KymcoForum.com
Scooters - 50cc => Agility 50 => Topic started by: reg on June 17, 2013, 08:36:53 PM
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Hi all, i bought a used agility 50 with 8k on the clock. soon realised it was way down on the performance of my two strokes ( 33mph) so fitted a 70cc big bore cylinder, new 'top-speed' variator, new belt and an 88 main jet. Top speed is still only 40mph. I have checked the valve clearances, the carb diaphragm for splits, all carb hoses and manifold, camshaft setup, auto choke, unrestricted the cdi, I cannot come up with any more ideas, guys have i missed something? i sure must have but cant see it. any suggestions will be most welcome.
reg
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mmmmmmmmmmm you for got the drive bos needs to be repalced with a flat one.
With out the new one your belt will only ride so high on the pulles.
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Sorry guys i forgot mention that the variator boss is the unrestricted smooth type. I have also checked the rear pulley as sometimes these have a raised section to act as a restrictor. The only thing left for me to suspect is the exhaust. is it possible for an internal baffle to be defective?
reg
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Do you still have the stock air box or open airfilter. if have the stock box try drilling a few holes in the front side of it. Start with 2 holes and if you need more do one at a time. make the holes about 1/2 inch round.
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Also you can cut the muffler end off .
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Mark your inner variatior with ink then take the scoot for a run. Does the belt remove all the ink? Or is there some left towards the outer edge? ( use permanent marker pen ink)
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Mark your inner variatior with ink then take the scoot for a run. Does the belt remove all the ink? Or is there some left towards the outer edge? ( use permanent marker pen ink)
+1 on that. If it doesnt take off all the marker then your belt may be too short, i could hit 45-48mph on the speedo with my A50 still at 50cc's, over 50mph downhills. Your jetting may be wrong too, do a plug chop to see if its too rich/lean.
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http://s1193.photobucket.com/albums/aa351/streido/?action=view¤t=20120526_133808.mp4 (http://s1193.photobucket.com/albums/aa351/streido/?action=view¤t=20120526_133808.mp4)
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thanks guys, i am going to try marking the variator pulley as suggested. at 40mph the engine is revving very high. i did a plug chop and found it was running too lean and hot. put a 90 jet in now and its running just about right and a lot cooler. but still only 40 mph. are belts available in longer sizes?
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I can still hit 45+ on a stock belt no probs. You can run longer belts, 736 Malossi belt worked well for me in the past, but its a kevlar and i dont like kevlar belts myself. Sounds like worn rollers or the rollers may be too light. Or the torque spring is too stiff, stock, 1000rpm or 1500rpm spring works well depending on the rest of the set up, i found a 2000 rpm spring doesnt work no matter what i tried, its just too stiff for a 4t 50cc.
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Hi all, thanks to you all for the info and help. I ground down the variator boss, drilled three holes in muffler end and removed air box, changed to 6.5g rollers and fitted 1000rpm spring. 46mph anywhere very quickly with a few mph left if its a long straight. Acceleration is loads better too. I think i could still shave a bit more off the boss, i will check later and check the plug. Got a 90 jet in there for now but with no air box i might up it some more. Shortening the boss is like fitting a gear up kit. thanks again guys.
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Do you still have the stock air box or open airfilter. if have the stock box try drilling a few holes in the front side of it. Start with 2 holes and if you need more do one at a time. make the holes about 1/2 inch round.
Dont drill holes, just remove the restriction inside it and smoothen out any sharp edges and it is then already so good that the pressure in the intake can reach above ambient at WOT, which means that there is only very little restriction in it and that it is properly tuned in length and diameter to 50cc and 6500-8000 rpm. At rpm below and above this the pressure is just ambient or insignificantly below. :)
The restriction is placed where the white sealing is on the picture and will have to be cut or drilled out. :D
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Thanks for the air box tip baddi, its now much quieter and no loss of performance. Its impossible to detect the reducer, moulded as it is from the hose itself. I had no idea it was there.
I was able to smoothly carve it out with a craft knife. Glued air hose back with silicone as you showed in your photo.
I am not happy with all the hoses and connections that seem to be part of the 'emission breather system'. is it possible just to remove them and maybe keep a small breather hose to feed crankcase fumes into the air box?
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Hi all, thanks to you all for the info and help. I ground down the variator boss, drilled three holes in muffler end and removed air box, changed to 6.5g rollers and fitted 1000rpm spring. 46mph anywhere very quickly with a few mph left if its a long straight. Acceleration is loads better too. I think i could still shave a bit more off the boss, i will check later and check the plug. Got a 90 jet in there for now but with no air box i might up it some more. Shortening the boss is like fitting a gear up kit. thanks again guys.
Mark the variator again right near the outer edge, if you skim too much off though, there are two pitfalls... The outer variator will start hitting your starter bendix, and/or your kickstart spigot will not reach its mating face ( both of these faults can be remedied by fitting a washer right behind all your variator assembly )
Just shave it off 1mm at a time ;)
If you can get 53-57mph on the flat, that will be 60+ downhill
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Hi all, thanks to you all for the info and help. I ground down the variator boss, drilled three holes in muffler end and removed air box, changed to 6.5g rollers and fitted 1000rpm spring. 46mph anywhere very quickly with a few mph left if its a long straight. Acceleration is loads better too. I think i could still shave a bit more off the boss, i will check later and check the plug. Got a 90 jet in there for now but with no air box i might up it some more. Shortening the boss is like fitting a gear up kit. thanks again guys.
where did you drill holes in muffler exactly, and how big? did it make it a lot louder?
