Jan's shed

Show us that box of bits in your shed!
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JanBros
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Jan's shed

Post by JanBros »

new topic where I'll keep track of all stuff I'm doing

first I bought a new toy, off course it's green and a 2-stroke 8)

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bought it as a project for only 600 euro. without papers.
already bought a KMX200 frame with papers, so if I decide to put it on the road, the KMX number is going on the frame (apparently a KMX200 and KDX200 have almost nothing in common. totaly different frame/engine). possibly I'll only use it on MX-tracks. specificaly wanted the KDX200 because it's got almost the same power as a KX125 but has the easy driveability (widespread torque) of a KX250.

bought it to improve my off-road skills to become better at moped-MX :mrgreen:

ran almost immediatly after cleaning carb, so that's the good news. teared it appart and opened the engine, sadly KIPS valves are broken (seem to be crap, BDK makes steel ones, 145 £) and 2 cracks in the cylinder. rest is fine. don't what to do with the cylinder yet : sleeve or just use it as it is (filling the cracks a bit so the rings can't catch them). Don't think welding would solve it permanently.

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JanBros
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Re: Jan's shed

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since the KX500 is sold, decided to use the rolling frame from that project for my own KR, so that if I crash again (which probably I will some day :mrgreen: ) I can only damage/destroy an already non-original one.

RGV swing arm, R6 rear shock, ZX6R front

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bracket's for the KX500 engine need o be removed again

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gonna cut off the entire section and weld in a new one, I have an alu beam with the exact same size

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the weldded-in plate where the rear mount was bolted on clears the engine, so I'm gonna leave it in

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was afraid it would be hard to weld in the corner due to minimal space with the beam in place, so I first welded in some blocks, so the front weld could be moved to the middle

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bought the frame years ago on ebay-uk as it was already prepared (not fully done) to fit the KX engine, but for posting I told him he could cut off the rear frame. I welded it back on, but as it was just as a track bike, didn't put much effort into it and the position wasn't very accurate.
have one more adjusted rear/side unit, so decided to make the rear frame bolt-on, so in the future I could make a new rear subframe and use plastics from another bike, to save/not ruin more KR1-parts
made some parts to weld into the subframe-beams

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difficult to get the subframe back into the exact some position, it's slightly up at the rear

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Frunobulax
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Re: Jan's shed

Post by Frunobulax »

Looks promising! 8)
Cool to have skills and tools for welding.
stevo135+
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Re: Jan's shed

Post by stevo135+ »

Nice project bike!
I have a KMX 200 myself in boxes in the shed that's supposed to be my off road green lane bike when I've put it together. I've also got a re-plated cylinder with a load of porting work and head modifications by BDK racing. Not so ideal for an off road green lane bike but I didn't think of that.

Anyway I just saw the pictures of your KDX cylinder and that's a very strange exhaust port design isn't it?

The small cut out at the top of port is not something I've ever seen before, I wonder what the reason is for it?

And secondly 5 exhaust ports? That seems excessive but maybe its the ideal set up for a high performance engine? I'd love to know how having 5 small ports compares to the design from h***a, Suzuki etc where there's just a huge bridged port instead and no auxiliary ports used?
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JanBros
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Re: Jan's shed

Post by JanBros »

KX500 also has the 5-exhaust-port lay-out.
in the small cut-out on top of the main port is a valve. haven't studied it yet but it probably opens together with the KIPS.
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Re: Jan's shed

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finaly decided on the exhausts.
first I cut the starting "S" from original damaged pipes and tried to get them back into shape but that failed, especialy as on one of them the S was streched.
have 2 set's of pipes from which I can not find ot what they are, and without that information they are not worth much. One of them it's shape resembles that of the original very close so decided to cut of the flange, make new longer flanges myself that include a "Wobbly duct". the total length is now about 4cm longer which should put it's working range 500rpm lower.
the flange, everything sealed with viton rings :
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pipes as they where :
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everything welded :
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bended the rear bracket on the pipes so it fit's on a bracket that will be mounted behind the footrests
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just need to weld 2 hooks on the bolted support and order some springs
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JanBros
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Re: Jan's shed

Post by JanBros »

and so the project ends much sooner than expected :cry:

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RGV swing arm and oil tank don't like each other, one of them has to go. simplest solution is just fit the S swing arm.

RGV swing arm was fine in the KXR500 as that was a track bike with pre-mix.
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JanBros
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Re: Jan's shed

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went back to an original frame.
still had to make new exhausts. wanted to put on the exhausts shown above, but they didn't fit now since the chain was in the way :mrgreen:

so cut the belly's off, measured the remaining part of the pipes , chose the right cylinder-duct-connector-length so the pipes follow the originals as close as possible while hte header was a little longer. then made belly's and baffles myself, also a bit longer to lower the powerband a bit in the rev-range.

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outside does not look suoer-good, but then I suck at welding thin plates. but on the magic happens inside and there everything is grinded smooth

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then heat them until they are red-gloing to get hte weld-tensions out of them

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a bit of paint and they look a lot better
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had to ditch the side-stand to make space for the pipes for ground clearance, so made a new one
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and springs

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Re: Jan's shed

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forgot this topic ...

I've made a new dyno for my moped MX.
take the complete drive unit of a reach-truck, bolt an extra traction wheel on it, lay it flat and fix it on a chassis and you're done 8)
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software/hardware is an Ardyno with an Arduino Uno. Ardyno is a print made by Adegnes from 2stroke stuffing
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and placed in a Faraday-cookie-box
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video :
https://dl.dropboxusercontent.com/scl/f ... 2eho5&dl=0
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JanBros
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Re: Jan's shed

Post by JanBros »

with this one I can accuratly trace the engine's rpm to, which I'll need for the programmable ignition.
but first a lot of testing.
tested all my exhausts, with 185° and 188° exhaust-timing.
I gained about 10% with 188 (I used to run 185 up to now) , best vs worst pipe :
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next up testing some different heads
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JanBros
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Re: Jan's shed

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tested some different heads, and ended up with 13.6 CR and 55% squish area.
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btw : was going to end up with probably over 10BHP, which is too much for those rpm's, so I lowered the MOI of the dyno.

up to now played it safe with too rich carburation, so setup the main jet properly now.
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as you can see, the 108 main jet is the odd one, it's worse than the 110 meaning it's hole is also bigger and it's number is incorrect.
103 seems best but from experience I know that once the overev starts to realy built, the main jet is small at peak power and if helt for to long at peak, it'll burn a hole in the piston.
going to get somem more jet's, I think I'll end up with 106-108.

than started playing with the restrictor. I always make the pipes a bit shorter (and bigger hole at the end) with a stright tube attached to it. than I put insert's in it and play with it's internal diameter to get the best pressure/temp inside the pipe. but can't get overexited, because getting too small is bad for thermaly unsound engines (and all air-cooled ones are), because than the piston get's too hot. so I never go bellow 12 on a 50.
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