Crash course in roller / rear spring tuning for Honda Elite

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Crash course in roller / rear spring tuning for Honda Elite

Post by noiseguy »

From Arnadanoob:
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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
Last edited by noiseguy on Thu Oct 09, 2008 11:06 am, edited 1 time in total.
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Post by noiseguy »

More from Arnadanoob on spring tuning:
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Both the center and clutch springs do different jobs but keep in mind that it's the entirety of the transmission (boss, pulley, weights, ramp, belt, rear pulley, center spring, clutch, clutch weight and clutch springs) need to all work together in order to run properly.

The center spring is nearly a tension spring. It's job is to control the rate in which the belt drops down (which results in going into a higher gear).

When the bike is at rest, the center spring keeps the belt on the outsides of the rear pulley which is like 1st gear in a car. If you look at a mountain bike, notice the rear cogset, the biggest gear on the rear rim is the low gear. Conversely the smallest cog is the high gear. The spring strength controls the rate in which it switches gears.

A stronger center spring will allow the belt to drop into the pulley into a higher gear at a slower rate than a softer center spring (because it'll cause the rear pulley to resist pulling apart to allow the belt to drop down lower towards the center for a higher gear). If you use too strong of a center spring, your rear pulley will keep the belt in a lower gear (great for climbing but bad for higher speeds) for a longer period of time. The end effect is similar to using lighter weights at the front pulley (variator).

If you use too soft of a center spring it'll switch to a higher gear too quickly making it much harder for your engine to accelerate your moped. A softer center spring might be more useful for when you're on relatively level terrain and in need of a higher gear sooner (especially for you high mileage cross-country riders). The end effect is similar to using heavier weights at the front pulley (variator).

Strong center spring = upshifts slowly, downshifts quickly. For you technical peeps, the stronger spring resists compression (which allows for a higher gear) but is very willing to expand (which allows for a lower gear).

Softer center spring = upshifts quickly, downshifts slowly. For you technical peeps, the softer spring doesn't resist compression much (which allows for an easier upshift in gears) but is slow/lazy to expand (which determines the rate of downshifting to a lower gear).

You need to remember that you need to balance this out with your front pulley (variator) and the weights. Generally when you go with a stronger center spring, you use more weights. If you go softer on the center spring, you can use lighter weights. This isn't the rule, but it's a good way to start tuning.



The clutch springs are simple, it's the timing of when it engages the clutch. If you have it engage too soon, you'll have no power and it'll likely bog off the line. If you have it too high, all it'll do is rev up your motor more than necessary and it'll likely fly off the line. If you've driven a car with a manual transmission, I'm sure you can relate to letting out the clutch at 2000 rpms versus at 4000 rpms. The latter will take off faster because the engine will be at a higher power band. However this would be great for you big and heavy guys.

Lighter weight of rider = can use softer clutch springs (2000-3000 rpm)

Heavier weight riders = might need to use stronger clutch springs (3000-4000 rpm)
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