• We are no longer supporting TapaTalk as a mobile app for our sites. The TapaTalk App has many issues with speed on our server as well as security holes that leave us vulnerable to attacks and spammers.

Clutching help

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!


When people make warnings I am always curious if they have seen it first hand or a rumor, and you answered that thank you.
 

It's not advised to hit the rev limiter, but for the viper it needs to rev so close to the rev limiter for best performance that sometimes it happens. Haven't heard any news on the Evo flash lately but one of their big things was raising the rev limiter, for that reason. Also, powercommander now has some test modules out that will be able to increase the rev limiter, again for that same reason, so in a nut shell no you shouldn't be using the rev limiter for tuning, but you should be right there as close as you can be, and unfortunately sometimes you're gonna hit it. If clutched properly, 1-2 times on a take off are not an issue. If you're hitting the rev limiter at the end of a long run then it's time to keep tuning. When I'm riding mine and it hits the rev limiter once on a launch and maintains top rpm I'm smiling because it's running at it's best right there
 
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?
Just to clarify. The viper tach has a max rpm recall. Mine reads 9133 every time it hits the limiter but never see it that high myself as it doesn't change fast enough like you say. But there is no reason to think the recall is wrong. I also have another tach and both read the same. It might be slow to keep up but the max recall is correct for whatever rpm you hit the limiter. I do not think that rpm will hurt a 1050 motor. In fact myself and several other people are waiting for a flash to come out to raise the limiter because the power curve keeps going up to 9400 rpm and Yamaha set the limiter to low.
 
Not going to argue what RPM is safe but 9,400 would make me nervous. Blow a belt and you will see a few hundred RPM on top of that. Hope no one has a weak valve spring!
 
Just so you know I never hit rev limiter even at 9160. I believe the factory re flash might have moved limiter up some. Anyone else seeing this also?
I would never run on rev limiter constantly. No reason to. Guys two strokes we all commonly clutched within 50rpm or better. We have at least 100 or bit more to play with here. Take the time to get it done.
 
View attachment 103158 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.
Wow. How does the secondary look? What "minor" clutch tuning did you do? I will gladly try it. Maybe it will help me and others because stock and original ulmer setup with 8jp did not. Clutches looked terrible and never was consistent unless a new one was used every 500mi or so. What kind of top speeds are you getting with that Turbo? Worrying about hitting the Rev limiter is really kind of funny since that is the problem that most have stock! The cats are even worse than ours. They do it right out of box. Ours stock take awhile before it starts hitting it.
 
Very interesting thread, almost stickie worthy for everyone that is running a Ulmers kit. Just received mine for a rtx-le 2015, with a MRBP race can. Spec sheet set up is 6-2 secondary. And tungsten with 2 washers on the heel, and one washer on the tip.
I will install as is and try it out, just wondering if anyone else has installed this setup with success. I can't add anything to this discussion as there is next to no snow around here and none in the two week forecast , I have no issue readjusting weights later, just curious on the theory of the far heavier heel weighting than some are using.
 
Again I'm not using ulmers kit, but this year while clutching for the turbo I loaded the heel of my weights a bit heavier to keep it from hitting the rev limiter on a launch and letting the power build from like 8700 up. Sled just didn't have the snap I wanted, now with heels of the weights empty it winds right up very quickly and has way more snap.
 
I will only give one piece of advice on this because I don't need the argument. If you have questions on Allens kit, call Allen!
 
I understand. Allan is extremely buisy, seams buisyer than ever! Sounds like he will be getting cought up soon!
 
Agree as well, but I think it's important to keep the flow of info in this thread. There are many threads with weights and shim info on the clutching on the cheap mod, I have chosen to purchase a vendors kit and would like to hear results from people who are actually using these kits on their vipers. I believe it adds value to the kit, and there has been more then one person with questions if you read the thread from page one.

Besides, there is no snow so we are bored.:jump:
 
I need some help with general tuning questions....looking at brown grass.

What is the expected RPM change up or down from the stock secondary/stock belt going to the machined secondary/ulmer red spring in 6-2 position using stock belt?

What is the shift RPM change for each 1 mm thick shim added into the primary spring?

How much RPM difference is there between 6-1 and 6-2 wrap?
 
Last edited:


Back
Top