I need a crash course in roller tuning

MotorMaker · Post by **MotorMaker** » Tue Oct 07, 2008 2:52 pm

OK, I got a 36 pc. Set of OKO roller weights from VT today.
I am running a 99 SR SA50X
9.8-1 gears
OKO hi-speed pulley
Stock motor, carb,pipe,air box ect. ect.
2400 miles

Right now I top out at 40 mph.

I am told I should be at 45 or so.

What weight of rollers should I start with? I know I need to tweak it in. I am just looking for a starting point. And what increments Should I jump up in. 3g,6g,12g ? If there is another post on this please point me to it. Thanks in advance MM.

Arnadanoob · Post by **Arnadanoob** » Tue Oct 07, 2008 3:08 pm

This is a crude explanation but it goes something like this. Keep in mind that adjusting the weights often times goes hand in hand with the center spring tension at the rear pulley.

If you're a heavier rider (person's weight), you might need to go with lighter weights. How this works is that imagine one of those mountain bikes with gears on the front crank and at the back. The weights control the rate in which the moped switches up gears. Naturally like in a manual transmission car, if you shift up too quickly and you're tugging a lot of weight, you won't have the power to accelerate. Conversely, if you shift up too slowly, all you'll be doing is keeping it in gear too long, revving up the engine and won't be moving much at all. Using heavier weights will shift through the gears (upshift) much faster and will cause the moped to start upshifting at a lower rpm. Using lighter weights will upshift slower and "keep it in gear" longer but will upshift at higher rpms.

The basic formula is if you use heavier weights, you may need a stronger center spring at the rear pulley as well. If you end up using lighter weights, you may need to use a slightly softer center spring at the rear. This is all balancing. If you need a lot of power (higher rpm) to climb hills and/or you ride short distances you can go lighter on the weights. If you're one of those cross-country high mileage everyday riders that doesn't see a lot of hills, you can go a little more biased to the heavy weights. Using lighter weights may give you better acceleration at the cost of top speed coasting ability (similar to driving on the freeway in 3rd gear in a car). Using heavier weights will cost you some acceleration initially but giving you better high speed coasting ability (like being in 5th gear on the freeway), the rpms will be much lower at a higher speed.

My moped has a tach so I can clearly see the effects of what happens in relation to the speedometer. If I use heavier weights (like 10 gram weights all around) that is 60 total. The tach won't read much higher than 9000 rpms and it'll have a steady, non-spikey acceleration. If I dropped and used 7g weights (42g total), I notice that the rpms are in the 11k range, the motor winds up a lot and tends to have a spikey acceleration curve

Post by **noiseguy** » Wed Oct 08, 2008 9:31 am

I like this explanation... it's in Adv Tech Docs now.

Dac · Post by **Dac** » Wed Oct 08, 2008 2:43 pm

noiseguy wrote:I like this explanation... it's in Adv Tech Docs now.

i was just about to addd that myself.

Arnadanoob · Post by **Arnadanoob** » Wed Oct 08, 2008 4:22 pm

Thx for that guys, lol I hope it helps the peeps here. I'm new here and I hope to give back as much as I'm learning from this forum. I could add the rear pulley explanation which would explore the center spring matter(torque spring) into this but I figure I'd save that for later.

maddog · Post by **maddog** » Fri Oct 10, 2008 2:07 am

was it correctly derestricted? as only a few people know how to do this

MotorMaker · Post by **MotorMaker** » Fri Oct 10, 2008 2:24 am

Well, maddog how would you "correctly" derestrict an SR? I can't wait to hear this. Or are you just all talk?

Arnadanoob · Post by **Arnadanoob** » Fri Oct 10, 2008 4:42 am

If you're going to be even somewhat serious with tuning your own moped, the first thing I'd highly recommend is to get a set of weights of differing grams like that multipack VT sells. Get yourself one of those trays like the ones for tackle boxes (you'll find them cheap at a hardware store) and seperate the weights and start tuning. If you want to know how I started tuning with the weights, read the last paragraph.

Then get yourself a nice impact tool and a 17mm socket for the front pulley and try things out. Finding the correct weighting isn't a definitive right or wrong issue, this is a matter of flavor... sweet enough or too bland?

