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Post by broyager on Jan 28, 2024 1:50:05 GMT -5
Bought a couple of scoots today.. 2x for one pretty much
CV50 is a runner, needs a new voltage regulator (i am assuming) and registration.
CY50 has registration but needs a good teardown, electrics might need a good going over, along with everything else. Runs, but runs lean, with fairly extensive oily leaks, either around the oil tank or base / head gasket, and around the gearbox. Gearbox is dry sounding with a loose back wheel, at least needs a new gasket and good inspection.
My partner is keen on a scoot for her work, so the CV50 might be the one there. If i can convince my 6 year old he needs a scooter rather than a dirtbike... for when he turns 16... could hold onto the CY50. I don't think the 2nd hand market is strong in NZ, so more money spent is not necessarily going to mean a higher selling price. Haven't worked out what to do yet, could just blueprint the CY50 and sell it as a runner.
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Post by Zino on Jan 28, 2024 5:10:37 GMT -5
Nice Find
I would Rebuild one with your son throw a kit and a pipe on it .
and He will have a sleeper for a dirt bike
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Post by broyager on Feb 3, 2024 22:32:16 GMT -5
Made some progress. My main takeaway is what the fuck were Yamaha thinking holding it together with phillips head bolts...#@#!? Stripped 3 of them, I don't think they'd been off before.. cut some grooves and finished it with a flat head, and impact driver. Have a 5BM on the CV50 and 3KJ in the CY50 .   CV50  CY50  CY50 has an oil tank leak which has covered everything below... I'm going to keep them both stock and sell them on I think, replace the pistons, pin, bearing with yamaha oem ones, port the cylinders a little, open up the secondary transfers which look tiny. Raise the cylinder too, the piston doesn't get anywhere near the floor of the exhaust port. See if I can remove the head gasket and still have acceptable squish. Will get medium torque springs for both clutches for the hills round here - stock are so soft.. Crankshaft is rock solid on the CV50, no movement at all, so will leave that alone. CV50 needs, so far; belt battery regulator rollers air filter primary drive gear bearing reeds - to get rid of the metal ones jets - larger main's for modifications replace some of the oil and fuel lines remove emissions system sort rust on the tube which holds the engine mount bolt - looks nasty, bolt is pristine..
strip rust off the exhaust and paint bend exhaust bracket back, has been on it's side at some point do something with the wheels, thinking sandblast and powder coat (possibly a bit pricey) clutch, brake pads and variator look pretty good CY50 probably all of the above plus new brake pads because it's drums all round gears may all need replacing as it's currently dry, will need to have a look fuel petcock body repairs throttle cable fuel tank cap
ignition surround?? has been screw drivered at some point.... rear mudguard (currently has lights which attach to the back of the rear tray) - could replace with the light and mudguard cluster on aliexpress which looks way better. I know the 5BM would be a great candidate to keep and upgrade, but the PGO is soo much easier to work on, all the bolt lengths etc are the same pretty much, and I can get to the engine only taking one small panel off. I don't really like the shape and looks of the Ligero though, and it's about 20kg's heavier..... |
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Post by aeroxbud on Feb 4, 2024 7:45:30 GMT -5
Those engine mount tubes always look terrible. Get all the crud from the rear wheel thrown at it.
Old Phillips screws are no fun to remove.
