2001 KMX 125 Poor Bottom & Top end

[2StrokeNoob]

I have a 2001 KMX, it was imported from france and was supposedly fully derestricted.

It should be making around 20 bhp but the top speed is currently around 60mph and the low end acceleration is decent but I know the bike is under performing compared to other KMXs I have seen and rode.

I thought there might be a restriction in the exhaust / expansion chamber but I found nothing welded in, my mechanic friend told me there was no restriction on the exhaust so I'm honestly very confused.

If anyone could offer any advice I'd appreciate it. Thanks

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As you've posted nothing about it's history with regards to mileage and piston/ring changes, i'd start by checking compression or taking the barrel off and measuring the clearance between barrel and piston skirt at the bottom.

If you don't know when the piston and rings were last changed, this needs doing anyway, otherwise it could go bang at any moment and cause further damage to the cylinder and crank.

Other options are a dirty carb, blocked carb jets and passageways, or a clogged air filter. It's also possible for the expansion chamber and silencer to get clogged with soot and oily deposits. The expansion chambers cam be taken off and either filled with caustic soda or set fire to, in order to burn off the internal soot. The silencer depends if it has baffling material or not. Some allow the material to be taken out and changed.
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TZR250 2MA road, TZR250 1KT road, TZR250 2MA race, TDR250, YZF-750R Boost colours.
Jaguar S Type 3.0 V6 Sport R, VW Transporter T5 GP LWB Shuttle 140ps DSG.

[2StrokeNoob]

[redeem ouzzer]

You need to get it on a dyno, otherwise it's just guesswork.
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Be a REAL MAN!

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Has it got KIPS, Their version of power valve?

If it hasn’t got the servo and just a blanking plate, rotating it to fully open will lose a bit of low to mid range but up the top end by a fair whack.

https://www.bikechatforums.com/viewtopic.php?t=85130#post_1010430
____________________
TZR250 2MA road, TZR250 1KT road, TZR250 2MA race, TDR250, YZF-750R Boost colours.
Jaguar S Type 3.0 V6 Sport R, VW Transporter T5 GP LWB Shuttle 140ps DSG.

[stevo as b4]

As others have said it could be several things. But forget mileage it's an import bike with no history. Start with a compression test on a hot engine. I'd want 150psi+ on a KMX that's in fine fettle. But remember that compression testing alone on a two stroke won't tell you the full story of the condition of the internals.

There's no substitute for a strip and inspection on a used two stroke that has no history or you know how it's been used or maintained etc.

Get it on a dyno before though as it's your diagnostic friend. I want a std KMX with a smooth road tyre to see 19.5-20bhp or its below par, but the number isn't important due to dyno variations, the shape of the curve and the peak power and torque rpm will tell you more.

Kawasaki KIPS valves like any two stroke exhaust valve system have their issues, and they can break or seize.

Come back with a compression test reading and a dyno graph. But get the spanners ready as the kind thing to do will be a top end re-build at least on a bike of this type and mileage and with no idea of its history.