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Should Rear Wheel Spin Freely?

phaedrus

phaedrus

Just got it firing!
Joined
Jul 1, 2011
Messages
14
Location
Scotland
Hello everyone, been following the forum for a while but this is my first post.

I put my Griso 8v on its new Becker Griso-lifter stand, and tried to spin the rear wheel... I could turn it with a little effort, but it didn't spin freely. Seemed like the brakes might be dragging.

Am I worrying about nothing or should I investigate further?
 
There is quite a bit to turn. There will be some drag from the brake caliper (should be very little), but most of the resistance is getting all of the gear drive moving. If the rotor doesn't get overly hot during a ride, and there is no gear noise, you should be fine.
 
Thanks John, sounds like its not a problem. There's no noticeable gear noise, and I can push the bike relatively easily.

I'll ride the bike for a couple of miles without using the back brake and then check the temperature of the rotor. Well, once my ECU comes back from Todd I will.
 
As it happens John, I had my 2010 Griso 8v (Termignoni exhaust, no dB killer) on the a dynometer last week. RWHP peaked at 94.7.

The bike is specified as having 110 BHP, so discounting any effect of the exhaust that'd be a 14% loss. I'm told that 15% is a typical figure for any bike, so it looks like the CARC isn't having a dramatic effect.
 
phaedrus said:
The bike is specified as having 110 BHP, so discounting any effect of the exhaust that'd be a 14% loss. I'm told that 15% is a typical figure for any bike, so it looks like the CARC isn't having a dramatic effect.
Click to expand...
Thanks for the info. I think Pete or somebody wrote that there is a slight negative HP effect with the Termi in relation to the stock '8' exhaust, so comparing to the advertised 110 BHP figure is pessimistic. Either way, 15% loss appears reasonable for shaft drive.
 
On the original issue only, I recall asking about that on my then-new (beloved but gone) Ballabio.

There was clearly some very slight, albeit detectable, touching of pad to rear wheel rotor.

I can still hear the tech's answer: "They are supposed to kiss a bit. So, don't worry about brushing lips; only get concerned if they French kiss." :laugh:

Bill
 
And I can still remember you serving me up that wisdom when I asked around about the front brake pads touching :)

As an aside, should we be concerned by peak power loss that most likely goes with a torque increase?
 
Hi Pheadrus,

I wanted to try with my G12 first, before I wrote an answer here.
I was busy with a few jobs on my G12 during the last winterweeks, like polishing the headers.
Now I've tried my Griso, I'm happy again, spring is at our front door...
About spinning the rear wheel freely...
When my engine is running with my G12 on his stand (back wheel up...), gear in neutral.
Deu to "resistant" by his gear oil, the wheel is turning slowly.
In his gear, clutch engaged, the wheel stops.
So turning the wheel doesn't cost much effort. ;)

Power of my beast... a lot...
On my dyno runs, we started at 91.2 Hp at the back wheel. :?
This with Mistral High rise exhaust with db killer attached.
That will be a bit less as with standard exhaust. My mistral db killer wasn't only a db killer, but also a Hp killer.
At the end, with open BMC airfilter, adjusted mapping WITH db killer we reached about 100 HP at the back wheel...
But without the nasty db killer, we flew up to 112 HP!!! :mrgreen:
So the original Mistral db killer was also a Hp killer. :sick:

Ride on...
Ad B
 
Thanks Ad B, appreciate you taking the time to look at it. Your findings support my conclusion that the resistance is normal... The CARC gear drive seems to be the culprit.

Interesting to hear about the increased HP with the dB killer back in place. I'd removed mine from the Termignoni (sounds great) but I'll be putting it back in now. I read elsewhere on this forum that the engines benefit from some back pressure in the exhaust.
 
phaedrus said:
As it happens John, I had my 2010 Griso 8v (Termignoni exhaust, no dB killer) on the a dynometer last week. RWHP peaked at 94.7.

The bike is specified as having 110 BHP, so discounting any effect of the exhaust that'd be a 14% loss. I'm told that 15% is a typical figure for any bike, so it looks like the CARC isn't having a dramatic effect.
Click to expand...

There will be a significant loss in the driveline but the CARC wll be no worse than any other system for turning the drive through 90 degrees.

94.7HP sounds a bit weak. My stocker with the original, really crappy, map made 100-ish. Opening the airbox and fitting an open pipe robbed it of about 4HP. With the #68 map and Termi with dB killer in it makes 104.8 and that was on a hottish day, at altitude.

As I've said before, set-up is vital. If the TPS is off, valves are loose or tight, or the TB's are out of ballance the engine will react very poorly, far worse than one would expect it to behave given seemingly small discrepancies in tuning.

Pete
 
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