KX Riders
Maintenance & Technical => KX500 Steel Frame Conversion (SFC) => Topic started by: doorslammer on April 09, 2012, 09:30:40 PM
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hey guys
well as things go i bought a mates 2003 kx250. A little backstory, he bought it blown up, had the suspension serviced and resprung, and rebuilt it. it go 3 laps into a race and called it quits, they put it down to a crank they didnt replace, a new set of cases and crank and it was time for round two. the second tank in and i was following and it locked up hard, it got real sketchy watching it lock up through a whoop sectionwhile trying to find an exit :-o
anyway he was fed up with it and wanted it gone, considering it had all the suspension serviced and set-up for my weight i took it looking for another project :-D
anyways heres the carnage of the motor, not much worht keeping
(http://i205.photobucket.com/albums/bb149/doorslamer/kx500/IMG_0256.jpg)
(http://i205.photobucket.com/albums/bb149/doorslamer/kx500/IMG_0257.jpg)
(http://i205.photobucket.com/albums/bb149/doorslamer/kx500/IMG_0258.jpg)
(http://i205.photobucket.com/albums/bb149/doorslamer/kx500/IMG_0259.jpg)
(http://i205.photobucket.com/albums/bb149/doorslamer/kx500/IMG_0260.jpg)
and here is where it sits now after a quick clean, should be picking up a 95 500 motor late next week if im lucky
(http://i205.photobucket.com/albums/bb149/doorslamer/kx500/IMG_0272.jpg)
(http://i205.photobucket.com/albums/bb149/doorslamer/kx500/IMG_0273.jpg)
any input, tips or ideas, im open.
cheers Toby
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Glad to see more 03/04 KX250 conversions.
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thanks flyin, you post gave a heap of useful info.
anyways i picked this up tonight.
has a little weld on the clutch cover, bore measures 86mm.
(http://i205.photobucket.com/albums/bb149/doorslamer/kx500/IMG_0279.jpg)
(http://i205.photobucket.com/albums/bb149/doorslamer/kx500/IMG_0281.jpg)
still trying to work out what pipe to use. everyone seems to be happy using a cr5 pipe with the kx section welded onto it. why isnt anyone just modifying a kx pipe.
unfortunatly i couldnt get a pipe with the motor, so i havent got a front section to weld onto a cr pipe (unless a 250 pipe will work, i doubt it but i havent checked yet)
so has anyone used a kx500 pipe? did it take much to modify?
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Nice looking build you got going, that 250 sure went out with a bang
I believe the K5 pipe is too high, you wouldnt be able to fit it through the frame under the shock reservoir. Ive seen pipes with the lower section of a kx5 pipe and upper section of a cr5 however. And just so you know a 250 pipe wont work with a 500, different stinger size ect
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I used a KX pipe and modded it on my first two hybrids, then started using CR pipes, performance was about the same and ease of install was much easier. JFAB modded a stock desert pipe for an aluminum framed bike, there is a post here at KXriders about it, didn't look to bad
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cheers guys, going to ring around and see if i can find a busted kx5 pipe someone is willing to cut the front section off.
anyway, about to order some parts (piston, gaskets etc) but i need a set of reeds as well. just wondering if someone could identify this reed block. it has a boysen sticker on it.
(http://i205.photobucket.com/albums/bb149/doorslamer/kx500/IMG_0298.jpg)
is it worth it? would it be better to just get a v force or standard cage with C/F reeds?
i like the angle on it, seems to match the 250 well, hopefully it will make carby/airbox alignment easier.
(http://i205.photobucket.com/albums/bb149/doorslamer/kx500/IMG_0297.jpg)
cheers Guys.
ill be getting into the serious stuff soon haha
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Have a look through Motorrad's engine build thread, im sure you'll find the answer in there
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That is in fact a Boysen RAD valve, I have not used the Rad valve, I ave V-force on mine, but Boysen makes good stuff so I'm sure its good.
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A problem that I see with using the Rad Valve, Im assuming that it is from the 500 engine that was in a standard 500 frame, will be that the carb will go into the shock. I tried a 04 KX250 intake with a 250 V Force 2 cage. It was still close to the shock and a bit too short. I was always afraid that the carb would pull out of the airboot. I ended up sucking a reed with the V Force 2 also and it wouldnt run right anyway. I ended up going back to the 500 reed cage with a set of Boyesen reeds and a 91-94 KDX250 intake. The KDX250 shares the same reed cage and reeds with the 500 and the intake was angled better, more clearance for the shock, and is a little longer so the carb sits in the airboot much better.
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Well hit a bit of a snag, ended up fracturing both my left and right Foot, and have now got a plate in the right. After spending a month in hospital I'm finally home but still not walking...
Anyway back to the bike, those who are using cr500 pipes what muffler do you use, can I use either a cr500 or kx500 muffler. Also can I cut the front section off the 250 pipe to adapt to a cr pipe or is it too small?
