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Old 26th September 2008, 16:16   #46
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Quote:
Originally Posted by fieroid View Post
The CBZ Xtreme has a 128 main jet.
Mr Prajeep, the Unicorn has a 24mm venturi while the CBZX has a 28mm one.
Unicorn has a 115 main jet.

Thanks for confirming joel
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Old 26th September 2008, 16:29   #47
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Originally Posted by fieroid View Post
Whats the venturi size of the Dellorto u running now?
Also running the CDi without the TPS means, you will be running an advanced map all the time. The ignition is most advanced when in the shut position. The Karizma has over 5 maps and the TPS keeps switching maps according to the throttle position. you will now be running just one map.
Instead keep a spilt cable like the RTR/F2 and run the TPS switch.
That's a brilliant idea to regarding the Fiero TPS switch! But tell me would the resistance values be similar to the Kaizma's TPS? I thought with te TPS disconnected the igniion would be in retarded mode, and there is a lack of punch in the midrange but it easily revvs to redline even during load. This is similar to my Bullet with a retarded ignition timing. Anyways i'm not use about the timing as i haven't checked with a timing gun. So i'll take what you say to be correct.

Does the RTR come with the TPS switch like the Fiero or should i ask for Fiero TPS switch? I'm using the CBZ (old) cable with the accelrator pump cable disconnected. It's easy to reconnect the cable to work the TPS.

Carb is a 28mm Dellorto. Stock main jet was 105 pilot is 38 (or is it 35 have to check again).
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Old 26th September 2008, 16:52   #48
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I dont understand why u running a 28mm venturi carb. FYI the karizma runs a 30mm venturi.
Its better-off if you can run an eliminator's 31mm CV carb. Its the best bet, but then damn hard to source. A new one will cost you 12k from a Bajaj showroom. try some 2nd hand option thought.
The Fiero does not have an ignition advanace switch(Fiero has a seft adjusting timing), its only the RTR/F2/Apache which runs the TPS switch with a split cable.
I doubt if you can use the RTR switch directly..What i meant is you can use the existing Karizma switch itself and make it operate from the cable by making some new contraption.
I've seen manu bikes with TMs, VMs and all kind of carbs on 4-stroke....but none can match the smooth fuel transition of a CV carb. Also since you are not going racing and its only street commute, a CV makes the best sense.
Either stick to the stock carb (with a 127.5 mainjet, if u running a freeflow filter) or get a different CV. The next bext in business is the BS29CV. Although its 1mm smaller than the keihin on the Zma, its the bets to tune and get better results. Fuel efficiency is also better with this mikuni with performance as a bonus.
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Old 26th September 2008, 17:51   #49
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Quote:
Originally Posted by fieroid View Post
I dont understand why u running a 28mm venturi carb. FYI the karizma runs a 30mm venturi.
Form what i've read over the years the impression i've gained is that a slide carb even if it's venturi is 2mm lesser than a CV would flow as good. Throttle butterfly causes a restriction of atleast 2mm at WOT in a CV carb.

Quote:
Its better-off if you can run an eliminator's 31mm CV carb. Its the best bet, but then damn hard to source. A new one will cost you 12k from a Bajaj showroom. try some 2nd hand option thought.
12k is too much let me know if you come across any used BSR31

Quote:
The Fiero does not have an ignition advanace switch(Fiero has a seft adjusting timing), its only the RTR/F2/Apache which runs the TPS switch with a split cable.
I doubt if you can use the RTR switch directly..What i meant is you can use the existing Karizma switch itself and make it operate from the cable by making some new contraption.
Will have to figure it out then!

Quote:
I've seen manu bikes with TMs, VMs and all kind of carbs on 4-stroke....but none can match the smooth fuel transition of a CV carb. Also since you are not going racing and its only street commute, a CV makes the best sense.
Either stick to the stock carb (with a 127.5 mainjet, if u running a freeflow filter) or get a different CV. The next bext in business is the BS29CV. Although its 1mm smaller than the keihin on the Zma, its the bets to tune and get better results. Fuel efficiency is also better with this mikuni with performance as a bonus.
Yep what you have said is true. But i have to see how it's going to perform with the slide carb and have to check the efficiency i get with this carb. To satisfy my curious mind. Once the Keihin jets arrive I may as well switch back to the CV if the Dell is giving me crappy fuel economy.

