Suzuki Burgman USA Forum banner

1 - 20 of 21 Posts

·
Registered
Joined
·
52 Posts
Discussion Starter #1
Has any one played around with heavier rollers in the variator. I don't care about sliders, or lighter rollers, just heavier rollers, say 23g or heavier. If so what were the results?
 

·
Registered
Joined
·
1,479 Posts
Lighter roller weights = faster take-off acceleration, lower top speed.
Heavier roller weights = slower take-off acceleration, higher top speed.

This is the general rule for roller weights in a CVT. Of coarse other factors are in play such as the contrast spring strength and variator ramp angles.

What are you wanting out of your Burg? That is the question. If heavier weights give you that then you will be happy.
 

·
Registered
Joined
·
52 Posts
Discussion Starter #3
I have been tuning 2-t scooters for 15yrs, I understand the basics. What I asked is if anyone has played around with heavier rollers, or anything over 19grams and what were their results.
 

·
Registered
Joined
·
3,396 Posts
Thing is, few riders want to stress their engines for the sake of 0.1 mpg.
 

·
Registered
Joined
·
3,396 Posts
By moving rpms out of the sweet spot. Remember this ain't a Harley Potato House -- a bit younger and spirited engines.
I guess it's OK to increase roller weight a little if your on the light side of the pond.
 

·
Registered
Joined
·
52 Posts
Discussion Starter #7
Bolzen- Please explain how it stresses the engine and you can get real technical, I understand the jargon.
Where is the sweet spot?
What is the light side of the pond and what is the pond.

Thanks
 

·
Registered
Joined
·
1,489 Posts
I believe "light side of the pond" is possibly a reference to rider weight.

I've been running 20g sliders because that's all I could get locally when I did my swap. I don't see much if any difference in performance from the stock 19g rollers other than the rpm drop ( which was my goal). Right now I'm at around 45K miles (43K of them with sliders) and I find the engine feels a little bogged down until I'm at 55 mph+. Running 40-45 mph @ 3.5-4K rpm, I notice more engine vibration which I equate to more stress on the engine. This particular speed vs rpm characteristic is a recent phenomena for my scooter. I think it results from the combined effect of my worn set of driven plates (45K miles on them) combined with my new variator plates (< 6K on them). While this may not correspond exactly to what you would see with 23g rollers I think it is indicative of what lowering your engine rpm does. Personally I think that you want the engine to be running 5-6K rpm at your typical riding speed. I was seeing that when my plates were fresh and I had 20g sliders. I think if you went with 23g variator weights, the transmission would start gearing up at rpms that are too low on the engine performance curve. I can't give you exact figures but the sense that the engine is straining more is easily perceptible when running at or below 4K rpm at speeds above 40-45 mph.
 

·
Registered
Joined
·
3,396 Posts
You place much heavier loads on bearings when lugging the engine -- that generates heat and leads to frictional losses.

Now if the load is big e.g. with a heavier rider and you want to accelerate, the scavenging of the chamber is poor, hot gases stay longer in the cylinder which transfers the heat to the walls. So the optimal range depends on several conditions but hardly ever lies on lower rpm.

The worse thing is that Gaz wants to change only the roller weight, but rollers don't have a 'lowering gear' effect.
 

·
Registered
Joined
·
52 Posts
Discussion Starter #10
Chatman- Thanks for telling your experiences, it was interesting and helpful.

Bolzen- You have no idea what you are talking about and certainly not how a constant velocity transmission works.

"The worse thing is that Gaz wants to change only the roller weight, but rollers don't have a 'lowering gear' effect."
Since you say I am going the wrong direction, what all does need to be changed?
 

·
Registered
Joined
·
3,396 Posts
Gaz, you didn't ask about transmission but engine lugging. Dunno what are you waiting for -- put in 50g rollers and be happy at last!
 

·
Registered
Joined
·
52 Posts
Discussion Starter #12
Gaz, you didn't ask about transmission but engine lugging. Dunno what are you waiting for -- put in 50g rollers and be happy at last!
This reinforces my statement, because you can not lug the engine without lugging the transmission.
 

·
Registered
Joined
·
1,489 Posts
how a constant velocity transmission works.
Just a minor clarification. I'm pretty sure CVT refers to Continuously Variable Transmission.

But to the original topic...

You basically have three potential variables in play. The engine rpm, the weight of the rollers/sliders and the torque load on the driven plates. All three interact to deliver the end result. Increase rpm attempts to drive the variator plates together. Counteracting this is the spring force in the driven plate assembly and the effect of torque causing relative rotation of the driven plates to each other. This relative rotation of the two driven plates in reaction to the instantaneous torque demand adds to the spring force to attempt to keep the driven plates apart. Increasing your roller/slider weights in effect adds a scale factor to the rpm contribution so things tend to start transitioning at lower rpms. At the operational endpoints things will be pretty much the same, e.g. initial rpm vs speed and cruising rpm vs cruising speed will not change much for a given system, either sliders or rollers. The weight of the rollers really comes into play with how the scooter behaves during acceleration and in the middle speeds.

Not excruciatingly correct, but reasonably good for imagining how stuff works.
 

