139qmb CVT and front end questions By cdoublejj (Read 3,167 times)

[cdoublejj]

So i blew a belt today and after inspecting the damage there was crap ton of black powder, i'm guessing belt and clutch material witch seems semi normal from the 139qmbs that have ever looked at. there was also some drive belt fraying it looked like tender just few small dust bunny sizes about few cm in diameter not to dense.

the belt lasted for some time a year or 2 so i'm not convinced i have one of those scoots that has that problem of them breaking to much. i was gonna open up the clutch area on the CVT a little bit i think it was this or scooter rebels that had some people whole sawing the bit of cover that goes over the clutch bell, i was gonna do something a bit similar but, not as big of a hole i was gonna do 2 smaller holes just encase of rain or road debree. actually i might describe it as cutting out 2 slots.

i also wanted to know about this...

enviromoto.ecrater.com/p/4703356/ncy-performance-variator-teflon-coated

i've been thinking about getting one for a while. are they snake oil like the hot rod CDIs and coils? i tried one of the scrappy dog scooters cams it made it run 10 whole mph slower but it gained 1k rpm on the top end. i also tried a CDI it didn't do crap it made things run worse stock and with the crumby cam.

so i'm bit weary about some of these after market parts and was curious if any one know about this one.

also on the front end, my forks is there any maintenance i need to do?

is the black dust and small bits of frayed CTV belt normal?

EDIT: Would this clutch bell help to keep things cooler specially with my slot mod

enviromoto.ecrater.com/p/6055776/ncy-139qmb-gy6-50cc-performance

i was also wondering about this would this be any more efficient then my current CVT? would it have a higher top end ratio. I'm maxing out my stock CVT on some of the down hills

enviromoto.ecrater.com/p/6055029/ncy-139qmb-transmission-kit

[Bashan]

Black powder is normal but needs to be cleaned up. I think your belt did OK for how long it lasted and there's nothing wrong with that system to cause it took break IMO. You need to dismantle the variator and clean it up. When you reassemble put sone high temp grease sparingly on the center boss, that cylinder that fits in the middle. Getting some extra air to the clutch will help cool it and some holes in the CVT cover enhances that; we've had several guys on the forum do that with good success.

All of those products that you provided links for are good stuff, NCY makes quality parts. Those are good prices too. I don't think you'll notice a huge change in performance but they will definately last longer with fewer breakages. So no, they're not snake oil but they are over-hyped on how much performance increase you'll feel in the seat of your pants IMO. That clutch bell would help cool things down.

Here's a PDF on disassembley and cleaning of the entire CVT. This is another PDF on setting up a CVT. And finally, here's three great articles from Battle Scooters on performance tuning for your CVT. Can any of you 50cc guys offer your thoughts on performance upgrades on a 139 for cdoublejj? The front end rarely needs service unless there's a gazillion miles on your bike or the front end is diving. This manual addresses front end servicing at the very end of the PDF. Do not hesitate to ask more questions. Rich

[cdoublejj]

a friend of mine does some really good work on bikes told me they needs to be serviced at some point all of them i guess he was right. I just probably have enough miles, 02916/2 miles.

i certainly have thought on 49cc perf upgrades. witch reminds me after i need to update my thread "faster" after this. there is crap ton of improvement you can do with out buying parts already. with a 35mph top speed base line witch is good starting point i believe 49cc perf upgrades are very underrated and ignored.

i was thinking the after market variator cup would help the CVT ride the power band a bit better. if that makes any since?

i was curious about this little bit too... i have friend with an identical scoot and it has a low rpm knock and it isn't the cvt or the likes

www.enviromoto.ecrater.com/p/11515339/naraku-heavy-duty-16-tooth-gy6-50

what i'm really curious about is weather it's higher quality and what the balance and weight is like but, i'd probably have to buy it my self to figure the balance and weight.

EDIT: my dad went to local dealer to pick up a belt and the guy said he had never seen this size of belt on a 50 before. it is a 729 12.7 30, is this normal?

[sprocket]

I love NCY and most of the parts on my scooter are NCY.. but -- the teflon rubs off fairly quickly on the variator...perhaps not their best effort. It is a friggin' engine not cookware!

All the 'Orange performance stuff' is the same as stock generally, maybe with a few circuit board tweaks... stick to NCY or other name brands

Clutch bells do nothing for hub cooling...the only think that makes a difference overall is the size of the variator pulleys...but it is limited by the rear end gearing which is limited by the engine.

I grease my front forks with lithium white grease about 3 times a year...

