Conceptual questions By mcgyvre (Read 1,048 times)

[mcgyvre]

After reading a year old thread started by crazieness, I have decided that my local unarmed bandit, upon selling me the ONLY weight rollers they carry, sold me rollers WAY too heavy for my bike. She couldn't even tell me what the weight was on them, but mine were toast, so I didn't have an option to stay afloat. The question I want to ask in regards to crazieness' thread is this - does mixing weights really work this way? It seems to me that if I mix 3 lighter weights with 3 heavier weights, the 3 heavier weights will still push the variator together at the same time that 6 heavier ones would. What is the point of the lighter weights if this is the case? I recall reading somewhere a while back (probably a different, no longer consulted forum) that mixing weights does not work. Can someone (Alley - hint, hint) please explain the theory on this? Next concept question concerns drive belts. Am I understanding correctly when I think that the only difference in the 842 vs the 835 is slightly better low end AND top end? It seems to me that the shorter belt will not settle all the way down into the bottom of the variator at low end and the same in the drive clutch at top end. With respect to the belt exclusively, won't the 842 give slightly better low end and top end performance? Last question, as I don't want to overload one thread with too many questions at once - am I correct in starting with the CVT system to begin to increase my performance? I realize that this could be a matter of opinion for some, but if my tranny isn't delivering all my engine has, it's pointless to start anywhere but there. If this theory is incorrect, please, feel free to assault me verbally (nudge, nudge @ guitarman! : and set me straight. Along these same lines, it would make sense to do the exhaust system next. Basically, leave the engine alone until I have done all I can to deliver everything it can give - i.e. air intake, exhaust, CVT, fuel delivery, etc. before diving into electrical, i.e. plug, coil, CDI, regulator, and THEN go for the engine with valves, cam, carb and intake, and after ALL that, then look at BBK. Does this concept seem sound? If I have the right idea, is there a better order? It sure feels good to ask questions about improvements over repairs. All input is welcome. Okay, I lied. I have to ask one final question - is there any significant or specific differences between a generic QMJ157 and my BN QMJ157? I have a ZNEN 150T-9.

[Bashan]

The BN engine is sometimes called the GY6-B. It is specific for the 16" wheels. There's a few parts that are interchangeable with the QMJ157 but most are not.

You mix heavy and light weights to achieve a specific overall weight average. If you put three 10g and three 12g rollers in you in effect have six 11g weights. That's all it does. You must space them out evenly, don't clump three of the same weight on one side.

[mcgyvre]

Rich, I must be missing something about the weights. A certain weight will move outward at a certain RPM. Seemingly, a 14g weight will move outward at lower RPM than a 10g weight. Conversely, the lighter weight will drop sooner as RPM drop. I am just failing to grasp how this mixing of weights creates an average. On acceleration, it will act like the large weight roller as they will spin out before the lighter rollers. It also seems that the lighter rollers would drop down sooner as RPM decrease, leaving 3 heavier rollers taking all the load and pressure. Unless I am failing to grasp a basic concept, the only time these 2 different weights would share a common variator position is either at rest or once the RPM rise to the point that the lighter weight rollers RPM is reached to allow them to 'catch up' with the heavier weights that were pushed out sooner. Again, not seeing how this is an average, other than adding total weight and dividing by 6. I would expect the variator to react to whichever weight would react first. Even if the 3 heavier weights were not enough to force the variator together as soon as 6 heavier weights, the 3 lighter weights could not help until high enough RPM are reached to push them outward. What am I missing?

[Bashan]

The variator postition of the weights is always the same. The centripetal force pushes all of the weights out together, they are all in contact with the ramp plate and inner pulley at all times. So the heavier ones indeed have more force on the inner pulley than the others, that is why they average themselves out. Imagine just three thirteen gram weights in there, you'd have a force of 6.5g per weight. Add the three 11g weights and now you have more force, albeit less than the 13g weights, yet more in aggregate, pushing out against the pulley. It is like a strong guy and a weak guy pushing a broke down car, it still moves faster with the weak guy added even though he's not as strong. The CVT clutch provides a constant pressure on the belt via the torque spring. It squeezes the belt and pulls it down into the variator. That is what pushes the inner pulley back to the ramp plate when the RPMs drop. So the weights are never slack in there, they are always squeezed between the ramp plate and inner pulley, there is no dropping down or going out first, they march in lock step. There is always constant pressure on all of them at the same time and the force of the weights simply averages out. Even when the RPMs are dropping the centripetal force is still pushing them out. That force only stops when the RPMs stop. So you asked about an easy upgrade, switch to a higher tension clutch torgue spring. It holds the variator inner pulley back longer so you stay in lower ratios longer. That gives you better acceleration and hill climbing. But eventually the RPMs overcome the spring and you get your top end to boot. You can fine tune that by using different roller (or slider) weights. Rich

