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Post by korn858 on Mar 17, 2013 22:55:17 GMT -5
Thank you for all your help. I really appreciate it! I think I'm going to go for the 59mm BBK. I'm guessing I'll need to rejet the carb? Anything else? I'll be taking it apart soon, and I'll get a better idea of what's going on.
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Post by millsc on Mar 17, 2013 22:59:22 GMT -5
rejet and don't overtighten anything, put one of the circlips in the piston before you put it on the crankshaft rod, keep organized put the bolts with the parts you took off, take your time and line the cam up right. make sure your battery is charged lastly take your time if you get frustrated take a break.
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Post by skuttadawg on Mar 17, 2013 23:00:36 GMT -5
Have you tried a compression test ? Have you taken it apart already or guessing the rings or piston is fried ? The plug looked dark to instead of whiteish like when its too lean . Did you check the oil level and color . If your going to install a new piston kit I would get a matching head too . Why buy one shoe instead of a pair ? Check out Walters website as he only sells GY6 parts and has some high compression ( more HP) kits as well as stroker cranks and cam here www.scooterelements.ecrater.com/ . Now those 6xmm BBKs would require the case to be bored at a machine shop or buy the tool around 150 plus shipping I bought the Haynes Chinese Scooter repair manual as it is a great source of data , how to with pictures and a must have for wrenchers . I always buy a Haynes or Chilton repair manual for all of my cars and trucks since it has exploded diagrams and wiring schematics which is very good to have handy |
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Post by teddy554 on Mar 17, 2013 23:03:39 GMT -5
 the whole top of the spark plug was melt off
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Post by skuttadawg on Mar 17, 2013 23:49:37 GMT -5
Really I have to relook as my eyes are bad and the lighting in the den is dim . I had put on a Uni vent cover which is smaller than the big red airfilter and upjetted to a  MJ and it ran perfect . Well later I put on the red normal filter and only went around the block with the 90MJ just to test it out . Dang it soft seized on me and it melted the prong off of my NGK iridium and I have never had that happen before . I only rode maybe 1/4 of a mile and had to push it home . I was using a BRP7HIX and went to the 8 after Brent suggested it to me as that is what hes uses in his 2Ts . I think the GY6 is CR7 something so maybe you can try and 8 in that series . I had a Honda CR125 that I hot rodded and thought hmm a hotter plug may yield more power . Well maybe so in the winter up north but I could feel the increased heat coming from the engine and it did not run as good as before after riding a short time . I premixxed 32 to 1 and had very large jets as it would ether bog or scream since it was set up for racing instead of trail riding . Stock CDI ? Some of the aftermarket CDIs do have advanced timing which can burn stuff up if too far advanced . I would drain the oil and look for tiny ring or piston dust and inspect the oil screen for junk . Have you messed with the needle clip ? Did you turn in the air/fuel screw ATW in and back it out 2.5 turns ? |
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Post by rockynv on Mar 18, 2013 4:30:57 GMT -5
the whole top of the spark plug was melt off Melted off or busted off? Don't see heat there just carbon. Did you have a bunch of smoke come out the exhaust when it happened? You may had had a valve drop and take out the plug and top of the piston. You won't really know until you take the head off and give it a good inspection. |
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Post by millsc on Mar 18, 2013 8:08:06 GMT -5
yeah tear it down before you buy any parts  |
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Post by korn858 on Mar 18, 2013 11:58:26 GMT -5
Thank you all for the help. The top of the plug seems to have been push down "crushed." No smoke when it went kaput. The way I adjusted the A/F was to set the idle at 2,000 rpm. Back out the Air screw till I reached max idle, it went to about 2300/2400 RPM, then turned clockwise a 1/4 turn, and then set the idle to 1500 RPM with the fuel/idle adjust screw.
With the 59mm BBK, what size jet would provide enough fuel. And on a side note, my scooter is completely stock. ie: Air filter, muffler, cdi, and so on.
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Post by urbanmadness on Mar 18, 2013 12:16:43 GMT -5
My first guess would be you dropped a valve. I just had one come into the shop that did that. new head, piston and barrel, rings... split the case to clean out all the piston shrapnal. It had a 1" hole in the piston. The good news is it's all back and running and the customer is very happy.... If you didn't put a hole in the piston, it will be really stright forward. Make sure you don't over tighten the head/case studs... they only need 26ft lbs.... and if you snap one... then things get ugly quick. Take your time, note how it comes apart and take pictures if needed. When removing connectors and lines, pieces of masking tape and a sharpie come in handy. Just number them... when putting it back together, or before putting it back together... watch a few youtube vids. Things like the timing tensioner are easy explained via video but harder to explain in a forum. |
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Post by korn858 on Mar 18, 2013 13:33:53 GMT -5
Well, I decided to get some help with this en devour. I know a guy who loves taking apart and fixing small engines. I'll get all the plastics off, and let him do the tear down and rebuild. I'll show him some of the youtube videos, and pass along all the help I've received here. I'll take pics, and keep all updated on the trials and tribulations. So far, my parts list includes: 1. 59mm BBK. 99.99 2. Matching head $74.99 3. Jet for the carb. Still not sure what size I need. 4. One spark plug. |
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Post by devo344a on Mar 18, 2013 16:26:37 GMT -5
I just bought the 50mm----100cc big bore kit from scrappy i ordered the stage3 performance pak, 20mm carb --A9 camshaft bigbore head it ran great but i used the stock head and it ran the compression up to high and snapped the timing chain and when ordering the heads there is a short and long valves if you order the right one your ok i didnt know about it thats why i put on the stock head while waiting for the short rocker assy
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Post by rockynv on Mar 18, 2013 22:32:20 GMT -5
Just be carefull with the two bolts outside the riming chain area of the head. These are east to overtighten leading to a hairline crack in the thin part of the head casting where the timing chain rides that will seep oil which will then be blow around in the cooling shroud. Some of the bargain heads can be very brittle in this area and will fracture immediately or after only a few warmup and cooling cycles if you snug them up too much. The fracture will not always be visible to the eye and may only chow by doing a dye test or for more immediate results taking off the cooling shroud, connecting an air line to the vent on the valve cover, pressurize the block to about 2 or 3 psi and then spraying soapy water (cheap dish soap works just fine) on the engine and observing where the air bubble form.
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Freshman Rider
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Post by korn858 on Mar 19, 2013 11:12:55 GMT -5
Thank you all again for all the useful information. After doing a little research I decided to go with the stock set up from scrappy's. The 59mm upgrade is not worth the 10cc/5% increase. I understand to really maximize the upgrade I would have to change the muffler, and go to a uni-air filter, and then spend a lot of time tuning. For my use, running short errands, I decided against it.
Once I get it going again, I'm thinking about selling it, and getting a Kimco, perhaps a 200cc.
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MJ and it ran perfect . Well later I put on the red normal filter and only went around the block with the 90MJ just to test it out . Dang it soft seized on me and it melted the prong off of my NGK iridium and I have never had that happen before . I only rode maybe 1/4 of a mile and had to push it home . I was using a BRP7HIX and went to the 8 after Brent suggested it to me as that is what hes uses in his 2Ts . I think the GY6 is CR7 something so maybe you can try and 8 in that series . I had a Honda CR125 that I hot rodded and thought hmm a hotter plug may yield more power . Well maybe so in the winter up north but I could feel the increased heat coming from the engine and it did not run as good as before after riding a short time . I premixxed 32 to 1 and had very large jets as it would ether bog or scream since it was set up for racing instead of trail riding .