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Post by infrared on Sept 20, 2015 17:27:57 GMT -5
I'm in the middle of doing this big bore kit. I am definitely better off leaving the 50cc head on and getting my money's worth of that cylinder until it wears out. Can't get the piston back in the head. This is not as easy as everyone says. You need special tools.
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Post by infrared on Sept 20, 2015 17:46:46 GMT -5
The point I am making here is many people say this is a simple job. It is not that simple. It's more like an 8-12 hour job requiring many special tools like ring compressor..
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Post by Deleted on Sept 20, 2015 17:55:36 GMT -5
I have never done it myself, but on the videos I have watched, they did not use a ring compressor and I wondered how this was possible. They just said to slowly rock the piston side to side when sliding it into the bore. I did not, at that time, nor now, see how that would work.
Bill
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Post by katastroff on Sept 20, 2015 18:01:18 GMT -5
The only ring compressor i ever used is my fingers.
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Post by katastroff on Sept 20, 2015 18:31:03 GMT -5
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Post by derbiman on Sept 20, 2015 18:58:05 GMT -5
I have done numerous top end replacements and big bore kits and have never used a ring compressor. It may be easier for you to start the piston into the cylinder first then gently slide the cylinder down over the engine studs. Leave enough room so you can install the wrist pin and clip.You should be able to seat the cylinder. Also,make sure to apply oil to the rings and piston.
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Post by Fox on Sept 20, 2015 20:54:46 GMT -5
The point I am making here is many people say this is a simple job. It is not that simple. It's more like an 8-12 hour job requiring many special tools like ring compressor.. Your fingers are all you need. I always start with the piston tilted so the bottom side of the rings are in and then with my thumb and middle finger I work the rest of the rings in from the bottom up while applying pressure to the cylinder so it slips onto the piston once the rings go in. Oil is your friend here. A little motor oil to make things slippery is helpful. Once you do it a few times you get the hang of it. Not bragging here but swapping a top end usually only takes me about a 1/2 hour and I have never owned a ring compressor. Granted I have done a whole lot of them but you'll get faster too. The part I dislike the most is pulling the body plastics, exhaust and the fan shrouds etc... so I can get to the top end. The rest is the fun part.
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Post by Silar on Sept 20, 2015 21:18:49 GMT -5
Just my 2 cents.. I've installed a BBK in my scooter and from experience, it really isn't that hard at all. The cylinder bore is actually chamfered (angled) at the very bottom of it where the piston slides in so it's almost like it automatically compresses the rings as you put it in. What I had more of a problem with was the cooling shroud that goes around the engine. Seems like it took me forever to figure out how to remove it without damaging or breaking it..
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Post by spaz12 on Sept 20, 2015 22:42:01 GMT -5
I'm in the middle of doing this big bore kit. I am definitely better off leaving the 50cc head on and getting my money's worth of that cylinder until it wears out. Can't get the piston back in the head. This is not as easy as everyone says. You need special tools. It is possible guys that he has a ring (or two) that won't fit because they are too big and will not close... I suspect this might be the case because as everyone here says, they are easy to do.
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Post by spaz12 on Sept 20, 2015 22:48:25 GMT -5
If when you squeeze the ring(s) together and they do not go all he way flush inside the piston groove, then they need to be filed down very carefully. I think that 90GTVert might have a video on this ??
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Post by infrared on Sept 21, 2015 0:04:01 GMT -5
Thanks for all the great replies. I am definitely going to go all the way here with vasoline to get the rings in, oh honey. Kidding aside, I wasn't. 72cc it will be and I am following the useful posts made here on how to get this done. To do a complete job including shroud and exhaust, you are looking at 3 hours minimum. And why would anyone want to rush through something so critical?.
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Post by ams417 on Sept 21, 2015 0:29:33 GMT -5
Thanks for all the great replies. I am definitely going to go all the way here with vasoline to get the rings in, oh honey. Kidding aside, I wasn't. 72cc it will be and I am following the useful posts made here on how to get this done. To do a complete job including shroud and exhaust, you are looking at 3 hours minimum. And why would anyone want to rush through something so critical?. I'd say it depends a lot on a person mechanical aptitude and ability. Experience and efficiency come into play as well. I'd wager I could completely rebuild a horizontal minarelli from a pile of parts to a running scooter in under three hours on the floor in my garage with less than idea conditions, and with none of the "special" tools. I'm not saying it's bad if it takes you three hours to do a top end. Just don't get too upset if someone says it should take 30 minutes. It's all about perspective. I put a transmission in my sons car in six hours start to finish. The labor book mechanics bid jobs out of called for nine hours. If it take you longer and you end up with a running engine, you still accomplished your goal.
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Post by jkeney on Sept 21, 2015 7:59:02 GMT -5
It can be done, and if you need help you know I am local.
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Post by derbiman on Sept 21, 2015 8:33:07 GMT -5
If you don't have time to do it right the first time,you certainly won't have time to do it the second time. Take your time. Don't worry about the clock. Check and double check before putting everything back together.
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Post by Fox on Sept 21, 2015 15:27:43 GMT -5
Yeah there's no time limit. It's better to walk away and come back after an hour or a day rather than to get all frustrated and angry.
I was just trying to say that it's not as bad as you think if you stare at it for a while first and see it going together in your head in a systematic way and map the steps out. After you do it a few times it gets easier and easier like anything else. Even if I practiced day and night for weeks I'd probably never be able to do what this girl does as fast as she does it. That's okay though cause chances are she won't ever be as fast at a Gy6 rebuild as some of us.
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