I started off playing with my new weight set, this started off with all 3 gram weights (3 x 6 = 18 grams). My engine rev'd up amazingly high to 13,000 rpm but my speedmeter climbed in speed very slowly and my top speed was laughable at 30mph. The experience was like driving my car in 1st gear and never shifting into 2nd gear. Then I got stupid and tried with all 13 gram weights (13 x 6 = 78 grams). My moped's rpm never reached much higher than 7,500 rpms, on a level ground it felt dull and lacked any sort of "punch" but it accelerated steadily and it seemed decent once it got up to speed. The experience was like starting off in 5th gear in a car from a stop and keeping it in that gear all the way. My top speed exceeded my speedo's max reading of 55mph (keep in mind my moped is modded decently). Then it was a matter of finding the middle ground between both. I tried 8 grams all around, then 9 grams then I had to decide which felt better. For my own preference, I opted to keep it a little dull on acceleration for more top end speed.

MotorMaker · Post by **MotorMaker** » Fri Oct 10, 2008 5:49 pm

I finally got time to tear into my scooter today. These are the rollers I purchased from VT.

I agree with you. Organization makes things much easier.

These are the 6 rollers that came with the High speed pulley.

First I tried 3-5gram rollers with 3-8 gram rollers for a total of 39grams

It lowered my top speed by almost 5-mph.

Second I installed 3-7's and 3-8's for a total of 45grams.

I got my top speed back to 40 with this set up.

Third run 3-8 gram and 3-9 gram for a total of 51grams.

Slightly slower hole shot. Same top speed.

Fourth run3-8's and 3-11's. Total: 57
Result: Less take off speed. Same top speed.

Fifth run 3-8gram and 3-13gram for a total of 63.

Dismal hole shot. Same 40 mph top speed.

Top speed variance in last 3 runs: 1 possibly 2 mph.
After each change I rode once around the block (4miles) North,south,east and west to cancel out any wind.
There are little or no hills around here. And I am very heavy. I ride 22 miles to work and back, 11 miles each way. All back roads at wide-open throttle.
After all this tweaking I ended up putting the rollers back in that came with the high-speed pulley. I was sorely disappointed in this whole exercise. At least now I know. I never would have guessed that the pulley rollers I already had were "in the sweet spot" for my weight and riding conditions. I think my next step will be to change out my 9.8 gears. I am confident that will change my top speed.

Arnadanoob · Post by **Arnadanoob** » Fri Oct 10, 2008 8:27 pm

Good job on the experiment, I'm sure you can understand how it feels when you alter the weights now and how it affects acceleration power and top speed.

Keep in mind that gear upgrades are a very good investment but if your engine is near stock (power wise), you might hit the ceiling regarding the HP demand in relation to higher speeds. Good tuning requires total balance (which essentially means you need to upgrade everything in sync).

When you hit your 40mph top speed, is the engine revving up high like you're hitting the rev limiter or is it the point in which you simply don't accelerate more?

steffen707 · Post by **steffen707** » Sun Jan 11, 2009 10:29 pm

What are you suppose to use to lubricate the roller weights? I see in the previous pics that somebody used graphite lube.

chevyguyjay · Post by **chevyguyjay** » Sun Jan 11, 2009 11:09 pm

nicely posted. not bad.

Kenny_McCormic · Post by **Kenny_McCormic** » Sun Jan 11, 2009 11:15 pm

jonsteffen wrote:What are you suppose to use to lubricate the roller weights? I see in the previous pics that somebody used graphite lube.

Honda uses grease.

scooterwerx · Post by **scooterwerx** » Mon Jan 12, 2009 1:40 am

the rollers dont do anything for top speed. they only determine when the CVT "shifts". you can feel when it does, the rpms will drop usually at 20-30mph if your in the ballpark. the only way roller weights will affect top speed is if, A. they are far too light, and the variator never "shifts" to high gear, or B. if the are far too heavy, and there is insufficient torque to pull high gear to top speed. if its A it will scream and scream but only go 25mph or so. if its B, the performance will suck going uphill, and downhill will kick *. you want it so the "shift" is smooth and seamless, but still gets into high gear. you can feel when its right, and when its wrong. a tachometer helps tremendously...

jesse1234 · Post by **jesse1234** » Wed Feb 11, 2009 12:09 am

so much helpful info....

do you know what the weight of the rollers that came with the high speed pulley were?