I have a 2001 SM400. Immediately I did not like the primary engagement RPM. The 425 engine felt like it had more to offer on the lower end than maybe it was given credit for. So I decided to experiment with the shift weights. The 400comes with 10BH weights, I changed to 10MH which are 3.5 gr. heavier. I noticed a change and at first I was pleased with the results, the engine did not have to rev so high and it did not seem to have an extremely negative effect on the low end torque. But now I am not so sure it's where I want to be. What other configurations (ie. spring changes or settings)can I do with the clutch to tweak out a little better performance out of my beloved yellow 400 ?

White City

 

This is something I didn't think about until just now. You said it was like when you were already moving, then got on the throttle, it didn't seem like your rpm's would come up for good acceleration. If this is so, then you could change your spring setting in the secondary to a stiffer shift. With more tension here, your engine will have to rev a little more in order for it to pull itself through the gear changes. This in theory will not change your engagement but just slow down your shift, making the engine work a little more for its gear changing. You may notice a slightly slower shift however you should also notice a little more torquey feel.

 

I would try a green primary clutch spring first, and go from there. Cost is about $15-$18.
Takes 10 minutes to change once you get the belt cover off
and only a few bolts to turn

If you can change oil, you can change this spring

Only you WILL raise engagement RPMs just a bit

Woke up my Xplorer enough to definately tell.

If you want more details, I can give you more

Farmr

 

Try what elroy said first its free. The spring in the secondary clutch should be black and in the two and two positions of the helix and sheave. A stiffer setting should raise the rpms of the upshift but affect nothing else. I have tried the green spring on my HO and didn't like it much. Since you have added heavier weights the white may be worth a try though.

Good luck

 

Shaggy is right. For the 4 strokes, go with the white spring first. I had a brain spasm & thought when you said 400, you had a 2 cycle 400.
Sorry about that.
If you don't need much, just a little 'tweaking' I would try changing around the tension in the secondary clutch. I have heard they don't tune as easy with the EBS clutch as without, but maybe it is just because people don't have as much experience with them yet.
Good luck

 

Save the headache, and save the hassles. Call HPD 763-389-3336. They test these machines over and over. They'll hook you up.

Ken P.S. no, I don't get paid by them. I use their products, they work great, so I steer others their way.

 

There is a lot of mis-information about the driven clutch. Do Not "ever" change your driven clutch if you want to change engine speed. That only causes the secondary to become inefficient and creates eventual loss of power to the rear wheels. If you want to change the rpm's work on the drive clutch only. Adjust the drive clutch first via spring and then flyweights to get the correct engine rpm. If you want to lower engagement, do so with the proper drive spring and then flyweights to control the shiftout rpm.

By makng the driven clutch "work harder" to shift out only makes the clutch setup less efficient. What you really want is to be able to upshift as quickly as possible by pulling the heaviest weights it can and still be in the proper power range of that engine / pipe combo. Too heavy of flyweights can cause an engine to bog, and/or not accelerate quickly also.

Also by tightening up the driven spring you lose efficiency providing that the sheaves are gripping the belt correctly without slipping in the first place. This tightening requires more rpm to overcome that extra tension which results in a power loss. It may work for a one time "quick fix" to adjust rpm but the loss is still there and will reduce power output. Only adjust the driven clutch to get the right amount of backshifting that you need and to keep the belt engaged and not slip against the sheaves. Belt slippage and/or overtension will cause a heat buildup in the secondary and tremendous loss of efficiency. It can also cause premature clutch/belt wear. You need just the right amount of tension, more tension doesn't help at all. Adjust the drive clutch first via spring and then flyweights to get the correct engine rpm.

When a roller secondary is used you need more tension to make up for the achieved efficiency and lack of friction of the roller bearings. The rollers less friction requires more pretension then to get the correct amount of backshifting. But to do this on a conventional clutch is counter productive and will result in poor acceleration, backshifting and lower top speed.

I'll bet that this causes more power loses than any clutching mistake. It's a case of where more tension is not always better.

Trader Jack
www.godigital-design.com/schultzmotorsports

 

I have a 2001 Scrambler 500 4x4 and I called HPD and talked to one of thier people and told him how I ride and let him recommend what I needed
they pretty much specialize in this area. All in all I received my kit and installed it in less than an hour start to finish. I'm very happy with the results.

01 Scrambler Ugly duckling muffler, pipe, jet K&N Clutch kit(springs and weights)

 

Thank you Jack, for reminding me of that. I knew it, but forgot for a moment.

Yes, yes, the FRONT pulley should be adjusted for operating/accelerating RPMs and the rear clutch messed with only if you need to change the backshifting.

 

This is out of the 2001 Polaris sportsman 400/500 duse & H.O. service manual.

"The driven clutch, helix/movable assembly has several different spring locations which affect clutch shifting and RPMs. The greatest amount of spring tension will raise engine RPMs during clutch upshift and allow quicker backshift or downshift when pulling or negotiating a hill, for example. The least amount of tension will create a slower downshift and a harder upshift."
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The two and two setting in the 400 sportsman's driven clutch can go only one setting higher. The two and one is the heaviest setting. I am curios as to how this small change could cause any of the belt/overheating problems outlined in Jack's post?