16/40 or 16/42?

[bch3779]

I want a little more bottom end on my busa so I'm changing the front sprocket to a 16T. My question is should I stick with 16/40 or go up 2 in the back for a 16/42 combo? I am 6'2" 175lbs. My Busa is stock height with stock swingarm. I have no plans on lowering it or extending the swingarm. It is a streetbike althought I occasionally go to the strip with friends to race for fun. It seems most people who are running the 16/42 are lowered and extended. Also, from what I have gathered you lose alot of top from the 16/42. Any input would be appreciated!!!

 

[bch3779]

Oh.. and I forgot...I come off a Honda RC51 so I'm kinda into the twisties. I don't want too much engine braking in the turns.

 

[atticdog]

I would start off changing 1 sprocket and see if your happy with it
changing the rear is easier than changing the front so start off with that



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[Busapig]

Isn't it a good idean to change the front and rear at the same time if you have ridden a decent amount of miles on them??

 

[atticdog]

Yes if they are worn
then you would also need to replace the chain at the same time

 

[Puzzled]

What amount of top end speed do you loose with such sprocket changes? 16/40, 16/42? Is it substantial? Next what are the gains in relationship to the "seat of the pants" feel?

 

[ohzone]

You may want to consider a 43 tooth rear this will shorten the wheel base, give you the bottom end you want and because of the shorter wheel base make the bike turn in easier, this is the route I went!.
The 16 front will increase the wheel base and make the turn in actually slower than stock and the smaller sprocket makes the chain turn through a smaller arc, possibly increasing wear if you don't keep the chain adjusted correctly.

mind you we are only talking small degrees anyway

 

[MET]

I would change all of the sprockets and chains if you show wear. Then I would go with the 16/4o for starters. Go up to 16/42 if it seems you need or wnat more..

 

[SHWELL]

I thought if you went up one up front it was like going up 2 in the rear. Going down one up front does not seem right. 18/40 will give you better low end performance.

I am not sure about this, but that is what I have been told this week?

?

 

[Puzzled]

One down in the front is close to two up in the rear. They are not both up or down. One goes up and one goes down. Screwy isn't it?

 

[fstbusa]

17/40 = stock = 0.425
16/40 = one down front = 0.4
17/42 = two up rear = 0.404
16/42 = one down front/2 up rear = 0.381

they are close but not the same.

 

[Puzzled]

thanks fstbusa that's perfect.

With the 16/42 what kind of mph loss should be expected? Same combo, does that create a wheelie bike?

 

[bch3779]

Well..went with 16 to start...noticeable but still not enough so i went with the 42 also. I definately like the way it pulls now..not too hardcore as i expected. I wouldn't say it is 100% wheelie prone but in 1st u have to be careful. Seems it wants to break the tire loose before it wheelies in 1st. 2nd she hovers and 3rd if u hit it hard enough u may feel the front getting light. Other than that she pulls nice and hard. Acceleration is awesome. I did a speedo healer to correct my speedometer because I think this gearing change throws it off by -17.5%.

 

[hooken203]

With 16/42 my busa was at a little over 175 mph at around 95 to 9800 RPM. I cant tell you what it does with stock gear.
I think that was at the speed limiter. Not sure.

 

[Puzzled]

Thanks guys. The speedo correction box, simple to install and calibrate?

 

[hooken203]

Yellow box is a way easy install and calibration is a snap.

 

[Puzzled]

Thank you.

I've looked at several bikes that were not calibrated and wondered if it was something difficult to do as they were not done.

 

[ohzone]

check out speedohealer.com
cheaper and a larger range of adjustment
both are the same quality

 

[fstbusa]

speedohealer only has a 2 yr warranty and yellow box has a 10yr warranty.