Tuning the variator weights shifts the power band and there are some advantages in doing this...CVT parts may be better quality but performance... nada

[cdoublejj]

so basically the ncy performance variator sheeves are the only thing that does any thing? hopefully i can get a 60cc bore up soon might have to turn the stock head to fit the larger diameter jug and piston. if gain enough compression i might be able to port the exhaust side. are there any ways to make the engine quieter it seems to me more noise comes from the black than the pipe.

has any one dissected a stock pipe? I also devised a way to delete the retarded vacuum system, i use need to find an old school 80s or 90s carb and run the vacuum line form the intake to the petcock. i'm starting to think the vacuum system makes it less reliable, my scoot idles weird due to a small vacuum leak.

it also hurts acceleration because the vacuum runs the slide versus just a butter fly carb. what do you guys think about this theory?

EDIT: can any one tell me the "MM" of the side of the carb that goes in the rubber intake boot (not air cleaner boot) on the gy6 139qmb, i was gonna look at other carbs for the heck of it on ebay maybe i can learn something.

[sprocket]

You need the vacuum hoses to at least the petcock and the ACV valve on the carb, or it will run like sh!t.

[cdoublejj]

Whats an ACV valve. i wonder why they even implemented the vacuum system, i'm thinking emissions.

[Alleyoop]

Here is the ACV valve but you may not have one it all depends on the type of carb you have.
Alleyoop

[cdoublejj]

my whole idea is to delete all of that except for the intake to petcock. i believe mine does have ACV atm. I'm thinking a nice mikuni would work nice and acceleration might be better with out a slide. i would probably have to work the choke ordeal though, maybe i can find mikuni with electric choke. i could see cold starts being hard with straight carb like mikuni.

[Bashan]

Oct 14, 2011 21:29:01 GMT -6 cdoublejj said:

Whats an ACV valve. i wonder why they even implemented the vacuum system, i'm thinking emissions.

The air cut valve prevents backfiring when you snap the throttle shut on decelleration by changing the air/fuel mixture. Try unplugging it one time (plug the removed hose!) and you'll soon put it back on as your neighbors start to glare at you. I agree that vacuum systems are a PITA. But you might as well get used to them, they're an easy way to actuate components on everything from cars to boats. If you didn't have vac systems the next choice would be electric servos which would be off the scale expensive. I'm like you though, every vac hose you eliminate is one less potential problem. My naked Bashan has one vac hose, it runs from the intake manifold to the ACV. I use clear to see if any gas is leaking by the diaphragm:

And yep, there's no auto-choke. There's a piece of gasket material behind the mounting plate. Rich

[sprocket]

I agree with Rich.. I have one vacuum hose... to the ACV and I use a manual fuel shut off...

The most hassle going to flat slide etc is reworking the throttle cable and choke...

www.teamcalamari.com/dox/tekcarb24.html

[cdoublejj]

any reason to go with a flat slide, people seem to talk about the mall the time. wouldn't need a rather small carb to better accommodate 49-60cc.

[sprocket]

Some people like the flat slide.. I find them very hard to keep in tune...

[cdoublejj]

I'd just assume look for a 50cc - 70cc round slide off of something jap.

[cdoublejj]

well now it's super borked, after the drive pully giving us problems as in the nut not coming off in eitherdirection with the big impact we spread the sheevs in the back just sort of stretched on there. rotated ita few times to make sure the belt centered up and the sheevs contracted witch they did how ever it wouldn't start it has spark, not so sure about fuel. when i do get it started the drive belt chatters like crazy till over 4k if i apply the brakes any at all it damn nears dies or just dies. if it does idle it chatters and vibrates like crazy.

i'm censing more than one problem. i checked my vacuum route i'm already running straight from the intake to petcock and have been for some time. i deleted a few extra hoses and a capped off Tee and ran a single hose from intake to pet cock, to eliminate the chance of a leak, that and the Tee was so brittle that i accidentally snapped it in half when checking the fit.

Any ideas? Kind of disheartening out of all the troubles i have had from it this is the worst.

EDIT: fuel is visible in the tank and fuel filter. Valve lash was sett only several months ago, the plug looks fine, tan in the center black on the edges. i have fixed the loose ignition circuit gremlin a twice before and it's geting a healthy spark so i don't think it's a harness problem. the scoot ran just several days ago.

EDIT: SOLVED the belt went on much easier the second time the drive pully must have gone wacko when it popped a belt. it was stuck wide open so to speak at the top end ratio.