Scooter dies if it falls below 2K RPM

[ykdavid]

I am new to the scooter seen so I'm shopping around for a ride. I found a '08 ROKETA 250 for a great price. Only problem is it will die if the RPM drops below 2000. The owner says he still rides it but he has to rev it at stops. I think it may be an easy fix, My thinking is it may be something with a sensor or something in the carburetor. Not sure that's why I'm posting.

any help or wisdom would be greatly appreciated.

[greenzhiqiang]

Might not be the best fix, but the easiest fix would be to adjust the air fuel ratio so that it doesn't go below 2k rpm. That's what I would do until I could really fix the cause.

[ykdavid]

I'm thinking the guy that owns it never really maintained it so it may still be BONE STOCK. You know factory oil, factory plug and nothing aftermarket. I'm thinking it's ether flooding or not getting enough gas but I'm not sure how "if you keep the RPMs up" it will run fine. I'm thinking that something would be out of sync. right?

[WarrenS]

It might need the valves adjusted.

[ykdavid]

any ideas on what the worst possible case could be and cost to fix?

[h3nry]

Worst case the Carb is in need of replacing (cost wise, up to $150 max) and it should cost little to nothing to fix. It may just be a vacuum leak or something else simple. Just clean it all and do a "Wellness check"

[ykdavid]

alright I got a different question for you guys: Once I get my scooter whats is the process to be street legal? and maybe in the order it needs to happen right now I only have my Class MP Licenses.

[dsm4g631]

Adjust the valves.

[peacedawg]

mine was doing the same thing first thing to do is a valve adjustment and while you have all the fairings off check vacuum line going to fuel pump mine had a y adapter in the vacuum line and was installed backwards the fuel pump could not get enough vacuum to operate properly soon as I did those two things oh one other thing was i put in an iridium spark plug and it runs real good now. you also might want to check the fuel enricher {auto choke} if your new to your your scooter take lots of pictures as you take it apart and put the parts in little plastic bags and label them

[snugglebunny]

its your valves
it if dies when coming to a stop
or hard to get running
thats the common occurrence of valve adjustment needed

[ykdavid]

Is their a video on youtube about this ?

[snugglebunny]

YEPPERS
just type in Roketa 250cc valve adjustment

and your questions about getting legal ?

no idea what state your in
so just google your states DMV
most states give you 30 days to get your MC license
but check 1st
if your patient you can call 'em

[leo]

Jan 11, 2013 18:11:11 GMT -5 ykdavid said:

alright I got a different question for you guys: Once I get my scooter whats is the process to be street legal?

the law varies a little from state to state.
it's generally regarded that engines 50cc and over is a motorcycle.
your best bet would be to get this information from your local DMV and police departments.

[skuttadawg]

Valve adjustment , then air/fuel screw adjustment then idle speed adjustment . Does the tire spin at 2,000 RPMs ? My 2T with BBK would do that but I am installing a larger idle jet and 1.5k clutch springs so it can idle high without enganging the clutch . 1k springs may work better so the clutch will engage at 1,000 RPMs higher than stock

Also check and R&R if need the vacuum tubes as low RPMs do not produce as much vacuum as when riding and may not suck enough fuel

[ykdavid]

I live in Atlanta GA & I plan on getting the 250 in a couple of weeks. I'll keep you guys posted.

[ykdavid]

Just watched this video www.youtube.com/watch?v=i4PAshnNCoE

Doesn't seem too hard. I think with the right tools it wouldn't take more than 1 hour and 1/2 But watching this video makes me wonder if my engine is the same. The guy in the video said 0.10mm on top and 0.18mm on bottom, is that the same for all 250? If not is there a web site for the proper specs for all engines. Remember I don't have my 250 yet so I can't say what the numbers are. I just want to be thorough and do it right the first time. I also noticed the guy never said anything about darning oil before hand. My understanding with car engines is there is oil in the area, I only thought about this when he was adjusting the bottom valve.

[richardthescooter1]

If you have this engine, its the same engine In the video he unhooks shock and let down tire down (you don't have to do all of that) you don't even have to remove back fenders unless you want too. let me know and I'll tell you how to take some shortcuts.

Attachments:

[richardthescooter1]

Here is how I did my last valve adjustment .004 intake (top)
Exhuast .005 (bottom).

Attachments:

[ykdavid]

Is this something that comes from wear and tear or something that the manufacturer doesn't do a great job at?

[richardthescooter1]

No, Just as you break scoot in and the valved get seated, every so often you have to adjust the valves, even motorcycles valves need adjusted too by times. (There will be about a 1/4 cup of oil or so when you remove the bottom valve cover) The scoot will alway let you know when its time to adjust them, stalling at stops, hard starts, cranking to many times to start scoot...

[ykdavid]

Where do you guys buy your tires? online?

[Deleted]

No.
If it dies when it falls below a certain RPM the first thing to check is the low speed screw adjustment on the carburetor.
Not saying it can't be the valves, but always start with the simple stuff.

[richardthescooter1]

I agree with 8307c4, until you have your scoot we are guessing, when you get scoot, check it out and go from there. A good PDI won't hurt either

[robert1c]

Start with the scoot on the center stand with the seat open and the little cover off to access the carb
remove the right side lower panel (to access the bottom of the carb)
then start it and watch the RPMs and the back tire (should not be turning).
underneath the carb there is a screw. turn it all the way in then back it out 2.5 revolutions and wait for the RPMs to catch up.
then turn it a qtr turn and wait till the RPMs catch up. you are looking for the highest RPMs.
once there then go to the top of the carb.
there is a screw is by the throttle (the adjustment screw) turn this screw counter clockwise qtr turn and wait. look at your RPMs and the tire. continue this until the back just wants to turn but doesnt. the RPMs should be around 18~20+. this should be it.
now you can try to fine tune it by going for a ride to warm it up and then check both screws again from their current position to see if you can get a little more out of it.

i would also try to run a little seafoam through it since its most likely been sitting.