How do I know if I need a new top end

On a 2001 CR80. What are some symptoms

Hard to kick over. You will get a gradual (usually) degradation in the ease of kicking over. Sometimes you will get the sudden loss of compression. Usually that is preceded by a sudden loss of power or some sort of chatastrophic failure. Most guys tend to do a top end on the hourly schedule or a seasonal schedule. For guys that ride the track, they tend to to it at the end of the race season or just before the start of the new one. Hourly wise, anywhere between 50-100 hours. The high rev, sand and dunes riders will be doing it sooner typically. Some guys try to stretch the dollar by reusing pistons and just replacing rings and bearings. I don't recommend it personally. The cost of a new piston in addition to all the other parts is minimal. Way cheaper to replace to a piston than a whole jug and head, or worse yet, bottom end.

The best way to figure you need top end replacement is by checking compression, if you are less than 150 psi then you are in need.

piston and rings are the best way. the piston after a while develops some abnormal wear in the skirt area and some are know to crack at the weak point and fall into the crankcase, not a good thing.

On a 2001 CR80. What are some symptoms

I have '02 CR 80. Did you end up doing your own top end? Just need a new piston kit? I'm a Shadetree mechanic only.

My 80 will fire briefly, then dies with oil on the spark plug. Rings?Seals?

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