[BackOnABikeAfter40years!]

Ok, so about 75% of the way back home on my return journey, around Amarillo, I noted that all of the sudden, my RPM's didn't drop at highway speeds like the Scoot had done consistently since about mid August when I installed the Dr Pulley 21g sliders & new OE Suzuki Belt + Malossi Yellow clutch spring.

Until that point in the trip, the RPMs were consistently around 6200 - 6400 for 74mph indicated.

Now, it's at 6800 rpm for 65 indicated, quite a downgrade.

When it first did this, it seemed to be stuck at this new higher rpm setting, then for about 20 miles, it re-functioned as before, with lowering RPMs - btw it almost feels like hitting the Overdrive button (WHEN working well).

Now, my conditions were totally demanding, IE I was battling headwinds, speeding Semi trucks, along with being fully loaded down, so I was probably pushing the edge of what this modest sized Scoot is capable of.
Probably she was operating at 98.5% of capacity.

Btw, other than the RPM's it runs at now, it all functions well, clutch action is smooth, no chattering.

So I was thinking / guessing what could have happened:

- Did I glaze my belt or burn the edges so now it rides lower in front pulley, from excess loads ?

- Did the Sliders wear the ramp edges to a sharp point, and now it restricts how far apart the front variator mech can spread ?

- Did something happen to the rear clutch, like the Malossi spring gave up ?

I'm not happy with it as it is.

This engine IS a high revving unit, so this doesn't preclude my using it, just makes more RPM's & slower cruise speed. And yes, MPG took a hit, it's now not at 65 mpg as the most of the trip was, but spot on 59-60 mpg, due ot the higher revs I'm sure.

My plan is to disasemble the CVT in search of the issue.

I'll have new Belt on hand, just in case, and I'll also obtain a new Suzuki factory CVT filter unit.

But hoping for insight on potential causes from you guys.

Many thanks ahead of time,

David

 

[JRoss]

my money is on a flipped slider or two.

 

[BackOnABikeAfter40years!]

my money is on a flipped slider or two.

Can they DO that ?
I mean they're sliders not flippers !
Confused in Texas

 

[JRoss]

Can they DO that ?
I mean they're sliders not flippers !
Confused in Texas

 

[JRoss]

before you pull the variator out, get a good grip on the ramp plate to keep the sliders in place, carefully set it down ramp plate up and remove the ramp plate.

 

[BackOnABikeAfter40years!]

Ok, I see it TY for pic.
Is there a particular cause / how to prevent in future ?

 

[JRoss]

Ok, I see it TY for pic.
Is there a particular cause / how to prevent in future ?

weak (stock) contra spring is my theory. pretty sure I have a couple flipped right now but probably won't pull the cvt apart until spring. haven't been riding piglet much the past month, have put about 5,000 mile on the tractor since I got it in july.

when the sliders were new (and a new belt) it would do 80 mph indicated (~72 measured by GPS) at 6,000 rippums. now it takes about 6,400-6,500 rippums for 80 MPH indicated. however there are other contributing factors, the belt has 14,000 miles on it, and the original variator faces are pretty worn (29,000 miles).

 

[zrx212]

The rear pulley sheaves sticking or not opening/closing smoothly due to lack/bad grease in internal guide pins, etc., as it needs cleaning and servicing, etc. could also be the cause.

 

[Dave_J]

Not helping but I think I'll stick to my 650.

 

[BackOnABikeAfter40years!]

The rear pulley sheaves sticking or not opening/closing smoothly due to lack/bad grease in internal guide pins, etc., as it needs cleaning and servicing, etc. could also be the cause.

Thanks to all for the input. So, a weak contra spring could allow Sliders to flip ?

Also, a poorly lubed - on internal guide pins - rear pulley sheaves could allow sliders to flip ?

OR you're saying that Sliders could be FINE, but sticking rear pulley sheaves could keep revs high / prevent RPMs from lowering ?

The Contra Spring was brand new, along with Belt & Sliders - so unless the Contra Spring failed, maybe this doesn't apply here.

BUT, I failed to pull rear sheave apart more fully - I recall feeling time pressure to reassemble CVT assembly and I did manually move the sheaves but did NOT re-grease them.
Sounds like my bad, my failing to Re-Grease that's likely the cause.

I will search for videos showing this process of Rear Pulley Sheave Disassembly & Re-grease.

Also, Noob question alert:

Do ALL CVT scooters have essentially the same Rear Pulley layout, in terms of a Re-Grease Maintenance ?

Just hoping to be ready once I pull it apart.

This is such a learning process. I know FAR more than 90 days ago - but have SO much more to learn.

TY to all.

David

 

[nulldevice]

Heavy truck traffic turbulence, heavy load, high headwind. My money is on simply a lot of load on the motor/drive train keeping the weights from going all the way out to drop the RPM.

If it didn't magically get better after you unloaded and got out of the headwind then a full belt check and lubrication of the cvt is called for. Don't forget to lube the front shieve spacer as well.

 

[Dave_J]

David, the sliders can flip when you lift the variator up and turn it 90 degress to slide in. If you do not keep the two half's squeezed tight the whole time they might flop.

