Team-BHP - Honda CBR 250R : Answers to some commonly asked questions

Hi Aargee, thanks for an useful list. A few questions below if you don't mind:

Quote:

Originally Posted by aargee (Post 2771744)

Q. The bike has more torque, can I shift from 1 to 3 or 3 to 5 etc?
A. Though there's no hard & fast rule, remember, this is a very very bad riding style; always follow linear gear shifts

If you are not going to lug the engine - say you are upshifting at 7-8krpm from 3rd, any other particular reason why this is not recommended?
I understand this is bad riding style, just curious on the mechanical effects of it.

Quote:

Originally Posted by aargee (Post 2771744)

but never change to any size other than the specified stock size for a very simple reason it leads to speedo error & in ABS it leads to poor braking. Be it ABS or STD, stick to OE size only.

Could you please explain on how the ABS models lead to poor braking on upsizing? By upsizing I mean the tyre width (140 to say 150) and not the wheel radius (stays at 17).

Thanks!

Quote:

Originally Posted by dustom_99 (Post 2772367)

What exactly would be scary about that? It is an idle adjustment screw.it would either give you a few more revs our a few less. Changes hence done to air flow and charge composition are still taken care of by ecu. It only make mixture slightly richer, but only for idle jet, not for main, also it opens throttle throat just a bit.

I don't see how would that be a scary advice, specially for a bike rider(this one being into performance bike category)? Bikes are dangerous by there very nature,i would ask you not to chance your life on them.

If you honestly believe that the idle screw adjustment is as simple as that, I guess the good people at Honda is being more than a little cautious by making sure that screw is held by a lock nut, give explicit warning in the manual, etc, etc.

I was not aware that the CBR250R has come into the performance category. Thought it was a premium commuter bike. In that context where mileage and reliability is more important, it would not be wise to adjust settings.

But if you are planning on performance mods, go right ahead and tear that engine apart. But then again, what's idling got to do with performanceplease:

You're right, maybe "scary" is the wrong word to use in the context of motorcycles. Perhaps I should have used some other adjective? Like "Foolhardy"

Cheers

Ride Safe.

I'll go with gthang here; one of the most experienced & wise gentleman said this on the other forum...

Quote:

Adjusting this will increase or decrease the idle RPM, and the ECU can adjust,and compensate through the idle air valve actuation...but ECU action is to an extent only.Opening the throttle valve more than the idle air valves range will definitely increase the idle RPM, but lead to higher,off acceleration idle ,and roll on ....just as Ashwin had experienced..hence it is generally not advisable to play with MPFi idle setting without knowing the PROCEDURE FOR THE PARTICULAR ENGINE...just my thought.

and what did Ashwin say?

Quote:

^^^^
My household own's an MPFI car and what I've noticed in that is that, even if we try raising the idle by increasing the cables tension, the idle will be bumped for a while, but after the computer starts to notice it, it will automatically lower the idle, irrespective of the tention on the cable.

So I believe its best you guys do some more research on the same. Ride safe.

Quote:

The thing is that for the time being in my car I get a bump in idle and even though after a while it settles down automatically, the accelerator behaves different from stock, theres a change in per gear roll on as well, and the ECU cuts off earlier than its supposed to, and to bring everything back to normal, we'd have to set the cable tention to near default and then reset the ECU to get things back to normal, in cars its done by disconnecting the battery for a night.

So in your case the worst case scenereo could be that you'll have to reset the ECU. But still, better safe than sorry.

Quote:

Originally Posted by niranjanrvce (Post 2772392)

Always follow linear progress when upshift or downshift; when doing so the sync is maintained between the speeds of crankshaft, primary gear, clutch, sprockets & the rear wheel. When you do two upshifts/downshifts, one cannot do it ASAP like one shiftup/down, yielding to improper sync between all of them causing more wear & tear on all the bearings, sprocks, chain & primary gear. Do it once & you'll observe a loud clank when shifting down (not shifting up)

Quote:

Originally Posted by niranjanrvce (Post 2772392)

Could you please explain on how the ABS models lead to poor braking on upsizing? By upsizing I mean the tyre width (140 to say 150) and not the wheel radius (stays at 17).

