Gears

[Enticer]

Has anyone had an Apex or Attak chain case apart? If so, what gears did they finally end up with?

 

[snowbeast]

38/24 but the reduction gear is now 31 so topend will suffer by a few.

 

[jtssrx]

38/24 but the reduction gear is now 31 so topend will suffer by a few.

What are you talking about?

 

[snowbeast]

He asked what gears it has,and woody today told me that was what came stock in his apex,and thats what came in the 03 shorty as well.

 

[jtssrx]

you mentioned the gear reduction that's why I was confused.

 

[welterracer]

38/24 but the reduction gear is now 31 so topend will suffer by a few.

I thought the lower gear gave it more topend as the motor know revs to a higher RPM... 03s/04s only ran 10,300... the 06s are supposidly running 10,500..

 

[snowbeast]

That was my understanding to guys,but Keith Woods and Bender are seeing max power at or around 10,200 and even yamahas dyno graph indicates max power @ 10,100 i am confused to the protos i rode both reved right to 10,100 and creeped to 10,500 so i guess some guys are clutching them to the lower numbers,and i bet it works better in a short run 1/4 or less,but maybe when running the rail beds and stretching it out the overev will help,to early to know right now,sorry if i confused anyone,and Woody was the one who mentioned the gear reduction may cause the top end to fall off a little,so he figures on overdriving his clutches,i used his set up two years ago with very good results.

 

[Srxspec]

At 10,200 rpm the Apex clutch will spin 200 rpm less than what the RX-1 clutch did. With the 24/38 gearing the Apex in theory will be 2.6 mph slower when both clutches are fully shifted out, this would be in ideal conditions. Is it something to worry about, nah cuz I'd rather have the 7 hp that the RX-1 is short!

 

[sx7001]

I think you have that backwards,the apex should spin faster.

 

[jtssrx]

I think you have that backwards,the apex should spin faster.

The Purpose of the gear reduction is to slow the speed of the primary clutch. I thought Yamaha slowed it more because the Peak power of the apex was going to be 10,500 RPM's. If the peak is 10,100 then they should have left the reduction alone in my opinion.

 

[Srxspec]

The Apex clutch will spin slower if you run the motor at 10,200 like the RX-1 does. In dyno sessions from Bender Racing and myself as well, the 150 FI motor has made it's peak power at 10,100 to 10,200 rpm rather than the 10,500 rpm Yamaha has recommended. Since the Apex motor made HP at a higher RPM initially, Yamaha chose to go to a 30/37 primary reduction gearing rather than 31/37 like on the RX-1 to slow the primary clutch down to the same rpm as what the RX-1 ran.

RX-1:
31/37 gear reduction
10,200 x 83.7% = 8537 clutch rpm

Apex:
30/37 gear reduction
10,500 x 81.1% = 8515 clutch rpm

Now if you spin the motor down at 10,200 rpm on the Apex like the magazine dyno results have shown it to make power you will slow the clutch down to a slower clutch speed than the RX-1.

Apex:
30/37 gear reduction
10,200 x 81.1% = 8272 clutch rpm

 

[welterracer]

Allen..

What would be the top speed then with the clutches fully shifted out...??

WOuldnt the apex theoretically have a higher top speed as it has more power at the track and can over come terrain more easily? (REAL WORLD)

 

[Srxspec]

The Apex will probably be able to pull a better top speed because unless you change the gearing in the chaincase it will probably pull further through the clutch travel using more area of the clutch sheave since it has more horsepower. On top of that the Apex will also be much quicker accelerating to top speed.

 

[TT670]

Did some figuring, with an operating rpm of 10,200 rpm and a 8272 clutch speed(rounded off to 8300) and a 24/38 chaincase gear ratio, at 1:1( full shift) calculated top speed is 112.6mph. Now run the engine at the advertised 10,500 with an 8500 rpm clutch speed and the top end goes up to 115.3