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Clutching help

kviper said:
You may be right but I would sooner see him low and work up than on the rev limiter for a weekend and not be able to make changes.
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Takes ten minutes to add or take out weight. That's what's nice about ULmER kit. I usually get up a little early and go test.
 

cannondale27 said:
Good. Just have yet to see any 8jp running clutches that didn't show obvious signs of slipping. None. Take a pic.
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20141225_173830.jpeg
This is after a 65 mile ride on tight trails and some rail beds. Sled is boosted to 190hp. Belt has 3100 miles on it and is the original belt that came with the sled.
 
You guys can do what you wan't to your sled's but I surely would not recommend running on the rev limiter! It's hard on valve train! Some day when you loose a keeper you'll know what I'am talking about.
 
I also wondered about turning the secondary spring higher but he said it wouldn't hurt anything with that spring. I still have one more washer I could take off the heel to bring my rpms up a bit more. I'm no pro when it comes to clutching just know enough to get myself into trouble so all your help is greatly appreciated
 
it could just be me coming from an apex. but i could tell a huge difference in mine soon as they got dirty with dust, right around the 500 mile mark. i would lose performance and top speed was dropped nearly 10-15mph. It also took a lot longer to get up to near top speed. soon as i would clean them i was good to go for another 500 miles. I ran last year with the stock belt and put just over 1000 miles on it. not a bad setup i don't think but it had to be cleaned to get the best performance. i hope the new clutch setup and running the 8dn will be the answer.

subaru2006
 
kviper said:
You guys can do what you wan't to your sled's but I surely would not recommend running on the rev limiter! It's hard on valve train! Some day when you loose a keeper you'll know what I'am talking about.
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What?? The rev limiter is there just so you cannot get anywhere near overrev. I have to ask, how many Yamaha 4 strokes have you seen lose a keeper? Or are you just guessing? Not trying to start a fight but when I see claims that do not match what I have seen I like to know if I am wrong.

Picture below is my brothers RX1 head after he blew a rod. The tolerances are so close that when he blew the rod the piston hit a valve and broke the head off the valve...also bent a couple more. The point here is even with a disaster like this the valve keepers stayed on and in place.

OK, sorry for the rant back on topic now. :)

apehead.jpg
 
Studroes144 said:
Gotta jump in and give a bit of advice, I don't know how the weights from Allen's kit are setup or how you adjust them but the clutching theory is all the same, one thing that you shouldn't do is adjust your secondary spring wrap to alter your engine rpm, yes you can wrap the secondary spring tighter and it'll raise rpm, but the reason that's happening is because it's slowly the shifting process of the clutches which ultimately makes you slower everywhere. If you're buying a clutch kit from a vendor and your rpm is either too low or too high, adjust the weights accordingly. Again I don't know the weight profile of the setups being used here but on my kit last year it was very crucial not to load the heel of the weights at all, if the sled cannot pull 8800+ rpm right of the line when u wack the throttle you need to start taking weight out of the weights, the viper needs to be running as close to the rev limiter as possible to be at it's best performance. And one thing to remember, even when you have no weight in the heel of the weights and you have weight in the tips, that is controlling the rpm at launch somewhat because of the centrifugal force. If it were me I'd set the secondary at 6 and 1 or 6 and 2 and adjust accordingly on the weights the get it to rev 9000 rpm, just remember it's gotta rev up as quick as possible and hitting the rev limiter once or twice on a launch is not a bad thing, that method has proven to be the fastest setup we've seen when using a radar gun with actual speeds and times, if we lugged it along in the rpm it was always slower, let the engine scream.
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^ x2
 
stingray,LOL! so because it hasn't hapened to you it hasn't happened? It has not happened to me or any of the four strokes I deal with but I don't know of any one bouncing off the limiter for a tuning tool as the motor looses loads of power at that point. However I have herd of cases. Talk to any motor builder and ask if it's advisable! If you wan't to advise it that's fine, and I don't need to argue with you either as I don't care what you think of my post's! If you think my advice is stupid that's fine, ignore my post!
 
Hitting the limiter once or possibly twice is fine with the viper, the difference in power from 8800 rpm to 9000 rpm is very noticeable, the sled needs to rev high for optimum performance. It'll run just fine at 8800 and never hitting the limiter, but there's performance left on the table by doing that
 
Correct me if I'am wrong but if my memory serves me right limiter is 9,200? If you hit the limiter you are at 9,200! Your tac don't keep up with actual RPM in a quick rev situation. It's not the RPM at limiter that causes the problem long term. I think it has to do with the sudden drop in cyl pressure at high RPM caused by the limiter.
 
Rev limiter may be around 9200..but whenever I see it, even on longer wot runs when rpms may creep up the highest I've ever seen my tach is 9160 and you can feel the limiter hit, whether it's actually hitting at 9160 or a delay in the tach I have no idea
 
When I was first dialing my Turbo Apex in it was hitting limiter so quick that with the RPM I was seeing on the tac I was questioning another problem. I believe I read that the Viper tac's are off some also?
 
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