Quest for higher top speed

[91cavgt]

"Buy a bigger scooter"

"A scooter with 12" wheels wasn't designed to do that"

"It can't be done so why try?"



Those of us that are looking for a few more mph on the top end have heard it all.  Some maybe deterred from trying to reach a new goal because of the insurmountable odds.  But don't be discouraged!!  I'm creating this thread so that we as a community can share info with each other in an attempt to gain a few more mph of top speed. 

Personally, I don't ride my scooter at top speed all the time but there are times when I have to ride on major highways so having that little extra would be nice.  For the most part though, I would like to get a little extra MPG out of my Like, and if I can gain a few more MPH in the process then that's even better. 


So, here is what we know.  100% bone stock, a Like 200i has a top speed of right at 60 mph (level ground, no tailwind). 


The modifications that most of us have heard about is removing the intake restriction at the inlet of the air box.  I did that modification and gained just shy of 1 extra mph of top speed.  So I took the air box lid off and removed the cover over the air inlet.  Both of those combined was enough to put the top speed right at 61 mph. 

Just today I ventured into the realm of replacing the rear tire with a larger one.  I replaced the stock 130/70/12 with a 140/70/12.  This new tire is 10mm wider and about 14mm taller overall than the stock tire.  It is a Michelin Pilot Sport.  I found it on Ebay for $50 shipped to my house and the local Kymco dealer installed it for $37.  So after the tire install, I went out on a test loop and found to have a new top speed of 62 mph on level ground with no tailwind.  Just to make sure the road was level, I road the other way on it and still came out to have a top speed of 62 mph. 





I believe the exhaust to be a pretty big restriction at this point.  This tire should have given a full extra 2 mph, but with wind resistance being so great at this speed, the tiny exhaust outlet is really restricting this motor.  However, before I move on to try an exhaust system out, I am going to be experimenting with new rollers to see if I can get another mph out of it first. 


Ohh, I almost forgot.  Weather plays a role in your top speed.  The hotter it is, the lower the power output of the motor.  The higher the altitude is the lower your top speed will be as well.  So, during today's testing, the outside air temperature was at 93 degrees with 55% relative humidity, 74 degree dew point making it feel like 103 degrees.  It's hot!!  The city where I live is also at 470 feet elevation so that shouldn't effect the top speed any.   

[91cavgt]

1st attempt at roller change;


I used three 16 gram rollers and three 17 gram roller for a combined average of 16.5 grams. 

Pros;

Lower engine rpm from 20 mph till about 40 mph
Same top speed
More docile for in town riding but still enough power to stay ahead of traffic

Cons;

Decreased hill climbing power
speed drops more than stock when hitting hills or in a head wind


At no time did the engine seem to be struggling or bogged down, but the higher decrease in speed when hitting hills or a headwind is not acceptable for me.  If I was just riding in town, I think this would be a great weight as it lowers engine rpm which should increase fuel economy. 

[Stig / Major Tom]

Our stock LIKE roller weights are what ? 13  or 13.5 gr. ?
You used rollers, not Dr Pulley 'sliders'?

[91cavgt]

2nd attempt at roller replacement.


This time I went a lot in the opposite direction.  Three 12 gram roller and three 13 gram rollers for a combined average of 12.5 grams.  This is a lot lighter than stock but I am VERY impressed with the results. 


Pros;

Gets to top speed faster
No decrease in top speed
Acceleration has been improved
VERY small drop in speed when going up hills or into headwinds

Cons;

Higher engine speed means more engine wear and worse fuel economy



I am very impressed with this setup.  I was concerned about top speed because you can tell the engine is revving up higher, although it is not a huge increase in RPMs.  I was able to hit 60 mph without getting into a tuck and when I did get into a tuck, the speed went up to 62 mph pretty quickly.  At one point, I did see the speedometer pass the 100 kph mark but I am unsure if I was going down a very slight hill or just what was occuring.  At one point, I did go down a very short but steep hill and I took it at full throttle going downhill.  When I got to the bottom of the hill, the speedo registered 68 mph, and the rev limiter had not kicked in!  I have a feeling that when I add a pipe, this setup will be VERY nice. 

[91cavgt]

Our stock LIKE roller weights are what ? 13  or 13.5 gr. ?
You used rollers, not Dr Pulley 'sliders'?

I was told the stock rollers are 14.5 grams and my fiance's scale reads them as 14 grams, but it doesn't read fractions of a gram.  I used rollers to narrow down what works and what doesn't so that in the future I can get some sliders and won't waste a lot of money experimenting.

[claynine]

Thanks a bunch for your posts.  I just hit 1000 miles on my Like.  I have a big windshield so 53 is top speed for me right now.  I posted may thoughts about restrictive exhaust a couple times and there is a pipe out there apparently ready to bolt on. 

http://www.ebay.com/itm/130689567631?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

Even though the picture just shows the exhaust can, I was told via email that it has all provisions for the stock emmissions (O2 sensor) equipment and is a direct bolt on.  I am still searching for others though.    This was posted by 91cavgt  in a post I started called back pressure.

[exhalent99]

Good thread.

Since in Ontario, Canada - where I have my motorcycle license,  the Like is not considered a restricted speed, I will be expected to take it on a 100km/hr highway at some point during the full driving test.

I have gotten to 100km/h a few times but it took a while to get there from 90...

I dont really care to cruise around at that speed, and I feel it performs best at 80km/hr one up, and at 70km/hr two up.

I would however like to be able to cruise at 80 going two up without it feeling the least bit sluggish.

About the airflow restrictor, I have removed it and really didn't like how it sounded and felt it lost some pep. I also did not notice any gain on top speed WOT. I put it back....

BUT if I had an exhaust that didnt kill the horsepower with back pressure I think the airflow restrictor would really need to be out.

Larger rear tire is a great idea, as is slightly lighter rollers or sliders.  Of course the exhaust is probably going to make the biggest difference.  So, has anyone ordered Iit yet?

[Vivo]

Please don't forget that larger tires gives more stress to the brakes and increases braking distance... you have to stop a tire with a larger mass... 



These are Yamaha Mios 110cc racing on our tracks.....


Except for modified engines... other factors for speed are:


1. Aerodynamics... lesser wind resistance, the better
2. Weight... the lighter, the better
3. Tire diameter... the greater the diameter but lesser road contact/resistance, the better...

[91cavgt]

Please don't forget that larger tires gives more stress to the brakes and increases braking distance... you have to stop a tire with a larger mass... 

While this is true, the overall increase in tire size is not very much, and the brakes on our Like's are very good.  However, in the future I do plan on putting some better brake pads and replacing the brake fluid with Motul 600 RBF. 


It should be noted that if you're going to go faster, at some point you NEED to do something to help your brakes cope with the extra speed.  If you don't then it is a recipe for disaster.   

[91cavgt]

After riding today with 12.5 gram average weight rollers today I found that I was able to cruise at 55 mph while at part throttle.  So it appears as though this may actually save some fuel due to not having to be just about at wide open throttle just to cruise at 55.  I'll update this thread in a couple of days for updated fuel mileage.