[junkishya]

This post is off the current topic as it does not talk about mods to Karizma .. however I thought it's worth mentioning it here !!

I've had owned RD350 for nearly 12 years ... when my brother wanted to buy a bike for himself I suggested him a Karizma 3 years ago .. I actually used to call the bike a "KARISHMA" not a Karizma, jokingly ..

Last week I rode the bike along with my wife from Bangalore to Nandi Hills .. This was the first time I realized the Karizma's capabilities .. I was able to touch and remain steady at 120kmph .... 120kmph is not uncommon on an RD but the same on a Karizma carrying 2 people (90kg + 70kg) .. I thought it's pretty amazing !!

The speed was based on the Karizma's speedo and Verna's speedo that my Bro was driving side-by-side !!

The point I wanted to make here is "If that's what a 3 year old stock engine can do .. then I wonder what it would do with some skillful mods on it !!!"

[muneemmk]

So what exactly is the end results as of now which Carb are you running right now the Dellorto or the Keihin ? and what jets ? The Keihein is the Karizma OE Carb right ?

[Sankar]

Right now the bike is sucking through the stock Keihin with 130 mains (removed the 135), 40 pilot and modified slide. At this point of time there is no conclusion or end result because the changes have not reached the final stage. The airfilter is stock so it has to be changed when the uni comes, and jetting again checked and finalised. Bike is a lot better than stock but the stock paper filter is stifling the top end. I have removed the snorkel and it makes a slight improvement.

Edit: The manifold when compared to the carb venturi is pretty small. It narrows down to about 26mm at the manifold exit. And there is a steep change of angle inside the manifold, i guess it will hurt the flow at the top. I shall update this with the correct size later.

[fieroid]

So you find the stock carb better. Good.
on the 29CV, you dont need to bore the slide man. You dont get any upsize slides too.
Good luck with your jetting.
one thing let me tell you, no amount of carb perfection can match engine works in itself. Improving the flow, compression and related mods will make the engine much better and these carb mods will work best.
All this could give you 3-5% gains on the dyno.
So with the 130 mains, you dont find any flutter even with the stock airbox?

@ CBZ X has a 128 main jet but the thread is reverse. :(

[Sankar]

Originally Posted by fieroid

So you find the stock carb better. Good.
on the 29CV, you dont need to bore the slide man. You dont get any upsize slides too.
Good luck with your jetting.
one thing let me tell you, no amount of carb perfection can match engine works in itself. Improving the flow, compression and related mods will make the engine much better and these carb mods will work best.
All this could give you 3-5% gains on the dyno.
So with the 130 mains, you dont find any flutter even with the stock airbox?

@ CBZ X has a 128 main jet but the thread is reverse. :(

Yep stock carb is better I did some basic maths, pi r square, and found out that even with the throttle plate in the middle it should flow atleast 4.8% more than the 28mm slide carb.

There is no flutter at the top end even with the 135 jet! I have changed to 130 just to see what difference it makes in revvability. I have removed the snorkel from the airbox, that's the only change to stock airfilter setup.

I think HH have deliberately reversed the htread on the CBZx jets to prevent swapping :( What if we change the emulsion tube also? Is the carb body reverse threaded?

[balenopower]

im planning a k&n filter along with 130mm jets as well.Let me know the 130's feel.

[fieroid]

I told you, a larger dia carb be it CV or otherwise will still flow higher..even with the butterfly. This should shut a few mouths too
The carb body thread is not reverse, hopefully. Only the mainjet was reverse.

Did u check if the needle on the stock carb has slots for settings?

[Sankar]

Originally Posted by fieroid

I told you, a larger dia carb be it CV or otherwise will still flow higher..even with the butterfly. This should shut a few mouths too

Yep even i was of the other opinion till you corrected me and made me think!

The carb body thread is not reverse, hopefully. Only the mainjet was reverse.

Did u check if the needle on the stock carb has slots for settings?

Yoohooo Prajeep.... where art thou? How about opening up your CBZ-X carb and leting the world know what you find

The needle in the Keihin is non adjustable. It has a thick washer kind of thing at the top in place of the circlip.

How about using another needle, for eg a BS needle, in this carb? If the taper and length are similar then i think it should work. I have access to a BS26 that's not being used.

[fieroid]

Originally Posted by Sankar

The needle in the Keihin is non adjustable. It has a thick washer kind of thing at the top in place of the circlip.

How about using another needle, for eg a BS needle, in this carb? If the taper and length are similar then i think it should work. I have access to a BS26 that's not being used.

Its always expected on these OE Keihin CVs. makes tuning even more hell.
But but, to use the BS needle, you need the needle to lock-up with a plate + washer + screw system which wont probably be an option on the Keihin. If the needle is not locked rightly, it would not control the main jet in the right angle..could lead to offset issues. I'm sure you know what night mares a badly set-up/screwed carb can lead to.
Also the stock keihin carb has no flow angle. The BS has a 15 deg flow rake which can give a mild draft to the fuel flow and can work along the flow lines of the inlet port. A contoured port is the best thing you can have. These are a few things that make the BS29 so much tempting over anything else. You can play with almost everything in that carb and no worry of damaging parts too, everything is available. Risk as much as you want while tuning.

[Sankar]

Originally Posted by fieroid

But but, to use the BS needle, you need the needle to lock-up with a plate + washer + screw system which wont probably be an option on the Keihin. If the needle is not locked rightly, it would not control the main jet in the right angle..could lead to offset issues.

The Keihin has the lock plate and spring arrangement that will hold the needle in place. But a small washer, of the same size as of the present one, has to be put above the circlip so that the spring could apply pressure on the needle.

The BS has a 15 deg flow rake which can give a mild draft to the fuel flow and can work along the flow lines of the inlet port. A contoured port is the best thing you can have. These are a few things that make the BS29 so much tempting over anything else. You can play with almost everything in that carb and no worry of damaging parts too, everything is available. Risk as much as you want while tuning.

Wow flow rake is new to me! Could you tell me what it is? Does the carb angle the flow better.. when looking through the carb it's almost straight!

[fieroid]

Flow rake and port is a whole different subject. They will matter with radical set-ups. I think I should not have mentioned this.
Just wanted to say how much better the BS29 is over the others. You can try one and see the difference.

[Sankar]

Originally Posted by fieroid

Flow rake and port is a whole different subject. They will matter with radical set-ups. I think I should not have mentioned this.
Just wanted to say how much better the BS29 is over the others. You can try one and see the difference.

Er.. ok But tell me is it related to the angle of the throttle plate at WOT? Anyways lemme see if i can source a BS29 to try on!

[Mpower]

Whats the stock compression ration on the Zma? Maybe there is some scope for improvement there. Also, intake vavle size anyone?

trying to understand why the stock bike is low on power even through it has the largest displacement.

[scorpian]

have a look at this,

[SunnyBoi]

Ummm a RXG carb? whats so special in that?