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  #11  
Old 06-10-2004, 12:15 PM
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Default Re: New here - looking for top end pointers - please!

     

I'm pretty sure I understand, however....
I'm going to print this out and have it by my side while I'm doing the job. I actually need to see what you guys are referring to. I've never pulled one of these things apart before. I'm sure it will all make sense as soon as I see what I'm dealing with.
Thanks for help!

Jim
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  #12  
Old 06-10-2004, 12:44 PM
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Default Re: New here - looking for top end pointers - please!

DC, thanks for the plug. It looks as if I got beat to the punch though! Everyone has brought up some excellent points and reading through there isn't much left to add. I'll put in my $0.02 to add to what has been said, but some things I do are not neccessarily required, but I'll include them anyway (designated with a *).
  • Before dissassembly take the time to clean everything to reduce the chance of dirt falling in the engine.
  • "Before" compression test.*
  • Measure squish clearance using a piece of 0.125" solder (if I've never had that particular motor apart before).*
  • Remove and clean carb, set float level and record jetting specs.*
  • Remove head and check for warpage.
  • Remove cylinder, and as others have said, DO NOT PRY THE CYLINDER OFF! Use a mallet! I just had the base of a '99 CR250 machined (0.010" off) because the previous owner tried prying the cylinder off.
  • Look for signs of scuffing or any unusual wear on cylinder bore and piston skirt(s).
  • Take your time to disassemble and throughly clean your powervalve and its associated parts.
  • Clean cylinder (soap and water), deglaze the bore (use soap, water and a scotch brite pad), remove debris (rinse followed by compressed air), and reoil with a light layer of oil and some paper towels. Keep running paper towels through the bore until they come out clean.
  • Check ring end gap on old rings.*
  • Check the ring-end gap on your new piston rings (YOU MUST DO THIS). Place them in the cylinder (1 at a time) and use the new piston to push them down evenly 1/2" from the top of the cylinder. Use a feeler gauge to check the ring-end gap, should be @ 0.012". If it's less pull the ring out and draw file a little off, and then reinstall and recheck. Repeat this process until you get your 0.012" (on both rings).
  • Use a little assembly lube (or premix) on piston pin bearing when installing your new piston.
  • Circlips should be new, and installed in either the 12 or 6 o'clock postion, no exceptions. If not the clips can work themselves out and cause major engine damage.
  • Don't install the piston backward (arrow toward exhaust port)
  • Torque the head studs in a star pattern (1,3,5,2,4,6) to specified torque.
  • Don't overtorque the head studs!!!
  • Recheck compression.*
  • Recheck squish.*

Wiseco makes the piston as a 'one size fits all', so they're no need to worry about if you got the right one or not. The Wiseco piston is also forged as opposed the the stock cast piston. It will tend to grow more during warm-up, so take your time to heat cycle it (let it idle for 10 minutes and then shut it down and completely cool off) two or three times before riding it. Always be sure to give the bike adequate time to warm-up everytime you ride. It is possible to put a cold bike under enough load to make the piston expand faster than the cylinder. Good luck, if I think of more I'll let you know.
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  #13  
Old 06-10-2004, 01:23 PM
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Default Re: New here - looking for top end pointers - please!

I've come to the right place I see.
You guys have upped my confidence level a ton...

Jim
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  #14  
Old 06-10-2004, 01:56 PM
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Default Re: New here - looking for top end pointers - please!

Ok I guess I better clearify the "pry it off" statement I made. There are better places to pry on the cylinder then where you are going to have to put a gasket or seal it. I meant slight pressure not a 4 ft pry bar. It is like everything else, you have to be carefull. If it comes off with just the mallet, that's great!

Quote:
Don't install the piston backward (arrow toward exhaust port)
You are saying the arrow DOES point toward the exhaust port, correct?
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  #15  
Old 06-10-2004, 02:03 PM
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Default Re: New here - looking for top end pointers - please!

Quote:
Originally posted by brokenbones
Ok I guess I better clearify the "pry it off" statement I made. There are better places to pry on the cylinder then where you are going to have to put a gasket or seal it . . . .

. . . . You are saying the arrow DOES point toward the exhaust port, correct?
Where on the cylinder do you have a spot to pry with that doesn't have a gasket or get sealed? : Remember you're dealing with aluminum (read: SOFT!). The one I'm working on looked like they used a screw driver and I'm sure thier intent was to pry gently, but damage occured regardless.

Yes, I meant to say the arrow should point at the exhaust port when the piston is installed correctly.
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  #16  
Old 06-10-2004, 02:45 PM
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Default Re: New here - looking for top end pointers - please!

Well of course there is no seal between your intake and the tranny. There are places to pry if you are carefull. Like I said if it comes off with a mallet, great, if not pry. Generous amounts of WD-40 or another penatrating oil are definatly recommended.
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  #17  
Old 06-20-2004, 08:53 PM
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Default Re: New here - looking for top end pointers - please!

Moved to the Knowledge Base at the request of another member Good advice!
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  #18  
Old 06-20-2004, 09:32 PM
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Default Re: New here - looking for top end pointers - please!

DC, you were not kidding.....Faded Is The Man. He could easily dismiss JimMs' inquiry as a tired subject, as he must have answered the same question a hundred times, he is still carving out well crafted advice.BRAVO! BTW JimM, you can search through past related posts from the home page, Checkitout!
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  #19  
Old 06-21-2004, 10:46 AM
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Default Re: New here - looking for top end pointers - please!

Yep, much appreciated!
BTW guys, I've got my parts. I have one question before I begin. Do I need a ring compressor?
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  #20  
Old 06-21-2004, 01:31 PM
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Default Re: New here - looking for top end pointers - please!

Quote:
Originally posted by JimM
Do I need a ring compressor?
I have yet to "need" one, generally you can just use your hands and a little patience. If you can round up an extra set of hands it makes things even easier. Just make 110% sure that the rings are in the grooves and properly aligned with the pins so you don't risk catching one on a port. Try not to twist the cylinder on the piston, this can allow one end of the ring to pop out into a port. Also make sure the rings are installed properly, some have an up side (usually the print on the rings goes up) but read the instructions to be sure.
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