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Post by broyager on Feb 8, 2024 1:26:37 GMT -5
Interestingly, after reading countless threads about standard belt length etc, both of these scooters have what look to be the original belts. The part numbers match up with various online part websites. I'm using;
 Both 3KJ and 5SU are 772mm long, or thereabouts. This is pretty far off the 792 which I've come to understand is the standard length. Actual model numbers are 5SU9 (5BM) (CV50) and 4CGC (3KJ) (CY50). They both have identical wear patterns on their variators, and indicate about 9mm of unused travel.. so it seems pretty safe to assume that the belts are used as a restriction, so they can be sold as a moped (50kmh max), at least in NZ. Webike in Japan is my go to for cheap shipping, and in tsimi's post in a belt thread for jogs listed; 49ccscoot.proboards.com/post/354255/threadKN企画 (KN Kikaku) gave me this list via e-mail when I was looking for a belt for my Prebug. Long case 7019-SHORT-NS 17.7mm / 750mm 7019-L-SS 17.7mm / 762mm 7019-SS 17.7mm / 757mm Short case Stock 16.8 / 793mm Kitaco 16.8mm / 796mm 7020-SS 16.8mm / 800mm 7020-M-SS 16.8mm / 803mm 7020-L-SS 16.8mm / 806mm This lines up with the local parts shop (https://scootling.co.nz/) who sell the 7020-SS as a stock but upgraded belt for CV50 and the longer 7020-L-SS belt for modified jogs (aftermarket variators and 90cc versions), with the warning that stock scooters using that belt maybe seem or go slower. They also sell a stock item  with the provided measurements of 792-16.6-30. I might go for the 7020-SS considering I'll re-use the stock variator and clutch (largely) |
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Post by Lucass2T on Feb 8, 2024 1:38:00 GMT -5
Interestingly, after reading countless threads about standard belt length etc, both of these scooters have what look to be the original belts. The part numbers match up with various online part websites. Both 3KJ and 5SU are 772mm long, or thereabouts. This is pretty far off the 792 which I've come to understand is the standard length. Actual model numbers are 5SU9 (CV50) and 4CGC (CY50). They both have identical wear patterns on their variators, and indicate about 10 - 13mm of unused travel.. so it seems pretty safe to assume that the belts are used as a restriction, so they can be sold as a moped (50kmh max), at least in NZ. Webike in Japan is my go to for cheap shipping, and in tsimi's post in a belt thread for jogs listed; 49ccscoot.proboards.com/post/354255/threadKN企画 (KN Kikaku) gave me this list via e-mail when I was looking for a belt for my Prebug. Long case 7019-SHORT-NS 17.7mm / 750mm 7019-L-SS 17.7mm / 762mm 7019-SS 17.7mm / 757mm Short case Stock 16.8 / 793mm Kitaco 16.8mm / 796mm 7020-SS 16.8mm / 800mm 7020-M-SS 16.8mm / 803mm 7020-L-SS 16.8mm / 806mm This lines up with the local parts shop (https://scootling.co.nz/) who sell the 7020-SS as a stock but upgraded belt for CV50 and the longer 7020-L-SS belt for modified jogs (aftermarket variators and 90cc versions), with the warning that stock scooters using that belt maybe seem or go slower. They also sell a stock item with the provided measurements of 792-16.6-30. I might go for the 7020-SS considering I'll re-use the stock variator and clutch (largely) This is very useful information! |
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Post by broyager on Feb 12, 2024 2:26:46 GMT -5
So a bearing had come apart inside the CY50 gearbox Does anyone know if the small gear will press off this shaft also?  I have a line on 2nd hand gears from a jog CV50, which should work fine in the CY50, except the end of this primary drive is 10mm rather than 12mm on the CV50, other end that goes into the transmission cover is loose, and there aren't many standard bearings with 12x30x9, to fit a shaft from the CV50. The casing is the limitation, with 32mm for CV50 vs 30mm for CY50. CV50 bearing is 12x32x10 CY50 bearing is 10x30x9 I could get a new shaft but the price is reasonably high, if I'm not going to be using anything else that comes with it. The problem is I don't want to change the gear ratio, it only needs to get to 60km/h, as fast as possible, and all aftermarket gear kits seem to be 'geared' toward speed. CY50 stock Main axle gear is 38 Primary drive is 48x11 Clutch axle has a 13 CV50 stock Main axle gear is 42 Primary drive is 48X13 Clutch axle has a 13 Plan is Buy the 2nd hand CV50 donor gears, and press the main drive axle gear onto the CY50 axle which is still in good shape, use the clutch axle from the CV50 also, and buy this www.aliexpress.com/item/1005004237805888.html to replace the primary drive axle (48x12) and press off and on the yamaha donor gear. If I can press the small gear off and on to the existing shaft, then I won't need to gamble with the aliexpress gear. |
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Timmer
Scoot Enthusiast
Posts: 128
Location: Mechelen, Belgium
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Post by Timmer on Feb 20, 2024 15:05:38 GMT -5
If those are the adapter gears, i don’t think they’ll seperate. I’m not 100% sure, but i’ve never seen them get seperated.