Why is the BS29 better than the Keihin CV, could you please elaborate?
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Old 26th September 2008, 19:06   #50
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Quote:
Originally Posted by Sankar View Post
Why is the BS29 better than the Keihin CV, could you please elaborate?
Good question.
I doubt if the karizma's keihin has needle positions. Its normally just one standard. So forget needle adjustments. The BS29/26 has 3 needle slots which can take care of the most major parts of jetting. Again you get a varierty of pilot jet sizes from many indian bikes itself. 12.5/15/17.5/20. Also you can source jets from 97.5 to 132.5. So your jetting options are all taken care of. Moreover from my experiments, I've seen that the throttle response/venturi flow is better on the BS.
I have also tried the dello and VM28 on my Fiero 200. I have tried a mikuni 24mm too. Of all the set-ups, the BS29CV came the winner. Thats the carb which helped me get to 145kmph true. Although its a CV, it provides the largest flow area better than most carbs.
About the WOT, a 29mm CV will still flow 1mm more than a 28mm carb coz with or without the butterly, the overall venturi open area is what will matter. Just think of this from a proper experiment point of view.
Take 2 hoses..with 2mm difference is sizes. Keep a butterfly type restriction on the end of the larger pipe. Measure the flow by forcing water from one end, u'll still see that the flow was higher with the larger dia pipe despite the butterfly.
you could try many combinations with your 28mm dello, but u'll find better top-speed and overall performance only with a larger dia carb.
I'm talking from experience when we have literally dragged our karizma against a bragging fellow's bike who was proud he ran a 28mm VM and other works. The distance with which we beat, he had no say.

Joel
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Old 26th September 2008, 22:16   #51
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Quote:
Originally Posted by fieroid View Post
I have also tried the dello and VM28 on my Fiero 200. I have tried a mikuni 24mm too. Of all the set-ups, the BS29CV came the winner. Thats the carb which helped me get to 145kmph true. Although its a CV, it provides the largest flow area better than most carbs.
About the WOT, a 29mm CV will still flow 1mm more than a 28mm carb coz with or without the butterly, the overall venturi open area is what will matter. Just think of this from a proper experiment point of view.
I'm talking from experience when we have literally dragged our karizma against a bragging fellow's bike who was proud he ran a 28mm VM and other works. The distance with which we beat, he had no say.
Joel
So one more carb for me to try out... Now to find the time for it I doubt anyone here is having as much experience as you & Venu have got when it comes to modding fourstroke motorcycles. What is your opinion regarding the CV slide modification, enalrging the vacuum port. Have you tried that? I want to but i'm having trouble finding the correct drill bit.

With the Dellorto what i have noticed is that throttle response is ultra crisp off idle and it slightly flatspots in the midrange if not in the band. But if it's in the band and i whack open the throttle the bike just zooms off. I haven't tested the top whack yet to decide whether it's better over the stock Keihin or not. Fuel economy as expected is the pits, haven't measured it accurately though.


I don't know but i have this guilty feeling when i do this to my bike.. but somehow i can't resist not doing all these. Only the first service is over till now.
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Old 26th September 2008, 23:24   #52
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The CRF230(F&L) series bikes, whose engine config Karizma shares, uses two different carburetors for different applications. The non street legal F version is which is strictly for trails use a 26mm normal slide carb. The street legal L version that comes with lights use a 30mm CV carb (it even has the black cover over throttle linkage like our Karizma's carb)

Cam timing on both bikes are different though.

Edit: Old CBZ comes with a 26mm carb, isn't it?
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Old 27th September 2008, 07:50   #53
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Nope, more like 22mm
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Old 27th September 2008, 08:36   #54
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@Sankar,
The flat spot your experiencing at 4k,is due to the shift from the primary circiut to the secondary circuit......in the cv carbs this overlaps perfectly from one circuit to another,i faced similar issues with usuing higher number jets in my kzma,i somehow managed to get rid of it at 4k but then it started showing a flatspot at 6krpm...

What ieroid has said is true,but getting a eliminator carb is a real pain,the BS29 shud be easy to source tough even from the scraps....

@fieroid
R u sure the cbz extreme suns a 128 main jet???
I just need to be really sure coz the amonut of money i have wasted on buying kzma jets and oversizing them,i could have bought in a new pair of jeans....

Please confirm the same if its just like the kzma main jet ill plonk that in my kzma...

Does any body know who does a good job at getting the heads of the kzma to flow better????where could i get this job done from a reputable guy...?i just need a good polish job!Fieroid if you could help in this!!
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Old 27th September 2008, 21:18   #55
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Hi everyone, time for more updates!

I have finally made the bike run 'ok' with Dellorto. Mainjet is still the drilled item (size around 150). The flat spot has been rectified by using the thicker jet needle from the VM28. Now it pulss clean and strong. through the midrange and till the top. There is a fluctuation ind of feeling when the bike is at WOT. Top speed as on the speedo is 130, again with no crouching down. Earlier the bike used to do approx 120 on the same stretch while sitting upright. Acceleration has hugely improved, low end is very good.

But i'm not satisfied with the jetting. This is why: I can't set the idling properly on the Dell and the revs once past 4krpm, don't fall back as quick as i would like when i close the throttle. I have fiddled with the mixture screw; if i open it even by as much as one turn the idle would rise and the rpms wouldnt fall back. So now i have kept just before closed. Still there is an issue with idling and RPMs not dropping while i close the throttle. RPMs will drop but it will take 2 to 3 secs. Any idea as to why this is happening? There ain't no airleak anywhere. I have plugged the vacuum take off of the manifold that goes to air injection pump.

