Flyweight - Going from stock engine to big bore, change flyweight?
Flyweight - Can I run a calibration from 2000' to 10000'
Flyweight - Going from stock engine to big bore, change flyweight?
Question) Have your clutch kit on stock 800R x 154". 15.3g for 8150, clicker 4. Dropping in 860BB. Currently have Your mountain kit installed. What do you recommend for a set up for this kit at 6000 feet, spring change, pin weight, ramps?
Answer) With that 860 kit you are going to have to get the jetting close in there to get the engine to rpm correctly.
Jetting Commentary
You’ll find that the engine probably wont start to rpm to its rated until you are about 2 jet sizes away. The tuner must pay attention to the jetting to get the engine calibrated properly and then start to dig into the clutch if needed.
At this point I would not do a change to the clutching. You have to push off the dock with the new engine and go get your sea-legs with it, making sure you have the confidence its going to rpm correctly and going to make the power that its supposedly to deliver.
Don’t be fooled by more power = more flyweight. The only time you’ll see more pinweight is if the engine runs at either the same 8200 rpms or lower rpms.
Example) my test guy dyno’d his 800R at 150hp at 8150 rpms. After getting the big bore dialled in and dyno’d it, it went to 169hp at 8300 and had to increase 2 grams but there was an honest 19hp increase.
Another of my test guys went to 8500 with his big bore and had to go from (16g @ 800R) to (15g @ 860 to get 8500) and his sled had power by the hour.
Aaen's Principle) Weight determines rpms. If you need more rpms, then reduce the flyweight. If you need less rpms, then increase the flyweight. All testing is done at full throttle.
Bring your tools to change pinweight if needed.
Flyweight - Can I run a calibration from 2000' to 10000'
Question) is any clutch kit or calibration able to cover 2000 to 10000 feet, or is that to big of a gap?
Answer) First off lets analyze the engine HP per elevation. The percentage noted is information from RKT and TurboAl.
100% @ 0000' elevation [150hp]
89% @ 3280' elevation [136hp]
78% @ 6560' elevation [121hp]
60% @ 9850' elevation [102hp]
56% @ 13120' elevation [91hp]
53% @ 16400' elevation [86hp]
At 2000 feet, 144hp range with clutching that is calibrated that can cover a 10 hp range.
You go to 10000 feet with that 2000 foot calibration heavy enough for 140+hp however, there is approximately 100 hp.
You could be happy with your performance at home, but not happy with the performance out west at elevations.
At this point, a re-clutching/re-calibration decision is based on a deficiency so then to overcome the deficiency the tuner has to change the overall calibration for the higher elevation.
As BRP supplies calibrations for different elevations, so do clutch kit manufacturers. Its not as simple as changing a clicker for a 4000' elevation increase and expect near 100% performance.
Choices - For highest economy $, you can install high elevation components when you go to the mountains and then remove those components and run stock calibration back at home.
OR
Run a dual elevation kit so you can have the aftermarket capacity at home, however still requires that you change primary clutch parts for the elevations/power differences.
My first advice is to have the tools to do what y’all gotta do.
