My Top Speed Is...
 

I don't know if a thread has been started like this but I thought it would be helpful to start keeping track of peoples top speeds and the conditions that led to that top speed. For example:

Top Speed: 65mph
Bike: Bashan Storm 250 (Counter-Balanced Engine)
Front/Rear Sprocket: 17/43
Mods: Pod Filter Intake
Carb Tuning: 108 main/1 shim on needle
Rider Weight: 210 lbs

Good idea! I'll play. :clap: Note that my bike isn't broken in yet either.

Top Speed: 67mph
Bike: 2018 SSR Motorsports XF250 Street
Front/Rear Sprocket: 15/43
Mods: None yet
Carb Tuning: None yet
Rider Weight: 190 lbs

That's quite a nice bike! Very expensive but looks to be pretty top quality! Changing the intake and/or exhaust and some carb tuning should definitely put you over 70mph!

It is pretty nice. I have gearing changes planned as well as a slip on (and eventually the oh so nice Lextek exhaust later on) and a 6sigma jet kit in the plans for performance mods. I'm hoping I can get it to cruise at 75 mph like I've heard this bike can do. If not I can settle for 70. Lol.

Top Speed: 61mph (GPS verified). This was just today - my first run after dialing it in.
Bike: Bashan BSR250
Front/Rear Sprocket: stock. Also stock chain.
Mods: Mikuni VM26 clone and aftermarket exhaust. NGK plug. Airbox is stock, but all the auxiliary air hose stuff is deleted and ports are plugged.
Carb Tuning: 115 main - 25 pilot - needle in middle (3rd) position
Rider Weight: 250 lbs

Bike hummed along great at 45-55 (it was also a crazy windy day today) but felt a bit more unstable at 60, so I backed off. I think with better tires It would hit 65 on flat ground and still feel stable.

Top Speed: 62 mph (was 60 mph with stock rear 46 )
Bike: TBR7 2019
Front/Rear Sprocket: 17/44
Mods: Mikuni clone carb swap, Front \ Rear sprockets
Carb Tuning: 100 main/1 shim on needle, A\F 1.5 turns out
Rider Weight: 220 lbs

Top Speed:53 mph (according to the speedo not sure of it's accuracy )
Bike: TBR7 2020
Front/Rear Sprocket: 15/46 (? Stock setup currently)
Mods: Mikuni clone carb swap VM26, 110 Main, New non cat exhaust, Iridium
Carb Tuning: 110 main/ needle in the middle, A\F 1.5 turns out
Rider Weight: 190 lbs

2018 Hawk 250
Top Speed: 72-75mph*
Ekevation: 1100ft
Mods, Carb, and sprockets: Link in signature (too much to post here).
Rider Height and Weight: 6'4'' 270lbs

*My bike is limited by it's gearing more so than power. Via Phone GPS - 72mph is the most repeatable top speed I can achieve, with 75 happening on nice flat ground. So to be fair that is the top speed I have listed. I have reached 79mph on a few occasions, but I don't count those as official top speeds since they are hard to repeat without the right conditions.

Top speed: 72 mph (GPS confirmed)
Bike: 2020 TBR7
Front/rear sprocket: 17/44
Mods: CRF230F exhaust, UNI pod filter, PnP 10.3:1 head, front fork brace
Carb tuning: 120 main, 38 pilot
A/F 1.5 turns out
Rider weight: 210lbs

Elevation is probably an important factor to include as well.

Elevation: 3 meters above sea level

Elevation is very important indeed. My bike looses 5-10 mph on the top end during my ride home from work (LA area/sea level) up to the high desert (3-4,500k feet). I'm sure better tuning could help even things out, but I need my bike to be fastest on the big highways "down the hill".

Top Speed: 80 mph(not common though) 77-78 is more realistic.
Bike: SSR xf250
Mods: Pod Filter Intake, jet kit, amazon universal muffler, and now a cigar lighter.
Carb Tuning: 130 main, larger pilot (forgot size)
Rider Weight: 190lbs

59 MPH by gps, 63 on speedo

2016 Magician
Stock Gearing
Stock carb with 105 Main, 42 Pilot, A/F 1 3/4 turns
NGK plug
Rider weight 210.
Elevation 1500 feet

62 MPH by GPS

2019 Brozz250
stock from the box, except for NGK plug, and of course valves=set at .0025" & .004"
stock sprockets 17/46
stock carb & exhaust
1000' elevation
rider weight 205

Wow, that's amazing! You're not running rich???

I'm starting to see a trend that MAYBE counter-balanced engines like in the Storm and Brozz are about 5mph slower! That's kind of interesting.

