Roketa ; top speed and roller weight question

[coolscootdude]

I own a Roketa Sicily 150 and have 1300 miles in 2 months of ownership. Done with the break-in, oil changes (twice), gear oil change, carb cleaned , airfilter cleaned, and canged to iridium spark. Could never get past 50mph line although the Chinometer is accurate and people are getting more than that speed. Now my top speed is, believe it or not, 40mph .

once i ran out of gas and when i refilled it, couldnt start. I had to spray some starter fluid in the carb. When i ran out gas second time ( coz the fuel gauge is not accurate , appearantly ) ) my "Aid" brought lighter fluid along with gas instead of started fluid. I had no choice but to use it and it started for a few seconds and died. Finally i got it started with starter fluid. But ever since that lighter fluid incident my scooter doesnt go past 40 mph line.

do you guys think its the problem coz of lighter fluid or this might be due to some other problems ? (i also sprayed the Gumout Carb Cleaner and changed to Iridium Spark plug after this incident) . please help me out here....

Also, does anyone know whats the factory size of Roller Weights in Roketa 150cc ?

[earlwb]

Your OEM CVT drive belt is likely worn out and stretched. The OEM belts are pretty crappy and usually don't last long at all.
The stock OEm roller weights are typically 13g ones. If you are a heavy person 11g or 12g weights would probably give you better acceleration.
I'd suggest you get another intake manifold too as that will be next on the list to go bad.
Having a spare ignition coil and CDI would be very useful.

[coolscootdude]

Hey Earlwb,

Thank you so much for the response. This forum is so awesome , you dont know how much this site means to me especially for someone who owns a chinese scooter where the manual doesnt tell anything and there isnt any dealer support. Thanks for enlightening with some knowledge. It is always appreciated.

I will change the CVT belt and will get another intake manifold. What does your expert opinion say ? what kind of belt and manifold should i get ?

Do you think its greedy to go for Roller Weights thats heavier than 14grams ? I'm 150lb guy and need more top speed than accelaration coz i live in suburbs where the inner roads are 45 - 55mph limit and people do 5miles over the limit and they are always pushing me off the road.

[scooterollie]

Coolscootdude;
Welcome to the Dawg Pound! If you don't know about Stan Jessup's website for parts and information, look around here:
www.oregonvintage.com/
You will find what you need and perhaps answers to some other questions. Stan is a moderator here and a great source of information.

[earlwb]

Well it depends on it you have a long case CVT or a short case CVT.
The long case CVT uses a 835-20-30 belt. I suggest a kevlar belt as they last longer than the regular belts, but they do cost more though.
If I remember right the short case CVT is like 743-20-30 in size. Short case CVT's are typical on the scooters with 10 inch wheels, maybe 12 inch wheels as well.
Count how many bolts you have holding the side case on the CVT on and let us know.
You can also take the side CVT cover off and inspect the belt, it should have something on it with the brand and size of the belt too. But they have put on OEM no name belts with nothing on them as well.

[swampsniper]

earlwb said:

Well it depends on it you have a long case CVT or a short case CVT.
The long case CVT uses a 835-20-30 belt. I suggest a kevlar belt as they last longer than the regular belts, but they do cost more though.
If I remember right the short case CVT is like 743-20-30 in size. Short case CVT's are typical on the scooters with 10 inch wheels, maybe 12 inch wheels as well.
Count how many bolts you have holding the side case on the CVT on and let us know.
You can also take the side CVT cover off and inspect the belt, it should have something on it with the brand and size of the belt too. But they have put on OEM no name belts with nothing on them as well.

Any belt will last until the rubber body fails from heat damage. When the rubber craps out the cord material doesn't matter.
A Kevlar belt made out of inferior rubber is an overpriced waste of time. The rubber understructure determines cord life ,if the cords aren't supported, it doesn't matter what they are.
The cords depend on the rubber understructure to keep on keeping the stress close to equal, across the width of the belt. When the basic rubber starts cooking out from more heat than it can handle, the stresses on the cords are not evenly distributed.
What you get is a transfer of load to one cord, or another, from an even bearing of load.
It is all about rubber.

[daddyeby]

I disagree with the cvt belt. If you dropped 10mph in that short of time. I belive one of two things happened either you sucked trash into the carb when running out of gas or more than likely the lighter fluid worked on the diaphram or float or some other part in your carb.

[earlwb]

My OEm belt was a cheapie. At about 1800 miles I compared the old OEM belt to a new kevlar belt and the old belt had become thinner by 3 hundredths of a inch and about 1/2 inch longer.
The King's Kevlar belt I put on was 1 hundredth of a inch more wide than a new Gates belt.
What I found was on the old belt i was maxing out on RPM going 45mph. When I put on the new belt it was like having a new scooter. RPM's went back to like it was just after it got broke in.
I figured the kevlar belt would be less prone to snapping or breaking but swampsniper is right about rubber, it doesn't matter as far as the wear or rubber is concerned. But maybe they put in better rubber in the Kevlar belt versus the OEM belt.

[coolscootdude]

Great Big Guru Dawgs,

Thanks for the fast replies. Somewhere i read online that if you lost the power you need to adjust the valve. Do you think i should be doing that before Replacing the Belt or Super-cleaning the carbs ?

