Limiters i have found so far on s8 50 4 stroke

[Roytheroach]

The muffler has a cat built in, i chopped it off and fashioned a megaphone from an empty 88g co2 cannister, if you have access to a welder this is a great way to go, i shoot wonderful exhaust flames

I clipped the purple wire, i noticed a power gain for sure but i still have a rev limiter. At this point i can reach 37 mph before it starts popping and cackling. Im not sure what was interuppted by that purple wire but i can attest to a definite POWER change, NOT a TOP SPEED change.

biggest difference of ALL though, was a sneaky little restrictor washer in the intake manifold. Before removing i, i found that wide open throttle caused a bog, it was difficult to accelerate at the same pace as traffic, uphill was a challenge at 15 mph grunting like a depressed pig.
since i removed the washer, the engine starts easier, runs better, doesnt die at idle, and i can hold 30 mph up hill now

Next step is the variator boss

[Tseg]

Is this a 2015/2016 US model 4-stroke?  My 15 year old son will be getting one soon, and I'm ok getting him greater acceleration, but since all speed limits in my town max at 35 mph, clipping the purple wire sounds like a great solution to ensure he has quickness but does not speed.

[Roytheroach]

Is this a 2015/2016 US model 4-stroke?  My 15 year old son will be getting one soon, and I'm ok getting him greater acceleration, but since all speed limits in my town max at 35 mph, clipping the purple wire sounds like a great solution to ensure he has quickness but does not speed.

It is a 2015 4 stroke model x. Honestly i dont like clipping the purple wire. I am buying a new cdi (at $30 its worth it)  and reconnecting the purple wire. A fully derestricted cdi will have a better timing curveand only add a few mph, low 40's is my prediction.

Now the cvt variator boss, is the most successful limiter on this bike. Once removed, the bike would be in the neighborhood of 50mph. Leaving that one be, is the easiest way to limit your speed.

Removing the intake manifold washer was hands down, the best increase of acceleration.
You could probably leave the stock muffler on, and still see a good increase of power from this deristriction.
uphill power was cut in half by the washer

[Tseg]

Are you referring to the washer that is on the pin in carburetor?  If so, I saw a video where that washer was moved down a notch, but not completely removed.

[Roytheroach]

Are you referring to the washer that is on the pin in carburetor?  If so, I saw a video where that washer was moved down a notch, but not completely removed.

No, if you pull the carburetor out of the intake manifold, look inside. There is a washer jammed inside the intake manifold as an air restriction device. It reduces the inside diamteter of the intake tube for 1" to about 3/8". Removing this makes a HUGE gain in acceleration

[Roytheroach]

Got a chance to open the cvt today, the boss does not have a removable washer, the shoulder is part of the boss, so i will have to buy an unlimited variator boss

[Roytheroach]

Ordered a deristricted variator boss, it was the wrong size. So i ground the shoulder off and it worked. WARNING: it does not have enough power to get past 35 when i deristricted the cvt, rpms are too low, just ordered 5g weights to sit at 8k tpm hopefully

[Tseg]

No, if you pull the carburetor out of the intake manifold, look inside. There is a washer jammed inside the intake manifold as an air restriction device. It reduces the inside diamteter of the intake tube for 1" to about 3/8". Removing this makes a HUGE gain in acceleration

I've seen a few comments on the web about this air intake improvement... usually accompanied by a disclaimer "... accompanied by changing out your main jet...".  I guess this implies if one does not make main jet modifications one's spark plugs eventually will foul?  I then looked up main jet switch outs and it may be beyond my current competency as I think the carb has to be fairly dismantled to access the main jet? 

Did you do anything with your main jet?

[Roytheroach]

It actually makes it run leaner, youd want richer jets

[Noles4ever]

Hey Roytheroach:  I have the same scoot.  Where did you get the new CDI for $30.00?  I also need to order one.  Thanks

[Tseg]

It actually makes it run leaner, youd want richer jets

Fyi, I found this summary about the impacts of a lean main jet.  It certainly makes me think twice about removing that air intake washer without a plan to replace the main jet.


MAIN JET:
The main jet affects the jetting in the upper quarter of the throttle position. Coming into play at ¾ throttle on through to wide open throttle. Even though most people relate the main jet to their carburetor in general, the main jet is only responsible for the last ¼ of the jetting. The main jet does not affect the jetting for starting and idling. It plays no part on low RPM or mid RPM jetting either. The main jet is very important to your scooter’s overall tuning, but should never be over emphasized at the expense of needle tuning or other facets of your carburetion tuning.
When the main jet is Lean the engine will experience detonation or “pinging”. Exhaust note will be of a higher, tinnier type note. Engine will over heat easily and can be down on horsepower. A moderately lean main jet can cause engine seizures. A severely lean main jet can cause the engine to burn a piston (whole in top).
When the main jet is Rich the engine will be a bit flat or lazy at ¾ to full throttle, giving off a flat, dead sounding exhaust note. When the main jet is severely rich the engine will sputter in the high RPMs and have a lot of trouble making power up top.
The safest way to get the main jet setting as near correct as possible is to richen the main jet setting up until the engine begins to lose power and not rev to as high of RPM as before.
As a general rule, richen the jetting up as long as the engine likes it and continues to run just as well or better than the smaller size main jet previously installed. When the engine no longer continues to improve its performance you will know you have gone too far.

[Roytheroach]

Fyi, I found this summary about the impacts of a lean main jet.  It certainly makes me think twice about removing that air intake washer without a plan to replace the main jet.


MAIN JET:
The main jet affects the jetting in the upper quarter of the throttle position. Coming into play at ¾ throttle on through to wide open throttle. Even though most people relate the main jet to their carburetor in general, the main jet is only responsible for the last ¼ of the jetting. The main jet does not affect the jetting for starting and idling. It plays no part on low RPM or mid RPM jetting either. The main jet is very important to your scooter’s overall tuning, but should never be over emphasized at the expense of needle tuning or other facets of your carburetion tuning.
When the main jet is Lean the engine will experience detonation or “pinging”. Exhaust note will be of a higher, tinnier type note. Engine will over heat easily and can be down on horsepower. A moderately lean main jet can cause engine seizures. A severely lean main jet can cause the engine to burn a piston (whole in top).
When the main jet is Rich the engine will be a bit flat or lazy at ¾ to full throttle, giving off a flat, dead sounding exhaust note. When the main jet is severely rich the engine will sputter in the high RPMs and have a lot of trouble making power up top.
The safest way to get the main jet setting as near correct as possible is to richen the main jet setting up until the engine begins to lose power and not rev to as high of RPM as before.
As a general rule, richen the jetting up as long as the engine likes it and continues to run just as well or better than the smaller size main jet previously installed. When the engine no longer continues to improve its performance you will know you have gone too far.

I was starting to venture into lean territory so i put on a a 20mm dirtbike carburetor, ill be installing an a9 camshaft and porting the head soon. Expecting big results

[Roytheroach]

The pitbike carb just isnt working for me so i got an upgraded version of the factory carb, we'll see how it works out. I just installed an a9 carb and im running 50/50 ethanol with 93 octane

[AylmerFreerider]

Hey Roytheroach:  I have the same scoot.  Where did you get the new CDI for $30.00?  I also need to order one.  Thanks

I too am curious where you got a CDI for $30.  I have removed the purple wire from the harness instead of clipping and would rather have it in there than out.

Thanks