Unsafe To Use Yuminashi Variator With Dr. Pulley Sliders

[fun2scoot]

I see no other conclusion after reading extensively here on various transmission modifications, and now suffering a failure.

2015 PCX150 with Yuminashi Speed Control, 12 gram Dr. Pulley sliders, and reinforced Gates SB50026 belt. Bike has 5k miles with 4k of those on this mod.

Yesterday, long ride, mostly tucked, avg 70-75mph, throttle mostly pegged up and down hills. Sudden power loss and engine rotation ceased instantly. Pulled safely to road shoulder and performed some tests and concluded the belt was broken by freewheeling the rear wheel, and that the belt had wedged in the variator by the starter sound but no engine turning.

A deeply religious older couple with a truck and trailer stopped, loaded me and bike, carried us 2 hours out of their way to my home. (echoing now the 12 year-old boy in the movie Vacation reading Playboy when a stripper suddenly flies in the window and lands on his bed - THANK YOU GOD)

Here's the belt:


I spent several hours with lacquer thinner and a phosphor bronze wire brush removing all the melted rubber from the pulleys and inner casing. The rear pulleys were heavily adulterated with rubber so I brushed them to bare metal, but I don't remember if they were that way originally.
Were they black OEM?

The sliders still looked good after cleaning, so I reinstalled them with a new, spare Gates belt.
I guess I must self limit to 70mph - or die.

Will the OEM Honda belt work with the Yuminashi?
Should I switch back to rollers?
I've already read Clemence' thread

[j.d.b.]

That picture is enough for me to keep my bike all stock Honda.

[GeeGusKahn]

I see no other conclusion after reading extensively here on various transmission modifications, and now suffering a failure.

2015 PCX150 with Yuminashi Speed Control, 12 gram Dr. Pulley sliders, and reinforced Gates SB50026 belt. Bike has 5k miles with 4k of those on this mod.

Yesterday, long ride, mostly tucked, avg 70-75mph, throttle mostly pegged up and down hills. Sudden power loss and engine rotation ceased instantly. Pulled safely to road shoulder and performed some tests and concluded the belt was broken by freewheeling the rear wheel, and that the belt had wedged in the variator by the starter sound but no engine turning.

A deeply religious older couple with a truck and trailer stopped, loaded me and bike, carried us 2 hours out of their way to my home. (echoing now the 12 year-old boy in the movie Vacation reading Playboy when a stripper suddenly flies in the window and lands on his bed - THANK YOU GOD)

Here's the belt:


I spent several hours with lacquer thinner and a phosphor bronze wire brush removing all the melted rubber from the pulleys and inner casing. The rear pulleys were heavily adulterated with rubber so I brushed them to bare metal, but I don't remember if they were that way originally.
Were they black OEM?

The sliders still looked good after cleaning, so I reinstalled them with a new, spare Gates belt.
I guess I must self limit to 70mph - or die.

Will the OEM Honda belt work with the Yuminashi?
Should I switch back to rollers?
I've already read Clemence' thread

.
Hay fun2scoot
Are you sure it is not a belt failure vs Dr P slider failure etc.
Reason I ask is I had a very similar fail with Dr P variator, sliders, and Advance Pro setup.
.
see
http://www.hondapcx.org/viewtopic.php?f=19&t=4873
.
I am fairly certain that the belt is what led to my entire mess.
If you can stand it, read through the whole thing or at least read page 3 which shows my conclusion and why.
.
Line the belt pieces up as best you can and examine each section - top and bottom - there might be a clue there.
.
As to the reinforced Gates SB50026 belt - do you know the specs on it ? length, width, thickness.
.
Don't know answer to your questions but I have temporarily returned to a more OEM setup.
.

Just a thought
.
Sean

[Valiant]

I wouldn't say it's a "failure" per se. Just that the variator in and of itself already pushed the belt out to the very limits. Adding the Dr Pulley Sliders simply pushed it out further against the case.

Some product combos are not compatible. It's not the best idea to continually keep screwing with the transmission, as I ended up with a variator that wouldn't change positions with higher rpms(which is basically like riding in 1st gear). Find something that works and keep it there. People should understand that mods can only take you so far before buying a different bike is the only way to have a different ride.

[fun2scoot]

First of all, thanks Sean. I read your thread, and you certainly are the trooper! I like the Advance Pro setup - I think that was Sendler's idea.

I wouldn't say it's a "failure" per se. Just that the variator in and of itself already pushed the belt out to the very limits. Adding the Dr Pulley Sliders simply pushed it out further against the case.

Some product combos are not compatible. It's not the best idea to continually keep screwing with the transmission, as I ended up with a variator that wouldn't change positions with higher rpms(which is basically like riding in 1st gear). Find something that works and keep it there. People should understand that mods can only take you so far before buying a different bike is the only way to have a different ride.

Valient, I've been following your tribulations from the get-go. You are a tough dude!
Agree on your variator/ belt analysis; Am wondering if maybe the best setup (for me*) is the 45T final gearing in maddiedog's 'how-to' thread, matched to an OEM variator / belt. The PCX150 weight and handling are what I want - upgrading bikes is out. After it was road ready again, my friend followed me to the pub on his new R1200GS through the downhill twisties and was amazed that he could not catch me. He's a great rider and I was not trying - really!
The Yuminashi setup is superb: pulls where I want, great MPG, smooth. The con is the belts can only be gotten from Yuminsashi in Thailand and shipping is insane.
* I need best MPG cruising 65-70.

