Topic Approved

yes, it is possible.if i remember correctly had to change three gear sporks, and gear changer drum(and removed bald gear).everything else stock.
"no change in sprocketing "will lead to sluggish behavior in fifth gear .
better option(costly)..convert the bike to 135cc, 5 speed spec.
or change the final drive ratio to exploit each gear.
chamber, porting,better cdi(rdd) even more fun.

Proton had a fifth gear for RX100 in the early 90,s and ppl said it was great! they might still help you out.

Thnx for all the updates guys.

What I am really interested in is a STOCK Rx100 with a rx135 5 speed cog included.

I am not looking for any mods to the CDI, rear sprocketing etc.

I just wanna know if I add a 5th gear, will the bike reach 110 - 120 (true) kmph and return 45-47 kmpl.

I was getting 42 kmpl on my 4-speed RX100.

As far as performance goes, My RD and RXZ 5s do the needful for me.

thnx again

the 110 - 120 region is not possible for a stock bike, may give a few kmph more.

@Sixspeedtwin - I run on 4S barel with 5 speed gear box & on sane driving (around 60-70) the eco is around 43 & with 50's the damn bike gives around 47. Sprocketing is still 4S. Top speed it gives 110 on speedo not sure on the true speeds.

even stock rxz 5 speed doesnt do a true 120kph. RX100 stands no chance.

also, AFAIK, the 5th gear of 5 speed = 4th gear of 4 speed. The final drive ratio is 0.97
Cheers

Atul

Atul,
Even i want to add only a 5th gear to my rx-100. I am not lookign forward for speed increase as i use my babe only for city rides.
But i am looking forward for a smooth ride even at speed of 70.
So is it possible to add only a 5th gear without any performance or additional part changes, and if yes the can u tell me approx how much will it cost.

My Fundamental Question still stays unanswered ...

STOCK RX100 with ONLY a 5th gear added .... any change in the top speed and Fuel Economy?

Hope to get the right answer this time .

^^ nope because like atul pointed out, the final drive ratio is the same.. so what you get with a 5 speed gearbox is more closely spaced ratios for better driveability in the city. Thats all.

Maybe you could reduce the rear sprocket by 1-2 teeth to take advantage of the lowered gearing with a 5 speed gearbox, but the final drive will be as sluggish as it would be on a 4 speed gearbox. Hope that helps.

So you wont be able to achieve an overall increase in top speed unless you do one of the following -

- Sprocketing at the rear to change the over all gearing to a taller gearing. This will strain the engine more in the higher gears ( read 3-4 ) and also over all acceleration will be affected, though you will be able to hold onto a gear longer ( say you were shifting from 2nd to 3rd at 40kmph, you will be able to do it at 45 or so ).

- Increasing the revability of the engine at the higher side of the rpm, which can be achieved by porting, or installing a tuned expansion chamber, which is tuned for a boost in the higher rpm, so the engine revs beyond its current rev limit.

- Do both and get a overall boost in power, so the engine can handle the taller gearing, so the bike can accelerate well and also get to the top speed.


I was testing my RXZ 5 speed, on stock gearing and sprockets ( i think 15 front 34 rear or something ) , and at 6500 rpm or so it was close to 85 kmph. So im not expecting the bike to go beyond 110 kmph, because the engine can at most rev to what 8000 rpm or something???

4 Speed sprocketing is 15-34 & 5 speed is 16-38

4S is 16/34.

^^ ok so what sprocket size should i be running in the RXZ 5 speed

You beat me