General Biking Discussion Approved.

Thread is now approved mate, pour in.

Cheers,
Shamik

Thanks for the approval Aryan.

BBR rev box is an aftermarket performance CDI made for dirt bikes such as honda crf150f and crf230f..As most of us would know that these bikes share their engines with the CBZ,CBZ star, Honda Unicorn, CBZ Extreme, Hunk and Karizma..I went through a couple of forums and saw that people had tried fitting the BBR Rev Box on them already but were unable to start the bike..so they pulled it out and declared it unsuitable for the indian bikes..

However, the way i feel was that they somehow managed to forget what actually the rev box was doing apart from eliminating the stock rev limiter, it was actually advancing the ignition timing too.. You can easily work out that it won't work on stock bikes..The reason being that an advanced spark actually burns the mixture much before it can actually push the piston down in the power stroke and leads to pre-igniting..Hence the piston faces a sudden thrust downwards in the compression stroke and hence the bike refuses to start..

BBR rev box is actually the later stage performance mod one should go for..Going by the above explanation, how do i make the rev box work?? Make the mixture burn completely just when the piston starts the power stroke..Sounds Intriguing..But it's common sense.. Upjetting your carburettor and a free flow filter..

My bike already had an upjetted carb, a k&n air filter, a free flow exhaust, iridium plug before i went for the rev box..

Initially when i put in the rev box in my bike, she too refused to start..My fears came back to me, I thought to myself, may be those people were right,may be it's not meant for the Indian bikes..I already had a bigger pilot jet and a stock main jet in my carb regarding the upjetting required for a K&N..why only the bigger pilot jet?? That too is a big explanation i would take up if somebody's interested..

So, i tried kicking and pressing the self starter but she refused to start..My dreams of better performance were shattered..But then, the advanced timing struck my mind in that fit of hopelessness and anger..I pulled the choke(you can't start your bike this way too if it has stock jets), since i had a bigger pilot jet installed, it was throwing more fuel already..pulling the choke made it throw quite a large amount of fuel..i pushed the self starter and VROOOMM....VVRRRROOOMMMM....she roared to life..

The story doesn't end here..i could not have ridden her with the choke pulled all the time..More after all of the above sink in

Its sunk in, do write more, I am extremely interested in all the details.

Wow great job there. Okay sunk in uptill now!. Now please pour in some more info mate, i am really eager to know how u managed since i too own a Honda Unicorn with K & N filter and bigger main jet

WOW!! Congrats Man!!

I too have an altered CDI on my Karizma.
I didnt had the starting problem, I guess probably because as you stated that mine also had a K&N and upjetting already done. Mine is not the BBR one. Just got it from one of my friend who is a mechanic or rather I should say a pretty knowledgable mechanic.

What all improvement you have felt?

In my case, I hade just got the porting done sometime back on my bike so although I think there is a slight improvement in pickup throught the rrev range but nothing bombastic. Also what significant inprovement I observed was that at higher speeds lets say around 120 the bike feels less strained and more smooth. Somehow the Absence of Rev Limiter is something which I could not use because I dont rev the bike that hard lets say close to Rev limiter limit. I did try once but amount of vibration scared me.
My top speed didnt increase.

Please share your experience as to what improvements you felt.

Thanks for the interest guys.. So my bike started with the choke pulled and I can't explain that feeling of joy and happiness that i felt when i wringed the throttle and she responded..going against the current is not an easy thing, in this case the forums that said it would not work..So i realised that what the choke did was to actually richen the mixture and hence what i did was to retune the carb..just lesser than a turn of the fuel screw opening and everything was fine..The extra fuel was taken care of by the advanced timing..I pulled out the spark plug after a day of riding just to be sure and voila, it showed no evidence of rich mixture.. I felt like an old scientist who had obtained a totally unexplicable result..It took sometime for reason to show but I finally managed to explain all of what was happening.. The only downfall of the rev box is that the stock tachometer doesn't work..Since the dirt bikes don't have one..The stock Unicorn CDI has a 6wire socket and a 7th lone wire..this 7th wire gives the tachometer signal of the engine rpm..The rev box only has a 6wire socket..But so what, u do can feel the rev going out of the normal range if have been with the bike for some time, ain't it??

So now, i have both a bigger pilot and main jets because the bike can take the extra fuel without spurting..

@pranay- i feel your bike must be spurting and jerking around 8-9k rpm range??

@ rachit- The performance increase was as follows.
1) Considerable increase in torque throughout the rev range..
2) engine revs much freer however you need to be careful or you might harm the engine..
3)I have 14-38 sprockets on my bike, hence taller gearing..Below is the speed i have achieved on a few gears before the BBR rev limiter kicks in ..It does have one, i think at around 11-11.5k
All speeds on the speedo, so there is room for error..

1st-43
2nd-68
3rd-90
4th-115 and counting
haven't had a chance to push the 5th..
Speeds on higher gears don't increase in the same proportion because the engine starts losing power at too high a rpm..

Well it's good you are experiencing a good response rachit, but i have a completely different view and virtual methodology of engine head porting...

Wow!! I know how you must be feeling. Its really a great feeling when you achieve something and its even sweeter when that thing is increase in your bike's performance.

Good to know that your are having positive results.

Well in my case the Tacho works. Its just that when you are going at constant normal speeds the Tacho sometimes just jumps 1000 revs and then comes back again jumps and comes back (Only the meter reading). Rest I have not seen any problem as such.

Happy Riding Brother!!

whr do u stay...bcoz i hav seen a Unicorn showing similar performance in bangalore...i too hav a Unicorn and this guy just zoomed past me and I was around 70kmph

@raghav- well would have been somebody else..I am in the Capital of India.

@rachit- those vibs at higher revs are due to larger ports..I would love to know the range of max rpm on your bike and also the speeds if you can post them..

The bike is ok till about about 8500 RPM (though vibrates), as it touches the redline at 9000 RPM it shudders violently not just vibrate. At 9500 rpm it sputters and the revs get jerked back to 8000 rpm.
BTW you are experiencing some performance man, 4th gear 115!, whoa!! Its 105 in the 5th gear for my bike

I will measure the speeds and then let you know brother.

I have measured only one and that is 100 in 5th gear at 5700 RPM.
I have a smaller rear sprocket also. It is 38T instead of the 40T.
Top speed 140 and in the 4th gear I have gone till 110. I think the bike can probably do slightly more in 4th gear but I will need to try.