away from a 03, it`s a one shot wonder, different than the 02 and different than an 04-07.
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:lol: Picked up an 01 and will be doing the swap as soon as it arrives. Thanks guys, will post my progress here.
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:-oHave fun with it Big Green :wink:
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don46 could you post some pics of the swingarm mod and some close ups of the head stay and front motor mount?
OK so I finally have pictures to post
The width of the aluminum part of the swingarm is 49.7 mm s, The spacers are cut down to 45.2 mm, stock is 53.9.
I have more pictures of the motor mount and the head stay if you want to see them.
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More please! What did you use to cut them down with?
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The aluminum part of the swingarm isn't to critical, it can be off a little and not hurt anything. The spacer has to be square, I cut the swingarm on a mill and the spacers on a lathe. Like I say the swingarm isn't that critical, it could be cut with a hacksaw.
The attached pictures are for the head stay, the stock stay must be cut off and either a bracket such as I have or none at all. The bottom motor mount on the 250 chassis will fit, the front needs to be cut off and repositioned, and lastly the motor mount at the rear of the motor needs to be bored to 17mm
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Cool!
Step one - split cases and drill rear motor mount on drill press
Step two - after installing the motor install the bottom motor mount bolt
Step three - cut front mounts off, bolt them to motor and line up in new position, tack then weld
Step four - fab top mount for new head stay
Very straightforward IMO.
Thanks for the pics, appreciate them.
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Man this is killing me. I have an '02 250 as well as a 500. Good thing I don't have a machine shop! Or maybe it's a BAD thing. :?
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Man this is killing me. I have an '02 250 as well as a 500. Good thing I don't have a machine shop! Or maybe it's a BAD thing. :?
Crim, that is what killed me too.. But decided I wanted to keep my KX250 for track racing.. Now, I just use my YZ for the track only. I wouldn't dream on dropping a 500 into a track machine. I am much faster on a 250 on the track than a 500.. Just the power is easier to corner and jump with. But, trail riding? a 250 feels like walking.. ;-) Cool project though! I can't wait till work slows down and I can get out and just ride.. Can't even get that in these days.
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Cool!
Step one - split cases and drill rear motor mount on drill press
Step two - after installing the motor install the bottom motor mount bolt
Step three - cut front mounts off, bolt them to motor and line up in new position, tack then weld
Step four - fab top mount for new head stay
Very straightforward IMO.
Thanks for the pics, appreciate them.
I have fone three of these now, only 1 did I split the cases and drill the others it did while the motor was together, there are only 2 small areas that will have to be drilled maybe an inch on each side, the rest of it is hollow. I would cut the mount off the front before I tried to install the motor. Yea, I forgot about the pipe, that probably took the longest to get right, I used a KX 500 pipe and took the time to insure I didn't change any of the lengths. I have seen several with CR 500 pipes, most will say they work good, personally I've not tried one yet, I have one set up but haven't tried it yet. I looked at the Zip Ty pipe as well and thought it would be the easiest to modify. As far as taking the k5 on the track, I wouldb't be at all afraid to do it, it handles and feels like a 250. The 500 in my avatar is based on a 250f chassis, it handles like a dream, feels so light, but way to much fab work to get it right.
If you need any more pictures of something specific or questions, feel free to ask.
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the stock stay must be cut off and either a bracket such as I have or none at all.
How safe do you think it would be to go w.out the head stay? The old time air cooled bikes didn't use them.
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If you chose to leave it then reinforce your other mounts for the extra strain!
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Tell ya what. The only thing that's really keeping me off this job is the pipe. Everything else, I can deal with.
So what's the easiest way to handle the pipe?
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If I would have known about the Zip Ty pipe before I did mine, that's the route I would have gone. I looks like the CR pipe requires some work as well especially if you don't want to take the ball pein to it to get it to fit around the water outlet and the kickstarter. I think the Zip ty could be used easily
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I'd still have to cut up the Zip Ty, right?
What about the head stay? Think it would be OK to run w.out one?
