top end run gears

[wantboost]

running stock gears now,want to do some top end runs next weekend.what gears should i order?

 

[LazyBastard]

I would say that since you are running a nitrous system, that there is a possibility that you will be needing to gear HIGHER than stock. I would first try to determine if you are running out of gearing. What top speed HAVE you been running? What top speed do you *expect* to run?

 

[wantboost]

i have been running 115 radar no nitrous.would like to be in the high 120.

 

[Charged RTX]

I would stick with the stock gearing if you are running a 50-60 shot. I have heard of mod sleds in the 130s with stock gearing.

 

[LazyBastard]

rpm: stock/stock+od/25/25+od
10700: 121.60/127.68/126.67/133.01
10800: 122.74/128.88/127.86/134.25
10900: 123.88/130.07/129.04/135.49
11000: 125.01/131.26/130.22/136.73

 

[wantboost]

lazy i keep hearing people talk about od.is this cut clutches,who does this mod?

 

[Randy J Beyer]

Overdrive happens when you take the 1 to 1 ratio
and go into say 1 to .75 ratio.

Front drive clutch and rear secondary cutch are
equal when you are in 1 to 1 ratio. ( Same Diameter )

This means drive belt is running even on both clutches.

When you get into .75 to 1 ratio overdrive the drive belt
has crawled up the primary and is larger on the primary
and smaller on the secondary.

Over drive is faster in some cases if you are at the
right engine RPM and if you have enough power to
pull it and if your clutch will allow it to happen.

Stock clutches are limited in design from manufactures
and sometimes will not allow overdrive unless they
are properly machined.

Overdrive can be slower if not right in some cases!
Not to step on your toes Lazy Bastard !! LOL

 

[Randy J Beyer]

Oh and wantboost if you clutched for nitrous that means you
are clutched about 1000 rpm's under the rev limiter
so for you to get 120 mph off the bottle will be hard to do!

If your running on the bottle gear higher to take advantage of your power !

 

[Yamzilla]

Overdrive happens when you take the 1 to 1 ratio
and go into say 1 to .75 ratio.

Front drive clutch and rear secondary cutch are
equal when you are in 1 to 1 ratio. ( Same Diameter )

This means drive belt is running even on both clutches.

When you get into .75 to 1 ratio overdrive the drive belt
has crawled up the primary and is larger on the primary
and smaller on the secondary.

Over drive is faster in some cases if you are at the
right engine RPM and if you have enough power to
pull it and if your clutch will allow it to happen.

Stock clutches are limited in design from manufactures
and sometimes will not allow overdrive unless they
are properly machined.

Overdrive can be slower if not right in some cases!
Not to step on your toes Lazy Bastard !! LOL

And to add to your comments...the stock Yamaha clutch cannot even reach a 1:1 ratio until the helix is modified and the primary is modified. I'm familiar with this as I'm in the middle of doing both to go with my 22/40 gear-down. Also, beware of coil-bind. When I get this balanced out and going in the direction I'm targeting it's gonna be awesome!

 

[wantboost]

someone told me to put 5/16 lock washers behind the helix.what does this do?

 

[ROCKRTX]

Overdrive happens when you take the 1 to 1 ratio
and go into say 1 to .75 ratio.

Front drive clutch and rear secondary cutch are
equal when you are in 1 to 1 ratio. ( Same Diameter )

This means drive belt is running even on both clutches.

When you get into .75 to 1 ratio overdrive the drive belt
has crawled up the primary and is larger on the primary
and smaller on the secondary.

Over drive is faster in some cases if you are at the
right engine RPM and if you have enough power to
pull it and if your clutch will allow it to happen.

Stock clutches are limited in design from manufactures
and sometimes will not allow overdrive unless they
are properly machined.

Overdrive can be slower if not right in some cases!
Not to step on your toes Lazy Bastard !! LOL

And to add to your comments...the stock Yamaha clutch cannot even reach a 1:1 ratio until the helix is modified and the primary is modified. I'm familiar with this as I'm in the middle of doing both to go with my 22/40 gear-down. Also, beware of coil-bind. When I get this balanced out and going in the direction I'm targeting it's gonna be awesome!

Yammis clutch with a machine helix is good for 0.93 to 0.90 overdrive.
If that was not the case my theoretical speed at 1:1 ratio with my 23/38 gearing ( 110 MPH radar ) will not be achievable and my sled pass the 110 MPH limit.

 

[ROCKRTX]

someone told me to put 5/16 lock washers behind the helix.what does this do?

This allow the secondary for more overdrive if your helix is not cut for it.if you have a aftemarket clutch kit this is a waste of time because the helix is already machine for overdrive