KymcoForum.com
Scooters - 50cc => zx50 => Topic started by: sidthesloth on April 05, 2010, 05:46:53 AM
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G'Day All, I have a Kymco ZX50, it was having starting problems pretty much since we bought it in January
of 2009. It was built in September of 2007, so it was still quite new. When my wife had finished with it I was
using it but it was quite slow. While looking on the interweb I found this forum and was really inspired by the
help, advice and assistance from the people on here. It was starting to look like the engine was getting tired
so a new cylinder kit was looking like a possible solution. Well, cylinder kits, there are a lot more out there
than I would have imagined. Most people on this forum swear by brands such as malossi and polini but as I
don't have a lot of money to spend I was looking for more affordable options. I found a cylinder kit on
ebaymotors.com for $135 with free shipping. I bought one. When I installed it on to the scooter it over heated
within about 10 minutes seizing the piston. I added 100ml. two stroke oil to the fuel tank to compensate
for the larger cylinder. It still seized. I tried to drill out the jet in the original carb but with the stock airbox was
no good, it would not run properly. By this time I was quite concerned about destroying the cylinder so I
waited until the new exhaust and 24mm OKO carb arrived. After fitting these the improvement was massive.
Still running lean, the OKO carb had a #107 main jet. Finding out that these carbs use a Keihin type jet I went
to my local bike shop and found that they have a fair range of them, things were starting to look up. I tried a
#120 main jet but still not quite right, after trying 125 and a 130 I jumped to a 140, too far, so went back to a
#135 but that was a bit too big, so tried a 132 which was pretty close. I am currently using the #130 with the
carb needle at the second from lowest setting. Though not perfect, the scoot is running pretty damn good now.
I have also changed the pilot jet from a 45 to a 48 (the next one up at the local shop).
I have also replaced the front variator with a race variator from scooter assassins, less than $40 delivered
the change is just incredible, smoother power delivery and better acceleration, now the speedo needle goes off
the dial and half way through the fuel gauge. Before I started all this the scooter would do between 70~75 kmh
as indicated on the speedo, after adding the bridge to the C.D.I to cancel the rev limiter it would go to just on
80kmh, but the poor thing would be screaming. With the larger cylinder it revs out freely and doesn't sound like
it is overdoing it.
None of this would be possible for me without the help and encouragement I received from the people on this
forum, in particular zombie and Shaka, to these people I am truly grateful.
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Here are the links to the parts I used, please note my lack of experience, you may want to look for better but this will do for me.
Honda Dio 82cc Cylinder Kit:
http://cgi.ebay.com/ebaymotors/Honda-DIO-82cc-90cc-Big-Bore-50mm-cylinder-kit_W0QQitemZ230456317161QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item35a84454e9]
[url]http://cgi.ebay.com/ebaymotors/Honda-DIO-82cc-90cc-Big-Bore-50mm-cylinder-kit_W0QQitemZ230456317161QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item35a84454e9 (http://[url)[/url]
Honda Dio Racing Intake and 24mm Carb Kit:
http://cgi.ebay.com/ebaymotors/Honda-DIO-Racing-Intake-24mm-Power-Carburetor-Kit_W0QQitemZ330419082876QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item4cee83167c]
[url]http://cgi.ebay.com/ebaymotors/Honda-DIO-Racing-Intake-24mm-Power-Carburetor-Kit_W0QQitemZ330419082876QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item4cee83167c (http://[url)[/url]
Honda Dio Exhaust
http://cgi.ebay.com/ebaymotors/Honda-Dio-exhaust-pipe-for-90cc-Drag-race_W0QQitemZ330415509541QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item4cee4c9025
(http://cgi.ebay.com/ebaymotors/Honda-Dio-exhaust-pipe-for-90cc-Drag-race_W0QQitemZ330415509541QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item4cee4c9025)
Race Variator
http://cgi.ebay.com/ebaymotors/RACE-VARIATOR-for-KYMCO-ZX50-ZX-Fever-50-Fever-II-50_W0QQitemZ370358745354QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item563b19f90a
(http://cgi.ebay.com/ebaymotors/RACE-VARIATOR-for-KYMCO-ZX50-ZX-Fever-50-Fever-II-50_W0QQitemZ370358745354QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item563b19f90a)
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Nice write-up! I'm really exited about your scoot! It has been a pleasure offering advice and even better for the positive results! Thanks for the props! It has been interesting to watch the same scoot with different mods come to life! Ride On!