 

[s-steel]

as Dave said. put the sliders in the cup, sliding pieces on the ramp plate, then put them on the cup, boss pin after from underneath. make sure to always press the ramp plate to the cup, and when you mount it on the crankshaft, even till you mount it towards the end of the shaft, keep the ramp plate pressed to the cup so there is no slack and sliders dont change their position

 

[BackOnABikeAfter40years!]

I bet dollars to doughnuts my lube was lacking!

Dave I was very particular to hold variator tightly together the whole install process.

Plus she performed perfectly for roughly 3500 miles dropping RPM like an overdrive (Gear Vendors OD I had one on my Cummins HD Ram)

Same feel as that: just back off throttle pressure, boom RPM instantly drop.

So OE belt is probably ok ?

It has 5500 miles on it.

Sounds like I need inspect Variator - remove
C A R E F U L L Y check for flipped sliders - clean - Grease per Manual.

On driven pulley, clean & Grease per Manual - check Spring & clutch shoes.

 

[s-steel]

If I remember correctly I did mention the rear clutch needs to be taken apart when you posted about cvt maintenance a bit back. check orings and seals while youre there. check wiggle on the pins that go into channels arent lose. use high temp sticky grease. Mitch has a video on how its done. if you do remove the clutch shoes, use a light amount of grease on the posts.

make sure to mark the nut before oepning it so itll be easier to tighten back up. I used a small file and made a mark on both pieces. as the marker faded once on me.

you should measure the belt. there are minor differences between them. take some tape and wrap it around the outside and back around and place that tape on the floor side by side with the other. check with calipers the width if the belt too. should be ok. in my sym things are really tight and even a bit off really affects it.

for the slider cup, consider using some graphite powder or dry lube. I use some on the sliding pieces too.

 

[mikeyMarine]

sliders can flip even after they have been working great for a while. if you don't file off the pointy bits at the edge (a better than me 400 guy will hafta explain) I know because I didn't file them and 2 flipped on my first 400. Also dust blowout is a bit more crucial every time you open the case to change fluid or inspect belt , I'[m bettin if it was working good to start with , the clutch springs etc are good and it is just a slider

 

[JRoss]

The rear pulley sheaves sticking or not opening/closing smoothly due to lack/bad grease in internal guide pins, etc., as it needs cleaning and servicing, etc. could also be the cause.

yep this too.

the rear pulley assembly is what really controls the 400 cvt.

 

[Charbroil]

I used to own a snowmobile that occasionally flipped the belt upside down at high speeds. Sold it before I rectified the cause.

 

[zrx212]

Of course, there's other possibilities like slipping clutch and or grease contamination on belt or clutch, etc., etc. just need to dig in, ASAP. fairly sure I linked this before, around the 8min mark is where it gets exciting , generally this applies to all conventional CVT's, BTW, don't really need to replace all those seals unless they are leaking or damaged, although is a good idea to replace, check Ron Ayers.

The sliders will flip when a bigger gap than their size exists between the variator ramps and the ramp plate period, basic physics, its usually caused by delayed/erratic action of rear pulley, especially on deceleration, the sliders or rollers job is to push the front pulley closed against the clamping force on the belt by the rear pulley, they must work against each other correctly.
The other more common cause or condition causing sliders to flip, on most single cylinder scooters (or 360-degree twins) is "Belt Slap", is kinda of long-winded explanation about the perfect storm between, vibration, rpms, harmonics, causing belt oscillations, etc. But basically, it can upset the relation between the front and rear pulleys, causing delayed action, etc. Not an issue with stock round rollers, but very much so with sliders that can flip when a gap is created, the most common and effective fixes are shimming torque/contra spring, installing a new one or a stronger/stiffer aftermarket one.

 

[BackOnABikeAfter40years!]

Wow guys so much awesome info I can just give a bulk

Thank You reply !

I'm noting each suggestion and will investigate to see how / what applies.

I may just have NOT filed those 'pointy bits' on the ramp plate, sufficiently.

I should have made them more blunt. I'll use my grinder wheel next time.

Not a girls nail file lol !

I will watch that video to gain advanced guidance + read Service Manual in detail.

Q: I already have the Malossi Yellow Contra Spring, isn't that the Heavy one already ? Or is there one stronger or a way to shim this up ?

What you say here is what I'm pretty certain happened:

The sliders will flip when a bigger gap than their size exists between the variator ramps and the ramp plate period, basic physics, its usually caused by delayed/erratic action of rear pulley, especially on deceleration, the sliders or rollers job is to push the front pulley closed against the clamping force on the belt by the rear pulley, they must work against each other correctly.
The other more common cause or condition causing sliders to flip, on most single cylinder scooters (or 360-degree twins) is "Belt Slap", is kinda of long-winded explanation about the perfect storm between, vibration, rpms, harmonics, causing belt oscillations, etc. But basically, it can upset the relation between the front and rear pulleys, causing delayed action, etc. Not an issue with stock round rollers, but very much so with sliders that can flip when a gap is created, the most common and effective fixes are shimming torque/contra spring, installing a new one or a stronger/stiffer aftermarket one.

This all occured under hot heavy stress of whiplash traffic as I approached DFW, and heavily loaded, constantly speeding up followed by heavy braking.

No wonder, huh ?


TY - David