My 2008 roketa 250cc

[PhillyRich]

Hello everyone

I have a 2008 roketa 250cc I'm looking to do some upgrades but not really sure which ones are the best for wat I'm looking for the top speed is suppose to be like 65 - 70 I've been able to get it to do 50mph on back street it has good throttle response it takes off pretty quick here are some things I've done to it I changed stock air filter got one like them k&n filters which created a problem my back wheel now moves when on the center stand it didn't do that before I changed air filter I've played around with idle screw and that really didn't help my exhauast is loud to I think I'm missing a gasket but want to change that to just haven't really found one for my scooter or a good price and ideas on this will be good like I said before I would like to go a lil faster and make smart and best upgrades for my money o I also installed a boost botter that I really didn't see any improvement and tips well be gladly appreciated

Thanks,
PhillyRich

[bull]

do you have the Helix or Linhai engine clone?

have you done all the maintenance and drive it from its winter slumber?

the boost bottle, are you saying you installed a nitrous kit? If yes,was it a dry or wet kit? what orifice size are you using?

EDIT: where the muffler attaches is agasket within the pipe, also if that clamp bolt is loose it willleak exhaust and be noisy.

[PhillyRich]

It's the LinhaI clone I've changed oil,and flushed radiator the is not really nos wat u do is you tap a whole in your intake and you screw the fiting in then hook hose to the bottle but don’t really see any improvement in horsepower I thought it was missing something on the exhaust will a leak or missing gasket stop it from hitting top speed I also been looking for a aftermarket exhauast that's not to expensive

Thanks for any input
PhillyRich

[bull]

My thinking is that you are running out of fuel in the carb. IOW, the fuel pump is not supplying enough.

I have seen this issue with several scooters that have vacuum powered fuel pumps. My own 250b has problems starting because of a lack of fuel. There are videos and people complaining of it on you tube.

Yesterday I took a Ruckus 150 for a few test rides. It was hard to start and the owner carried a can of starting fluid. The test rides all showed that it was running out of fuel on hard full throttle running under stress.

Every quick test yielded no improvement, same as my testing on my 250b -- currently researching an electric pump that can do the job, but not flood the engine.

Since your little bottle NOS kit did nothing, I suspect you are running out of fuel as well, since NOS needs more fuel to work.

[Shadowfire]

Just FYI, I have experienced this problem on my Chinascoot as well.
If you're running out of gas at full bore, the problem most likely isn't the pump.
The problem is lack of vacuum; more specifically, its the cheapass hose clamps that the bike ships with. They are pretty much one-use items, and if you (for instance) take the vacuum hose off of the intake manifold, you need to replace the hose clamp with a new one when you put it back on.

I've also had the "carburetor bowl mysteriously empty after a few days" problems, although that was due to a slow leak on the carburetor drain line caused by, you guessed it, hose clamps. Once I replaced every vacuum and fuel line clamp with clamps from the local True Value hardware store, I no longer had any hard starting or fuel delivery problems (even after the bike was sitting for a month).

As a final note, my YY250T has a hard top speed (on a flat surface) of around 70mph. (I weigh 260 lbs.) The variator doesn't allow the engine to go above 6K rpm (although I can blow by redline on the centerstand), so I suspect it would probably have more oomph if the variator allowed higher RPMs, but I've no inclination to try tuning this bike, since I had a blow-by in the head gasket about 3800 miles into it (with mostly secondary street usage). If you want more speed, you're better off with a second hand Taiwanese or Japanese scooter (which will easily do 80mph with a 250cc carbureted engine) or just get a bigger bike. But yeah, it does sound like you have a fuel problem if you aren't getting over 55. (Make sure you use a GPS, the speedometer is not accurate).

[bull]

Shadowfire,anything is possible, but this youtube vid about these clearly shows the before / after-- and the Rough House I could see the lack of fuel in the filter and he had just replaced the lines with Tygon.

https://www.youtube.com/watch?v=LfNtOLYfIN4

float bowl emptying after a few days is one problem, but overnight is completely different.

[Shadowfire]

You're right in that it isn't guaranteed to be any one thing.
But, one of the things I did when I got the bike was clean out the carburetor. When I put it together the first time, I wasn't careful enough, and the float bowl cutoff plunger fell off into the bottom of the bowl.

Let me tell you: There is no way in hell that the a properly working fuel pump can't keep up with WoT on one of these bikes. The pressure-washer-like stream of gas coming out of the overflow tube would easily drain the 2gallon fuel tank in less than ten minutes.

What can cause it to gasp for gas, is a vacuum loss. The wider the throttle is open, the less vacuum is available to drive the pump. If you already have a leak in your system, opening up the throttle could well cause the vacuum at the pump to drop below proper operation.

[Shadowfire]

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[Shadowfire]

Anyways, all I'm saying is that the guy in the video probably would have gotten the same results (without the headache of wiring up an electric fuel pump) by replacing all the clamps. In any event, he obviously did that too, as evidenced by the worm drive clamps on the new pump.

[PhillyRich]

Thanks everyone

How about why the back wheel spins when on the center stand after I put a k&n aftermarket air filter

[bull]

Thanks everyone

How about why the back wheel spins when on the center stand after I put a k&n aftermarket air filter

That would be normal and expected. When you replaced the stock AF you increased air flow, which as it traveled through the carb picked up additional fuel, thus the engine speed increased, the engine cvt turned faster which engaged the clutch cvt and the rear wheel rotated.

[PhillyRich]

Ok thanks bull

[Ebuddy]

Agree with it being a vacuum issue. My 250 (Helix) will, on a flat surface with little/no headwind haul my 270lb. arse up to 72 mph, but that's near redline. I usually keep it to less than 7k RPM and can comfortably go 64-68mph, enough for the minimal freeway driving I do.