Does anyone know of another way to drop the engagement rpm, and still pull full RPM on the top.
I tried heavier weights with springs that have a low pretension and higher than factory end load(Dalton Blue 3/155) I was able to get the desired engangement (1350 rpm) but there was too much engine load to rev up all the way. That was with a 56.7 gram weight (really big for a 500 HO)
I dropped more weight to a 51.7 and my engagement rose to 1450 rpm but peak revs were 5700, way too low for the 500 HO
I dropped more weight to a 47.2 and my engagement rose to 1800 rpm but revs like a raped ape 6500 rpm easy
If I slowly roll on the throttle on the engagement is over 2000 rpm

I was thinking it may be possible to shim the primary sheaves closed a bit, however this may be tricky to avoid creep.
Kawasaki primary spring seems to be a bit lower engagement but I'm not sure how much difference this will make, I need to make up about 500 RPM.
One thing I might try is really load the weight on the lowend hole and lighten up the midrange and top end holes. This will probably drag the rpm down a bit until 20 mph then the engine will rev fast after that.


Any ideas on manipulating the engagement rpm please feel free to speak up

Brambles

 

did you try talking with Dalton.? or give Rick Ritter a ring....

 

Haven't talked to Dale about this yet, he's a hard guy to get a hold of.

I don't really want to bother Rick Ritter since I didn't buy any of my parts from him.

I see a bunch of guys trying to get a higher engagement but rarely see anyone trying to get a lower than stock engagement, this goes with the fact that there are not that may primary springs on the market that have a lower pretension than stock

I bought my Dalton blue spring thinking it had quite a bit lower pretension than stock, after reading Rick Ritters primary spring chart it is clear that the difference in pretension between the blue and the stock is very little, and it only affect the shift out rpm.

Back to the drawing board

Brambles

 

What is your secondary set at?You might try a step lighter on that with the set up you have that engages where you want it too.You will be looosing some back shift but it should gain rpms on top.

 

EBS secondarys don't have the torsional adjustment. I was somewhat shocked when I took it apart an found his out.

 

Im in the same boat as you, i want to lower the engagement on my scrambler....

i cant find any ways to do so, then im again im pretty dumb when it comes to clutching [img]i/expressions/face-icon-small-wink.gif[/img]

 

If you want to know a lot about how the clutches work do yourself a favor and purchase Olav AAens Clutch Tuning handbook.

It basically boils down to this. Engine max RPM is controll by the weights. Too heavy weights your max RPM is lowered. To light of weights and over rev. Now that works if you have the right springs to allow full shift out. You need to find out what RPM your max HP / torque is at.

To control the engagement RPM you need to go with a spring that has a lighter tension at idle. If you like your max RPM and have verified you are at full shift out then find yourself a spring with lighter tension at engagement but has the same tension as your current spring when compressed at full shift out.

You need to find the spring chart for the stock spring installed pretension (and fully compressed) and get one that is slightly lower than stock. Keep in mind that springs to tend to relax over time and heat.

I made up my own spring tension measuring set up. If you have a drillpress and a bathroom scale you are in business. Put the scale on the drillpress table and a piece of flat metal to protect the scale from the spring. Have a tape measure and compress the spring with the drill press until you are at engagement length and read the pounds on the scale. Crank it down further and measure the length of the spring for full shift out. Plot it out for all of your springs and you should be able to tune the primary to anything you want. A lot of trial and error. Makes buying a clutch kit look pretty easy, (let someone else do all the figuring).

Thats why it is important to know if you have done any engine mods to know where your peak horsepower / torque is realized and tune your clutching to make use of it.

Good luck

 

I do have Olav Aaens clutch book, the problem is try finding a lighter spring, The only spring that is lighter than the one I am running now and still has decent shift rpm is the Kawasaki 700 spring but I have yet to see any specific load data for this spring.

Olav Aaen and Lonn Peterson both mention to tune to top rpm, where most power is produced. They mention not to worry about engagement right away because there are different methods to adjust this. However they don't explain these different methods.

I found the Aaen book somewhat helpful but being aimed at the snowmobile industry it doesn't address the issues with the atv's.

Brambles

 

good post, xcrider[img]i/expressions/face-icon-small-cool.gif[/img]