Cheers
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use the cr500 silencer, is has to bend up where the k5 silencer just goes straight out
Hope you get healed up quick
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OD the 250 pipe is fine, much smaller inside dia. than the 500 though
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If you have a lathe you could probably chuck that 250 snout up & turn the inside out to the 500's inner pipe diameter. Save hunting up one from a k5
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don't know about the rest of you, but I still had to put a nice bend in the CR500 silencer to get 'er bolted up. Curious if the silencer offered by Service Honda doesn't fit better, as I'm sure I lost some flow due to the bend in mine...
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I didnt bend anything on mine. I used a homemade bracket similar to the rear bracket on a KX500 to hang mine. I wanted to be able to swap out the exhaust w/o any modifications.
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You didn't have issues with the tire rubbing it?
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Nope, everything clears.
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nice
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first off i love this site, lots of good info, but to get down to business :mrgreen: is it better to try and find a donor bike? or to piece one together off of ebay?? ive been looking and cant seem to find a bike thats not way to expensive considering what im going to do to it :evil:... and if i do piece one together how much of my original 500 can i use? i know i can get a frame, shocks and all that for a decent price but the rims are just way to expensive, might as well buy new! also i have heard of a few guys using the stock 500 swing arm, is that a good way to go or not?? will it even bolt up with the 250 linkage?? as you can tell ive never built a 250/500 conversion before.. thanks for the help
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I lucked out and already had the 250. The 500 fell into my lap after my brother inlaw lightly seized it and wanted to trade me even up for a DR350/435 dualsport that I had. I probably have around $500 into it after selling off the 500 chassis. Still have a few bits left that should knock it down to a couple hundred. Again, I was very lucky. I only used the engine, ignition and a few miscelaneous bolts and brackets from the 02 500. Everything else was from the 04 250 with the addition of a 96 KX125 carb top and cable. 91-94 KDX250 carb intake and the Service Honda KX500AF exhaust and FMF Q silencer. I did use the 500 throttle. The easiest way is to have both bikes and not sell off anything until the project is done. Ive seen 03 250s for as low as a grand and the 500s run from $800 to $4500. I wouldnt use the 500 swingarm, it would most likely change the leverage ratio of the shock. It wont even come close to working on a 04 250 due to a change in the linkage arrangement for that and following years.
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thanks for the info Hawaiian!! well then since thats settled was the build on the 04 as simple as the builds i have been reading abouton this site with the 99-01's?? and i already have a great running 99 kx500 that i fell into when a guy wanted to trade it for my 01yz250... i think i got the better deal :-D.. the problem im finding is the 250's are just so d**n expensive, its a good thing im in Afghanistan right now or i might get impatient looking for the right bike.. also what kind of mods did you need to get that service honda exhaust to work?? i have been to there site and i cant even find where they sell them, and i know i would not want the Q silencer... i like being heard!!!! do you know of any good sites to look for bikes other that craigslist?
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From what it looks like it seems to be about the same amount of work to do either one. The headstay has to be centered on the 03/04 frame for tank/petcock clearance. The headstay mount on the head needs to be shortened and a new mount hole drilled. Everything else is more or less the same. The pipe pretty much bolts right on. I clearanced it slightly to clear the coolant hose better on the right side of the cylinder. I didnt alter the pipe just so it can be replaced easily. The 03 frame already has a rear mount for the stinger. The 04 frame doesnt and needs to be welded on. I welded a mount to my subframe. Its been over a year now and it hasnt had any issues, very reliable and handles great! Took a little while to get the jetting straightened out and fine tune it. If you have to run a big tank you need to use a 05-07 KX250 2stroke tank. The 03-04 IMS/Clarke tanks will not fit. Same thing with the 03-07 KX125 tanks, they are the same as the 03-04 KX250 tank.
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WOW!!! your a wealth on knowledge!! i cant wait to get this project started!! I will be going to you for input since you know so much if you dont mind? im an alright welder for what needs to be done, but how hard is it to get the head stay cut and bead blasted?? is that somthing i should just send out to someone?
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Sorry for the late reply, I just saw the post. I had a machinest friend cut the head-headstay down and redrill it.
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thanks for the info Hawaiian!! well then since thats settled was the build on the 04 as simple as the builds i have been reading abouton this site with the 99-01's?? and i already have a great running 99 kx500 that i fell into when a guy wanted to trade it for my 01yz250... i think i got the better deal :-D.. the problem im finding is the 250's are just so d**n expensive, its a good thing im in Afghanistan right now or i might get impatient looking for the right bike.. also what kind of mods did you need to get that service honda exhaust to work?? i have been to there site and i cant even find where they sell them, and i know i would not want the Q silencer... i like being heard!!!! do you know of any good sites to look for bikes other that craigslist?
try "bikefinds" if you don't mind driving near by you will probably have way better luck finding one. found my 01 K5 on bikefinds. had to drive 8 hours none stop but oh well
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My vote as well, buy 2 bike's, the 250 & 500, you can usually get one around a grand a piece. From november to february the deals are the best. Then ebay what you dont need it will near zero the cost.
Bike finds is sweet, also try CL & one of my local newstations has a classifieds section that been the where the best deals have been. You can stuff a bike in your trunk which helps with gas if you do have to drive a-ways
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I parted out the remains of the 500 and knocked the cost down to around $500! I as lucky since I already owned the 250.