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nx650 engine in a xr650l


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Those engines are almost exactly the same inside and out. The only difference to affect power is the NX's airbox and dual exhaust. Swapping an NX650 engine into your 650L isn't going to give you a 12hp boost. The NX exhaust and airbox won't either. Keep in mind that the figures you find for the NX are brake horsepower. That's power at the crankshaft and doesn't include driveline losses through the gearbox, chain, sprockets, and rear wheel. Average for a bike seems to be around 12-14%.

I find it unlikely that a stock NX650 made any more than a few rwhp above what an uncorked 650L does.

Edited by HeadTrauma
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yea i was just woundering. becuase i like the styling of the nx650s.(frame, tank and side panels) and i wanted to convert one into more of a xr.(dirt worthy) and i just wanted to know incase later down the road i wanted to do engine swap. too bad its real hard to find one. its crazy to think how long that engine has been around for.

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its crazy to think how long that engine has been around for.

Yup. Honda probably put the design on paper no earlier than a year before the '83 XL600 came out(which may have been late '82 when most new models are released). By '86 they had an e-start version of the XR600 engine in the XL600LM(which was also rated at 44bhp...see a trend?). The '83-84 XL600R was rated at 43bhp and probably had a better likelihood of making that than the other RFVCs with higher ratings.

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The NX and the XRL have the same bore, stroke, cam, crank, and compression ratio. The NX's dual exhaust probably flow better, but there is not a noticable power difference between the two bikes (I've owned both). The 88 NX has the lower second gear which is nice, and a slightly smaller rear tire so the NX feels like it has more torque with the same gearing as the XRL.

On the down side, the NX has a 6 spline countershaft which wears faster than the XRL's (13 splines I think).

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