Poor braking, not experienced, just a hear say, but again, don't want to advocate anything that's not tried with AM parts or non OE.

Speedo error thing is bound to happen due to improper size of wheel that misleads the sensor at the front sprocks.

Quote:

Originally Posted by aargee (Post 2772469)

I'll go with gthang here; one of the most experienced & wise gentleman said this on the other forum...

and what did Ashwin say?

does that Household MPFI car has an idle adjustment lead screw. People tightning thecable for idle adjustment lets you know that it does not have any such arrangement. I have that same MPFI car in my household aswell.
I wonder how would crb250r Remember that (r) at the last , has it in the first place, ohh i remember, to adjust for fuel quality in various nations it is sold,ya right! (how do you adjust fuel quality with idle adjustment screw.) and whats up with that expensive ecu, if an stupid screw is used to adjust country specific fuel .
Any way its for the owners of the bike , who wants to learn something more than the manual would tell them will have to fiddle with small things like that on there machines.
i guess i am now outdated as far as working of idle adjustment screw goes. think i need to read a few pages (read wiki and how stuff works and also some internet forums) to get anywhere close to the real riders .

Quote:

Originally Posted by aargee (Post 2771805)

Yes, but do take out very carefully; just follow the instruction of "gradual acceleration" through the trip. If your round trip is not more than 4K odd kms, then simply go ahead. But remember to check...
- engine oil level every 100-200 Km (bike positioned straight)
- engine temperature bar every 100-200 Km
- top up coolant level before you start
- use 10W30 HMSI FS engine oil
- abnormal vibrations
- avoid unnecessary top speed checks
- prolonged use of T.W.O ride
- sudden speed bursts

Thanks aargee for your inputs, they make a lot of sense. I won't be doing more than 600-700 kms for this trip. I am yet to get used to riding long hours. The max I have done is 30 minutes at a stretch. BTW, I see "T.W.O ride" being mentioned - sorry for my ignorance but what exactly does it refer to. Also, I kind of like to build up speed gradually and expect to hit high-speed but won't be doing "top speed checks".

BTW, isn't there a good CBR 250R owners group India-wide or city wise. I understand there isn't a legacy and sense of elusiveness with the baby ceeber like there is with the NInja 250R but I am sure some owners love their machines and don't just treat them as "Premium commuter".

Quote:

Originally Posted by animeshb (Post 2773091)

BTW, I see "T.W.O ride" being mentioned - sorry for my ignorance but what exactly does it refer to.

TWO stands for Throttle Wide Open - when you open the throttle to its maximum.

Quote:

Originally Posted by animeshb (Post 2773091)

BTW, isn't there a good CBR 250R owners group India-wide or city wise. I understand there isn't a legacy and sense of elusiveness with the baby ceeber like there is with the NInja 250R but I am sure some owners love their machines and don't just treat them as "Premium commuter".

There is a Honda CBR 250R owners group on facebook. PM rk_sans. He is an admin on that group and that group has a large no. of owners/members. This might be restricted to Blore city though, I'm not sure. You could search on fb for such a group filtering by the name of your city.

Quote:

Originally Posted by aargee (Post 2773295)

https://www.facebook.com/pages/Honda...17426001669641
https://www.facebook.com/CBR250R
https://www.facebook.com/pages/Honda...39893632729674

Thanks, I am already subscribed to all of the above but I don't find any "good" content/discussions. I think I better stick to whatever happens on team-bhp.

