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post #1 of 12 (permalink) Old 03-28-2007, 09:55 PM Thread Starter
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Top End Rebuild -HELP

I'm rebuilding the top end of my yzf600 my question is....... The pistons are still attached to the crank. Is there a piston ring compressor tool to compress the pistons this way. I'm used to cars and knocking the piston in from the top but never while the piston is still attached. Any help would be great. Also any gotchas anyone might know with the rest of the rebuild.
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post #2 of 12 (permalink) Old 03-28-2007, 11:01 PM
 
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If you can see the pistons, you got the head off OK. If your problem is the valves, you don't have to go any further. If it's the rings, you really need the manual to do everything correctly. But generally, the block comes off the pistons still connected to the crank. The hard part is slipping the block back over four pistons and rings. It helps to have extra hands holding the cam chain and the pistons and the block. There's usually a lot of "lead-in" on the bottom of the block to get the piston/rings inside, but Yamaha may have a special ring compressor to make the job easy. If you break a ring, it all has to be done over again. Good luck.
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post #3 of 12 (permalink) Old 03-29-2007, 07:18 AM Thread Starter
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I actually already have the head and cylinder off with the pistons hanging out of the block. I've found a tool with a wrench and compression rings that I think would work but I'd need 4 tools because I need to put all four pistons back in at the same time. I searched the web and found someone used a radiator clamp to hold them but I think that would scar the piston.
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post #4 of 12 (permalink) Old 03-29-2007, 09:16 AM
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Quote:
Originally Posted by No Worries View Post
If you can see the pistons, you got the head off OK. If your problem is the valves, you don't have to go any further.
Okay- good till there

Quote:
Originally Posted by No Worries View Post
If it's the rings, you really need the manual to do everything correctly. But generally, the block comes off the pistons still connected to the crank. The hard part is slipping the block back over four pistons and rings. It helps to have extra hands holding the cam chain and the pistons and the block. There's usually a lot of "lead-in" on the bottom of the block to get the piston/rings inside, but Yamaha may have a special ring compressor to make the job easy. If you break a ring, it all has to be done over again. Good luck.
HUH?!?!?!

What kind of a way is that to put an engine together? Seems like a recipe for headaches and broken parts!
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post #5 of 12 (permalink) Old 03-29-2007, 11:00 AM
 
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What kind of a way is that to put an engine together? Seems like a recipe for headaches and broken parts!
On modern motorcycle engines the valves and/or rings usually go bad. Taking the block off the engine with the piston/rods connected to the crank means that the engine cases don't have to be split - a major headache. The only problem is dropping things down into the crankcase. Honda makes a special ring compressor to ease the piston/rings into the bottom of the block. I've never done it, but saw it being done.

If you think that is interesting, the crank on my 1979 GS1000 is built-up with roller bearings. Each piston rod is pressed-on in a hydraulic press with crankshaft roller bearings. With roller bearings instead of plain bearings, my Suzuki runs on 5-10 pounds of oil pressure. It was super-complicated and isn't done anymore.
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post #6 of 12 (permalink) Old 03-29-2007, 11:06 AM
 
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Quote:
Originally Posted by oldman2007 View Post
I actually already have the head and cylinder off with the pistons hanging out of the block. I've found a tool with a wrench and compression rings that I think would work but I'd need 4 tools because I need to put all four pistons back in at the same time. I searched the web and found someone used a radiator clamp to hold them but I think that would scar the piston.
If you could make a sleeve out of teflon-coated plastic, the hose clamp wouldn't scratch the piston. They use this flexible plastic to slip between leaf springs on cars and trucks so the leafs will slide against each other easily. Maybe you can buy a foot of it at some automotive store.
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post #7 of 12 (permalink) Old 03-29-2007, 11:09 AM
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You should be able to just pinch the rings together with your fingers as you slide the cylinder over the piston. Kind of a pain but thats how I did it on my 2 stroke.
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post #8 of 12 (permalink) Old 03-29-2007, 11:10 AM
 
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Also, since two pistons are at TDC, and the other two are at bottom dead center, you only have to insert two cylinders at a time into the bottom of the block.
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post #9 of 12 (permalink) Old 03-29-2007, 11:18 AM Thread Starter
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Thanks for the good information No Worries. I'm going to look for the plastic. I also thought about only needing to slide two in at a time but you helped sure up my thoughts.
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post #10 of 12 (permalink) Old 03-29-2007, 07:06 PM
 
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If you could make a sleeve out of teflon-coated plastic, the hose clamp wouldn't scratch the piston. They use this flexible plastic to slip between leaf springs on cars and trucks so the leafs will slide against each other easily. Maybe you can buy a foot of it at some automotive store.

I cut 2-3" wide strips out of plastic gallon milk cartons. Works for me.
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post #11 of 12 (permalink) Old 03-29-2007, 07:53 PM
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Vverrryyy eenteresing...

Would a normal (smaller) ring compressor/sleeve work? I don't know if they completely open, which you would need to get around the connecting rod once it was in.
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post #12 of 12 (permalink) Old 03-30-2007, 12:31 PM Thread Starter
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I actually found an interesting thing someone used wide zip ties to do it. Milk jug would work too... thanks for all the help....

On a sidenote I actually found the tool Yamaha uses but can't find anywhere to purchase it from... I think I'm going with the zip tie route.
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