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New top end rebuild! Break in period? Torque specs?


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#1 2001blackshee

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Posted 20 September 2010 - 11:48 PM

As im waiting to get my clys back from FAST , and start my rebuild.. I want to know the torq specs on the cylinder bases and the head.. do you guys recommend doing heat cycles and re torqin the nuts? And im curious on the break in period!! What should i do and what should i NOT do? On my 2 stroke dirtbikes , i ran a full tank of gas , before opening them up!! Would that be suitable? Any other things i should be checking and inspecting while doing the rebuild.??? Im ordering a full rebuild kit, gaskets and all, im getting new head bolts, and a new o ring kit.. Any info or recommendations are appreciated.... Thanx in advance!!!

#2 12 0 Clock P I M P

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Posted 21 September 2010 - 01:18 AM

As im waiting to get my clys back from FAST , and start my rebuild.. I want to know the torq specs on the cylinder bases and the head.. do you guys recommend doing heat cycles and re torqin the nuts? And im curious on the break in period!! What should i do and what should i NOT do? On my 2 stroke dirtbikes , i ran a full tank of gas , before opening them up!! Would that be suitable? Any other things i should be checking and inspecting while doing the rebuild.??? Im ordering a full rebuild kit, gaskets and all, im getting new head bolts, and a new o ring kit.. Any info or recommendations are appreciated.... Thanx in advance!!!




20 ft lbs on all the nuts...cylinders and head nuts.....torque in sequence 10 -15 - 20 lbs to ensure equal torque

each guy has thier own method for break in...some run it balls to the wall on a fresh rebuild...others do heat cycles....engine builders can offer a better/safe method for u

#3 2001blackshee

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Posted 21 September 2010 - 10:04 AM

20 ft lbs on all the nuts...cylinders and head nuts.....torque in sequence 10 -15 - 20 lbs to ensure equal torque

each guy has thier own method for break in...some run it balls to the wall on a fresh rebuild...others do heat cycles....engine builders can offer a better/safe method for u



Thanx for the info bub!!! I talk with jeff from FAST , see what he recommends

#4 AKheathen

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Posted 21 September 2010 - 10:50 AM

a big guy like jeff is gonna use a fine hone(better) heat cycles with the rad cap off, then retorque the head and run it hard, with the same oil and ratio you will be running.

#5 Jereme6655

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Posted 21 September 2010 - 12:25 PM

hey AK....how many heat cycles do you usually run through before givin her a good beat-down?

#6 2001blackshee

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Posted 21 September 2010 - 02:15 PM

a big guy like jeff is gonna use a fine hone(better) heat cycles with the rad cap off, then retorque the head and run it hard, with the same oil and ratio you will be running.



How long do you do ur heat cycles for? And i never heard about running it with the radiator cap off!!! Whats that all about???

#7 shawn941

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Posted 21 September 2010 - 09:24 PM

How long do you do ur heat cycles for? And i never heard about running it with the radiator cap off!!! Whats that all about???

i ran mine 3 heat cycles,,till the engine is at operating temp. i consider a heat cycle. once through the field to make sure she is warmed up and then wot after that. the faster the rings seat the better. i just did mine 4 weeks ago with vitos super stock pistons and she rips....

#8 AKheathen

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Posted 22 September 2010 - 11:55 AM

3 heat cycles ideally. get her hot just sitting there idling and playing with the throttle now and then. the point of the cap being off is that the cooling system would stay pressurized as it cools off and the head loosens. that time is when a leak is most likely to start. no cap-no pressure= no leak. retorque the head and give her hell. keeping a load on it is what cuts the rings best.

#9 2001blackshee

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Posted 22 September 2010 - 02:17 PM

Well after waiting to hear from Jeff from FAST... HE was the bearer of bad news..The shitty ass port job that was done on my bike before i purchased it.. took so much off, theres a stress crack on my cylinders... just cant catch a break... Ill now be looking for some newer cylinders...

#10 shawn941

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Posted 23 September 2010 - 05:39 PM

Well after waiting to hear from Jeff from FAST... HE was the bearer of bad news..The shitty ass port job that was done on my bike before i purchased it.. took so much off, theres a stress crack on my cylinders... just cant catch a break... Ill now be looking for some newer cylinders...

i have a stock pair of juggs unported,,,the right side piston melted so they need bored. pm me if interested