roketa 50cc poor power after new belt By jwarling (Read 9,083 times)

[jwarling]

The drive belt on my roketa sicily 50cc thrashed out. I replaced it withthe proper # replacement and there was a big change in the "power". At low speed and initial acceleration it seemed normal, but at 20-25 mph it can hardly make anyincrease up hill or againest thewind. Down hill and with the wind it will get up to normal speed of 35mph. Engine seems to run fine buta loss of power at higher speeds. I thought it must be a wrong size belt and it was "over"geared, so I tried another from a name brand company. same result. The cluth and centrifical mechcanics were cleaned and checked twice.

Anyone have a suggestion??
Jim W.

[Alleyoop]

Did you check your Variator and rollers to see if they are all there as well as no flat spots on them and that they are all in correctly and have not got out of position.
Alleyoop

[jwarling]

Thanks for the reply!
Yes they all seem fine. I watched the variator and clucth with the cover off and everything seemed to move inand out normally when the revs went up and down. It appeared belt went all the way to the top edge of it's pulley when reved up.
Jim W

[Alleyoop]

Well the 50s do slow down quite a bit going up a hill they do not have the power to pull a load up a hill and against the wind. So if it is getting to around 35 mph on the flats that is par for a 50cc. To get it to climb better you need more RPMS, so you probably should put in lighter weights to get it to raise the rpms on it and that will help going up hills and against the wind.

So weigh your current weights or if you know what grams they are try 1 and 2 gram lighter weights. For every gram you go lighter your rpms should go up by 500-600 rpms. Usually 5-6 gram weights are pretty good for the 50s to pull some rpms.
Alleyoop

[jwarling]

Allyoop,
I could try changing the rpm,s, but thatstill doesn't account for the change in operation,acceleration and power after changing the belt. Could there be a degree of sizing differences in new belts even tho the numbers are the same?
Will changing roller weights affect the top speed? Where is the best place to get different weights?
Jim W

[Bashan]

If your old belt was worn enough the width is decreased and the variator may have been pushing out farther. The new belts are wider and hold the plate back, just floating balloons here. If you need parts, including rollers, I'd suggest the banner parts vendors that contribute to our no Google ad fund. They're all honest knowledgeable guys. In no particular order they're Mainely Scooters, KidNMe, BPNW, Scooter Elements, or Absolutely Scooters. Rich

[cdoublejj]

one of the plastic shims broke on my variator plate after replacing my belt replaced with new plate and shims which helped some, however i noticed it runs faster just before the belt completely wears out as it is thinner and makes for different gearing.

[jwarling]

cdoublejj,
Maybe thats my problem! The only plastic is the 3 "c"clips that fit the variator onto the main casting of the unit. (the weights are inside these two pieces. Are there shims that I lost or missed on the shaft of the unit.
Jim W

[sprocket]

New belts should be sanded on the edges that touch the pulleys..there is a varnish coating to keep the belts fresh and the pulleys can be roughed up with 120 grit emery cloth...

[cdoublejj]

Apr 29, 2012 13:36:43 GMT -6 sprocket said:

New belts should be sanded on the edges that touch the pulleys..there is a varnish coating to keep the belts fresh and the pulleys can be roughed up with 120 grit emery cloth...

ya don't say... whats this do for the CVT? does it make it catch better or run smoother?

[Alleyoop]

whenever you put on a new belt you will notice some loss of top end speed and loose of exceleration that is because the belt is slipping. Like Sprocket said the belt has some covering on it and when it wears off the belt will grab better on the pulleys.

As for the weights I AM ASKING if you took off the Variator or just put the belt on without taking the Variator out. If you didn't and did just a belt change with the Variator still on when the belt thrashed the weights mostly got out of position and is why you lost whatever you had before.

WHENEVER the belt gets thrashed you HAVE TO take the Variator off and check the weights crap one or more may have come complety out and maybe one went sideways.
That is Variator checking 101 when a belt gets shredded.
Alleyoop

[jwarling]

Thanks for the replies !
I had the variator apart twice, cleaned all the rollers and casting with thinner. It does not feel like the engine is reving like a slipping belt. It feels like the gearing up is higher so that the engine can not pull it at speeds above 20mph. I will try roughing up the belt and pulley and let you know the results.

Jim W.

[jwarling]

I thought I would follow up on what is happening. I did take a closer look at the new belt and the corded outside edge was not "even". Some areas were proud of the edge and about half was even with the tapered V portion. I assume the tapered part shoud make contact evenly with the entire edge. I sanded the edge of the corded outside portion so that the entire taper was evenly V-ed over the entire belt. This helped , but still seemed over geared for the power of the engine.
an idea had been rattling around my skull that if the pulleys were a little futher apart on the variator the rpms would not run the belt up the pullys as quickly, increasing the rpm and before the belt got all the way out on the pully. I shimmed the end of the shaft bearing that the variator pullys ride on. This spread the pully about 1/16th of an inch. This really changed the feel of acceleration and power when accellerating at the higher end. Top speed now about 35-40 with higher rpms at the top end.
Anyone think this will cause any problems to the variator?
I weighed my 6 roller weights. About 50grams total. Would lighter weighs accomplish the same as the "shim" by raising the rpms before the pullys start moving?