How can I make my TBR7 as fast as possible?

[Tbr2d2]

Hey all,
I have a 2020 TBR7. Original top speed b4 the speedo needle fell off was 63 wot. I'm trying to get to 70 wot, that way 60/65 is more comfortable on the engine. I have an aftermarket 27mm carb (iknow its smaller) with a 102 jet that definitely got me higher revs (no I didnt try the 102 in the 30. Will that get me more?). I also switched today to the 17 tooth front. Seemed to gain me a few more mph (guessing by feel) and definitely seemed to take longer b4 I had to shift.

[culcune]

Not sure if the smaller carb will net you higher top speed, but your countersprocket swap surely will. Exhaust swap definitely will help, and someone with a TBR7 should be able to point you in the right direction.

[kingofqueenz]

2 words "down hill" ... :lmao:

Just kidding

To be honest, I do not think sprocket size ( especially the 17 tooth front ) will increase your speed in top gear at wot ... it will just make your gearing taller.

Increased horsepower will come from increasing airflow in to and out of the engine.

Head porting, intake and muffler mods etc.

Not my expertise by any stretch, with apologies

[shiftclick]

2020 TBR7 owner too. Did the 17 up front and threw in a Mikuni knock off and I think the 110 jet. Also threw in a Uni style foam air filter and bypassed the onboard air box. Didn't make a huge difference, but did make a difference. My top speed is probably right around yours although it's new enough I am still breaking it in. There's a youtube video out there somewhere where a guy takes a 250 cc and swaps out the front and rear sprockets for various sizes and gives you a chart showing top speed, fastest 0-60, 40 pull, etc. Let me know if you can't find it.

[kingofqueenz]

Here's 3 vids...

https://www.youtube.com/watch?v=GhSK0gn-7ww

https://www.youtube.com/watch?v=C6_FtVTjKng

https://www.youtube.com/watch?v=O35AwCp-6b8

[Mudflap]

A windshield and skinny street tires will help.

[JerryHawk250]

Free flowing exhaust and air filter. Sprocket change to a higher gear ratio and the best performance mod is the porting and decking of the head. At least a 30mm carb. Though there won't be a huge increase in top speed, it does do higher speeds with less effort.

[paulsstag]

Hey all,
I have a 2020 TBR7. Original top speed b4 the speedo needle fell off was 63 wot. I'm trying to get to 70 wot, that way 60/65 is more comfortable on the engine. I have an aftermarket 27mm carb (iknow its smaller) with a 102 jet that definitely got me higher revs (no I didnt try the 102 in the 30. Will that get me more?). I also switched today to the 17 tooth front. Seemed to gain me a few more mph (guessing by feel) and definitely seemed to take longer b4 I had to shift.

After watching a couple videos on the KTM 790 S a KTM 790 R and the difference in commuter and highway travel was a bit of a surprise . One of the guys testing at different speeds on an interstate said the front fender itself played such a big roll on how they felt. The R model has a high fender and S model has a fender close to the tire .

It has been mentioned here before that the front fenders act like a big parachute . Just reading the other posts on this it is possible to change the gearing to get the rpms in the meat of the power band at a desired speed, as has also been mentioned is power mods that helps get up to those speeds easier and to maintain them once there.

Has anyone here removed the front fender and possibly the air deflectors on the fuel tank to make the bike more aerodynamic and see if the bike maintains speed better? It would be pretty quick and easy to try this, beside the ugly factor it is certainly worth a try.

Paul.

[2LZ]

If I lost 50 pounds, Q would gain quite a bit of top speed.

[Rocket tests]

I build rocket motors, that would get things really moving.
https://youtu.be/RyeoKRUrt3c

[Tbr2d2]

Ya I saw that 1 too! I need to check my history. Ya mines a knockoff as well. I'll try the intake info. I'm still stuck there. Thanks!!

[Bruces]

Three words “hyabusa engine swap “ ........’nuff said .

[shiftclick]

Finally got to take my TBR7 out for a top speed run after installing my +600 HP Hawk digital cluster...

20827

[Megadan]

Gearing is the most crucial part of the the whole equation.
With the CG250 engine you basically end up with a top speed right around 7000 to 7500 rpm, and cruising rpms between 6 and 7k for highway use.