Btw i have received the Keihin jets this afternoon Main jets are 130, 135, 140, 145 and pilot jets of size 40 & 42. Stock jets of Karizma are 125.5 mains and 35 pilot.
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Old 28th September 2008, 14:17   #56
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Since the time i received the Keihin jets i was being impatient to put it in the carb and replace the Dello with the Keihi. Last night i managed to find ultra thin drill bits and a needle file. Alongwith the jet upgrade, 40 pilot and 135 mains, i enlarged the slide vacuum port and cut 7 coils off the slide retun spring. Idea is to reduce the spring preload on the slide to increase response.

After these mods i had to see how this will relate to slide response. So again i connected the carb to the vacuum cleaner and tested with vacuum cleaner in high and low mode. As i open the throttle plate the slide reacts quickly and goes up and down as fast as i open the throttle plate, this should translate to better throttle response on the street. And another thing that i noticed was that the slide never used to go up fully and the bottom end sticked down into the venturi by about 5 to 6 mm depending on the vacuum. After the mods the sliderises completely up and out of the venturi. This has to be because of the shortened slide spring.

I installed the carb on to the bike today morning and gave the bike the routine Sunday wash & clean up. I haven't gone for a test ride yet. Just checked the response off idle and inside the compund. Seems good.

Edit: Filter as of now is stock. I'm expecting the filter this week.

Last edited by Sankar : 28th September 2008 at 14:23.
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Old 28th September 2008, 16:51   #57
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@Sankar.

(But i'm not satisfied with the jetting. This is why: I can't set the idling properly on the Dell and the revs once past 4krpm, don't fall back as quick as i would like when i close the throttle. I have fiddled with the mixture screw; if i open it even by as much as one turn the idle would rise and the rpms wouldnt fall back. So now i have kept just before closed. Still there is an issue with idling and RPMs not dropping while i close the throttle. RPMs will drop but it will take 2 to 3 secs. Any idea as to why this is happening?)

Pilot circuit is lean.........u need a bigger pilot jet......i think in the dellorto carb the pilot screw controls air,thats the reson why when u open this screw ur making the mixture even more leaner....

I suggest you increase the pilot jet size..it will for surely solve ur rpm hanging problem..

Are u sure you will manage to get all the parts your modifying in your carb?
it took nearly 3months just to get the air screw when i ruined its head.....
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Old 28th September 2008, 17:25   #58
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these are very interesting developments and i would like to pursue your final course of actions on my zma as well. where did you source the keihin jets from??
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Old 28th September 2008, 20:33   #59
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Quote:
Originally Posted by scorpian View Post
@Sankar.
Pilot circuit is lean.........u need a bigger pilot jet......i think in the dellorto carb the pilot screw controls air,thats the reson why when u open this screw ur making the mixture even more leaner....

I suggest you increase the pilot jet size..it will for surely solve ur rpm hanging problem..

Are u sure you will manage to get all the parts your modifying in your carb?
it took nearly 3months just to get the air screw when i ruined its head.....
The pilot circuit of the Dello was okay. The pilot jet size of the Dello is 38. I compared the hole with the Keihin jet and Dello's is slightly bigger. So it can't be lean. And when i close the mixture screw it is better. In Dello the screw controls fuel like the Keihin.

I'm ordering a slide diaphragm assembly eventhough i don't need it now. Just in case if it's required. The slide spring i can source from another CV carb.

Needles, Jets, Screws, etc etc i'll surce from abroad i'm not going to waste my time with the dealer I'm not sure about the slide diaphragm assy thats why it makes sense to get it from the dealer if available.

The Dello's idle hanging problem was due to manifold air leak. Dello's spigot is slightly smaller than the Keihin, but it was getting clamped in securely in the manifold so i thought it was fine. But actually there was an airleak. So i have two options:

1) is to source a manifold with a smaller dia (will the CBZ-X manifold fit the head?)
or
2) Buy another Karizma manifold and fit the Dello using Anabond (red) RTV silicone sealant (i've had good experience with this on my bullet, a carb installed using red RTV was so friggin tight that i had to cut the manifold to extract the carb)

Quote:
Originally Posted by gt_mustang View Post
these are very interesting developments and i would like to pursue your final course of actions on my zma as well. where did you source the keihin jets from??
Yep that's the point of this thread, open source! No need to re-invent the wheel in case anyone else follows a similar path

I sourced the jets from Jets_ R_Us_____Jets_R_Us_____www.JETSRUS.com
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Old 28th September 2008, 20:59   #60
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Wished to edit the previous post by it was a bit too late after dinner

I went for a test ride this evening. The jetting is a bit rich at the top. I think 130 mains should be perfect. 40 pilot is okay it's not too rich, but 38 should be better. Unfortunately i didn't order 38.

The bike performs better without the TPS. I'm not saying this after this particular test ride but it performed better with TPS disconnected even when everything was stock inside the carb. With TPS i feel as if the revs have hit a wall when nearing redline.. without TPS it revs freely.

Also the throttle response has increased big time, the carb doesn't feel as if it's a CV anymore. The response is much like that of Dello's, instant. And it doesn't get bogged as well. Earlier there was a slight lag after i open the throttle and the bike gains momentum, now it's immediate.
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