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Post by simon1987 on Jun 15, 2022 18:23:21 GMT -5
Hi guys sorry for my english, I have GY6 2007 Sprint Filly 80cc, yestarday just lost power. I also have trouble with oil leak from seal on cranksaft on the side where is variator. I open it and it was very dirty so I cleaned all variomatic and rolls were dirty and greasy, cluch seems ok, belt also but the scoot doesnt want to move. There was oil in engine and belt is ok also. Im new with scooter reparing and dont know much so any help is welcomed.
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Post by GrumpyUnk on Jun 18, 2022 8:48:32 GMT -5
If the belt, variator and clutch pulleys got oiled, then they must be cleaned of all residue. The belt is unlikely to be usable after getting oiled, but it may work if cleaned thoroughly with detergent. I do not think a solvent of any sort should be used on the belt. The rollers and variator insides should also be cleaned of any oil residue.
The crankshaft seal can be replaced without disassembly. I think there is a video on YT demonstrating, or perhaps on-site. Using a sheet metal screw driven into the seal, and a lever or slide hammer, the seal can be pulled from its cavity. A new seal can be driven in using a length of pipe that matches the seals outer diameter.
Drive in flush with the surrounding metal, of if there is a groove on the crankshaft, leave the seal a smidge outward so its edge rests on a different spot of the crankshaft.
tom
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Post by simon1987 on Jun 29, 2022 6:26:15 GMT -5
If the belt, variator and clutch pulleys got oiled, then they must be cleaned of all residue. The belt is unlikely to be usable after getting oiled, but it may work if cleaned thoroughly with detergent. I do not think a solvent of any sort should be used on the belt. The rollers and variator insides should also be cleaned of any oil residue. The crankshaft seal can be replaced without disassembly. I think there is a video on YT demonstrating, or perhaps on-site. Using a sheet metal screw driven into the seal, and a lever or slide hammer, the seal can be pulled from its cavity. A new seal can be driven in using a length of pipe that matches the seals outer diameter. Drive in flush with the surrounding metal, of if there is a groove on the crankshaft, leave the seal a smidge outward so its edge rests on a different spot of the crankshaft. tom Thank you very much, so the belt is not usable any more.... I trien to replace oil seal and oil still driped. My friend said that probably i need to change crancshaft I will try it to do it, never did it before. |
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Post by GrumpyUnk on Jun 29, 2022 7:12:57 GMT -5
Take a close look at the crankshaft where the lip of the seal rides on the metal of the crankshaft. If there is a groove, you may be able to replace the seal and not drive it in so far as normal. That would move the contact point a bit further out, and avoid the grooved area. Doing the seal is a lot cheaper, easier, and quicker than replacing a crankshaft. Given that you need to install the connecting rod on the crankshaft, which implies taking the crankshaft into at least two pieces, using a PRESS, I would avoid that as putting it back together and having it run true requires some dial gauges and a bench where you can roll the crankshaft, and additionally, the tools to adjust... For me, not gonna happen.
tom
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Post by simon1987 on Jun 29, 2022 14:24:40 GMT -5
Take a close look at the crankshaft where the lip of the seal rides on the metal of the crankshaft. If there is a groove, you may be able to replace the seal and not drive it in so far as normal. That would move the contact point a bit further out, and avoid the grooved area. Doing the seal is a lot cheaper, easier, and quicker than replacing a crankshaft. Given that you need to install the connecting rod on the crankshaft, which implies taking the crankshaft into at least two pieces, using a PRESS, I would avoid that as putting it back together and having it run true requires some dial gauges and a bench where you can roll the crankshaft, and additionally, the tools to adjust... For me, not gonna happen. tom [b I think crancsaft is gone that zhing conecting the piston and crancsaft moves up and donw ,left and right. I want to lear it I will watch all the videos on youtube if I can't do it I will take it to garrage someone to do it for me. Here all parts are cheap cranksaft are from 30$ cinese and kymco crancsaft good quality is 70$. I will try to put 64cc BBK or maybe 80cc depend what crancshaft I get. |
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Post by GrumpyUnk on Jun 30, 2022 9:08:16 GMT -5
If the connecting rod(connects piston to crankshaft) is loose on the big end, (crankshaft end) then either the connecting rod or crankshaft, or both, need replacement. It should not move 'up and down' on the crankshaft journal. It should be able to slide a bit side-to-side. If you can 'rattle' the connecting rod on the crankshaft journal, then it is likely the bearings are worn or damaged.