That being said... Without head work, with a full exhaust, intake, and a well tuned pz30 or vm26, and the right gearing it wouldn't be unrealistic for a tbr7 to have a top speed somewhere around 70 to 75mph.

[shiftclick]

Gearing is the most crucial part of the the whole equation.
With the CG250 engine you basically end up with a top speed right around 7000 to 7500 rpm, and cruising rpms between 6 and 7k for highway use.

That being said... Without head work, with a full exhaust, intake, and a well tuned pz30 or vm26, and the right gearing it wouldn't be unrealistic for a tbr7 to have a top speed somewhere around 70 to 75mph.

You are dead on correct. I was still at 6,000 RPM today when I hit 70 so I know I had at least 1000-2000 RPM to go when I ran out of road. So I think my 17t front and 46t rear (is that stock) would get up to 75 mph, but cruises easily in the 55 - 60 mph range without breaking a sweat. I bought the 45t rear, but not sure it's worth installing it. Thoughts?

[2LZ]

Gearing is key but can only go so far. I over-geared Q and actually lost top speed. She ran out of torque. I dropped a tooth and gained basically 5 mph, though I did gain RPM's in the process. Of course, it was hauling my lard ass.

[shiftclick]

Gearing is key but can only go so far. I over-geared Q and actually lost top speed. She ran out of torque. I dropped a tooth and gained basically 5 mph, though I did gain RPM's in the process. Of course, it was hauling my lard ass.

Interesting. So if my TBR7 came with a 15t front sprocket and a 46t rear sprocket, installing the 45t would increase my top speed to 75 or 80 mph. Now it might be worth installing (one of the nut's/bolts is stripped on the back 4 wheel hub pressure plates thus the delay).

[Megadan]

Gearing is key but can only go so far. I over-geared Q and actually lost top speed. She ran out of torque. I dropped a tooth and gained basically 5 mph, though I did gain RPM's in the process. Of course, it was hauling my lard ass.

Agreed, there is a limit to the gearing. It takes X power to make Y bike move Z fast not including variables like wind, tires, etc. Run out of power, and that's all she wrote. That is part of the reason I like to include RPM ranges to try and land in. It helps eliminate a little bit of guess work by giving an area to aim for.

In reality, no CG powered dual sport is ever going to see beyond 75mph, and they have to be geared pretty tall in order to even reach those speeds.

Interesting. So if my TBR7 came with a 15t front sprocket and a 46t rear sprocket, installing the 45t would increase my top speed to 75 or 80 mph. Now it might be worth installing (one of the nut's/bolts is stripped on the back 4 wheel hub pressure plates thus the delay).

No, if you went from a 46 rear to a 45 rear sprocket and stayed with the 15 front, you would only see about a 2mph gain at 7000rpm.

Now, if you added a 17 front sprocket combined with that 45 rear sprocket, you would then see about a 4.5mph increase at 7000rpm.

The funny thing is, us Hawk guys are actually geared way taller than you TBR7 guys thanks to our larger 18 inch rear wheel and tire setup. Roughly translated our rear sprockets need about 3 to 4 more teeth than your TBR7s to roughly equate to the same overall gearing (Same MPH and RPM).

A very popular Hawk setup has always been a 17 front/45 rear, or a 16 front 43 rear, or 15 front 40 rear. (all basically the same ratio). A 17 front 45 rear on a Hawk will generally yeild about a 65-68mph top speed, and a bike that can comfortably handle 55-60mph without being completely maxed out. It is moderately highway capable without sacrificing too much in the way of acceleration.

For a TBR7 to achieve a similar gearing, you would need a 17 front and 42 rear sprocket.

Now, me personally, for a Hawk that is going to be 80% road and highway, I loved my 17 front 43 rear sprocket setup. With a VM26 clone jetted very well, an exhaust, and a pod filter with more road friendly tires, I could cruise along all day at 60-65 (RPM's right at 6000-6500) and just hit 70mph at 7000rpm where peak power occours. That was about the limit of that bike with my big and tall self in the seat. I could occasionally crawl into the low 70's if the wind was calm, but that was really pushing it hard.

