I recently ported the cylinders and I will be running Bill Cudneys piston kit. Boyesen petals in stock cages and reed spacers. Gearing is stock. Aftermarket can, Top rpm will not change by these mods. I am running the EPI clutch kit. Are there any mods i should do to the clutch to take advantage of the engine mods? This is used mainly for ditches and trails, which is what i would like to clutch for.

I would run the sled first to see if there is any chnge. If any it should over rev. Then it will be as simple as adding weight to the pins since you already have a kit in there.
:hallo7:

youll probably be adding weight.

Thats what i thought, I already have a pin weight kit from Goodwin. How will I know when I have enough pin weight? And what will I be looking for the machine to do when I add more pin weight?

Thanks

Just keep adding weight until the engine rpm is too low. Say you make a run and rpm is right on, add another gram and try it again. If the rpm is still right try another gram. keep going until the rpm is just too low and never reaches the desired peak. Then you have enough weight.

Rad Chad- Thanks thats exactly what I was looking for.

*joe throws wrench into conversation*

You will know you have enough or more than enough pin weight when the engine falls below its peak rpm that you want. ideally you will use the weight "required" to keep your engine pulling at the rpms you want.

You could be out on a lake/road/field, wherever, and testing the weight you add, drag racing the sled and running it to top speed where it will go no faster for a 1/4 mile or 1/2 mile or more.
You might be surprised by the amount of weight you put in as your acceleration could be better thru the midrange as such and may have gained a few mph on top.
So now you think you found the right flyweight because your sled runs like gangbusters on this flat ground.

Now you have this setup completed and go out on a trail where there is deeper snow, and rolling hills where you can get midrange speeds of say 50 mph and drive safely. You come down a hill, let off the fuel to go thru the bottom of the hill, then get on the fuel to accelerate up the hill...
...You just lost a few hundred rpm and the engine just hangs there until you get over the top of the short hill.

You get that sinking feeling wondering what the hell is going on???


...now what? :hallo2:

I'll take a stab... When you add the extra resistance " from the hills" and variation of the " on/ off" throttle to a setup that was very good on flat event. What you have now is setup that is thrown into a different environment than intended for use and acts like it's in the wrong gear. If your secondary dosen't have the right "sense" to put you where the RPM's stay the same in a situation like this, you need a different helix to put you where the RPM's a maintained throughout. This is where a helix with a shallower end angle will help with the "backshift" and keep you in the right "gear". -Grover :withstupid: :p

I concur...

Like he said. -Grover :hallo3:

umm uhh...it's just a theory.
...i might have been drunk. :hallo4:

I know it helps. Why did edit all that? Grover :hallo7:

Well I read what I typed and I understand it from studying that "hot pipe, cold pipe" and what it does to clutching...

then reading "yeah what he said"... I thought, oh here we go, once again I'm opening my big mouth going right off into the wild blue yonder when you explained it pretty good already.
...i have a disease...its called "elaborating"

hahaha...

sorry! :hallo5:

Yeah, but you do it well! I enjoy your post and the "extra" you put behind it. Some people think out loud and some write out loud. I'm the former not the latter(hate this typing thing). Keep it up! How's the racing thing going? -Grover w00t

I got a few emails asking to put this back....


Lets look at some parameters here...
You could be out on a lake/road/field, wherever, and testing the weight you add, drag racing the sled and running it to top speed where it will go no faster for a 1/4 mile or 1/2 mile or more.

You run the sled like I mention going across the flat stuff, there may be little load and the sled can pull the flyweight you throw at it. Look at the time that you test going Wide Open Throttle... HP increases as pipe temperature gets hotter. Many sledders know that when they can run their sleds for a long time the sled just seems to get faster and faster. The pipe gets thermally efficient and the engine makes gobs of hp.
...But, you suffer torque in lower rpms.

So now with the same flyweight you go running thru these hills or deeper snow, you have to let off the fuel to drive safely, you get back on the fuel and engine just hangs there at a lower rpm. You go up the hill, the speed maintains, the sled does not accelerate and the engine just stays at one lower rpm, maybe slowly climbing.

Engine is making less torque, the primary is pushing very hard and the secondary does not compensate backshifting to let the engine maintain a higher rpm.
From my experiences there are a couple of things to do to get the engine to climb back up to an rpm required...
Smaller angle helix needed for the speed the sled is going "at the speed where you had the bog or low rpm"
OR
Just a simple clicker change...
...or maybe a combo of the two.

With the helix change it will resist better the push from the primary, the rpms will be higher. The secondary just won't let the primary push so the engine cannot do anything but rev higher, staying into the power better. This way you get more work to maintain and/or accelerate thru the heavily loaded area.

With the clicker change you are making the resistance to the flyweight pushing from the ramps having an increased angle. The flyweight has a harder time to climb up this increased angle so the engine has to produce more rpm before the primary will start to push the secondary open.

Going back to the helix bit you know that the engine is making more power but torque is down. A smaller helix angle is required when you are on the fuel.
Depending how long you let off the fuel determines how much you slow down. The pipe cool's in temperature and the torque will increase. So now with this lower speed and lower temperature, you want to take advantage of the torque by using a larger helix angle. The helix makes the engine work harder, the engine works harder, the pipe gets hotter, hp increases and as the hp increases you want to utilize a "required" angle for the torque available at the speed you are going.

You don't want to use a 50 angle to go 70, 80 or 90+mph, right? But maybe a 37 could be the required angle to go that fast. You don't want a 37 angle anywhere in the bottom of the midrange, because there would be rpms like crazy and no acceleration. The rpms would be high and you miss the opportunity to capture the torque that happened way back there.
So say for lack of better numbers a 50/37 would work better than a 50/44 for all around use.

Mudwiser writes:
This is used mainly for ditches and trails, which is what i would like to clutch for.

Ok so it sounds like you will be doing most of the driving in rough terrain and high loads. What would you want to clutch for speeds of 30 mph to 80 mph in rough stuff where you need the power at your thumb tip?

As far as mods go, I would go ride the sled in the areas you ride 90% of the time and make notes of what you don't like of how the sled runs. Then from there you can make a decision on what to do next from the symptoms you seen. You'll make a change to compensate for the things you don't like of your sled.