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Post by stevec on May 15, 2014 12:27:02 GMT -5
i traded my taotao GT 5 for this Jonway, they are both 2013 and the Jonway had 38 miles on it. the guy likes the taotao because it has the 52mm bore and other upgrades done. i looked all over the internet and can not find another YY50QT-4 Jonway zuma clone, the only model they have is the 150cc that looks like mine which is odd, i must have a custom order or something. my original plan was to sell the taotao and buy a bintelli sprint from superior scooter but no one wanted the taotao even though it runs great, i was lucky to find someone that wanted to trade.
ok so here is my issue. the Jonway bogs at full throttle while riding but not on the center stand, i tried adjusting the mixture and it did nothing, it has a Keihin carb from superior with the stock Jonway jets in it and it is a great carb in my opinion. originally i had to ride with the gas cap open because the emission system was junk, even though i only put in a half tank it kept pulling gas through it, i vented the tank and now it runs with cap closed. i just removed the PAIR system which all it seemed to do was blow hot exhaust into the air intake, i had the pipe welded where the hole was for the PAIR. i checked the valves and they are both set at the right settings. it has an NGK spark plug already in it that came stock and it is caramel color like it should be. if i back off a little on the throttle it picks up speed and the RPMs go up like normal.
i am leaving it a stock 50cc, it goes plenty fast enough to get me around, will be even better once i get the bogging issue resolved. i'm sorry for long post, i try to mention all of the details, any help is greatly appreciated.
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Post by stevec on May 15, 2014 20:50:11 GMT -5
I'm wondering if the stock main jet is too small, all i have for an extra is a #90 and that is probably too big. it was bogging with the original carb, the original was not as good as the current keihein. i've pretty much gone through everything and everything looks fine. if i let off the throttle and hit it again it speeds up then bogs again.
what is a good main jet size for a stock 50cc? i don't know if it is a secret 63 or not,it is the 139QMB not the 1P39QMB.
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Post by scooterpimp on May 16, 2014 6:16:55 GMT -5
Is it possible that carb may be gummed /dirty? The new gas goes bad quickly , try running fresh tank of gas with fuel cleaner in it first. Use fuel stabilizer too. Not sure if available in your area , but lucas fuel cleaner in small plastic bottle works great for such things. Just did this to the 2 scoots I recently aquired & made a big difference after riding them a while. Also make sure cap is venting/ clear. Then upjet main if still bogging
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Post by 90GTVert on May 16, 2014 9:44:57 GMT -5
Could be the main jet. Proper size will vary sometimes from carb to carb and definitely with big elevation and temperature swings. 75-85 is the popular range for a stock setup. You can get 10 jets from PFS for about $15 or buy individuals there or from JetsRUs, ScrappyDog, or eBay sellers.
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Post by stevec on May 16, 2014 11:52:28 GMT -5
thank you for the replies.
the keihein carb is brand new, the original carb stopped working at 40 miles and i had tried to clean it out but scooter still wouldn't run. i had a #90 jet that i had bought from scrappy dog scooters and i put it in to see what would happen, wasn't sure if it would be too big. i started it and let it get warm and then adjusted the fuel mixture and so far no bogging, it seems to have more power than it did before, i also added a fuel filter, the scooter came without one. Jonway makes a good scooter, the fit and finish on this one is very solid and it has stainless steel bolts, the only thing i am doing above stock is installing a kevlar belt so i don't have to worry about getting stuck. the tank has a vent line that goes part way across the high part of the frame, i have it placed where it won't pick up dirt. the canister was a joke, i had to ride with the gas cap open when it was on there and the PAIR system did nothing so i had the pipe welded over the hole from it and removed the whole thing. i'm fairly certain i have a secret 63, the #90 jet didn't work on my taotao that had a 49cc piston, it burned very rich and flooded out.
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Post by stevec on May 18, 2014 20:13:41 GMT -5
100 miles and the #90 jet is working beautifully, i checked the plug and it is the right color. getting decent fuel mileage and engine purrs, no stutters or erratic idle. this scooter came stock with a bando belt, NGK plug and stainless steel bolts and hardware. the best chinese scooter i have owned, i know some people don't like jonway but i love this one. just wish they made more than one YY50QT-4, seems weird not even the jonway dealer can find one.
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Post by 90GTVert on May 19, 2014 7:13:21 GMT -5
Glad it worked. Thanks for the updates.
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Post by stevec on May 29, 2014 19:51:59 GMT -5
Considering putting in a 72cc upgrade, the crank can handle it and i won't have to change the head, air box or exhaust, the keihin carb already has the right jets installed for it. i don't want to buy a mainland china junk kit, scrappy dog scooters has it for $70 but does not mention where it is made. what is the best quality kit? i need one that will last, i don't want to have to keep changing parts.
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Post by hawaiigy6moder on May 30, 2014 3:44:37 GMT -5
If you got the coin the NCY kits are pretty good and are made in Taiwan, I run the 100cc ncy bore and head and I'm enjoying it completely. Growsun is a decent China bore kit too, honestly China makes decent bores but crap heads,.... You can use the stock 50cc head with the 72cc kit
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Post by stevec on May 30, 2014 5:34:52 GMT -5
I've used growsun on prior builds and you are right about the heads, they are not very good at all, you can bend a valve just by farting on the seat wit the engine off.
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Post by 90GTVert on May 30, 2014 6:58:51 GMT -5
Not sure what's the best, but Hoca, NCY, and Naraku should all be good Taiwan made stuff.
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Post by stevec on Jun 1, 2014 19:11:10 GMT -5
i have the 63cc in it now that came stock and it runs excellent, i am not sure it is worth the effort to go just to 72cc and i don't really want to tear it down to replace the crank so i can run a 50mm piston. i can go a decent speed and it is only slow up steeper hills, i am thinking if it ain't broke don't fix it. i am wondering if a performance CDI and coil would give it a little extra boost, i don't want to waste money if it is not a noticeable change.
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Post by scooterpimp on Jun 1, 2014 19:45:39 GMT -5
i can go a decent speed and it is only slow up steeper hills, i am thinking if it ain't broke don't fix it. i am wondering if a performance CDI and coil would give it a little extra boost, i don't want to waste money if it is not a noticeable change. If It aint broke dont fix It. Words to live by!!!
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Post by 90GTVert on Jun 2, 2014 12:20:33 GMT -5
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Post by stevec on Jun 2, 2014 19:59:55 GMT -5
TY for the video, i saw that one earlier on youtube, i watched the progress of project taotao. i don't think it is worth the expense for a second less time to reach 30mph, if it was more drastic it would be worth it. i have 160 miles to go before engine is broken in, i am at 440 miles right now and it runs strong, i did oil change at 100 miles and 300 miles, will do another one at 600 with 10W40 scooter oil and i will check valve lash. it takes a while to start going on steep hills, that is where i thought having a better CDI would help out, as far as overall speed i can cruise at 40mph verified by GPS, speedometer is off by a few mph.
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