Don't know what to do: Order replacement belts from Yuminashi, or go to 45T / 15T final gearing.
Now I'm REALLY confused. Yuminashi lists two kits for the PCX: 23430-KZR-S00 and 23420-KWN-000. HELP!

[Valiant]

Hmm? Have you looked at anything in the 250-300cc class? I ride a CB300F right now. 350 lbs, 70 mpg fuel economy, does 80 mph fairly easily.

The final gearing extension does you no good if you don't already have a big bore kit, it's like riding a bicycle uphill on 10th gear, you just don't have enough power to move it.

[fun2scoot]

Yes, thanks Val, I have. Due to multiple leg surgeries I can't get my knees past 90° for long. Honda's CB300F is impressive but I swore off chain drive in the '70s. Thanks though.

And thanks for the update as to needing more displacement to use the 45T gearing. Didn't know that.
Guess I might aw well order those belts from Thailand...

[Valiant]

Maybe the Forza or a Burgman then?

The Daytona reinforced belt is available from Japan. I believe they charge less for shipping than Yuminashi does in my experience, but I suppose that all depends on where you live.

[waspmike]

I'm going with incorrect belt unless otherwise advised. I cannot find any reference to Gates SB50026 even on Gates site. When in doubt use an OEM belt.

[fun2scoot]

Maybe the Forza or a Burgman then?

The Daytona reinforced belt is available from Japan. I believe they charge less for shipping than Yuminashi does in my experience, but I suppose that all depends on where you live.

Thanks but the PCX 280 lbs. is indispensable for me.
I need to go pull the sliders and put the rollers back in, I'll measure the belt then. One too short will not reach top speed. Too long will rub case.

I'm going with incorrect belt unless otherwise advised. I cannot find any reference to Gates SB50026 even on Gates site. When in doubt use an OEM belt.

The SB50026 must be custom made by Gates for Yuminashi. It is available nowhere else. But then again, even with shipping it is only slightly more costly than locally sourced Kevlar belts because the Baht is so undervalued. Comes out to ~ $47 per belt -here- buying 3. It is the right one to use and I will substitute.
I posted a letter to Gates 33 days ago asking about sourcing. No reply. I'll re-post with Return Receipt, and, if they are ignoring me it will cost them thousands to continue doing so.

[sendler2112]

Yes. go back to rollers with that vario. maybe the sliders were pushing the belt over the edge of the vario and shredding it. Get it back together and run it up and down on the center stand with the cover off to see that the belt is tracking straight and not coming up too high.

[fun2scoot]

Right. Installed the OEM Yuminashi 10g rollers and cleaned the F/R disc faces meticulously (I had NO idea how important this is) free of fingerprints* and went for a cruise.
+400 RPM at speed ( MPG will drop slightly). Rollers add ~ +1000 RPM to takeoff vs sliders, (which is now in power band - OK), max speed 71 MPH (break in yet?).
Logically, the belt is not, will not, reach the inner case with rollers, vs sliders with which 75 MPH (GPS) had been achievable.

Yep, Yuminashi included rollers with the vario - use 'em!

*Use cotton gloves for handling belt-contact surfaces; fingerprints cause belt stutter.
Oh, never run without cover due to essential support bearing in cover.

error correction:

It is the right one to use and I will substitute.

I will not substitute.

[waspmike]

Here are specs for SB50026: 815x21.8x30 for Honda PCX 125.



Photobucket has shrunk it a little anyone wants a bigger version PM me.

[nribeiro]

Strange...
I know a person who installed Yuminashi vario and Dr. Pulley sliders and top speed of 87mph. No problem what so ever.

[dasshreddar]

Strange...
I know a person who installed Yuminashi vario and Dr. Pulley sliders and top speed of 87mph. No problem what so ever.

I can only do 81mph on the stand... with Yumi vario/dr.p sliders, but i too have had no problems with this set up.

p.s. forza set up does 89 on the stand

[fun2scoot]

I can only do 81mph on the stand... with Yumi vario/dr.p sliders, but i too have had no problems with this set up.

p.s. forza set up does 89 on the stand

Please; what belt are you using?

[dasshreddar]

GATES belt #4 on the chart?

[fun2scoot]

I wish I could use that belt but the Yuminashi belt specifications diverge from the 2013 and the 2015 PCX150.
Their parts pages are not well written, but they make it clear that the longer (SB50053) belt for the 2013 kit should not be used on the 2015. Why, I have no idea.

Looking back, the rubber that the failed belt left on the inside of the case may have come from riding WOT up and down hills for over an hour. Downhill the rev limiter kicked in a lot so the belt must have gone further out than Yumi expected.

[dkazzed]

I heard that Dr. Pulley sliders were only designed for stock variators and aftermarket variators should use rollers.

[FRossi]

I'm using the stock belt on my 2013 pcx 150 and the Yuminashi 2015 kit. Top speed on road is 130kmh and 140 on Central stand. Im planning to change the belt at 1/2 mileage of the original setup... I've already rode 7k km