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top end life for 300

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my 09 300 is at 78.4 hours atm, and will be at 100 in a week or two, so am wondering if i should bother doing a top end or not, i ride a bit of a mix of terain, some tight ST, some MX, some fire trails and hill climbs, we live in the mountains with loging pines around and there are some massive steep (40-45 degree's), long, sandy hills that ya can hold it flat out all the way to the top (somtimes a mile or more) so she's seen her fair share of high RPM's and high load in that time, should i do a top end at 100 hours?

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Have you been doing compression checks at regular intervals to see if the engine has begun to lose some compression?

If not, buy a base gasket, pull the top-end off to measure everything, and compare that to the specs in your manual. That will give you a pretty good idea of the wear rate so you can judge when your rebuild schedule should be.

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unfortunantly i don't own a compression tester, i'll do a top end at 100 hours anyway i think, it wont hurt for what she'll cost, and i can measure everything and see for next time.

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unfortunantly i don't own a compression tester, i'll do a top end at 100 hours anyway i think, it wont hurt for what she'll cost, and i can measure everything and see for next time.
I completely agree. I am like you, for the cost of a top-end kit, if I'm pulling the engine apart, it's getting a new piston and rings. My time is too valuable.:)

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What else will you replace? The manual says something about a main bearing,suspension rebuild, con rod bearing, ck tranny, reeds, slide, etc. Mine has well over a 100 hrs and is running great. What kind of signs should I look for? thanx

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When I do a top-end rebuild, I replace the piston and rings, the air filter, wrist pin and bearing, the spark plug, the reeds, and the pipe o-rings and crush washer. I also re-pack the silencer.

While it's apart, inspect the bottom-end. The manual will give you the acceptable tolerances for end-play, etc.

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i'll be inspecting the reeds, bearings and what not, but i don't have the money to go replacing everything in there untill i need to, apprentice wages suck, piston, rings, base gasket, wrist pin, wrist pin bearing and give the powervalve a good cleaning is on the agender as it is, if i find anything else need's replacing i'll see to it as it comes up but i'm expecting 300 hours at least from the bottom end with what i've heard of these bikes.

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i'll be inspecting the reeds, bearings and what not, but i don't have the money to go replacing everything in there untill i need to, apprentice wages suck, piston, rings, base gasket, wrist pin, wrist pin bearing and give the powervalve a good cleaning is on the agender as it is, if i find anything else need's replacing i'll see to it as it comes up but i'm expecting 300 hours at least from the bottom end with what i've heard of these bikes.

Let me know what you find at 100 hours...my bikes got about 40 on it now...just curious.

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