DT125R ARCHIVE

xGINCATx · Guru

Changing sprockets for more top speed..?

NathanDavies · Guru

May not pull with an 18 tooth, depends how much you weigh, try 17 mate.

RudiRulez · DTR Senior Member

18/53 hmm, i dont think anyone here has gone that drastic, my guess itll have really bad acell and may even bog when u reach 6th so youll end up with an even lower top speed, if your trying to hit 100 on a DT just by changeing the sprockets ill tell u straight up it aint gonna happen.

http://www.activeboard.com/forum.spark?aBID=66365&p=3&topicID=33447860

^^^^^ link might be helpful to you.

-- Edited by RudiRulez on Saturday 12th of June 2010 04:20:47 PM

RudiRulez · DTR Senior Member

NathanDavies wrote:

Dep pipe racing reeds and all derestrictions apart from snorkle which is a load of **** and a 17 tooth sprocket, engine wasnt tuned or anything

nah dont beleive it, engine would have been revving at over 12,500 rpm, 12,500 rpm in 6th gear on a DT with just a few minor mods is just unheard of.

fray · Guru

I dont believe it either tbh!

NathanDavies · Guru

Oh and if your going by that graph you made then that explains why your saying im lieing!
My 15 tooth sprock, in 1st would get to 16 against your 21, and top of 6th was 83 against your 73. So according to that graph i should have 5mph more in 1st and 10mph less in 6th?

RudiRulez · DTR Senior Member

Engine Speed vs Road speed is Linear, the gears are a fixed ratio! the only thing that can make my graphs wrong are tire sizes(varies from manufacture and tire wear) and tire deformation at different speed which i havent accounted for, please take into account that shift point is 9,500rpm and given that your riding a DTRE that doesnt actually have a rev counter how would you know if my graphs are out when you dont actually know what your revving at?

NathanDavies · Guru

Because revving flat out in 1st i achieved 16 compared to you 21, so if i was revving more then 9500 revs then it makes it even more wrong. In 6th i rev flat out and get 83, your graphs says 73? Oh i was using standard tyres, TW302's, correct me if i'm wrong.

RudiRulez · DTR Senior Member

the low speed can easily be a speedo error, my dt speedo doesnt count anything under 10mph, when you are running flat out and hitting 83mph its just means you are revving higher than my anticipated 9500rpm shift point, if you look at my graph and match the lines up 83mph equates to roughly 10,500rpm which means my graphs are perfectly plausible.

those numbers in the top right are just meant as a guide, i used 9,500rpm as a shift point because thats about where my powerband dies out and i usually shift but as you said if you in top gear your not gonna stop revving at 9500 your gonna carry on going and take the engine as far as it will rev which is usually 10,000+rpm, if you want to interpret the graph properly you need to match up the lines.

NathanDavies · Guru

Fair point about the graph, as i say applying maths doesn't always work, do we not come across things that dont seem plausable, e.g. anomolies, in which i think this DT was an anomoly.

woll · Guru

wooooaaaaaah there lads fvell the love :D
Rudi your graph maybe wrong, its a computer calculation allow for slight error :)
and nath maybe your speedo right maybe its wrong who knows lol
And yes i've have more than enough to drink but that dont matter lol

NathanDavies · Guru

Ha good night mark biggrin

?
What was the score boys last time i checked was 1-1?

RudiRulez · DTR Senior Member

NathanDavies wrote:

Ha good night mark ?
What was the score boys last time i checked was 1-1?

finished on 1-1 we played a terrible game tbh, luckily im not really into football so i couldnt careless biggrin .

craigbulmer · Guru

No DT which is 'lightly' tuned can ever reach those speeds. For a start, no dt can pull that hard in maybe 3rd net alone 6th. An RS125 properly derestricted does 110-120, that has a highly tuned engine, nicosil plated bore, huge carb, race cdi, all that crap, plus the fact, its a race bike. So much more aerodynamic and ROAD TYRES. Knobbles wouldnt take that.

Put me on that bike and if it goes over 100 il throw my dt off a bridge.

Dickhead · Nonce

fastest ive had my dt 250 is 155 kph and thats got arouund 50 horses it gets ther easly but is held back buy gearing

no stock dt will go over 100 ever even with exhaust reeds etc

dts aint a very powerfull bike 20 hp around that ?

my dt used to go off the clocks with the 16 front sprocket now put a 15 usaly stays around 80

tires make a big difrence think if you have say a mt 43 or a golden boy

the higer profile will be just upgearing the bike

craigbulmer · Guru

Im not calling you a liar nathan, just i dont think its possible and so much so id bet my bike on it lol.. id have to see it with my own eyes to believe it.. sorry but.. no way

fray · Guru

Ive been thinking lately about dropping my front sprocket down to a 15 but i dont wanna lose too much top end. Has anyone got a 15 on the front and standard 57 on the back? How does it perform?

craigbulmer · Guru

Ive read a few posts on diff sites and stuff.. top end wont change that much.. still reach 80, just rag the bike more. Always higher in the revs.

fray · Guru

Sound so they still reach 80 with a 15 front then! Will prob make a nice difference in acceleration aswell!!

Like robin says a change in rear wheel / tyre profile can alter gearing slightly so im gonna see what its like when ive got my supermoto rims on next week as ill be dropping from an 18inch rear wheel to a 17 inch rear wheel.

Dickhead · Nonce

best thing about going 15 tooth is you can always use 6th gear i had a big one at the time and you had to rag it more to keep in the band

NathanDavies · Guru

ive got a 15 tooth Fray, did have 14, fuk that was rapid, yeah 15 is orite mate, but gets to top end really quick 0-50 for me is about 8 seconds, and im quite a big boy lol, but doesnt go from 50-80 that fast , 70-80 is pretty slow.

craigbulmer · Guru

You had a 14! What was the top end? Did it wheelie much haha

Whats the 15 like on fuel? Is it lower mpg cuz of higher revs everywhere?

NathanDavies · Guru

Oh and with a 14 tooth i had 72.

craigbulmer · Guru

Ragging the bike to death at 72

craigbulmer · Guru

May have to order a 15t, give it a try :P

fray · Guru

NathanDavies wrote:

ive got a 15 tooth Fray, did have 14, fuk that was rapid, yeah 15 is orite mate, but gets to top end really quick 0-50 for me is about 8 seconds, and im quite a big boy lol, but doesnt go from 50-80 that fast , 70-80 is pretty slow.

cheerz mate!