clutch\rollers

[CRBOGGAN]

Have stock drx90. I just put in a new ztr 1500 spring and koso4.25 rollers. First thing is what was weight of stock rollers?
What size is stock spring? The new spring is about 3\8" longer
when put side by side. The stock setup was great just want to go back as close to it as I can. Reason for putting in new was at a race last night after 3 laps when he came by bike sounded like it was slugish and not throwing up a roost. Am I working in the right direction? Thanks for any help.

[dericsdad]

Your old spring was worn-out, which is why it is shorter.

Is it air or liquid cooled? Any porting or other mods? Pipe?


Try going to 4.5/5 gram rollars staggered. if your all stock it should be close with that spring... maybe even all 5's. You'll have to experiment a little.

[CRBOGGAN]

No mods L\C. Just tried it out all seemed good with 4.25 rollers. But may try heavier just to learn.

[CRBOGGAN]

marked pulley with marker and had my son make a wide open pass about 300' turn and come back then shut down bike removed cover. It still had 1/4" mark left. Is this about right or should I try heavier rollers? Bike left out good spun tires on the pavement.

[bulldogfallon]

CVT advice needs to be taken carefully.....

Personally I believe 300' is too long of a distance for testing, but it does show that your belt travel can be better.

The roller weights in relation to the torque spring set your shift speed (how fast and at what rpm your pulleys shift at)

Best advice is to get a tach so that you can see what each change means to your set up.

The lighter the weight the higher the rpm you will shift at...which means you can go right past your peak power and make less hp than with the heaveir rollers.

If you put heavier rollers you will lower your shift rpm to a closer number to where the stock set up makes power.


Do yourself a favor and get a tach on that quad...

Change rollers and watch the rpms change at marked distances and it will start to make sense in no time.

There are many other factors to successful CVT tuning (variator, belt type and length etc)

For most of our stock 90cc applications we were arounf 4.75gr with the ZTR1500 spring, but each machine has it's own quirks.

We have a couple CVT articles in our tech area...try reading the one from Stage 6 and see if it helps.

The pic from that one says the most to me...it shows the rpms rising and then it flats lines at an rpm (shift speed) and then once the pulley sfinsih shifting the motor takes back over and rpms rise again.

The idea is to make that flat line (shift speed) right at or below your maximum power rpm.

This allows the engine to run at once rpm (peak power) while the pulley shift (providing the increased speed w/o more rpms).

Good luck :)

[bulldogfallon]

Originally posted by CRBOGGAN
marked pulley with marker and had my son make a wide open pass about 300' turn and come back then shut down bike removed cover. It still had 1/4" mark left. Is this about right or should I try heavier rollers? Bike left out good spun tires on the pavement.


I don't believe in tuning solely for belt travel...you either have it or you don't..but you can always try other components to see if they help achieve the higher ratio for more speed.

Rollers weights set shift speed (rpm that the motor locks at while the pulleys change ratio)

If this is the case,then changing the rollers for the sake of belt travel could also sacrifice youe shift rpm.

Ex)

If you ran 5 gram rollers and your shift speed was 10,000rpm...but peak power was made at 10,500...

Could you achieve more belt travel with a lighter roller weight?

Yes---The lighter roller weight would allow your shift speed to be closer to 10,500, so you have the potential to make more power and more rpms providing the potential for more belt travel.

The heavier roller makes the quad shift below peak power, so the only time it would achieve peak power is after the pulleys shift out and the motor takes back over....really not usable power on the track.

But you 300' test may be deceptive in the results.....cause it could give the engine time to take over and pull again providing belt travel...but not within a usable distance.

[drxracing]

WOW!!!!!!!

[bracey]

bulldogfallon can you tell me where i can find the tech articles that you are talking about

[dblacks]

http://www.g-forcepowersports.com/faq1.html