To match that (A perfect match) on a TBR7, it would be a 17 front and 40 rear

There is always a compromise factor though, as with anything. People that live in low altitude flat lands that aren't me sized like JerryHawk, they can get away with even taller gearing and achieve higher top speeds. I live in an area with a lot of decently steep hills, so I have to keep my gearing a bit shorter so I don't struggle to maintain speed up said inclines while my bike is trying to fight the wind resistance and weight of a 6'4'' tall 270lb man. Thus my bike is geared equivalent to a 17 front 45 rear. Will it go faster with taller gearing, sure will. It has the power to do higher top speeds, I even damn near hit 80 once. I compromised on a loss of top speed to be able to climb and accelerate. Going above 70mph on these bikes is honestly something I will leave to the incredibly brave.

Other factors that can translate to different results between our bikes is also the tire diameters. Bikes with a 21 front and 18 inch rear tire have more moment of inertia to overcome and generally have a lower top speed than a bike with a 19 front and 17 rear, which means they have a little more power on tap for acceleration and overall top speed. I know that a Brozz and TBR7 unmodified struggle a lot less to reach past 60mph. A hawk with no mods, even with the right gearing, is hard pressed to go any faster than about 62-63mph.

[JerryHawk250]

Very well said Megadan. :tup: Yeah, us light weight flat landers @ sealevel have a slight advantage. ;) To help you understand how tire size plays a big part of gearing. Here's a link to a gear calculator. Load the Hawk data. This will give you the correct information for the TBR7 transmission gearing. Input your rear tire size to replace the Hawk info. You can play around and see what the different gear ratios. https://www.gearingcommander.com/

[A1R 250 bob]

Hey all,
I have a 2020 TBR7. Original top speed b4 the speedo needle fell off was 63 wot. I'm trying to get to 70 wot, that way 60/65 is more comfortable on the engine. I have an aftermarket 27mm carb (iknow its smaller) with a 102 jet that definitely got me higher revs (no I didnt try the 102 in the 30. Will that get me more?). I also switched today to the 17 tooth front. Seemed to gain me a few more mph (guessing by feel) and definitely seemed to take longer b4 I had to shift.

Grease Rat: Like the sign says, "speed's just a question of money. How fast can you go?"

My bike budget is minimal, mainly because the "other one" believes that money is better spent on her ideas. However this 2019 TBR7 can nick 70+ carrying 225 pounds verifying by a GPS phone app. My mods were to un-tamper proof the carb and put in a 110 main, 17 tooth counter sprocket, and drill 3 - 3/8" holes in the muffler around the normal exhaust exit bypassing some of the baffling. Still use the stock chain but baby it with constant cleaning and lube. the crankcase has 10w30. I did buy an 8"x 10" sheet of Plexiglas at Lowes for a windshield.

The elevation average is around 614 feet above sea level.

The bike really does not like to remain at top speed and seemingly prefers 55 to 60 MPH, where the vibration is not as violent.

[NzBrakelathes]

Grand canyon vertical drop - fastest it will ever go.......

[A1R 250 bob]

Grand canyon vertical drop - fastest it will ever go.......

I bet one could exceed terminal velocity (120 mph) by attaching rockets.

[NoBs]

2020 TBR7 owner too. Did the 17 up front and threw in a Mikuni knock off and I think the 110 jet. Also threw in a Uni style foam air filter and bypassed the onboard air box. Didn't make a huge difference, but did make a difference. My top speed is probably right around yours although it's new enough I am still breaking it in. There's a youtube video out there somewhere where a guy takes a 250 cc and swaps out the front and rear sprockets for various sizes and gives you a chart showing top speed, fastest 0-60, 40 pull, etc. Let me know if you can't find it.


Which is all well and good if you have the power to take advantage of the taller gearing.. I went one LESS tooth ( 14 ) in the front and seemed to have lost nothing at top end. Of course it will rev a bit higher at the same MPH.. Anemic performance may show its ugly head if one goes overboard on the sprockets..

[Rocket tests]

I decided against building a rocket pack for the tbr7, instead i spent the last 3 evenings porting, polishing port matching, and decking my head.

All I can say is WOW!, what a difference. Hills which would bog down at 45mph are now conquered at 60mph without bogging. I havent changed the factory gearing from the 15 front and 46 rear sprockets. I'm able to hit 70 on a flat road and almost 80 downhill, this is referencing the stock speedo (still waiting for my digi dash). First gear handily lifts the front wheel without need to lean back and I can clutch wheelies in second. I'm 6', 210 lbs and couldn't be happier with the mods.