[Alleyoop]

Oct 23, 2014 8:28:59 GMT -6 mcgyvre said:

Rich, I must be missing something about the weights. A certain weight will move outward at a certain RPM. Seemingly, a 14g weight will move outward at lower RPM than a 10g weight. Conversely, the lighter weight will drop sooner as RPM drop. I am just failing to grasp how this mixing of weights creates an average. On acceleration, it will act like the large weight roller as they will spin out before the lighter rollers. It also seems that the lighter rollers would drop down sooner as RPM decrease, leaving 3 heavier rollers taking all the load and pressure. Unless I am failing to grasp a basic concept, the only time these 2 different weights would share a common variator position is either at rest or once the RPM rise to the point that the lighter weight rollers RPM is reached to allow them to 'catch up' with the heavier weights that were pushed out sooner. Again, not seeing how this is an average, other than adding total weight and dividing by 6. I would expect the variator to react to whichever weight would react first. Even if the 3 heavier weights were not enough to force the variator together as soon as 6 heavier weights, the 3 lighter weights could not help until high enough RPM are reached to push them outward. What am I missing?

I agree, just an example: If before you changed to 3 and 3 weights you had all of 1 weight say 13g and say at 7000 rpms you where doing 50mph and you then took out 3 of the 13g and put in say 11s or 12s. To reach the same top end speed say 50mph your RPMS would now have to be higher than 7000. Reason being is to get the variator to move out the same distance as with all 13 gram weights now you have less force at 7000 rpms due to only 3 weights actually doing more work to squeeze the belt up higher.

So in my opinion and .02 cents, mixing weights is not really doing you any good except producing higher rpms to reach the same speeds you were capable of with all the weights being the same. And may I add you could wind up loosing some top end, I know I did when I was experimenting with the cvt and mixing weights.
Alleyoop

[Bashan]

Right on Alley. The only reason to mix weights is to save money by buying a mix and match set to experiment with different averaged weight totals without having to buy all the individual weights, or achieve an odd weight average like 11.5g. The higher the aggregate weight total, the more aggressively the inner pulley is forced out. Mixing them does not alter the pulley advancement profile. Progressively angled ramps do that, or a different main spring. Rich

[drahken]

the whole weight pushing on the outside of the variator when it reaches a certain amount of force overcomes the contra spring in the rear driven pulley of your cvt.

if all the roller weights where one gigantic block. and you cut off a slice. its like instead of 6 x6 grams 36grams in your variator. itd be like 3x6 3x7 6.5 x 6 39grams... did i add that right?

see the rear driven pulley in the cvt is using the contra spring to keep the belt from going down in the back. and its going to take so much force. if you took it off and wrapped the belt around the driven pulley maybe.. like, nailed it to the wall, and then grabbed the belt and pulled it to the bottom of the driven pulley thing. if you where to take a scale. it would take. so many ft lbs.

the front shifts it by the roller weights in that variator with the ramps. the centrifical force, when it spins, adds up to ft/lbs. of troque. when you get up to your driven pulleys give point, the freaking variator shifts, and off you go into 2nd gear.

ive mixed max for me 7 gram and 5 grams roller weights. that much of a difference.

see if youy took and pulled the belt to the bottom of the driven pulley. and used a scale, and figured it took 50ft /lbs, a random number, ok. so no matter wht it takes 50 ft/lbs until the spring in the back starts to wear and become weaker.

so it doesnt matter if you pull the belt by hand, at 25ft/lbs and someone else you get to help you does it too, at 25ft/lbs. the freaking driven pulley is going to be shifted. if you do it yourself its the same. so it doesnt matter.