About 65 (phone GPS) or 72 indicated. I have a 2020 TT250, and I have a 42 rear sprocket. I have rejetted. Funny I decided to rejet again on my 2nd oil change. I lost like 10 MPH up top. I backed out just about everything I had done (went from 112 to 117 main, needle from #3 to #4 and from 2 to 2.5 on the IMS, and then went back). One thing I should have realized would have cost me tons was a switch from 10w30 to 20w50. I changed that back out too. Now the bike is back to what I mentioned in my first sentence. Oh yea, the miss I had at WFO, got rid of that by replacing the "torch" plug with a proper NGK.

Top Speed: 68mph
Bike: Bashan Storm 250
Front/Rear Sprocket: 17/42
Mods: unifilter pod and outerwears cover, car customs exhaust.
Carb Tuning: 118 main 38/40 pilot depending on temp
Rider Weight: 225 lbs

70mph on speedo
Bashan Motomax 250
17/46
NGK, stock exhaust and airbox
110 main, 1.5 turns
190 lbs
16'

Top Speed Consistent 74-76 mph GPS (80 mph when the stars alien)
2016 Hawk 250
Keihin PE30 carb,125 main,32 slow. Pod filter
Ported & decked head 10:1 CR
Direct Ignition Coil
17/40 Sprockets,
NGK DPR8EIX-9 Plug
De-Cat Exhaust with Ebay muffler
Dual Oil Cooler
Rider weight 175 lbs

Elevation Ground Zero.

Bike: BMS CRP 250
Fakuni 30mm, 110 main, 25 pilot
Top speed: 60 on the dash.. so probably 55. And I was pegged, full throttle, slightly downhill. Shortly thereafter, my whole rear wheel flew apart. Nobody died!

Gonna go to a 40t on the rear soon.. let's see what happens! I think stock gearing is like 15/50 or something

All Bashans are geared with 17/46 gearing.

Where's Azhule when ya need him! Didn't he set the Land Speed Record on his Bashan WILL? As I recall, there may have been a sonic boom when he did it.

well, hopefully that 40t works wonders! It's already here waiting to go on

I have a 42 on my storm and I don't think I would go any lower. Pretty noticeable loss of bottom end. You get used to it and it does knock the rpm down a lot on the top end.

68 mph Brozz gps measured (new carb and exhaust, stock gears)
59 mph Hawk gps measured (new carb, baffle removed, 17t front sprocket)

Top Speed: 110 km/h GoPro GPS
Bike: Lifan 150cc
Front/Rear Sprocket: 17/46
Mods: 65.5 piston, PWK 28, enhanced ignition coil, Custom cdi, rewired and improved stator. Iridium NGK plug
Rider Weight: 180

85 to 90 kph with 15/45 gearing and 18 inch wheels.
Measured with GPS
125 ccm, 11 HP

Do you think the 9mph difference is strictly due to gearing???

53-56mph for us weirdos

Impressive for a 125cc! My first China bike was a crappy 125cc that peaked at about 45mph!

Yes. And maybe exhaust as well.

07 Lifan 200 GY5 (CG200) stock gearing 17/46, derestricted exhaust, jetting, pod filter, ~65mph.

68 Trail 90 with Lifan 140 17/45 gearing ~55mph.

OOOOK, I'm truly baffled now! I replaced my exhaust with the typical, cheap CRF230 eBay/Amazon exhaust this weekend (which is disgustingly loud, btw...any way to quiet it down???). I bumped my main jet to 115 and added another shim to the needle, for a total of 2. Pod filter intake. My top speed is still pretty pegged at 65mph. Do I need to loose 80lbs before I can get it to go 70? What's the deal???

66-67
 

My top speed is 66-67. This is not GPS, but based on 70mph indicated minus 3 to 4mph. This is what the speedo is off when I pass one of those radar signs for speed...it is the same in a 35 zone and 45 zone...so I think this is close.

Bike is a 2018 CSC TT250. Aftermarket exhaust, Mikuni VM26-606 carb, Uni filter, 47 rear sprocket, Conti GO! street tires, large Nelson-Rigg Panniers, RX3 windscreen. I am 173 lbs, 6 ft.

Changing out to a VM28-49 carb soon, so will see if this makes any top end difference. Don't really care, just want some more punch. https://www.denniskirk.com/165143.sk...ikuni+VM28-49&

How do you adapt that to the intake manifold with the 2 holes that comes on all of these bikes? Is there an adapter or something?

Weight (yours) and power will be key. Also, do you lay down forward for aerodynamics? You could try a new head or porting your stock one. The thing with Chinese dual-sports is most people do what you did with yours, exhaust, carb, and gearing, but you don't necessarily get much more top speed out of them, but rather lower revs, making your ride a bunch more comfortable, but not much faster, at top speed. Megadan has advice on the matter based on his Hawk, and he uses a Nibbi carb and has done head work on his Hawk.

Your overall gearing (sprockets and tire diameter), the mods, and the engine in question... 65-68mph is about right.