Quote:

Originally Posted by aargee (Post 2771744)

Q. What's the good startup & shutoff procedure? Can I switch off the bike at signals to save fuel?
A. If you care for your bike, then every time you start (not when the engine is operating at optimal temperatures) the engine, allow the engine to idle until the RPM falls down from 2K RPM, it doesn't take even 25 seconds. This will also help to lubricate the internals of the engine which is good; ride like you're breaking in the engine for first 1-2 Kms, by then the engine reaches optimal temperature after that start riding normally (not rip off). Its worth to switch off the engine at signals, if your wait time is more than 15-20 seconds. Stop the engine using the Engine kill switch & allow it remain in the OFF position (or ensure that the fan doesn't run when you switch to ON position as the fan draws power from battery). Switch to ON 3-5 second before you leave the signal & start the engine.

My take - I always wait for the temp gauge to show the 3 bars before going over 5,000 revs.

Quote:

Q. Why does the RPM goes to 2K RPM & then falls down when left idle? Is this normal?
A. The bike is equipped with auto choke facility; hence everytime the bike is started there's more fuel let in by the ECU & hence the higher RPM; once the ECU learns that the bike is warm enough (not optimal operating temperature) the choke is cut off & hence the RPM falls down

If you have ridden the bike and parked it for an hour or thereabouts & when you switch it on, the revs will show ~2,000. Blip it once (under 4,000 revs) and the revs will fall back to idling.

Quote:

Originally Posted by Sheel (Post 2773753)

My take - I always wait for the temp gauge to show the 3 bars before going over 5,000 revs

Though I do it too, but don't adhere to RPM; say, I ride above knocking RPM's. Any specific reason?

Quote:

Originally Posted by Sheel (Post 2773753)

If you have ridden...the revs will fall back to idling.

This happens even at cold start

Quote:

Originally Posted by aargee (Post 2771744)

Q. Why only 6th? What about other gears?
A. In any gear, DO NOT lug the engine OR over rev the engine. Lugging is the state in which the engine runs on lower speed in higher gear & revving is viceversa. Run at adequate speed & optimal gear. This is only an example & not necessary to be followed...
Gear shift 1-2 at 3000-3500 RPM
2-3 at 3300-3600 RPM
3-4 at 3800-4400 RPM
4-5 at 4200-4800 RPM
5-6 at 5000-5800 RPM
and do a quick gear shift; this means, do not keep holding the clutch for longer time duration when shifting the gear.
Always remember...you can even rev the engine occasionally, but never EVER LUG the engine

Good collection of information aargee!

Have a question on this point. On a recent ride, a friend was accompanying me on a Pulsar 220. I really don't ride hard - more than at a steady 110 kmph or so. My friend said that on open stretches too, it looked like I was shifting too soon. I usually shift at around the numbers you have mentioned here. Basically, I shift by engine note. Don't allow it to lug or over-rev. He said that I would get more "power" and can touch higher speeds if I was to shift at around 6000 rpm for moving from 5th to 6th gear. I did try but somehow felt the engine was straining when I do that. Is this fine to do? Or am I right in shifting at these rpms.

Quote:

Originally Posted by Sheel (Post 2774088)

Knocking RPM's? This is new to me. Didn't get you

Try this (just once is fine, no big deal, but not often though) - Notice the engine sound difference between 6th gear & 3300 RPM versus 6th gear & 4400 RPM; notice the engine noise & stress & keep that throughout the gears.

Quote:

Originally Posted by Sheel (Post 2774088)

Surprisingly it doesn't on my CBR.

It does; we tested it on another customer's CBR at ASC. It works.

Quote:

Originally Posted by naveenroy (Post 2774143)

Or am I right in shifting at these rpms.

Higher speeds hmm...let me break the myth...

there're two things, can you reach 145 & how soon you reach 145. If the question is on can you reach 145? Absolutely YES, shift from any gear, you can reach 145, but the only question is the time; how soon to reach, shift almost (or at) redline for every gear, at 5th gear, redline does 142 Kmph, you'll only need a little push to reach 145 at 6th. Just for the numbers, say, if one takes about 30-35 seconds to reach 145 by shifting at 6K RPM, doing redline shifts will get you (just example, not measured really) between 20-25 seconds.

Did I answer your point or confuse you?