[Alleyoop]

SAY WHAT!! So what are you saying are you agreeing with me or what
Alleyoop

[Bashan]

I think he's a freaking politician!

[Guitarman]

Simply put, the variator requires X amount of weight to push it out. More pushes faster, Less weight, slower.

The slower it goes out, the better your low end. The faster it goes out, the better your top end.
Take your pick.

Personally, I'd start with the engine itself as far as upgrades go. If you plan on doing a BBK or something, do it now because it will change everything else. THEN do your tranny and exhaust.

So;

1. Engine upgrades
2. CVT Upgrades to match new engine. (Belt, weights/sliders, final gears..)
3. Exhaust to match new engine.
4. ONLY if you have a limited CDI, then change it for an unlimited one.  Not a massive difference, but it will get you more rpm's.

This should give you the most bang for your buck.  Or is that bangin'?

[Alleyoop]

Simply put, the variator requires X amount of weight to push it out. More pushes faster, Less weight, slower.

The slower it goes out, the better your low end. The faster it goes out, the better your top end.
Take your pick.

SAY WHAT!! So what are you saying are you agreeing with me and rich or what
Alleyoop

[Guitarman]

Yes, I'm agreeing with you Oopster. It's just that the poor guys head was swimming with all that techno babble. Had to put it into street English.

Ah.... Mis-spelling...

[cyborg]

Poopster?? what???

[mcgyvre]

Oct 23, 2014 18:46:26 GMT -6 drahken said:

the whole weight pushing on the outside of the variator when it reaches a certain amount of force overcomes the contra spring in the rear driven pulley of your cvt.

if all the roller weights where one gigantic block. and you cut off a slice. its like instead of 6 x6 grams 36grams in your variator. itd be like 3x6 3x7 6.5 x 6 39grams... did i add that right?

see the rear driven pulley in the cvt is using the contra spring to keep the belt from going down in the back. and its going to take so much force. if you took it off and wrapped the belt around the driven pulley maybe.. like, nailed it to the wall, and then grabbed the belt and pulled it to the bottom of the driven pulley thing. if you where to take a scale. it would take. so many ft lbs.

the front shifts it by the roller weights in that variator with the ramps. the centrifical force, when it spins, adds up to ft/lbs. of troque. when you get up to your driven pulleys give point, the freaking variator shifts, and off you go into 2nd gear.

ive mixed max for me 7 gram and 5 grams roller weights. that much of a difference.

see if youy took and pulled the belt to the bottom of the driven pulley. and used a scale, and figured it took 50ft /lbs, a random number, ok. so no matter wht it takes 50 ft/lbs until the spring in the back starts to wear and become weaker.

so it doesnt matter if you pull the belt by hand, at 25ft/lbs and someone else you get to help you does it too, at 25ft/lbs. the freaking driven pulley is going to be shifted. if you do it yourself its the same. so it doesnt matter.

Whatever you been smoking, keep it away from me. I'd be very concerned with whoever can make sense of this. I am quite certain you understand what you are saying, but, for goodness sake, who slices weights? Until someone I trust tells me differently, I will continue to believe that the heavier weights will react first, then strain to overcome the contra spring until the rpm increase enough to let the lighter weights help. No matter how you slice it (lol), it will always be 6 of the same weight and it will always be a tightrope compromise. Thankfully, I have been around long enough to know who I trust. Thumbs up, gang. Thanks!

[drahken]

im not explaining for your benefit. trust whoever you want. you asked the question, how does a cvt work. cause you didnt know how it ran and didnt know if or why putting multiple weights in done anything.

as im telling you nothing will happen. ive put a spread, and thats all thats really talked about mixing weights. or, maybe some of the lingo im using too you might not get, like rollers, sliders.

mixing rollers and sliders., ...

anyway, you would since the variator spins like a plate, want to even and space out any mixed roller, "weights". roller weights is a things. weights" , is, just single rollers, each one individually.

you can do it just spread them, of course, even. who cares. and the spread, on weight distribution, ? i dont know. ive said i done 2 grams, a 2 gram spread, 7g 5g.  as in my 6 weights, as in the scooter thingey roller weights", where 7's and 5's.  3 7s 3 5's mine took 6 roller weights.  half, half.  

ran ok, for me.