·
Registered
Joined
·
52 Posts
Discussion Starter #15
Chatman- The " constant velocity" remark started among my friends who all ride as a ribbing to me because of the sound the scooters make which is a constant drone under acceleration. I have heard it so much, that now I refer to it as such, but I do know the correct name for CVT. You have to admit, they do make a constant droning sound.

The statement was made that if a person changes the roller weights much heavier than factory that it would stress the engine and I wanted to know how?
 

·
Registered
Joined
·
1,489 Posts
The Cliff Notes version is that you are holding the rpms down during high load events increasing stress on the engine. To what extent is debatable. Forum member Quantum Mechanic (search on his posts and you certainly find some references) is probably the most knowledgeable in this area.
 

·
Registered
Joined
·
52 Posts
Discussion Starter #17
Chat- As I posted earlier, I have been tuning two stroke scooters for a long time. I am presently playing with one where I have gone up 80% on the roller weight from what the factory installed and it is carrying 100lbs more than max load capacity all the time for the last 25,000 miles. It runs great and I have had no problems ( it runs like a scalded dog with a 135lb person aboard) . That is the same as you putting 34.2g rollers in the 400's variator, then pile the weight on. I also know of hyper milers that have gone considerably higher in roller weight than the 21g that is available in the interest of gas mileage with no ill effects. The CVT handles all this very well. Theory vs reality.
 

·
Registered
Joined
·
1,545 Posts
Chatman- The " constant velocity" remark started among my friends who all ride as a ribbing to me because of the sound the scooters make which is a constant drone under acceleration. I have heard it so much, that now I refer to it as such, but I do know the correct name for CVT. You have to admit, they do make a constant droning sound.

The statement was made that if a person changes the roller weights much heavier than factory that it would stress the engine and I wanted to know how?
Hi qaz, you ask the question. Chatman is about right in what he is saying. The heavier the weights the more this may stress the engine. It depends how heavy you go and what sort of riding you do as to whether this is a problem. You'll find the burgman 400 engine a bit different to what you are used to. Ok so why does it stress the engine? All the Burgman 400's are short stroke engines. As you may know, this means they have low piston speed inspite of high rpm. That's compared to a long or longer stroke motor. This makes it a lowly stressed engine even when cruising at high rpm. It's happy and will last and last! This means the engine is designed to rev to be efficient, develop it's power, and importantly, to last a long time. For example, one of my customers put 21g slider weights in his 2008 400 and it laboured in the sort of riding he did. It felt like the bike was overgeared and it wasn't developing the power it needed. Sure it cut the revs down, but too much for most of his riding. He was revving at just under the 6000rpm mark at actual 70mph (indicated 75). This was making his engine labour. It was like riding in too higher gear. He was using more fuel not less. Headwind slowed him unless he wound the throttle wide open. Not good. All this was causing his engine stress. Short stroke high revving engines don't like low revs under load as it increases compressive wear factors on the engine bearings and piston/rings etc. It can have a significant effect on engine wear, increasing it exponentially. How much it may affect a particular engine depends on how it's ridden ie: country roads mostly or highway work at speed. Also whether the bike is used two up or solo and the weight of the rider too. You prolly know all that though. So choose your weights carefully. Others on here have tried 21g plus and found them to be unsuitable, overgearing in effect the bike for normal cruising. But others have found the sweet spot weight for them and the way they ride. Good luck with what you want to do and let us all know how you are getting on with it. You may have to experiment a bit to find what you are looking for.

PS. just one point. All my experience of slider weights and rollers has been with the later 2007+ bikes. Some on here may recommend a good weight to go for on the earlier bikes.
 

·
Registered
Joined
·
2,787 Posts
Just a minor clarification. I'm pretty sure CVT refers to Continuously Variable Transmission.

But to the original topic...

You basically have three potential variables in play. The engine rpm, the weight of the rollers/sliders and the torque load on the driven plates. All three interact to deliver the end result. Increase rpm attempts to drive the variator plates together. Counteracting this is the spring force in the driven plate assembly and the effect of torque causing relative rotation of the driven plates to each other. This relative rotation of the two driven plates in reaction to the instantaneous torque demand adds to the spring force to attempt to keep the driven plates apart. Increasing your roller/slider weights in effect adds a scale factor to the rpm contribution so things tend to start transitioning at lower rpms. At the operational endpoints things will be pretty much the same, e.g. initial rpm vs speed and cruising rpm vs cruising speed will not change much for a given system, either sliders or rollers. The weight of the rollers really comes into play with how the scooter behaves during acceleration and in the middle speeds.

Not excruciatingly correct, but reasonably good for imagining how stuff works.
This is just about the only post in this thread that displays intimate knowledge of how the CVT (Continuously Variable Transmission) drive in our scooters, most scooters, and most snowmobiles works.

The only thing I would add is that the weight of DRP sliders does affect overall behaviour because of their distinctive shape and the fact that their "sliding" has affects the variator's pitch diameter in a way that rollers cannot.

I have run sliders between 15 g and 20 g and and the difference in acceleration and rpm at higher speeds is immediately noticeable and nearly "dramatic". Having done that I settled in on four 15 g and four 18 g sliders as the optimum for my '03 and my taste, maximum acceleration with any consideration of fuel economy "thrown out the window" (if there were a window to throw it out of)...
 
1 - 20 of 21 Posts
Top