In that case, complete replacement of both would be in order. The 63cc kits are a good bit of increase over a 49cc, and the 72cc are even better as far as uphill pulling power and acceleration. They do put more strain on the connecting rod, but should have a decent life if the lube is maintained in the crankcase. Keep the oil full and changed regularly, and it should last.
There are some YT videos on crankshaft replacement(I think in India) and how they must be adjusted and aligned to get them to run true. A press is absolutely necessary, along with a rest fitted with bearings to allow crankshaft rotation for trueing and adjustment. If you can get one pre-assembled with connecting rod, you can do an R&R without need for machine shop work.
tom
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Post by simon1987 on Jun 30, 2022 12:49:06 GMT -5
If the connecting rod(connects piston to crankshaft) is loose on the big end, (crankshaft end) then either the connecting rod or crankshaft, or both, need replacement. It should not move 'up and down' on the crankshaft journal. It should be able to slide a bit side-to-side. If you can 'rattle' the connecting rod on the crankshaft journal, then it is likely the bearings are worn or damaged. In that case, complete replacement of both would be in order. The 63cc kits are a good bit of increase over a 49cc, and the 72cc are even better as far as uphill pulling power and acceleration. They do put more strain on the connecting rod, but should have a decent life if the lube is maintained in the crankcase. Keep the oil full and changed regularly, and it should last. There are some YT videos on crankshaft replacement(I think in India) and how they must be adjusted and aligned to get them to run true. A press is absolutely necessary, along with a rest fitted with bearings to allow crankshaft rotation for trueing and adjustment. If you can get one pre-assembled with connecting rod, you can do an R&R without need for machine shop work. tom On these crancshafts I think bearings are integrated there are two berings that ccan't be replaced. I dont know how to post pictures here but I think those are like plug and play, dont know yet I need to get rapidciger for removing a magnet. Dont know if its ok to put some links from other websites on the forum. Thank you Tom for helping me. |
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Post by GrumpyUnk on Jul 2, 2022 7:54:08 GMT -5
The crankshafts are 'built-up' in that they are not one piece like non-cycle crankshafts. To replace means to take them out, by splitting the case, and then install new. New will likely need a connecting rod as the most common failure point is the connecting rod big-end bearing. Pressing apart, installing new, and then pressing together require a big hammer or a press. Once aligned and pressed, small adjustments to the parts must be made to get the PTO and flywheel ends to run true. You can observe it being done, as I noted, on YT videos. The one I remember was done in India or Pakistan. The whole procedure was demonstrated. There is a fellow in Britain that also has shown the adjustment to fix runout problems. I KNOW I could not do it.
You cannot replace the connecting rod big-end bearing without splitting the crankshaft. The bearing is not a 'plain bearing' like auto/truck engines use. It is a roller bearing with multiple small rollers that are retained by the connecting rod itself, which does NOT come apart.
I do not understand reference to magnets.
tom
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Post by simon1987 on Jul 2, 2022 16:01:26 GMT -5
Hello Tom,
Sorry for my ignorence and bad english, I watched many YT videos about replacment of crancshaft, and got impresion that I can do it. Crankshafts for GY6 at least my model have bearings in the middle of the crancshaft. When I buy that special tool(radapzigrr??) for taking of the magnet I will disasemble block of motor, than I will put crankshaft in the frizer and worm the holes of left and right side of the
engine block.I dont have to put bearings in those holes one where is variator and other where is magnet just oil seals. I will disasemble it with hamer. Maybe because I never did it, I think its that easy like on YT because I saw that they didn't had any trouble or did adjusment of crancshaft. I wanz at least to try, thx again for answers. Just dont know if you understood me i will change crankshaft will not change bearings on old broken one.
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Post by GrumpyUnk on Jul 3, 2022 10:20:18 GMT -5
Oh. No. If you take it apart, you will likely not be able to get it aligned when you put it back together. One side will be slightly rotated on the 'pin', so one side will be at TDC before the other... not a good thing. The measurements are in thousandths of an inch, and it will shake a lot if the alignment is not measured and made good.
Watch a YT and see the process, note all the attention to alignment after they press it together.
A new engine would be cheaper than machine shop labor in most cases. If you have a 139QMB or GY6. They are very interchangeable, so brand it not very important.
tom
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