I recieved an order of various front sprockets today but unfortunately i ordered the wrong center splines. I guess I'll need to rectify this issue by purchasing another bike for them to fit on. The cost of these bikes makes them a blast to mod out.

[JerryHawk250]

Port and decking the head is the best mod I've done on my Hawk.

[Megadan]

Port and decking the head is the best mod I've done on my Hawk.

Especially when paired with a smooth bore carb and an open exhaust.

[shiftclick]

...and drill 3 - 3/8" holes in the muffler around the normal exhaust exit bypassing some of the baffling.

It's a little different on the 2020 TBR7, but after doing this, I had to adjust the idle screw and I could definitely tell a difference rolling down the road! Guess a performance exhaust is next up for me. Thanks man!

[kb21guru]

Run 140 and 39 jets and run methanol, if those jets let the engine run rich on 100% methanol, add nitro...Nitro bursts into oxygen and will in essence add oxygen to the rich fuel mixture thus leaning it down.

The gearing, the rear gear yields bigger changes than the front, the front gear is for fine tuning. For every rear tooth removed is like adding three teeth up front.
Plus when removing teeth from the rear, if you remove links in the chain...your removing weight too. The quickest way to gain speed is to add lightness.

On my Apollo 125cc RFZ 12/14 inch wheels. Stock gearing was 14/41.

If I run a 16 front gear and a 37 rear with the 12 inch rear wheel I'm running at optimal rpm and torque with a +26%ish gain in top speed but with a -26% torque loss. if I run the same set up with a larger 14 inch rear wheel I am lugging the engine.
Now, if I run the 16 front with the 41 rear gearing on the 14 inch wheel I am at just about the same as the 16/37-12 inch wheel. Why because it takes more power to turn a taller wheel so I have to add teeth to the rear to compensate.

Wheels are probably the best way to add speed. The lighter the wheel is, the less rotating weight (rotating weight is heavier than standing weight). Removing just 2 pounds of front wheel weight is the same as removing 12 pounds of static weight elsewhere on the bike.
But this comes at a huge cost, carbon fiber wheels is about the only way to really see a gain in wheel weight enough to make a difference. Sure alloy rims will remove 1/2 pound but then that's not really much of a difference, rotation wise.

Other ways to make a gain in speed is to do crank work, lightening the crank, angling the leading edge of crank. Working on the conrod (thinning) to limit turbulences and drag internally. And for gosh sake, do not polish anything, just port/match. Why? Polished surfaces create more drag when air and fuel is passing over it, than if it was a rough surface. A rough surface breaks the drag and allows the air/fuel to reach a higher speed.

Intake tuning is a thing too. Air/fuel speeds up in narrow long tunnels and slows down in wide short tunnels.
larger carbs don't always add power. Understanding how air and fuel flow, is a good key.

Simply bolting a large carb and gear is not the only way to go fast. There is many things that when combined will yield a faster bike.

But I don't see anyone really talking about the real way to go fast, just bolt on stuff........

Hey all,
I have a 2020 TBR7. Original top speed b4 the speedo needle fell off was 63 wot. I'm trying to get to 70 wot, that way 60/65 is more comfortable on the engine. I have an aftermarket 27mm carb (iknow its smaller) with a 102 jet that definitely got me higher revs (no I didnt try the 102 in the 30. Will that get me more?). I also switched today to the 17 tooth front. Seemed to gain me a few more mph (guessing by feel) and definitely seemed to take longer b4 I had to shift.

[ChillRider]

Well, my 2c from my experiences with my older Zongshen Sierra chinabike, used as a daily commuter in a daily 25/75% urban/extraurban commute (about 15 miles): with a 15-ish horsepower engine (and less than that to the wheel), those machines ain't built for top anything.

That being said, you can make them more comfortable for open road cruising, with the biggest benefit coming from a sprocket swap giving you a taller gearing. Even that way, calling it "highway cruising" would be a stretch. More like keeping 55-60ish mph for hours without keeping the engine constantly in the redline is more like it. If you push it hard you will get a higher top-speed also, but it's not something you'd like to keep for long. If you manage to get them to the point where you can safely keep up with commuting traffic on extra-urban roads and manage a few overtakes as well, that's really all you can ask of them.

