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Discussion Starter #1
Ok, I think I've read most of the base gasket replacement posts, but wanted to check in here before I tear into my bike. I also have the service manual, read through the procedure and belive I've committed all but the specific torque values to memory.



Status: 2006 TW200, 4800 miles, 145 psi cylinder pressure, constant weeping at the front of the cylinder base, and a tiny bit around the head gasket.



I have the 2010 base gasket, oring, head gasket, and new dowel pin orings ready to go and would like some feedback regarding:



How long should this take for your average WECSOG shade tree mechanic (can I do it successfully in one evening after work, or should I wait for the weekend for same day service)?



One man job or would extra hands be...handy?



I see folks replacing rings every time their cylinder comes off...why with this few miles on the engine?



Yamabond the base gasket upon installation? Why or why not?



Is there a sticky for this posted somewhere already...?



Thanks,

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Old school thought was never reuse rings and always hone the cylinder. I have reused rings without honing the cylinder on low mile bikes and never had a problem, as long as there was no detectable ring groove. The trick I use is to put the engine at top dead center between compression and power strokes before disassembly. Remove the head, then carefully raise the cylinder barely enough to reveal the piston pin retaining circlips. Carefully remove the circlips, then press out the pin. Remove the cylinder with the piston still inside as a set. Reverse to reinstall.
 

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Thanks for the cylinder/piston removal tip qwerty. A very logical approach.



regards, mac
 

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Discussion Starter #4
Well, I went ahead and dove in last night. Took about 3 hours and had to get the wife to lend a hand a few times.



Went fairly smooth. The front left rocker arm pivot had the front left head bolt blocked at the threads. Still not sure if the leak is fixed due to the residual oil and what was spilled in the process, but the original gasket was seriously detiorating from the inside out.



Pretty sure it's not going to last. There is at least a .008" mismatch between the left and right engine case halfs, so the mating surface isn't flat at all. Yamaha really dropped the ball when they made my engine. I can't really believe that would pass quality...



Mental note for next time: make sure the cam chain stays on the crank sprocket throughout the assy process. Trying to hook it back on the crank after everything is buttoned up is a royal PITA!



And next time, Yamabond is going to get a shot at the title.



Next up is adjusting the clutch pushrod...



Thanks for chiming in qwerty, wish I would have saw your post before I started as that's a pretty trick idea.



Cheers,

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I believe this case half mismatch is common in the 2006 model year, as the oil seepage seems very common. I have a 2006 that has had the base gasket replaced under warranty once, and is now in the shop again being completely torn down due to continued (and worsening) leakage at the cylinder base. Fortunately for me, I bought yamaha's extended warranty and all the work has been covered so far. The mechanic noticed the case half mismatch and is remachining the case, replacing the bolts, the base gasket etc... Thankfully, Yamaha really stepped up to the plate and have said to do whatever it takes to fix this problem.
 
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