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That is correct you would still have to cut the zip ty, but it doesn't look like it would be a big job. As far as the head stay, you could probably get by without it but you may ge more vibration, I just don't know. As far as the head stay, it could be made from steel rather than aluminum if your more comfortable with steel, not a big job to make. I did find a pipe in europe that was made for a 500 motor in a 250 chassis, it was a company in italy called Jolly Moto, but the price was $1400 US, that didn't work for me. SPES used to make a pipe, but now there all under the DOMA umbrella and they don't list one in the US, perhaps they do in Europe.
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Take a look at the job this guy did on his hybrid. That's one nice pipe! Can anyone make out who may have made it? There's a tag welded to it.
http://photos.everything2stroke.com/showgallery.php?cat=500&ppuser=8616
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Me thinks FloTek built that pipe. Guessing they had the bike to do so because it sure is a nice fit.
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Well I wonder if they kept the specs?
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Well I wonder if they kept the specs?
I was thinking the same thing, wondering if they kept the jig. You call? Price would probably be 500CDN or like 400US.
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Looking as closely at that pipe as my old eyes allow.... the first 4 letters are FLOW. Flotek it is not. I posted a link to that photo on DRN to see if anyone can identify the manufacter.
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1997 KX 250 chassis, 2000 KX 500 motor. Building an FMF Desert pipe, I had a Pro Circuit pipe before. I decided to go with a permanent "solution" to the coolant hose problem. I cut off the existing fixture on the side of the cylinder and had a new fitting welded onto the back of the cylinder like older CR 500's. I would probably just go around the hose if I do it again. Also since this is my hillclimb competition bike only, I did not worry about my kick starter hitting the pipe when folded in, as I will take it off after starting. And yes it does hit!!
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The hill climbers always come up with cool stuff. That exhaust pipe is trick looking, Nice welds. Wrapping the coolant hoses is a cool idea.
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Definately going to build my pipe to go around the hose. Didn't realise this was a problem but its not a big one.
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I have a crazy kind of bike friend who happens to be a welder by trade. I mentioned this idea to him and he offered his services. That takes care of a certain portion of the project. There's a machine shop nearby that has done some custom work for me in the past. There's another situation solved. I'd most certainly do a compression release during the tear down.
Just need to get answers on this pipe situation.
Then I need to get over the idea of sacrificing a bike. That will be the hardest of all!
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So Hillclimber, what did you use to fabricate that pipe?
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So Hillclimber, what did you use to fabricate that pipe?
I cut along one of the factory seams, rotated the pipe to where I needed it,tacked it, then made one more cut,rotation and tack weld. Just route the pipe to where you need it to go. Try not to change the internal volume and/or dimensions of the pipe much. Here is an interesting link to Two Stroke Pipe theory:
http://www.maxxtraxxusa.com/Tuned_Pipes_3608.cfm
Also download this PDF, very good info if you've ever wondered about two strokes in general:
http://edj.net/2stroke/jennings/
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Looking as closely at that pipe as my old eyes allow.... the first 4 letters are FLOW. Flotek it is not. I posted a link to that photo on DRN to see if anyone can identify the manufacter.
As far as I remember Flow make the formers that stamp out the aftermarket expansion chambers, it said something about it in Eric gorrs book but I can't find the exact wording right now.
I assume that they have also done so for the Zipty spannie but I can't see anything about it on my zipty spannie :?
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Thank you Hillclimber. I suspected that's what you did. Looks pretty good, though a bit impractical for the every day rider.
I kinda thought that Flow was the name on that pipe, but since ya cant see the rest of the tag on it, I wasn't sure. Do they have a website?
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Something worthy of note:
http://www.ftzracing.com/images/atvpipes07.pdf
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I kinda thought that Flow was the name on that pipe, but since ya cant see the rest of the tag on it, I wasn't sure. Do they have a website?
I looked today but after throwing various search criteria into Google came up with nothing worthwhile :-(
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I heard back from the guy on Everything 2 stroke:
I had the pipe custom made by a guy who makes production kx500 pipes. It's a one off pipe made from stampings so it looks like something you could go buy but you can't. I tried to get ahold of him not to long ago because I want to build another bike with a kx450 but I could not get him on the phone or to call me back I will try again and get back to you...