Enhancing fuel/air flow to the engine and keeping valves well-adjusted, esp. on those carbureted chinabikes, will certainly give you more low-end grunt and better acceleration under all circumstances (always welcome), but they simply don't rev all that high to begin with, and their engines + gearboxes are often based on older 5-speed designs, where the lack of a 6th gear really shows.

E.g. the CDI of my Zongshen Sierra is capped at 8000-ish revs I think, while an obscure "performance" version of it claimed to go up to 9000 rpm. Even with a massive increase in power but without increasing revs (like this guy who turbocharged his Yamaha TW200 (https://www.youtube.com/watch?v=1c04jRnlESg), same engine), even with the tallest practical gearing, I'd still get no more top speed. Better "pull", yeah, reaching top speed faster, yeah, keeping it while going uphill and riding pillion yeah...but not higher, without more RPM.

With my current setup, in some particularly favourable conditions (e.g. downhill, tailwind, etc. ) I've found myself looking for a 6th gear, feeling the engine screaming and having something more to give... but nope, the revs were already maxed out, and there was no 6th gear :)

Going to an even taller gearing than what I currently have (14/42) would make the bike suitable only for long distance cruising, but painful to ride in stop & go traffic and hilly areas. Keep in mind, my bike also has the oddball rear 15" cruiser wheel and street-oriented tires.

[TxTaoRider]

As long as we are limited to 5 gears, and not much horsepower, gearing will always be a huge compromise. A 6th gear would sure help.

[Oldenslow]

I think folks need to keep something in mind when they are thinking about upping speed on many if not most Chinese bikes. While the drive trains may well be able with modification to drive these bikes to 70+, the rolling gear -- tires, wheels, suspension, brakes, chain -- are not, generally speaking, the best for that kind of speed. I have not examined every Chinese model sold in America and have ridden only three, but although after break-in and a new spark plug my DF250RTG will run at 73 on reasonably flat road the suspension begins to feel distinctly sketchy the more over 55 I go. Certainly, this can be addressed with money and time, and if you can afford both it can be a lot of fun, but the question then is -- shouldn't I have bought Japanese to begin with?

[Megadan]

I think folks need to keep something in mind when they are thinking about upping speed on many if not most Chinese bikes. While the drive trains may well be able with modification to drive these bikes to 70+, the rolling gear -- tires, wheels, suspension, brakes, chain -- are not, generally speaking, the best for that kind of speed. I have not examined every Chinese model sold in America and have ridden only three, but although after break-in and a new spark plug my DF250RTG will run at 73 on reasonably flat road the suspension begins to feel distinctly sketchy the more over 55 I go. Certainly, this can be addressed with money and time, and if you can afford both it can be a lot of fun, but the question then is -- shouldn't I have bought Japanese to begin with?

I rode my first Hawk om highways at 65mph all the time with minimal time and effort into the suspension. Set the rider sag with preload spacers and put in the appropriate type and level of fork oil. Even on knobby tires, with the pressure at the right level, and regular spoke checks, I was never finding myself feeling "sketchy" on that bike. Minimal effort, minimal cost.

[Megadan]

As long as we are limited to 5 gears, and not much horsepower, gearing will always be a huge compromise. A 6th gear would sure help.

The absolute truth is spoken here. If you do the math on adding that extra .8:1 6th gear on a Hawk, you can basically run a 17f/50r sprocket setup while still having a very capable highway gear as if you were running a 45 rear sprocket. Not counting the not very off road suspension into the equation, it would definitely make them a much more capable all around dual sport by being able to handle both off and on road a lot better by retaining a crawler friendly gear AND a highway capable gear.

