Cylinders fitted with liners.

[Pete.]

Saying that cast iron liner is just as good as a hard plated ally cylinder is like saying and air cooled engine is just as good as a liquid cooled one.
Nikasil is hard - very hard. Hardness means lower friction and lower friction means lower losses. Aluminium has more than 2.5 times the thermal conductivity of iron so the more heat you can carry away the more heat - and power - you can produce in the engine. Big-power bike engine builders have found this time and again, nikasil barrels take some supreme abuse before they let go. If you're smearing nikasil barrels on a crosser it's probably more of a piston problem than a cylinder one. The barrels should out-last the pistons many times over.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[monkeyman]

Do you believe that if he were to buy that new barrel, slap it on the bottom end with no other modifications, it's going to make a 10% increase in power over simply refinishing his existing liner?

Do you think that there would be any power hunting modification you could make to a KMX 125 that would cause the cast iron liner to be a limiting factor? And if so what modification would that be?
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Im not the best, but im in the top one
RM 250, Husky TE610, K1 GSXR 750

[Pete.]

Do you have any non-stupid questions to ask? If you're going to call me out on something I've said at least base it on something I've said instead of throwing leading questions at me based on other people's input. I've made no assertions on power increase anywhere here. My comments have been on frictional losses and thermal transfer.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[stevo as b4]

OK some fair questions. But until or unless I strip the top end I won't know exactly what the current cylinder is like. Apart from the heat transfer issue, which on a std bike wouldn't really be an issue, there's the port matching of the liner to the ports.

As you bore out a two stroke, the ports get lower effectively de-tuning the motor. If the liner is matched to the lowered ports power might be lost?

As for tuning, well it's going to make more heat, via exhaust and ignition modifications, and so shedding heat from the cylinder will be more of an issue. I've already sourced a bigger aluminium radiator with larger cores and more tubes.

I understand what your saying about quick easy re-bores on off road bikes that suck in lots of dust and crap off road. This bike is a garage Queen that doesn't go into the muddy stuff or wannabe MX riding etc.

Jetting is off slightly, as im on pre-mix and sorry but my new carb is going to be Mikuni not Keihin. Is that really going to make much of a difference though? I've heard alot about this Keihin is better business, but I'm yet to understand why if the bore size is the same?

[monkeyman]

[arry]

[sickpup]