Variator "Shifting"

[streido]

In the mean time I've ordered a new drive belt that I should have next week.

Be sure to check it,different manufacturers use different codes to measure/list them. Ive bought 729mm long belts that were only 716mm and 720mm long when i measured it. the best thing is to order OEM stock Bando belts to be sure they are correct,or do the magic marker thing too.

[tuko]

Be sure to check it,different manufacturers use different codes to measure/list them. Ive bought 729mm long belts that were only 716mm and 720mm long when i measured it. the best thing is to order OEM stock Bando belts to be sure they are correct,or do the magic marker thing too.

Oi,
Quality parts I see. Well last night I ordered the Naraku V/S belt for the A50, which they claim is made by Bando.  Time will tell for sure.  When I have the variator apart again, which will be soon I will do the magic marker trick. With that said, I can comment that I could see already that the belt is travelling further up the variator face after removing the restrictive boss.


Tuko.

[streido]

You can just about draw the marker line with the variator and belt still all in place.

Naraku belts seem ok length wise normally, the ones i tried were spot on.

[tuko]

Thanks to the rain, the Land Rover is drier so the A50 is parked.
I did see though, when I was testing the various roller weights that the markings on the outer drive plate indicated that the belt was climbing higher on the disc. I would say stopping about an cm from the top.

Yes, I have been pleased with Naraku stuff in the past so I'll see how they do with the A50.


Tuko.

[streido]

If its stopping a cm from the top then thats a good few mph top end your losing. Mine goes to the top edge of my variator, if i draw a marker on it then go for a ride it takes it all pretty much off clean, at most i have 1mm-0.5mm of marker left on the very outside edge.

[baddi]

I'll just add something to the marker thing:
Draw a line on the rear pulley aswell, as the combination of lines on the front pulley (variator) and the back pulley will let you read the CVT much better.

Line on front pulley not fully gone + line on rear pulley gone = too short belt.
Line on front pulley fully gone + line on rear pulley not gone = too long belt
Line on front pulley not fully gone + line on rear pulley not gone = wrong roller weight or worn down rollers.

Of course, the lines should be read farest away from the shaft on the front pulley and closest to the shaft on the rear pulley to read max gearing.

[zombie]

Nice tip Baddi!

[wordslinger]

..yeah, been doing that...

               

[tuko]

Thanks for the suggestions/tips guys.

I finally got a few hours in the garage yesterday and I have plenty to report. 

I replaced the 1000rpm contra spring with a 1500rpm spring and installed the 5.3g rollers in the variator. Before test driving the A50 I marked the variator face with a black marker (sorry I for got the mark the clutch pates). Took it for a test drive and as I suspected she quickly shot up to approx. 25kph and stayed there. When I removed the variator I can see that the drive belt stopped approx a cm from the end of the variator.

So from here I installed the 8g rollers and took it out again. This time she went up to it's new top speed of approx. 70kph. With the variator removed again, I can clearly see that the drive belt has moved further out to the end of the variator face with approx 1mm of marker remaining.

Changing to 8.5g roller and out again, this time about the same as with the 8.0g weights with the top speed being approx the same. With the variator removed I can barely see any ink left on the variator face edge.

I even changed the rollers to 9.0g weights and test drove that, this was where performance fell off, throttle response and pick up was sluggish..... I put the weights back in the case and gave up on them direct. 

The above tests were with the 1500rpm contra spring, so I conducted it all again with the 1000rpm contra spring and the original spring. For me the 1000rpm contra spring felt the best but I do question the originality of the "original" contra spring. It's a black spring with blue paint down one side. The Naraku contra springs that I have, the 1000rpm spring is blue and the 1500rpm spring is yellow. So I'm wondering if the original contra spring was replaced at any time to a slightly stiffer one or is that the original colors for them?

I did check the drive belt and it's an Kymco original that has plenty of wear on it which measured 17mm across the top. Before work tonight the new Naraku drive belt came in the post, so she'll be installed tomorrow.

What really makes me scratch my head in disbelief is that I have to go to heavier weights to get any solid performance where others here on this forum go with lighter weights.  I've not owned the A50 for a month yet and have no idea what the previous owner has done but I'm working in the direction that I want.

