Gear Ratio's seem out

[Digitalize]

Just wondering really.

Own a Rieju RS2 Naked 50 (From new July 2009), and im pretty sure 6th isnt right.

Basically, when in 5th, it will pull to 50Mph aslong as theres no wind and its a 'good' day. But changing into 6th will give me nothing, its like a cruising gear. Cant give you any idea's of RPM's as it doesn't have a Rev Counter :/

Just wondering if there's any jiggery pokery i could do to make it a shorter gear and more useful.

I have had the bike back to 0 on the speedo which is roughly 75mph, and it felt like it was redlining in any other gear, and is useless as i have to going down a long hill to do it, and thats whats made me think 6th is way too tall, as no 50cc set up for road use will pull to 75mph...

Any help would be great.

[Kickstart]

Hi

Expect some mickey taking about mentioning 75mph and a 50 in the same post!

You can change the sprockets to alter the ration. If you want to lower the gearing (ie, make 6th more useful) then use a smaller front or larger rear sprocket.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[buddy]

75mph!!!
the problem is with your speedo nevermind your gearbox



i realise that he said its at 0, get over it its a joke
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When this baby hits 88 miles per hour... you're gonna see some serious shit.

[kingsmith]

haven't you thought that maybe it is an cruising gear..



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honda cg 125 copy cheap and crap, perfect for work..
suzuki gsxr600 srad 2000
passed 12/11/09 happy boy

[27cows]

I had a Rieju MRX125 and that only did about 70 (at a push). The one thing that stood out was the utterly ridiculous location of the battery - perfectly placed to get a lot of mud and shite off the back tyre all over the terminals. It did pull OK in top gear, though.

[stirlinggaz]

my mitos the same, dont think there more than 200rpm max between 5th,6th & 7th! in standard gearing.
altering the front makes 5th more useable but once into 6th, thats it.
cheers,
GAZ

[Digitalize]

I did say roughly dunno how accurate it is, its atleast a couple mph out, probably gets worse as it goes past what it should read. It was no way under its own power, was down a hill on a long dual carriage way.

Would changing one be better than the other, or does it not really make a difference? Havent got the foggiest where to get a new sprocket though :/ and im assuming i would have to tighten the chain as the size of the sprocket has changed?

Cheers guys so far.

[Kickstart]

Hi

Too small a front sprocket will increase chain wear, but not sure what your stock one is to have any idea of whether this would be an issue.

However a smaller front sprocket might mean shortening the chain, while a larger front sprocket might mean you don't have enough length in the chain to compensate.

Going down one on the front and up on the back would solve this problem, but not sure on whether that would lower the gearing too much.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Digitalize]

If someone could point me to somewhere i can get sprockets, perhaps i could get both, and have a play around. Just wondering what kind of money im going to be looking at (imagine it cant be much)

Only annoying thing with making the gearing lower to get 6th to work, is already im changing into second at less than 10 mph, although making it lower would probably mean i could constantly pull away in second....

[Flip]

[Kickstart]

Hi

Pretty much any bike show should be able to get you some replacement sprockets (although normally you replace chains at the same time, will depend on how much life there is left in the chain).

Looking at the JT sprockets catalogue they only list a single size of rear sprocket and a few front sprockets:-

https://www.jtsprockets.com/52.0.html?&L=0&sel_uid=3884&p=

Suspect someone like B&C Express could happily make you an alternative size rear sprocket but don't expect a 1 off to be that cheap.

However unless you are really losing anything from having the higher gearing then it might well be worth just keeping 6th as an 'overdrive' and rely on 5th as your normal top gear.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Digitalize]

Cheers for the help, seems i can only go down 1 (Assuming 11 is stock as its bold) although i will check on the bike.

I seem to remember when it was de-restricted i got back a bag with a small sprocket in, so its possible he switched them when working on it, although i'm not sure why he would of, unless it was wearing quickly.

I'm only mentioning it as my friend has an 05 Rieju RS2, and he doesnt have this problem.

[Kickstart]

[Digitalize]

Ok cheers, i did think the added fairing would make a difference, making it more aerodynamic, but i shall see.

Im going to give the can a clean (horrible grease build up) and will check then, im grateful for all the help, and your massive knowledge Keith!

[Kickstart]

[Digitalize]

I Gave the can a good clean, but the baffles are practically black and stiff :/

The Sprocket is 12t, not 11t, and i can't find the Sprocket i got back from the garage, so can't check that one

Im a tad nervous checking for the air filter and spark plugs etc, as its basically a brand new bike, but i guess i need to get used to servicing my own bike.

If i can get hold of an 11t, then i will fit that, and see how that goes. Whats the best way to change a sprocket?

Cheers

[Kickstart]

Hi

Depends on how worn it is. If worn then replace both sprockets and the chain (the old worn bits will rapidly wear the near sprocket to match).

As to actually changing it. Remove the front sprocket cover. Remove whatever is holding the front sprocket on (could be a large nut, could be a small plate with a couple of small bolts, could just be a circlip). Support the bike, slacken off the rear wheel spindle, loosen the chain adjusters and move the front wheel as far forward as it will go (count the number of turns on the chain adjusters so you undo them both the same number of turns). With luck this will give you enough clearance to slide off the front spocket, and once it is off you can unhook the chain from it. Reassembly is the reverse. If you don't have enough clearance then probably easiest to remove the rear wheel spindle and move the wheel further forward.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Digitalize]

A chain and sprocket kit is just over £50 on eBay, which i'll probably do when i'm near to selling it (Mayish/June for when i'm 17)

Will have a root around for the original sprocket, if i can't find it, ones £10 off ebay, so not too much.

Is giving the chain a good wash and clean useful? I've kind of neglected maintenance on it

Obviously want to do it now while its not proper riding weather, and i don't need the bike to get to and from school every day.

[Kickstart]

[cholyoake]

[Digitalize]

Neglected this

Cheers for the advice, once the weathers better im gonna book her in for a service (Will be about 5000Km on the clock by March/April, so not too far off the 6000Km) Get new sprockets and chains, knock back down to the 11t to see if it helps (Aswell as the usual top end rebuild, mainly for resale, but peace of mind too, its 6000 miles isnt it?). Then when im off college, have a play around with the Oil/Fuel ratio, it seems to be running pretty damn rich on both at the moment (1L of Oil in about 400Km, 10L fuel in about 300Km)

Sorry for everything being in Km, its a spanish bike

Must clean the damn thing too... Weathers made it awful muddy.