Two Stroke Motocross
Two Stroke Motocross Forum => Vintage Two Strokes => Topic started by: naked racer on February 20, 2011, 08:42:49 AM
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i was just given a 1979 yz 100 that need s rebuild im a tight ass so i dont want to do a full rebuild just the main things
i have only taken the barrel off to see why it was siezed and found shavings of the piston and the barrel stuck to the rod and the crank bearing is fu##ed,
so far i cant see anything else wrong untill i take it apart but im hoping thats all i will find,
how much would it cost to get the barrel honed out and a new pistin
as for the crank bearing am i able to go to my closest bearing shop and get one or do i need a geuine bearing
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You can buy bearings from your local bearing shop, no problem.
Just ask for a C3 grade bearing. High speed.
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I'd bet money the lower rod bearing is shot. Meaning either a new crank or a crank rebuild.
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Some things you shouldn't go cheap on and that includes 30 year old 100cc motocrossers.It will need a crank assy. and a new piston and bore.
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you could probably rebuild the crank as long as the rod is straight. but definitely replace all the bearings.
As for the honing the cylinder that all depends on the amount of damage.
the gouging my be so deep that resleeving the cylinder is your only option, the piston depends on how much you have to take out of the barrel. take it to the machine shop see what they say before you go buy a piston.
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Set it up to use either KT100J kart pistons they have a step of 0.05mm which means you never need to rebore and the cylinder will last forever. A KT100J rod (if it has a 20mm crank pin) is a great idea also. Kart stuff is cheap as.