Re: Honda CBR 250R

Yeah...my freind has gone for the whole race speecs...full system exhaust, PC5, sporckets etc. Thats why need reviews from someone who is already using them. Will keep an close eye on this thread.

I don't remember the name of the shop but I think it was Globe tyres. Get your machine and I can accompany you to KB to that shop. I got the bosch horn from one of my freinds who had one extra. Its lound.

Re: Honda CBR 250R

I will bother you once I get delivery of the bike. Should I PM you my no?

Re: Honda CBR 250R

dropping a teeth in front will lower the gearing ratio hence increase in acceleration on the other side top-end will reduce alone with FE as distance travelled in same rpm reduces.
while dropping a teeth at rear with increase the gearing ratio.. making the gearing " tall" increasing top-end if the machine can pull along with increased FE.

however increasing-decreasing a teeth at front is an ideal, easy and cheap mod. so i want to keep the rear stock but increase the front teeth from 14 to 15 which will drop the rpm by 500 (estimated) for a given speed compared to stock setup.

another issue is the wrong speed.. for CBR250R the speed is calculated as per rpm from a probe near the front sprocket. now with a change in sprocket +- you will still see the same speed no matter what..

for example : my bike does 65 kmph at 4000 rpm in 6th gear. now with a +1 front sprocket i will be doing similar speeds at say 3500 rpm. the RPM meter will show fine however it will show the relative speed to 3500 rpm.. roughly 53-54 kmph however the machine will be still doing 60kmph ( this is speculative).

similar stuff with -1 sprocket. at 4000 rpm machine will do 60 instead of 65 however meter will still show 65 at given rpm though you are going slower.
speedo healer is the option to fix it.

also cbr runs 7-8% optimistic : while you are doing 100 kmph on the meter the actual speed is somewhere near to 93-94. adding +1 teeth will solve this issue.
i will be running close to the meter shown speed..

hope i did not confuse you a lot


exhaust system, power commander , ecu mapping doesn't make sense to be true. machine is 26 bhp costing 1.7 lakh onroad (non-abs). spending 30% of amount of the machine cost just for say 3-4 bhp gain makes no sense to me. if you want a faster bike. dump this.. save money and get a 390 else a ninja.. which a tested , stable and far more reliable than a custom setup. above that India is not yet a place for performance tuning for motorcycle atleast..

even after all the setup tell me a place where you have a dyno to test out claimed bhp output. the only reason for sprocket change is .. chain set is prone to wear and tear and is a consumable hence eventually will have to buy another chainset in 18 months or so .. rather than buying OEM front sprocket i'd take 15T for say 500 bucks more and will enjoy mile crunching on highways with lower rpm and it will solve the issue of very short 1st gear...

will keep you posted with the changes...

on a side note : i have seen busted engine running with PC + akra FFE .. as they did were not tuned well .. resulted in broken rocker arm and camshaft and imagine running out of warranty due to the mods.

Re: Honda CBR 250R

Changing the sprocket sizes will indeed affect the bike's performance. Putting on a smaller front sprocket or a larger rear sprocket will increase your launch speed, at the cost of your top end. Putting on a larger front sprocket or a smaller rear sprocket will increase your top end, but decrease your launch speed.

Re: Honda CBR 250R

Well, it did confuse me quite a bit. But i think reading it slowly and understanding it will make a difference, a job i must do from home.

Thanks mate..!!

Cheers
Ride Safe
Krishna

Re: Honda CBR 250R

its a 250.. and with idiot filled roads in india... faster launch speed is inviting " yamraj " faster ...

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easier way is :

+ teeth in front = lower acceleration, high top-end, better mpg ( upto certain limit)
+teeth in rear = better acceleration, lower top-end , lesser mpg

- teeth in front = better acceleration, lower top-end , lesser mpg
-teeth in rear = lower acceleration, high top-end, better mpg ( upto certain limit)

most people opt for front sprocket change:
reason

quicker
cheaper
more effective


for hypermiling and if most of the riding is on highway with less of hills
then you can go for combination sprocketing.

as 15T can fit directly in place of 14T however bigger than that it will be housing issue
and some mods needs to be done to accomodate the bigger front sprocket.

so folks for longer highway runs and not doing more than 100kmph on average can go for

14/38 stock
15/38 (tall)
15/37 (taller)
15/36 (extreme tall) bike wont have enough juice to pull this ratio well. however you will cruise at far lower rpm than stock. (not sure of FE)

another option is to change the tyre to more tyre height.

what we have now is 17/70/140 you can move to 17/80/140.. this will give 10mm increase in Tyre height hence similar setup like +1 sprocket in front. however under 10k the tyre height will reduce as well while the sprocket will last longer

more confusing stuff for you..

Re: Honda CBR 250R

[QUOTE=theironhorse99;1055194]its a 250.. and with idiot filled roads in india... faster launch speed is inviting " yamraj " faster ...

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easier way is :

+ teeth in front = lower acceleration, high top-end, better mpg ( upto certain limit)


I have been using the 15T front sprocket for the last 3K Kms., there is no noticeable difference in fuel consumption. The major difference being the ride ability in the first & second gears increases making city riding comfortable.

Re: Honda CBR 250R

[QUOTE=nsengg;1055210]the actual FE difference would come only once you start munching miles over the highway with sustained speed...

however the rideability being better for lower gears is a reason good enough for the change
thanks for the info on the practical usage. atleast it wont impact i any negative way...

Re: Honda CBR 250R

now that was easier to understand..!!

Cheers
Ride Safe
Krishna

Re: Honda CBR 250R

Not yet saar!!!! It's still in the list of pending mods, I have decided to switch to 15T at 20K~25K kms when I will be changing the chain set completely.

Re: Honda CBR 250R


you still running on your first chain set or second one ??

20-25k is impossible target for 1 chain set .. if its the second chainset then you are looking north of 33k kms..

Re: Honda CBR 250R

Im running on my first chain set, completed 12k kms and still has loads of life on it..!! Is 20k too much to ask for ?

p.s : the svc guys were telling to expect somewhere near 10k.

Cheers
Ride Safe
Krishna

Re: Honda CBR 250R

I am on my first set...and much like Krish, I have quite a bit of life left on the chain and I am at 15k.. Guess 20K should be very much doable.

Re: Honda CBR 250R

mine changed at 17k.. sprocket were in very good condition and infact the chain was good too however my chain developed a peculiar issue or severe uneven slack which was also created by the SVC itself as some ass*** mech once tightened the chain and i ran the bike like that for a few 100 km's before setting it myself.. by then the damage was done...

Re: Honda CBR 250R

Had got a new speedo under warranty after it went for a toss after around 9000kms, Now again the same problem after the speedo ran 3500k kms. This is not the quality I expect from honda. 😑


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