Some things to consider.

1. How/where the CG250 makes power. Unlike the OHC "CB250" engines like the ones found in the Apollo DB36, or the Venom X22R, the CG OHV engine, especially the 230cc variant, is a low reving motor that makes good strong low to mid range torque and mid range hp with the top end HP tapering off fairly quickly past the peak at 7000-7500rpm. That means that even though the Rev limiter for the CG250 is 8500rpm, it doesn't really have the power to pull itself there, especially in a higher gear with taller gearing. Top speed is all about that high rpm energy, something the CG250 engine just doesn't quite have.

2. The setup of the bike in question AND the rider. Because the CG is not a high RPM power making engine, the compromise that is often made is to gear the bike taller with bigger front and smaller rear sprockets. This works well for the CG since it is such a torquey engine. The downside is, that there is a limit to how far you can gear these machines up before it negatively affects that power as delivered to the rear wheel.

Then there is the rider to consider. My top speed seems relatively low for my mods because it has me on top of the bike, a man the size of an NFL lineman. Compare my work to JerryHawk250's bike, the difference in gearing, but most importantly, the difference in the two riders. I have an easy 100lbs of weight on Jerry, if not a bit more AND I am a good half a foot taller than he is. I have to keep my bike geared shorter (bigger rear sprocket) than he does, which if you do the comparative math I would have +5 teeth out back vs. his setup . If I try to gear my bike like his, I actually lose top speed simply because the bike can't push me through the air. He is actually able to more consistently hit higher top speeds because of it.

Just to bake your noodle even more, we can compare my current bike to my last Hawk.

All things being equal, my last hawk was only maybe 3mph-ish slower than my current one in terms of consisten top speed. And that bike only had a Mikuni clone carb, pod filter, and ebay exhaust. It could generally hit 65-68mph vs my current bike consistently hitting 70-72. Gearing between them is nearly identical.

So why did head porting, a cam, and a bigger carb only net a couple of mph? Simple, the motor is still hitting peak power around 7000-7500rpm. The cam helped stretch the power a bit past that point so it doesn't fall on its face quite as fast and I can stretch it to 8000rpm in 5th, but it still lacks that top end power that is really needed to push higher speeds more effectively.

What's the difference between the two bikes then? Well, top speed doesn't accurately measure the real difference. My current bike would leave my old bike in the dust getting up to those speeds. Acceleration is effortless compared to my last bike. My old bike would struggle to climb certain hills that my current bike just tractors me up without skipping a beat. Basically, I make more power within the same power curve.

Plus, there is also basic physics at work too. The Kinetic energy needed is the square of the factor of increase in velocity. Or as often heard in simple terms, it takes 4 times the power to go twice as fast. So, in the grand scheme of things, I have maybe added 4-5hp to my Hawk with all of the work I have done, which is a respectable 25% increase and nothing to sneeze at.

If we actually do a little analysis of a stock Hawk, of which the fastest I have ever gotten one to go with a properly jetted carb and different sprockets (same ratio as current bike) was about 63mph. Fair assumption is that a Hawk with said properly jetted carburetor makes right around 14.5-15hp. That means that if I wanted my Hawk to top out at 93mph it would need 30hp (this is all oversimplified obviously, but it illustrates the point). Since I have added maybe a third of that amount of power, it stands to reason that my top speed on my current bike would be *drum roll* about 10mph faster (7.75mph if you do the proper math), which it more or less is.

I say this with the utmost respect, so don't take this the wrong way, but if your goal was to have one of these bikes carry you along at 70+mph on the highway for any length of time, you are barking up the wrong tree. Dual sports are very non-aerodynamic and their large diameter spoke wheels with heavy tubes and off road tires have a high moment of inertia that saps kinetic energy. Combine those facts with the relatively low power output of these little engines, and they just can't achieve what you are after. You can make one go 60-65mph all day, but beyond 70 is asking just a little too much. If you need more evidence of this, look at the CRF250L and its top speed of 80mph. That bike makes 10 more hp than our bikes do from a proper OHC 249cc liquid cooled motor.

Thanks, Megadan, for that explanation!

Another example:

Honda XR 650cc estimated top speed 110mph

Yamaha MT03 321cc estimated top speed 110 mph

Dual Sports are just not meant to be fast motorcycles

Wow, that is some great information. Thanks for being so thorough. I definitely don't plan on trying to drive for long periods at even 60mph, I was just hoping it would be able to hit 70mph if needed. I will say that since the exhaust I did notice it is definitely more lively. I was just shocked about the top speed not changing.

Also, I didn't know the Apollo DB36 had a different, arguably better, motor. I would have probably gotten that bike instead of the Bashan Storm had I known that!

Also, where does one get this CG250 performance cam I have seen mentioned a few times? I cannot find any information or where to purchase it.