I replied and asked for his name and employer. So far so good.
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I'm out, selling my 500 motor and moving to Alberta for work. Going to build a 310 for my 250 chassis.
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dude, you're not gonna do it? the 310 will still be pretty cool though...good luck man with the move.
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The deed is done, pending payment. I want to do the swap but the motor is paying my ticket and where I'm going will not have access to the tools I have here at home.
A 310 will still make good power and I get to keep my trike for the girlfriend to use. :lol:
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well good luck man, you need a motor or you got a donor 250 powerplant? still got the engine from the bike I sent ya, needs bored out anyway.
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More from Bryan from Everything 2 Storke:
Thanks for the reply.
There are a few of us at a forum on kxriders.com that are scheming to do the same swap. I would really appreciate any help you could come up with. My e-mail is gwcrim@yahoo.com. What was the fellow's name who made it? Who does he work for?
George
I got ahold of my guy and he told me that they are no longer stamping two stroke pipes and the dies for stamping them have been destroyed. He thinks he might have three sets left, if he does these are going to be in my hands next weekend. I know one set will be used for the kx450/500 I'm going to build these would be the last raw stampings to build my pipe left in the world makes me want to shed a tear for my two stroke I have been trying to get ahold of him becouse my intent was to produce this pipe myself along with radiators to make the Kx450/500 swap easy for others to do if you are going to do the kx250/500 swap use a 03/04 kx250 the head stay is on the back the same as kx500 and you can get tanks from ims that are only a little bigger than stock trust me your life will easier.
I invited him to stop by here and check the place out. He seems to be our kinda guy.
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thats nice work there bryan ....... stewart
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I knew my ears were burning. what's up! :evil:
Looks very neat, good job.
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BDI, how much would you charge to make me one of those head brackets? Thanks.
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It wouldn't have to be as pretty as yours just structurally sound. I was kind of hoping to keep it around $100. Do you have any of your rough drafts left?
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Bryan! Glad you showed up.
Keep me on top of that list for the..... well.... you know what. :evil:
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This thread rules!!! I just bought an 05 125 frame and swing arm. My plans are to do a 500 swap but am also open to just building it into a 250. I have plenty of questions.
Would the 05 125 frame be a good candidate for the 500? I've been told on other sites that it would not work. But I figure you guys would know more than anyone else.
Would the 125 frame be a better candidate for the 250? Would the 250 powerplant bolt right in or would modifications till need to occur?
Thanks for any help in advance.
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l have a question regarding this whole thing. Really how much difference is there between a regular old 500 and a 500 in an '02 250 chassis?
I'm the kinda guy that likes stuffing big motors into small packages, but before I start down this path, I was just kinda curious as to what exactly I'd be gaining? Is there a big weight difference?
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l have a question regarding this whole thing. Really how much difference is there between a regular old 500 and a 500 in an '02 250 chassis?
I'm the kinda guy that likes stuffing big motors into small packages, but before I start down this path, I was just kinda curious as to what exactly I'd be gaining? Is there a big weight difference?
Not only is the chassis stiffer, the suspension is head and shoulders better than a 500 suspension. the rear suspension hasn't changed dramatically since 89, different valving and maybe a larger diameter shaft, the 250's have gone through at least a 6-8 updates. The bike is much narrower than the K5 just an all around better handling bike. I used the K5 radiators and made the brackets for the lower mounts, they work perfectly. I've had a number of K5's, a Rocket Science racing framed K5, 2 K5's in 250 chassis and 1 in a KX250f chassis, and I can honestly say the newer chassis rule, the 250f is the best but way to much work.
As for Deviousfred, if your the guy from the other kawasaki forum, you can obviously make anything fit into a frame, my comment was that it wasn't easy and if you were going to do it find a 250 frame and save yourself alot of headaches. You could do a 250/500 mod in a weekend.
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I have a '93 KX125 and a '91 KX500. I was told (possibly incorrectly) that this series of chassis is the same between the 125/250 and very similar to the '98 model year.
