Kymco SC10AS 100cc and beyond:

[oldgeek]

I went on a ride yesterday and collected one of these, just a warning. The officer seemed very interested in the scoot, asked some questions like how fast, how many gears, so no clutch? LOL! He was cool about it, because scooters are limited to 35 mph here, he could have made big trouble for me. He stopped me on the Blvd long after it slows to 25 mph from 35 mph. He said something about 42 in a 35 I think, but actually had stopped me when I was already deep in the 25 mph zone so.......

Got back to the shop and took a peek at my new belt. oldskool said "it has plenty of life left!" I checked my notes, 77 miles on this belt I need something that counts each time the front wheel comes up, start measuring belt wear by number of wheelies. Probably +250 on this belt. Cost per wheelie, belt is $35 divide by 250 wheelies = 14 cents per wheelie. Completely worth it! Thought it is strange to come apart like this, on the outside. Also noticed the side of the belt that faces the CVT cover looks abused but the other side looks great. What could be causing this? Anyone?

[90GTVert]

Nice job on the speed award.

Contact with something for the belt issue? I wouldn't think a belt should delaminate without some form of contact. At least look over what's left of the outside and see if there are any signs or if you see anything in the CVT area. Another thought is maybe there was something wrong with that belt from the start? Try another belt and see if it happens again if you though that was the case. Some people have reported belts flipping over in the CVT. I guess if it started to flip, it could catch and strip/grind the belt... but I'd think you'd notice an "event" if that sort of thing was happening.

[oldgeek]

Pretty much rain forecast for today so I figured it would be a good day to put a new belt on the scoot. I did not find any obvious contact points in the CVT anywhere so I finished up and started the scoot while it was on the lift. With the scoot running I looked through the large openings in the CVT cover and noticed the belt flopping up and down quite a bit at idle. Upon closer inspection I noticed the belt was riding down in the rear pulley about an 1/8" or so. I shut it off and the belt was a bit slack in the middle. I took the CVT back apart and rechecked the rear pulley, everything was good, but I did not want the belt down in the pulley already just at idle so I changed the contra spring from a Malossi yellow to a Malossi red. More testing at idle found the belt was not nearly as floppy and now riding up in the rear pulley better too.

I also found a broken exhaust stud, this makes the third or fourth time one has broken. The last time a stud broke I found some OEM Honda studs on treatland and ordered them to have on hand for the next time. Took me about 2 hours trying to get a gasket and the pipe to line up, I almost screwed a bolt hole up in the cylinder flange because I did not realize a stud was started crooked. The pipe is such a PITA on this thing, It is so close to fitting but sooo far from just right that it is hell to mess with.

With only a new belt and a stiffer contra spring I took the scoot out on the wet side road at the warehouse. Top speed was back up to 60 MPH and launches were not as strong but seemed to be more controlled. It will still pull the front wheel up but it is not nearly as abrupt when it does, it also does not wheelie from a roll like it used to with a new belt. You would think it would require heavier weights in the variator to counteract the stiffer contra spring, but I feel like lighter weights may be needed now. It feels like RPMs at launch are lower with the stiffer contra spring. I think with the softer spring the motor was spinning up faster and snatching the belt into the rear pulley, giving me that hard pull and helping to destroy the belt.

I also have a theory as to why the 100cc+ Minas and my motor have such a short belt life compared to the Piaggio's. It may come down to the size of the rear pulley. I was recently looking at a Piaggio rear pulley and noticed how much larger it was compared to a Mina rear pulley and a Kymco rear pulley. The larger diameter of the Piaggio rear pulleys allow it to start off in a much lower gear ratio, which should help with belt life, particularly when it comes to the higher output and the larger cc motors.

[oldgeek]

After taking a ride yesterday I decided the stiff red contra spring really did not make things better just different so I went over my notes from previous setups and decided to change the stiff red contra spring to the soft white spring that I originally started with. I also lightened up the weights to 7g. After a ride down the strip with the Harleys (Spring rally for them this week) I believe the weights are a little light. Temps seem to want to run around 135 now, 10 degrees higher in general. I guess this is the first time I have ridden the 120cc in warmer weather. Maybe I need to rig up a fan or 2 for the radiators

[oldgeek]

I have been playing with the harley riders the last couple days, I think they are saying this is the biggest turnout ever. This scoot normally vibrates quite a bit but it seems to vibrate more than usual the last couple days. I put it on the lift to take a look, the crank and CVT all look ok even the new belt is looking pretty good. The motor mounts are shot, I knew that but kinda ignored it. The gear oil looked horrible when I drained it, not many miles on it either.