The restriction is placed where the white sealing is on the picture and will have to be cut or drilled out. :D
hey thanks for this, i like free mods, maybe its not well known, with all my searching i'm surprised i haven't seen it until now
i did not cut my hose in half, i carefully cut out the restriction with fine tip wood carving knives, then dremeled the rough edges, took a while but hose looks totally stock from the outside. just did it haven't rode it like this yet. wondering if i have to upjet now, have an 88 main jet on there (i have a 72cc bbk, stock head no other mods)
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Hi, i just drilled three 4mm holes eaqually spaced in the rear of the silencer. The engine seems to rev easier, i guess my drilled holes are compensating for a slightly choked up silencer. its not any noisier.
removing the restriction in the intake manifold didnt make any difference, maybe due to my setup. I changed to a free flow fliter but the induction roar was very loud, i changed back to standrard intake (derestricted) and drilled ten 8mm holes along the bottom of the filter box. Speed now back up to 46mph, ( 70kph ). When i duck down behind the handlebars, boy racer style, there is no speed increase at all so i suspect i could still ' raise the gearing' a little more. Only problem is that i cannot skim any more off the variator boss as after checking the belt is rising up all the way to the edge.
That elusive 4mph i need to reach the magic 50mph is there somewhere i have just got to find it !!!
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cool I will drill some holes later, also going to grind the boss a little
the intake tube mod does seem to make a difference on mine, it seems to be running way lean now, I upjetted and am going to try it out later and also need to adjust the idle mixture screw, idling got rough after the mod
as for more power i don't know yet, though the scoot topped out at 42 before the mod actually 1 mph less than before my bbk, definitely lots of potential to get out of it still.
50 mph that would be nice, but yeah I agree it seems to be all gearing, i wonder would a race cdi help? So it can rev higher?
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i suspect i could still ' raise the gearing' a little more. Only problem is that i cannot skim any more off the variator boss as after checking the belt is rising up all the way to the edge.
That elusive 4mph i need to reach the magic 50mph is there somewhere i have just got to find it !!!
Was thinking why cant you literally raise the gearing? not the variator but the final drive gears.
i found this kit:
http://www.scooterdynasty.com/gearsnarakufinaldrivefor50cc4-stroke139qmbscooters.aspx (http://www.scooterdynasty.com/gearsnarakufinaldrivefor50cc4-stroke139qmbscooters.aspx)
couldnt find too many kits like this, changing gears doesnt seem to be a common mod, i wonder why, seems the cvt could compensate for the taller gears at low speeds
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Hi, I have seen gear-up kits advertised for the a50 but they always seem out of stock everywhere i look. i am convinced a gear up kit is the way to go. Its illogical to fit larger engine components without raising the gearing to apply that extra power. I know from my two stroke piaggios that a big bore kit is usually matched with a gear up kit. My engine is around 35% up on power so a gearing raise of 17% wouldn't seem too much for the engine to pull.
I might find out what gears are used in the a125 and see if they are compatible, although i suspect they may be too high.
I did my usual 20 mile each way cross country trip yesterday, first time since shortening the variator boss. The journey was transformed, its amazing what a difference those few extra miles an hour make. as the scoot was faster i was ' busier' instead of seeming like i was sitting there stationary with the road rolling underneath me. The 1000rpm clutch spring really helps the scoot to come back up out of bends, like dropping down a gear on a manual bike.
Very pleased with a50, very pleased with this site and its helpful team of members.
cheers
reg
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Hi, found this site helpful. I know its mostly about two strokes but the variator/gearing stuff is useful
http://www.pedparts.co.uk/blog/do-i-need-a-gearup-kit-with-a-malossi-or-polini-sport-70cc-kit (http://www.pedparts.co.uk/blog/do-i-need-a-gearup-kit-with-a-malossi-or-polini-sport-70cc-kit)
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cool thanks for the read.
i am wondering now if that gear set i posted would actually help, i read somewhere else that kymco already uses a taller gear set than most scooters but cant confirm.
the naraku set promises 10% if you have a 51-15 or 52-16 set which isnt much.
I counted the teeth on the gear in the kymco service manual and got 41, couldn't count the pinion gear due to the angle.
There is a Hoca set that offers 41, 42 and 46 on the big gear, 16, 17 and 18 on the little gear. So maybe the gears are already good?
EDIT: OK, never mond the 41 was from the illustration, the picture shows 52-16 gear set stock, this means the hoca gears could offer a big improvement
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Hi, i found the naraku gear up set here: http://www.pedparts.co.uk/product/1981/secondary-gear-up-kit--gy6-4-stroke-naraku-racing (http://www.pedparts.co.uk/product/1981/secondary-gear-up-kit--gy6-4-stroke-naraku-racing)
Going to order, its only a 10% increase but that will get me to the magic 50mph ! I dont want to sacrifice reliability so i figure its a modest increase in workload for my engine ( 68cc). Same reason i havent fitted an a9 camshaft or bigger carb. Planning a long trip later this summer so need it to last.