I also changed the main jet to an 88 yesterday but I must admit I've not really noticed a huge difference from the 82 that I installed 2 weeks ago. And even that, the 82 didn't really make any seat of your pants difference either from the 80 that it replaced. The old chinese scooter I had, I used a 92 main jet in that and that really worked well. So I'm up in the air if I should go a bit larger with the jet or go down smaller?

In the mean time, lets see what difference the new drive belt will make.


Tuko

[baddi]

For me it makes perfect sense with the roller weight, as the rollers force to compress the contra spring are weight x rpm (accually area x (mass x accelleration)), so as the stiffer spring requires more force to be compressed, the engine would either go higher in rpm, or you would have to install heavier rollers to keep the rpm at the same as before during accelleration.

[streido]

For me it makes perfect sense with the roller weight, as the rollers force to compress the contra spring are weight x rpm (accually area x (mass x accelleration)), so as the stiffer spring requires more force to be compressed, the engine would either go higher in rpm, or you would have to install heavier rollers to keep the rpm at the same as before during accelleration.

Thats the whole point in fitting a stiffer spring, to shift the gearing and raise the rpms. Same with the lighter rollers, it raises the rpm too, its finding that balance of spring stiffness to roller weight that keeps you in the rpm "powerband". No point fittinv a stiff apring and then going heavier on the rollers as then the rpms wont rise and ypu wont get any gain, your as well leaving the stock in if you do that.

These 4 stroke engines only really perform well under high rpm, under 6000-6500rpm they tend to die off in power and run like a pensioners mobility scooter. With you not being used to the noises coming off it at different rpms you may feel it is revving too high so might want to buy a cheap rev counter/tach? I got one off ebay for £10 ages ago and its been way useful for tuning and general info on the running rpms at different speeds. Lets you better know when you reach the rpm limit of 9000rpm so you can tune to the max.

[tuko]

Ja, trying to find that right combination of springs and rollers is no easy task! 

I'm sure I'll be at all summer til I get it just right as I don't feel that I'm really in the right rev band yet.


Tuko.

[streido]

Ja, trying to find that right combination of springs and rollers is no easy task! 

I'm sure I'll be at all summer til I get it just right as I don't feel that I'm really in the right rev band yet.


Tuko.

Well its only taken me 12-14 months to get mine to perform the way i want it to. Its a looooooong process but worth it in the end. If youever ride a stock A50 after you have yours tuned up you will soon see how far you have come and how much better it is compared to stock.

[baddi]

Thats the whole point in fitting a stiffer spring, to shift the gearing and raise the rpms. Same with the lighter rollers, it raises the rpm too, its finding that balance of spring stiffness to roller weight that keeps you in the rpm "powerband". No point fittinv a stiff apring and then going heavier on the rollers as then the rpms wont rise and ypu wont get any gain, your as well leaving the stock in if you do that.

These 4 stroke engines only really perform well under high rpm, under 6000-6500rpm they tend to die off in power and run like a pensioners mobility scooter. With you not being used to the noises coming off it at different rpms you may feel it is revving too high so might want to buy a cheap rev counter/tach? I got one off ebay for £10 ages ago and its been way useful for tuning and general info on the running rpms at different speeds. Lets you better know when you reach the rpm limit of 9000rpm so you can tune to the max.

The effectband is so narrow on these 4-stroke 50cc scooters, that even 5-800 under the effectband would be catastrofic. :p
But also a couple of hundred over would be, as it looses torque here too. My experience is that 6,25g rollers will keep you on 7200 rpm with the standart spring, so when you fit a tighter spring and have even lighter rollers than that, it blows my mind.

[streido]

Same here when you guys are running 7g+ rollers. I tried 7.5g rollers about a yr ago to see how they were and i lasted about 5mins before i hated everything about them, i just had no power, no revs, no torque, it died on hill and i couldnt get up to top speed unless i had an airstrip or something.

No way my revs were anywhere near 7200 on a flat normal road, usually i ended up down at 5000-6000 at most. On my 5.1g rollers, 1600 torque spring my tach normally reads between 7000-8400 once im up to speed, rises to 9000 down hills.

Anything over 5.5g kills my A50 on ANY torque spring stiffness, believe me, i tried lots of different combinations in the past and none worked as well for me as i have now. Maybe Scandinavia where you live is totally flat so your set up works there? Def doesnt wotk over hete tho, thats for sure.

Still say a tach is a must for tuning, takes away the guess work of what rpm the engine is running at.