I have not really torn (or looked very hard) at the two bikes side by side yet... I have some top notch resources for fabrication so that is not a deterant (short of spending $3k and 100 manhours).
What a KICKASS SITE BTW!!!
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Hello,
I've been a member for about a year and been lurking mostly,and I've learned alot. I've got a 5hun motor and a possible good deal on a 03 kx250 chassis. I am curious Don46 why you mentioned to stay away from that particular year? If not the 03 then what would be the best kx250(steel frame) candidate for the transplant.Any and all suggestions appreciated.
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Im not sure why don would say not to use a 03 chassis. When I built my bike I used a 02 chassis there are a few things the are a pain in the but one of them is the head stay, 02 chassis the head stay Is on the front this Is a pain to work around O3 the head stay is on the back just like the 500 all you should have to do is cut it off and shorten It up and weld It back. I would assume every thing else to be the same as far as mods go but I am very anal so I did a lot of stuff that other people don't bother with so doing things my way gets involved.
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The reason I would stay away from an 03, its kind of a 1 shot wonder, 99-02 are pretty much the same, 04-07 pretty much the same. If you were to get the whole bike the 03 would be fine, but if your going to try to get the parts don't use the 03 as there aren't as many, primarily swingarm and linkage are the biggest difference. I've pieced them togather from parts off Ebay and rarely do find 03 parts. I had an 03, it was a great bike, just all alone in design.
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The more you know :-) Thank's Don.
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grim..
i have pipes from FMF for the KX500AF conversion,(KXF450 based ),
but they would likekly work well in a kx250 to 500 conversion as well..?
but to be honest FMF simply took the low boy CR500 stamps, redid them slightly,
and yes they are dented to clear that water fitting,,
and not quite enough, =/
so i make a water fitting to change the hose angle slightly.. so all then clears well.
(on the production KX500AFs i am going to both use that water fitting, and mill the cylinder where the fitting bolts to, as there is plenty of material there to take down and help with clearence in a critical area..
with that said-
let me know if yioy want to give this pipe a try.
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I have pipes to they are the zip-ty low boy pipe and they fit perfectly and they were made for the kx500 I have been waiting on mufflers but totaly got screwed on that after waiting for monthes. I had posted that the dies to make these had been destroyed but that turned out to be false. I coud have more stamped but Its a large envestment and after all the crap I have gone threw tryng to have mufflers made I do not know If I want to deal with It
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saw your bike BDI,, nice work man.
and yeah i thought you had styated the dies were destryoed ..
as i anted to get one of those pipes as well to try out ..
i do have silencers,both regular and Q,
but they are made to fit with that KX 500AF pipe -
so its desgned towars the 450 subrframe-
but,
hey they might fit up with your pipe as well..?
i would imagine guys doing variuos conversions could work out the brackets,, ??
ive certainly cut them off often enough in the past for proto type bikes and relocated them?
just a thought for those adventurous enought to be doing the KX250 conv,
or whatever other conv..
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Thanks AJ your bikes are not half bad either. you see my problem Is this I need a muffler to build the pipes to so the whole project has been put on hold. I was supposed to be getting a brand new 06 kx450 with no motor but that deal got screwed up too I have had a string of bad luck on my new bike project the bike was supposed to be built by now and I have not got one pipe made. :|
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well if interested in a KX500AF style silencer,
to work back off of.. or a pipe ..
let me know (you too gcrim! or anyone else !)
ajwaggoner@servicehonda.com
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The reason I would stay away from an 03, its kind of a 1 shot wonder, 99-02 are pretty much the same, 04-07 pretty much the same. If you were to get the whole bike the 03 would be fine, but if your going to try to get the parts don't use the 03 as there aren't as many, primarily swingarm and linkage are the biggest difference. I've pieced them togather from parts off Ebay and rarely do find 03 parts. I had an 03, it was a great bike, just all alone in design.
