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Piston Replacement - Burned - Bronco

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I'm tearing down the engine this winter. I have a 2000S with 3600 miles and am putting the E base gasket in. Should I just replace the rings or should I spend close to 3X more and just get a new 12.2 cr piston kit? I have only really worked extensively on 2 strokes so really unfamiliar with how long a 4 stroke piston will last. Looking for your opinions.

Thanks

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You wont know the answer for sure until it's torn down.. If the rings did not seal,, and you have excess blow by.. or the cyl plating is showing some ware,, then yes, piston and rings. As Burned said.. rings only might do it.. but at the cost of a piston kit to freshen the top end up.. I'd plan on the piston kit.

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The miles are about 60/40 dirt/street. Would you go with the stock CR or get the 12.2 CR?

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The stock piston is the same E, K or S.. all the same.. The CR difference comes from the base gasket.. E & K have a single ply, S has 3 ply... Change the base gasket, and the S is at the same CR as the others.

Now if you’re talking about the JE or Weisco 13.5 piston.... then different story. Using the E, single ply base and the 13.5 piston will net you a higher CR then stock (umm, 13.5:1 😢 )

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With the 13.5 to 1, can you run it on 92 pump gas without issues? With Hotcams and Yosh CDI?

Also, how crucial is it to remove the O.E. chain tensioner and go with a manual adjuster? Any help, greatly apreciated.

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You really should run race gas with a 13.5 piston. Otherwise you're just asking for trouble. And you should just go ahead and buy a manual camchain tensioner. I used an APE unit it it was only $40-60. Machinist makes them too, from what I hear. I'd rather buy from him the APE, but check out your options. The factory unit is suspect. Its too cheap a fix to take a chance. Oh yeah, make sure you shim or upgrade the valve springs before the yosh cdi upgrade, but you probably already knew that 😢

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With the 13.5 to 1, can you run it on 92 pump gas without issues? With Hotcams and Yosh CDI?

Also, how crucial is it to remove the O.E. chain tensioner and go with a manual adjuster? Any help, greatly apreciated.

you need to run at least 100 octane fuel.

looks like you run a supermoto.the MCCT is absolutely needed on the pavement.

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With the 13.5 to 1, can you run it on 92 pump gas without issues? With Hotcams and Yosh CDI?

Also, how crucial is it to remove the O.E. chain tensioner and go with a manual adjuster? Any help, greatly apreciated.

you need to run at least 100 octane fuel.

looks like you run a supermoto.the MCCT is absolutely needed on the pavement.

You are joking , right ?!

100 Octane ? top I've seen is 98... 😢

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Try AVGAS from your local airfield. 100 octane but leaded. It's worth trying a gallon, just to see if it works.

Cheers

Ian

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1: No he is not joking.. Pump fuel aint going to cut it.

2: Avgas is not rated the same as automotive fuel.. 100LL avgas is not 100 Oct motor fuel.

3:Union76 sells "Rocket fuel" 110 leaded race gas, 100 leaded and unleaded race gas. And there are many other sources for race gas.

4:My 13.5+, Hot cam IN & OUT, will ping with any and all pump fuel.. 100 race gas works well, pump fuel and oct booster seems to work,, but have shown top be corrosive in other motors I've built, so I do not like to use it. Might just have been the pump fuel I was mixing with it.. But not worth the chance as long as I have a source for good race gas.

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You can buy race gas by the barrel. It's a bunch cheaper like that but it's still twice what you pay for premium easily. If you want high performance on any bike prepare to pay for it. There is no such thing as free horse power. I've paid high prices for every single gain I've made. The closer to max power the higher the price too. prairiedawg 😢

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