tuning a kdx 125? porting polishing (derestiction done!)

[mad4it028]

ok 1st off i have a full licence
i bought this kdx125 yesterday cheap for some green laneing
today i took it round the block to find how gutless it was proper slow
anyway i read that they are restricted in the expansion chamber and i need to cut it open to remove them now thats not a problem
but should there be anything left inside the expansion chamber when i reweld it back togeather?
roughly where do i need to cut to keep it as neat as possable and hopefully only have 1 cut?
thanks for any help Carl[img][/img]
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always looking to buy bikes crashed ,unfinished projects,none runners pm me
currently riding kawasaki z1000 only bike ive ever loved

[mad4it028]

anyone?
anyone ever opened up any expansion chambers?
what should be left? or should it be cdompleatly empty?
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always looking to buy bikes crashed ,unfinished projects,none runners pm me
currently riding kawasaki z1000 only bike ive ever loved

[mad4it028]

ok ive removed the restrictors in the exhaust fitted carbon reeds and dep end can its alot better but still as slow as fekk!!!

anyone got a kdx125?
are they always really slow?
is there anything eles i can do to improve performance?
will stan stevens be able to make a kdx not just quicker but QUICK???
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always looking to buy bikes crashed ,unfinished projects,none runners pm me
currently riding kawasaki z1000 only bike ive ever loved

[Beamexican]

Hi mate,

How quick is it now.
How quick were you expecting.

Rick

[Captain B]

Maybe you are expecting too much out the wee fella.

I've got a '93 KDX125 and its as slow as a weeks wages, but then I expected that as it is only a learner legal 125.

I have had a few DT125s including a derestricted one and even then it was nippy at best but far from being fast.

I'd think derestricted you'd be looking at somewhere like a 20-25bhp figure and 80/85mph top speed but it will still take a while to get there. Another option might be to play around with the gearing.

[mad4it028]

im now getting 62mph derestricted!!! thats on my sat nav gets there faster but top end is the same
new piston and rings coming and im going to open up the ports a fair bit after noticing that the out let port is half the size of the exhaust down pipe!! that cant be helping matters
ive got a spare barrel so if i make it worse hey ho...lol
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always looking to buy bikes crashed ,unfinished projects,none runners pm me
currently riding kawasaki z1000 only bike ive ever loved

[Captain B]

Even in restricted form I would think you should be getting 70mph, so there maybe something else not quite right with it.

What sort of mileage has it done?

I don't know much about these KDXs. I just bought this one as I wanted a cheapish wee run-a-round and always fancied a KDX in my younger years (always thought they looked harder than the DT).

Unfortunately there doesn't seem to be a lot of info on the web about the 125 but I believe they shared the mechanics of the early 90's KX125.

[mad4it028]

well i thought at least 80mph derestricted!!
ive checked stripped and cleaned the kips there working fine the engine sounds and revs crisp
it got dep race can
carbon reeds
jetted to suit
ive done a plug chop and its a nice brown colour
im fast running out of ideas
help please!!!!!!!!!!!!!
____________________
always looking to buy bikes crashed ,unfinished projects,none runners pm me
currently riding kawasaki z1000 only bike ive ever loved

[Captain B]

[mad4it028]

i just found this
https://www.motorcyclespecs.co.za/model/kawasaki/kawasaki_kdx125r%2091.htm
64 mph derestricted looks like the kdx is just plain slow think i'll tidy it up and sell get a dt or kmx
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always looking to buy bikes crashed ,unfinished projects,none runners pm me
currently riding kawasaki z1000 only bike ive ever loved

[Captain B]

I wouldn't necessarily go just by that article as I have also found a few other articles that say its top speed, when restricted was supposed to be 75-80mph.

But it obviously doesn't help that nobody seems to know or want to share their experience/knowledge of these bikes.

I've even been looking for a manual for mine but can't find much for it. I have managed to find a genuine Kawasaki manual (the ones that came with the bike when new) but the guy, on FleEBAY, in Germany, wants £51 for it!!!

[mad4it028]

ok ivge gas flowed the barrel now getting better speeds 75mph indicated which is more like it
and it comes right up off the throttle in 1st
gonna open up the ports a little next see if i can get a little more outta it

anyone know if ide gain by putting on a kx125 carb and inlet rubber jetted to suit the engine n if so where are the gains?
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always looking to buy bikes crashed ,unfinished projects,none runners pm me
currently riding kawasaki z1000 only bike ive ever loved

[stevo as b4]

The 64mph would have been for a restricted bike IMO! The KDX was a more modern design, and much better/stronger chassis wise than the KMX, which it tried usuccessfully to replace. The KDX's problem is that it's a sheep in wolfs clothing. It looks like a pukka 125 Enduro machine with it USD forks, and lots of suspension travel. The chassis was based on the perimeter framed KX's. The motor is a bit different to the KMX's but not that much really. They should make 24.5bhp in full power form, and do 80mph.

They were never as fast as the lighter but more weedy framed KMX, either at 12bhp or in full power form. The restricted KDX was tested by bike magazine at just 59mph. It's taller and bigger than the KMX, and does not make such good use of 12bhp as the KMX or DT. The flipside is that it's pretty tough, and decent off road for a compromised trail bike, and closer to a competition bike of the same era in off road ability.

[mad4it028]

the kdx was about long before the kmx the kmx has a very different engine to the kdx and a lot faster 24bhp for the kdx derestrivcted but only 65mph ish same as standard restricted only more low down power still shite tho its getting better now ande behaving more like a standard kmx
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always looking to buy bikes crashed ,unfinished projects,none runners pm me
currently riding kawasaki z1000 only bike ive ever loved

[stevo as b4]

[mad4it028]

1980 kdx
https://cgi.ebay.co.uk/Kawasaki-KDX-175-A1_W0QQitemZ180373126232QQcmdZViewItemQQptZUK_Motorcycles?hash=item29ff137c58&_trksid=p3286.c0.m14&_trkparms=65%3A7%7C66%3A2%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50
ive seen older but thats all i could find in 2min of searching were kmx about in 1980?
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always looking to buy bikes crashed ,unfinished projects,none runners pm me
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[Finglonga]

The KDX175 is a completely different bike to the KDX125 and shares nothing with each other. The KDX125 was brought out as a less aggressive softer user friendly alternative to the KMX125 at that was more MX inspired.
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Andy Sez....
F.Y.Y.F.F.

[mad4it028]

im sorry i didnt realise we were talking cc just kdx in which case you are right my bad sorry
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always looking to buy bikes crashed ,unfinished projects,none runners pm me
currently riding kawasaki z1000 only bike ive ever loved

[Captain B]

How did you get on with your KDX? Did you manage to get any more out of it?

Now that I've been using mine a little more I can safely say that (in restricted form) 65mph is as fast as mine will go on a flat with no tail wind (and definitely no head wind). I managed to get a couple original Kawasaki owner, service and model update manuals off FleEbay for it too, so I am considering giving it a decent going over in the winter months.

[ben350]

[mad4it028]

i ended up putting a kmx200 engine in it not an easy swap then i sold it now got an xr600 much much better...lol
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always looking to buy bikes crashed ,unfinished projects,none runners pm me
currently riding kawasaki z1000 only bike ive ever loved