Can anyone provide more info on a 500 motor in an '04 - '07 250 frame? This is a conversion I would love to tackle and I just want to see if there are any more "little obstacles" to overcome in doing this swap. I've tried the 250/500 search a couple of times and can't seem to find anything about these year chassis'. I like the fact of the newest 250 frames having the head stay in the rear. Any photos, links, or other info would be greatly appreicated. Thanks!!
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Well, I've made the first step toward doing my own conversion. I picked up a complete, great running 1993 K5 locally here in SoCal. This is definitely gonna be a slow process for me, just for the fact that I have waaaayyyyy to many projects to finish first. I just couldn't pass up the price on this one. Plus I have my '04 500 and '01 250 to hold me over until I join the best of both into one bike. I just couldn't bring myself to rob the heart outta my '04. (Being a last year K5 that I bought new in August of '04, I would of felt like I was killing that beast.) :evil: :-D
The '93 has some cool extras too. Talon rear hub, Pro-tapers', FMF pipe and silencer and whoever had the suspension redone had the Blue fork tubes stripped and re-anodized black. They look great! Like a factory applied coating!
Again, I'm looking for any extra info regarding a 500 motor in a '04 250 chassis. So, if anyone can provide some insight it would be greatly appreciated.
Thanks guys!!
Nick
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This is back on for me. Have an 01, gathering all the essential parts and having at it.
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go get it Big Dog!!! :evil:
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I've kinda backed off for now. I'm having a hard time swallowing that I'd have to sacrifice a perfectly good bike. Maybe if I find a good deal on an engine......
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Waiting for my 01 chassis to arrive. Suspect I will sell the bike off this spring though as its really overkill for a daily rider that isn't drag racing or sand duning.
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Came in the mail. Stoked!
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Suspect I will sell the bike off this spring though as its really overkill for a daily rider that isn't drag racing or sand duning.
I disagree... big-bores makes prime daily riders... IMO the tractor like low-end power makes them easier to ride...
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Hope so, means I don't have to sell and can save some money over buying a new one.
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Looks likes you got some fun work to do :-o
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Hi, I joined the forum specifically to find this information, as I don't even own a Kx500.....yet. I just want something different, the 4-strokes leave me cold, and My CR500 needs a bunch of chassis work to handle anything like the new bikes, plus, it's a Honda, blargh.
So, a 2004+ Kx250 with a 500 transplant is just the thing. Like cyclepsych0, I'm hoping that like the posts don46 made for the 99-02 bikes, someone can fill me in on the steps necessary for the newer generation.
Thanks in advance!
dk
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Hi, I joined the forum specifically to find this information, as I don't even own a Kx500.....yet. I just want something different, the 4-strokes leave me cold, and My CR500 needs a bunch of chassis work to handle anything like the new bikes, plus, it's a Honda, blargh.
So, a 2004+ Kx250 with a 500 transplant is just the thing. Like cyclepsych0, I'm hoping that like the posts don46 made for the 99-02 bikes, someone can fill me in on the steps necessary for the newer generation.
Thanks in advance!
dk
Yeah, Sorry, I've given up on the 250 chassis, I've got a steel 250f and the AL 450f chassis. I'm sure it wouldn't be a big deal to use the newer 250 chassis, just not my thing now.
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I've got a steel 250f and the AL 450f chassis.
How does your 250f frame hold up with the power of the K-5 engine???
I have a 04 RMZ 250 and just love the way it handels.
Dutchie
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I've got a steel 250f and the AL 450f chassis.
How does your 250f frame hold up with the power of the K-5 engine???
I have a 04 RMZ 250 and just love the way it handels.
Dutchie
I think I like the 250f steelie better than the aluminum framed bike, but to be fair I've had some time to dial the 250f in and not the aluminum bike and it has an Ohlins rear shock that works wonders. If you did the conversion you wouldn't be disappointed, it really feels narrow and light almost like riding a 125, seriously.
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With a aluminum frame there is more matriale of the frame it self to use for welding than the steel frame.
But I think that I would go for a 250f subframe and weld a alu thank at work.
?hlins works wonders on the suspension!! As you can see on my picture there's ?hlins shock and 48mm forks on :mrgreen: They make the woops disappear :-D :-D
Dutchie