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And ride on we shall :)
Thank you all very much. There will be more to go yet.
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great read ! especially the bit about the needle setting and jetting sizes , as i've just installed the cyl kit and am awaiting the new carb kit , 'cause the thirsty bugger just out drank the standard carb on the first run. looks like a quarter throttle run to work this week haha. So far , ive got the zx50 aka bug vibe , with the 82cc kit , race variator , cant remember the weight sizes, race clutch and springs and the limiter bypass (on a switch so the mrs doesnt over do it ) haha. the power and acceleration so far is GREAT! never thought i'd be wheelstanding the zx yewwwww. So yeah just gotta get this starvation business sorted and we're away !
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Be careful if you are running the stock carb and exhaust. I very nearly destroyed my setup with not enough fuel/oil and not getting the gas out fast enough.
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hey if you want the best of best bore kit get the polini corsa 72cc kit along with so 6.9 or 7.1 gear you will be doing over 75mph.
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Yeah, I would like to change the final gearing, but still have some other bits to do first. 75mph, a bit scary on one of these. could be fun to try though. :-)
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haha well i got the kit fitted , got the new oko carb and well, i should have waited till i got the jetting sorted 'cause she had a nice little lean out at about 100km/hr ...piston and rings are fried but the bore will be fine after a quick hone. so now i'm waiting on my new piston to arrive ...unless any of you would happen to know the appropriate wiesco or vertex piston replacement part no. ?
gotta love forums , thanks for all the help !
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Good to hear from another ZX50 rider! Too bad about the piston though! I'm not sure of any cross reference pistons. What kit are you using? Is it the same as Sid's? I think we can use all the info we can around here about kitting these ZX's!
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I wish I did Know of a replacement part #. They would be 1/2 the price.
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WOW ! ! ! and I'm just learning how to change a freaking TIRE! WELL... when the time comes when I need a new top end I'll look into a larger one.
Assuming a larger rod would come with the top end, Are you guys upgrading the lower end also?
How fast are you guys clocking on a GPS? Mine does about 42mph with the basic mods. (removed boss from the variator & cut the green wire)
Thats just fine with me for now. If anything I'll take more power. 50mph is fast enough on a 12" tire!
NEVERMIND i FDOUND THE HOW FAST SHOULD MY SCOOT GO THREAD !
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WOW ! ! ! and I'm just learning how to change a freaking TIRE! WELL... when the time comes when I need a new top end I'll look into a larger one.
Assuming a larger rod would come with the top end, Are you guys upgrading the lower end also?
How fast are you guys clocking on a GPS? Mine does about 42mph with the basic mods. (removed boss from the variator & cut the green wire)
Thats just fine with me for now. If anything I'll take more power. 50mph is fast enough on a 12" tire!
NEVERMIND i FDOUND THE HOW FAST SHOULD MY SCOOT GO THREAD !
...these guys got their super fevers screamin'....
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The Kymco crank/con rod is as strong as ANYTHING you can get after-market. There is no need to swap those parts out unless you are planning a single ring 13'000 rpm full race kit. Then I would have to bow down, and say the super fever is not the best choice for that. It's not the engine that lacks but rather the frame. Too much flex for a 70 mph street scoot. The earliest zx/sup... had a 10mm wrist pin set up, and if you have one of those then I would suggest simply replacing the crank w/ am 04 or newer
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mine is a 2005 so i guess the bottom end is OK.
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No Doubt! Check the bearings, as they take all the abuse. If they're good-you're good
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hey sid, hows that variator??.i looked at them on ebay. is it bigger than oem?, worth a crap?, can u tell any difference in preformance or even looks???.. seems like to good of a price!!!!!!! what all came in package??