Daddyeby , if there was something stuck somewhere in the carb , how would i clean it ? Do i have to take the carb out and clean it ? OR Just spraying the carb with Carb Cleaner like "Gumout Carb and Choke Cleaner" should solve the problem ?

Earlwb, I will check the belt and let you know. Do you think having the performance pulley- variator makes a significant difference ? Or its just something people upgrade just to feel good ? And regarding the Roller weight ; does the upgrade from 13g to 14g makes any drastic change ? I hear more weight = high top speed , which I'm aiming for. Should i go with 15g to 17g (if its available that is lol) ?

[tp555]

I would check the valve clearance anyhow. The spec is .002" which I don't care for.Mine had .004"
on the intake and .002" exh. I set both to .004". My scoot has 600mi.
It tops out at 60mph at 7000rpm. Its a roketa fiji.

[earlwb]

checking your valve gap is always a good thing to do. Engines do weird things if the valve gap has closed up.

Most 150cc GY6 engines seem to be coming with 13g rollers. Going to a 11g or 12g roller set helps with acceleration before the variator shifts into high on you.
Going to a heavier weight roller, lowers the rpms at which the variator shifts on you. thus you shift too soon.
But it depends on how much you weigh and whether you ride with a passenger a lot.
heavier people would find the 11g or 12g rollers nice for accelleration, but a small light weight rider might like a 13 or 14 or 15g roller weight more.
Roller weights won't affect the top end speed, unless the rollers are too light, like 8,9 or 10g on a 150cc engine. then the variator won't be able to squeeze together enough to let the belt get on the outer edge.

A new belt is wider and will ride a little higher up on the pulleys giving you a higher gear for higher speeds. So a old belt that has stretched and thinned out won't ride as high on the pulleys so you loose top end speed.

On my Roketa Fiji 150 the old worn belt would give me 45 mph at 9000 rpm. A new belt had it going 45mph at 7000 rpm.

[coolscootdude]

Earlwb,

what you are saying is just changing the roller weight will not give me any top speed whatsoever . Just gives me a bit of acceleration (if i put lighter weights ) but that will lower the top speed, right ?

I'm 150lbs guy who rides alone most of the time but sometime i put my lady on the back and cruise around and she is just 100lbs. I live in a suburbs were there arent many traffic lights so i dont need super acceleration but i'm definitely looking up my ways to get my ride going 65 mph which will be 15mph target gain in top speed.

I dropped my scooter at local garage to adjust the valve and also the mechanic told me that the way i sprayed Gumout Carb Cleaner in the carburetor doesnt clean the jets inside. he was telling me that some dirt might have gotten in the carb when i ran out of gas. So he'll be cleaning the carb for me. I will let you know how the performance would be after it returns from the shop. If the performance is still sloppy i will change the belt like you referred.

[earlwb]

Chaning the rollers will not change the top speed unless the rollers are too light which would slow you down then.
I am talking about 8g or so.
yes a lighter roller imrpoves acceleration up to a point depending on how light you go.

[coolscootdude]

Okay i get it.....So the whole purpose of having roller weights is to get a quick acceleration until you reach a higher gear , right? Damn those website who is saying heavier roller increases the top speed. I guess thats just the sales pitch and messing with people's head . Having said that , one question emerges... Does the high revving due to lower weights shorten the engine life ? I heard that if the engine is revving too much it will not last long.

[earlwb]

No the high reving is still within the engine's operating parameters, so you are OK.
If you go too light on the rollers you hit a point where it won't upshift.
Too heavy of a weight and it upshifts too soon.
If you have a tachometer, the idea is to not let the engine go over 9,000 to 9,500 rpm.
Unless you have hot rodded the engine.

[coolscootdude]

RESULTS !!!!!!

Okay ! Finally I picked up my scooter from the shop after valve adjustment and carb cleaned. Mechanic told me that the rubber between the cap and the carb itself was not sitting right so i might not get good performance as there wont be a vaccuum forming in the carb. (atleast thats what i understood) And he told me he sealed it with silicon glue for now till we replace that rubber.

When I pulled out of his shop i could feel some acceleration. And then for the very first time the scooter did 55mph and it was slightly uphill road (atleast it wasnt on flat road for sure) I had to slow down as the limit was only 40. I was so overwhelmed with joy. The scooter only did 50mph that was on somewhat downhill road and then the performance had dropped to 40 mph top speed before i took it to shop. Now all of a sudden after valve adjustment to .004 as told by some people on this forum , my scooter is doing 55 MPH. I'm thinking about throwing a party and celebrating it. lol.

Thanks to the genius guys and their responses. It is a great thing that atleast theres a scootdawg community for chinese scooters. I dont know what would i do without you guys .

I guess my next project will be ugrading its speed by atleast 5-7 mph . If this beast runs 60mph then i would be very satisfied.

[coolscootdude]

UPDATE :

Actual Speed after Valve Adjustment: 60mph

I guess i didnt push it to the limit yesterday . Today i took it on the road where the limit was 55mph and my scooter did 60 mph. This was a 10mph gain from the top speed from the time when it was broken in. And 20mph gain from the miserable stage i was before valve adjustment and carb clean.

For newbies looking for answers; like the gurus on here had recommended Valve Adjustment Really works and i'm the proof.

[vukarob]

hey cool , you might find that there was a slight leak in your intake manifold before which the "silicone" took care of , the valve adjustment would also have an influence .
Glad to read that you are back up to speed .
i'm having a beer on you .