I pulled the motor mounts out of the scoot without removing the motor from the scoot, it was rather easy to my suprise. I think I mentioned that I ordered some Prothane suspension bushings a while back, hoping to modify them to use in the motor mounts. When they came in I modded one of them using the lathe to see if it would fit a spare set of cases I had. I think it will work good but I only modded 1 of them and the motor controller for the lathe has since fried so I am stuck with only one.



I think I have 1 stock mount somewhere that I can use on the other side, maybe I can see which one lasts longer.

I refilled the gearbox with the last of the Amsoil gear oil I had. I am not really happy with it so I am open to suggestions on a better brand if anyone knows.

[90GTVert]

I've used Mobil 1 75W90 gear oil for a long time with no complaints in all scoots other than the TMAX because it's manual specifies a gear oil. With a good setup the gear oil still looks good in a couple thousand miles. When something isn't quite right, like gears lacking support or bearings wearing, then it gets dark quick. That's been my experience at least and I don't think the brand of gear oil has much to do with that.

[oldgeek]

I finished changing the motor mounts today, then cleaned up the CVT a bit and reassembled it. I went with slightly lighter rollers. I put 7g rollers in when I recently changed to the white contra spring, now I have a combo of 7g and 6.5g rollers. A quick test ride tells me I went the wrong way, I really needed heavier rollers.

[oldgeek]

May 19, 2024 18:47:42 GMT -5 oldgeek said:

I finished changing the motor mounts today, then cleaned up the CVT a bit and reassembled it. I went with slightly lighter rollers. I put 7g rollers in when I recently changed to the white contra spring, now I have a combo of 7g and 6.5g rollers. A quick test ride tells me I went the wrong way, I really needed heavier rollers.

Heavier rollers no good either, time to move back to the yellow contra spring.

[oldgeek]

I was extremely lucky today, cheated death I think. I made some tuning changes in the CVT and ripped down the side road to check results. Three times down and back hitting 55 mph each time trying to pull the front wheel up without much luck due to the rollers being too heavy. I stopped at the stop sign then proceeded to cross the street to get back to the shop. Again trying to pull the wheel up I felt something break and the rear wheel locked up and I slid to a stop almost laying it down. Now I know what the extra vibrations I have been experiencing were. You can see in the pictures there has been a crack in front of the shock mount for quite a while.





I am so lucky it did not happen at speed, I would be back in the hospital. I just got out of the hospital yesterday, they kept me overnight for something totally unrelated.

I have always worried about the single sided shock on scooters in general, high speeds and a heavy rider can't be a good combo for these setups. The fact that this set of cases was heavily corroded is not good either.

Only real damage besides the cases in the shock, it resembles a banana now. Also the CVT cover is broken, It has had a crack in it for three weeks or so under the clutch area, guess I should have looked for the reason it cracked.

[190mech]

Well crap! Hope you have a clean crankcase set around to start over again..

[oldgeek]

May 28, 2024 2:50:35 GMT -5 190mech said:

Well crap! Hope you have a clean crankcase set around to start over again..

I do have a couple spare case sets. I am not looking forward to all the work that goes into prepping them for a build.

[808ministroke]

Danm lucky you got out of that unscathed, That would have been me had my freind not pointed out the crack in my case, I get it it's alot of work to my a stock vase into a high performance one...

[aeroxbud]

Very lucky it happened when it did.
Looks like you need someone with a welder and a mini lathe who can easily make a torsion arm? 🤔😉

[oldgeek]

May 30, 2024 5:03:28 GMT -5 aeroxbud said:

Very lucky it happened when it did.
Looks like you need someone with a welder and a mini lathe who can easily make a torsion arm? 🤔😉

I made a torsion bar for my custom build. That unfinished project sits in the corner of Scootopia, I try not to look over there cause it bums me out LOL. I doubt a motor will get built anytime soon due to the summer season is upon us. To make matters worse my brother/business partner is unable to work for at least a month due to medical. That leaves me to do what I can which isn't much because of the cancer meds I was on are still affecting me over 5 months after I stopped taking them.

At least I still have scoots to ride. The blue Kymco and the red Kymco both run well and are plenty fast for what they are. They will be my therapy scoots for the summer.

[Lucass2T]

Outch thats a nasty tear. You're a lucky dude OG! Maybe go with a shorter rear shock to relieve some of the horizontal stress on the shock mount.