[gromorado]

I am planning on putting a Yuminashi 160cc big bore kit and opening up the intake and exhaust. I am mainly looking for enough power to stay with traffic around 60-65mph and be able to go up hills without losing too much speed. I am also not willing to open the case to replace the 4th gear at this time.

Here are my questions: (I am just over 200 lbs.)

Is the stock gearing going to be fine for this?

If I do change the sprockets what is recommended? Front/rear?

I am planning to run stock gearing/sprockets when I install the kit and go from there but I would like to get some feedback for the future.

Cheers!

Greg

 

[RACER X]

Sprockets are cheap and easy, worry about them later

$1000+ in hi-po parts are a bigger deal on a $3500 bike

 

[wondermuscle]

You might want to go up one in the front, this is better than two down in the rear as your chain will wear more on the slider with smaller sprockets.

 

[rkwfxd]

Mathematically, the Grom is capable of about 73 mph with stock gearing at redline.

I can not pull redline with mine. I have intake and exhaust mods. I can get to 8000-8500 rpms or so and top out at 60-61 mph.

Plenty for me and my roads.

I'm thinking with a BBK you will probably be able to pull redline or very close to it. That will get you into the high 60s or maybe low 70s. Once there, do you want to rev the engine at those rpms for a long time? If the answer is no, then you will need to start increasing the front sprocket diameter and checking you speed with a GPS until you get to a lower rpm that you are comfortable with you get to a gear that the engine will no longer pull.

Good luck and keep us posted.

 

[Hotrod_Hell]

You could also go two teeth up in the rear and one tooth up front if you didn't want to lower the rpms as much with just the one tooth bigger in the front sproket.


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[Yuminashi]

Hi Gromorado,

Take a look to the section about gearing settings in combination with the new 160 Ultimate Kit in the owners manual which you can download here: http://www.yuminashi.com/storage/eng...t MSX125.pdf

You should fiend the answer on your question, so I hope this is helpful...

Greetings,

Reggy

 

[akanploy]

caculate by the info of highest torque at rpm and highest hp at rpm to find the power band range in percentage then do change sprocket in the range of your result percentage that you caculate from the torque and hp. you can find what sprocket by using the same term of caculation with sprocket.

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[Shoebacca78]

According to this chart if i were to try 16T +1 Front 32T -2 Rear , I would be able to get to 83MPH!

1) Has anyone tried this before?
2) How long did it take to reach top speed?
3) Does the acceleration become unbearable at low speeds?
4) AT what speeds, do you experience slower acceleration the most? Is it just at launch or can the slower acceleration be felt from 0-80?

I accidentally bought a 14T front. I'm going to return it. I don't race friends so I don't see a need to have faster acceleration at the cost of dropping to 68.34mph compared to 73.22mph currently.

I think i want to try a 16T first. My top speed will be 78.1.

 

[LateNA]

My problem is that with the wind around here I rarely even saw 60 mph, so I went with a 14t front and love it. Do you find yourself hitting the rev limiter in 4th often shoebacca?

 

[Shoebacca78]

My problem is that with the wind around here I rarely even saw 60 mph, so I went with a 14t front and love it. Do you find yourself hitting the rev limiter in 4th often shoebacca?

I'm not sure how often yet. I just installed the chimera for 2 weeks, and have found that if I have a tailwind, I will be at least at 70 if not faster.

I hadn't been on the freeway that much in past two weeks either.



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[normsynorms]

I'm not sure how often yet. I just installed the chimera for 2 weeks, and have found that if I have a tailwind, I will be at least at 70 if not faster.

I hadn't been on the freeway that much in past two weeks either.



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I'm on a 14t. It's perfect for me. I can't reach the rev limiter with stock 15t. So I actually gained more top speed by going down in the front. The bike seems very sensitive to wind and terrain.. So I like having the smaller sprocket for hills and head wind.

 

[LateNA]

We don't really have any hills in south MS, but I echo ^this guy's sentiments.

 

[gromorado]

It was recommended I stick with the stock gearing. If I am pushing too high of RPM's down the road I will probably bump the front up 1 tooth but I don't think that will be necessary as long as I can maintain speed.

 

[CiscoSanJose]

Hi Gromorado,

Take a look to the section about gearing settings in combination with the new 160 Ultimate Kit in the owners manual which you can download here: http://www.yuminashi.com/storage/eng...t MSX125.pdf

You should fiend the answer on your question, so I hope this is helpful...

Greetings,

Reggy

Link no longer works for combination gear setup

 

[Shoebacca78]

Link no longer works for combination gear setup

This one here has from specific info programmed.

Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator