July 31st, 2016, 11:53 PM | #1 |
ninjette.org member
Name: Paul
Location: Turlock, CA
Join Date: Jul 2016 Motorcycle(s): '05 Ninja 250, '80 KZ750 Posts: 21
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How tough are pregen engines?
All I've ever ridden or owned have been Jap bikes mostly Honda and Kawasaki. It's a given that they are mostly bullet proof. But I got to thinking the other day that I just bought a second hand "beginner" bike with 15,000 miles and who knows how many clutch drops, stalls and redline max attempts in that time. Not to mention poor maintenance.
I'm not worried. The bike runs strong and fires right up every time. But I wonder if there was any special consideration to the beginner bike usage when designed? Maybe to.make parts simpler and or stronger for that purpose? What kind of life expectancy do the 250's have in competent hands? Any things that will wear out quicker in this engines? Anything to pay attention to? |
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August 1st, 2016, 12:38 AM | #2 |
ninjette.org guru
Name: Julius Michael
Location: Philippines
Join Date: May 2016 Motorcycle(s): GPX250-RII Posts: 296
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cam chain guide
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August 1st, 2016, 01:00 AM | #3 |
ninjette.org member
Name: Rolf
Location: Sweden
Join Date: Jul 2014 Motorcycle(s): Ninja 300 Posts: 70
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The engine isn't perhaps designed for beginners specifically, but it is conservatively specified. Low power output, low rpms (low for the bore and stroke that is), low valve lift, so that valve springs can be soft and load on the cam shafts reduced. Low torque and rotating mass means that stress on the clutch and gearbox is reduced. Another conservative aspect is that the design is unchanged (with minor refinements) since the eighties, and over a million units have been made.
There are some threads, about a guy named Bill among others, that indicate that the cam chain and sprockets wear out after 100 000 miles and are very difficult to replace, not worth the effort. Bill replaced the engine instead. |
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