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Post by broyager on Mar 12, 2024 21:05:13 GMT -5
Slow progress, finally have the godawful skunge cleaned off the 3KJ... took a few goes, in the end the heavy duty de-greaser won all the prizes. (naphtha, ethanolamine, propane and butane). Taking the cylinder off revealed a piston in very good condition, some really sharp, and quite jagged port edges, a reasonably large boost port, quite high transfer ports.  The porting calc I use says (if I have measure everything accurately) 168, 119, with blow down of 24.5. Exhaust port is already at 68% width of bore, stock. My plan is to use a 0.8mm base gasket, raise the exhaust port roof by 2mm's, keeping the existing shape, clean up the transfer port roof edges and this should come out at 180, 122, blow down 29, looking at peak power at 8000rpm, which afaik is where the stock pipe will run out of juice. Probably polish the exhaust port, but not remove any material, it's the D shaped port. Also smooth the skirt edges of cylinder and piston. Interesting that the boost port entry in the base of the cylinder is so huge, and the path in so small over the cylinder skirt, maybe this accelerates the air/fuel flow?? The KN Planning pistons I bought seem well made, but the skirt has a dual window instead of the single. Can anyone recommend the best way to open the skirt up? They were pretty cheap ($16usd) so no great loss if they don't work out. The 3KJ piston is looking fine anyway, so could just steal the rings from the KN Planning one. Haven't checked clearance yet. Will also delete the head gasket, and use copper spray or not, as the squish is wider than 1.5mm currently. 3KJ has the wavy head, and I haven't looked but I think the 5BM will have the proper squish band. I sourced some second hand gears and kick start assembly from an Aprio locally. Main order of parts has arrived. Still need to get the rest of the bearings for both scoots, and then oil seals, rubber dust covers, o rings some nuts and bolts (screws) etc.
Hope I made the right choice with the yellow torque springs.. bit of a guesstimate there. Lots of steep hills round here though.
Have regulators for both already, and a tail light assembly for the 3KJ to replace the lights hanging off the back of the rear tray.
*https://www.aliexpress.com/item/4001119609662.html?*
Bought a really good selection of main jets from here. Only need maybe 3, but cost was the same in the end, and someone recommended them as being good ones. *https://www.aliexpress.com/item/32242718025.html?* I'm thinking of keeping the CV50 as Zino suggested, because it has a buggered exhaust, something heavy is rattling around inside, and it has the front disc brakes, do a slight restomod on the CY50. I'm going to have to reshape the nose on that one, as there is a big crack, and a little bit missing. Don't really want to repaint it.. so thinking of removing the damage, and reshape instead... Bought them both for 700NZD or 430USD, so I figure I can sell one, and have a refurbished, fully unrestricted, road legal runner for free.. minus all the time spent lol... CV50 was originally sold, restricted, with a 2.5kw (3.3hp) power figure I think. The engine should be able to do 7hp afaik with all the inbuilt restrictions removed so at around 75kg it is probably going to be fast enough for these parts. Power to weight *should* be pretty close to the PGO with 70cc. |
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Post by broyager on Mar 13, 2024 0:02:53 GMT -5
Welll, I don't understand, the stock piston also has a dual window... Does this mean the mixture under the piston has to wait longer to cut through to the boost port?? Seems like it doesn't matter or Yamaha designers chose strength of both skirts over any sort of benefit.. Are those windows just for cooling the bore?  |
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Post by broyager on May 2, 2024 2:33:22 GMT -5
Making slow but sure progress. Rest of the parts arrived, seals, cables, nuts and bolts, indicator lenses, mirrors etc.. Had a good run with some epoxy paint, paints straight onto the clean metal, I will probably do one more coat   Took the 2x CVT cases into the local shop to get the bearings out, apprently they broke 2x tools trying to remove them... quite worried about the bill for the time... I should've just drilled a hole and bashed them out. The CV50 will have the plastic cover over it anyway, and the other I want to paint, so could JB weld over the hole, but apparently they got them out in the end.. Clean cases ready for new bearings and seals
One cylinder is ported and ready to go back on.
Doing the CY50 first.
Next hurdle is replacing the suspensions boots.... the one that holds the brake drum, looks like it needs to be taken out, I don't think the boot will pass over that mount...
Pulled the tree off to clean up the steering bearings, but I'm not sure if I needed to. It has sat outside for a long time at some point though so a fair bit of rust around and general degradation.
Have the gas tank sitting with vinegar in it currently, will wash that out on the weekend.
Should be plain sailing after that, except for paint... and I need to do some body work to the leg shield, which I'm not looking forward to.
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with the provided measurements of 792-16.6-30.