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G'day batman, the variator is the same diameter but the back is not recessed as much as the stock one so I had to grind a bit off the crankcase. I know it sounds bad but it isnt, only took a touch. I think it is better. see my thread different size variator in the tech/how to section.
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...need me a bigger variator,,,and some of them sliding things too...
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G'day batman, the variatop is the same diameter but the back is not recessed as much as the stock one so I had to grind a bit off the crankcase. I know it sounds bad but it isnt, only took a touch. I think it is better. see my thread different size variator in the tech/how to section.
...how does deeper help...
..different ramp angle??
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Ive been thinking about the Malossi Over-range, But I would prefer getting a stiffener for the frame first. It's not much fun feeling the bars move an inch or more (forward/back) on uneven roads at 60 mph. Makes me think it has to have a limit on how much it can handle. http://49ccscoot.com/brace.html (http://49ccscoot.com/brace.html)
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...hey, we could make that stiffner...
..does the over-range have a bigger o.d.?
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Yeah! I'm not sure on the specs., but MOST cases have to be trimmed/ground down for clearance. The end result is the exact same take off w/ a taller ratio for the top end. It is one of the Keys to a 70mph scoot. Most scoots cannot get there w/ out one! Your shop does aluminum fab right? That would be a great choice for material. (the hard marine grade stuff) You may be able to put a few out there thru the forum. The toughest one is ALWAYS the first one. After that I imagine about an hour to fab.
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...we do aluminum die casting...for the automotive industry...
..but i can get any kind of materials...
...i think i could dial in an o/r variator with the right weights....
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I like that cross brace! It's got me thinking about working on my Vento. I wish mine looked as nice as that one! Mine is a POS! The weather is getting nice out, I might have to start back on that project! ;)
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Yeah slinger. I would look at the Malossi or the Polinni first. I will try to look up a few, and see what if any mods are needed. (longer belt right off the bat) I still have that nc/50 chopper sitting in the shop ALMOST finished for the past few months so don't feel bad shaka. If I put my self to it I may have 20 or so hours to finish it. (including paint)
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...well, i've got to buy a new variator anyway (damned 3-roller excursion)
..so I might as well go for it...
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G’day all, has been a while since my last update. After much fiddling with this cylinder kit I have finished up cutting a spacer to raise the cylinder to line up the bottom of the transfer ports with the top of the piston @ b.d.c. Having done that I had about 2.7mm machined off the top of the cylinder to keep it level with the piston @ t.d.c. The way it is currently, it is running ok though there is some bog over ¾ throttle but I think that will be sorted with correct jetting, (I hope). I am currently running a 130 jet so will try somewhere around 125 or 128.
I still feel there is a lot more to be had from this setup but I have yet to find out how. So, will continue playing with jetting and plug indexing, maybe even trying with more height adjusting of the cylinder. :)
I will try to put up two pics of the port maps, one with the cylinder as new and the other as the cylinder is now, they are not too good but you will get the idea. In the first pic the line through the ports approx. 1/3rd. the way up is the top of the piston at bottom dead centre, in the second pic. it is at the bottom of the ports.
It may take a couple of posts to get them up so please bear with me.
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here is the pic of the port map as it is now.
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Amazing differance. I can't figure how they could sell it in the state it was.
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well, it has been a good learning curve for me. I certainly don't want to get agro over it. With a lot of help from you blokes it is up and going strong, with more yet to be released through the C.V.T. hopefully.
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...dude...cvt tuning can work wonders for your scoot....
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Looks much better Sid!!! You've come a long way in your port mapping skills as well! ;) I think it's pretty cool how your most recent map looks just like what the software program was showing! That software is sooo cool!!!
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..software??
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Once again Slinger your missing out on all the 2T fun! StepVino on SI.net created a 2T porting program I used to help Sid figure how to optimize his port timings. That's how we figured out how much to raise the cylinder and to shave off the top.
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M-O-O-N ~~~~~~~~~~~~ that spells moon ~~~~~~ Try to keep up Bro~
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...lol...it's what i do...
:D
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Fat Kid Falls of Scooter! (http://www.youtube.com/watch?v=FnWM3EmxeL4&feature=related#lq-lq2-hq)