[Cmhpowersports]

I own a 2021 tbr7 and yes, a dog from the factory. You all already know the usual mods so im here to talk top speed mods. I have tested all gearing setups and have some input. The stock 15-46 as you know is setup for off road torque and not top speed. Ive done as most have and changed to the 17t front sprocket but still not enough if you have to jump on a highway. Heres what i tried. 17t front for all rear changes. 1st was a 45 rear=no noticable change. I then picked up a 43, 41, 40 and a 37 and ran them all. I landed on the 17t - 40 rear combo running a crf performance exhaust with the PZ30 jetted 38 slow and 115 main. With this gearing on a levelish highway my top speed is 82 dropping back to 65 or so pulling grades. The43 rear works well too but i lose about 5-6 mph with the 43. Now running this 17 - 40 is a tall gearing so theres a tiny feather of the clutch pulling out hard in 1st gear but as long as the wheels are turning it still has all the low end grunt to climb mountains no problem

[Tomkay44]

It's a little different on the 2020 TBR7, but after doing this, I had to adjust the idle screw and I could definitely tell a difference rolling down the road! Guess a performance exhaust is next up for me. Thanks man!
My 2021 TBR7 has less than 10 miles on it so it'll be a while before I check top in. I want to be able to travel the 10 or 20 miles to the trails while not dogging it during break in or getting run over. The only mods so far are a 110 jet on the stock carb and a NGK DPR8EIX-9 plug.
I did buy a 17 tooth for the front but the stock chain's not long enough so it's not on yet. I was planning on leaving the stock 46 in the back for trail torque.
I see you've got a 428 chain, I'm guessing the 130 is the # of links (wrong?). Is the 428 more likely to fit in the chain housing than a 520 or a 530? Also, will it fit okay on the 17 tooth front I bought (that's not on yet) and the 46 stock back?
Hope I'm not breaking thread protocol by posting this question in your thread. If so, let me know so I can behave better.

[ToolmanTim]

Hi
I have the new 2023 TBR7D . Im looking for a 17 tooth front sprocket that fits the new 530 chain that comes with the TBR7D. Is there anyone that can point me in the right direction to purchase one?

[Bill Hilly]

A 13 tooth is as big as you can run, from what I gather. You therefore run a rear with less teeth to achieve the desired ratio. A 32 rear, and 13 front with a 530 is about like a 42/17 with a 428 chain

[CheapThrills]

I'm fat, so losing weight will help me.

[awander]

....The gearing, the rear gear yields bigger changes than the front, the front gear is for fine tuning. For every rear tooth removed is like adding three teeth up front.....

So, I think it's actually the other way around...You'd have to remove 3 teeth from the rear sprocket, to approximately equal adding 1 tooth to the front sprocket.

For example, with stock gearing of 15 and 46, the sprocket ratio is 1:3.07

Increasing the front sprocket by 1 tooth, so 16/46, the ratio is 2.88.
Decreasing the rear sprocket by 3 teeth, so 15/43, the ratio is nearly identical at 2.87

Doing it the way you said, where removing 1 tooth from the rear should equal adding 3 teeth to the front:

Decreasing the rear sprocket by 1 tooth, so 15/45, the ratio is 3.00.
But, increasing the rear sprocket by 3 teeth, so 18/46, the ratio is 2.56, nowhere near the same.

[ProDigit]

I think folks need to keep something in mind when they are thinking about upping speed on many if not most Chinese bikes. While the drive trains may well be able with modification to drive these bikes to 70+, the rolling gear -- tires, wheels, suspension, brakes, chain -- are not, generally speaking, the best for that kind of speed. I have not examined every Chinese model sold in America and have ridden only three, but although after break-in and a new spark plug my DF250RTG will run at 73 on reasonably flat road the suspension begins to feel distinctly sketchy the more over 55 I go. Certainly, this can be addressed with money and time, and if you can afford both it can be a lot of fun, but the question then is -- shouldn't I have bought Japanese to begin with?

My Lifan Xpect (a dual sport bike) could do 74+MPH GPS under the right circumstances, however, anything above 70 you'd have to tuck, and the front end started wobbling. Not as bad as on sports bikes, but enough to not feel safe.

I don't have that problem on my CFMoto 450NK, which goes to 110 and maybe even faster, with the right gearing, but zero wobble at 100MPH, not even when I try to make it wobble.

My Vader 150 does 74MPH as well in the right conditions. Both with the 150 and the CG250 (229cc). Zero wobble or safety issues at those speeds.

I think dirt bikes, and dual sports are more susceptible to wobble and the feeling of lack of safety at higher speeds, especially when turning, due to the suspension being tall and soft.