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Carb questions

12 posts in this topic

Posted

Would a 28mm carb with proper jets be ok for a 232cc 4 valve engine?

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Posted

I don't know.

A 150cc usually comes with a 24mm CVK.... Meanwhile, 250cc have either a 30 or 32mm CVK..... That's a 6~8mm increase.....  PWK/PE vs CVK further complicates matters. 2V vs 4V complicates matters worst. Now, you also have to factor in the actual intake size, the head in/ex ports and of course the exhaust......

In short, there is NO-ONE on the net that can provide you an answer..Every "custom" engine is unique.. You're going to have a trial and error session getting your specific engine, tuned the way you want... 

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So here's my advice....

First, people may get tired of me recommending an o2 sensor.... But the very fact that you're asking this question, tells me not that it would be helpful, but that you NEED one..

Second, there are many cheap 30, 32mm PWK carbs on ebay... Can get one for around $30 to the door.... Maybe wise to have some spares with a plethora of jets on hand.  

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Posted

Oh I hear ya. My question was basically has anyone experienced trying one.  

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Posted

Hey guys been a while for me in here finally getting things settled at my new place.

I would suggest going with Dan on the eBay carbs, at least for testing before dropping any serious money on a carb. If you contacted some of those sellers could ask to buy two sizes for a better rate(or at least shipping cost cheaper)

I don't know.

A 150cc usually comes with a 24mm CVK.... Meanwhile, 250cc have either a 30 or 32mm CVK..... That's a 6~8mm increase.....  PWK/PE vs CVK further complicates matters. 2V vs 4V complicates matters worst. Now, you also have to factor in the actual intake size, the head in/ex ports and of course the exhaust......

In short, there is NO-ONE on the net that can provide you an answer..Every "custom" engine is unique.. You're going to have a trial and error session getting your specific engine, tuned the way you want... 

-----------------------

So here's my advice....

First, people may get tired of me recommending an o2 sensor.... But the very fact that you're asking this question, tells me not that it would be helpful, but that you NEED one..

Second, there are many cheap 30, 32mm PWK carbs on ebay... Can get one for around $30 to the door.... Maybe wise to have some spares with a plethora of jets on hand.  

 Hey Dan you got any recommendations on those O2 sensors and meters, at least something worth getting that won't kill my wallet like my wife does lol. Been having serious troubles getting mine to run at idle, stripped everything off the bike where only the frame and cargo on it come to find out I've been sparking/arcing some wires causing trouble. So replacing it all so might as well get some other things.

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Posted

It all depends on the carb too,,a smaller ID flat slide will move more air than a vacuum carb,,,a 28mm flat slide will move as much if not slightly more air than a 30mm cv carb,,,with more instantaneous response and crisper throttle transitions,,,

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Posted

It all depends on the carb too,,a smaller ID flat slide will move more air than a vacuum carb,,,a 28mm flat slide will move as much if not slightly more air than a 30mm cv carb,,,with more instantaneous response and crisper throttle transitions,,,

right now I have a round slide 28mm nibbi PE carb. I'm just hoping I don't have to purchase another one right away. It's going on the Taida 232 4 valve.  O2 sensor is on the shopping list. But I prolly can't spend much more money for a bit after the hit to the wallet thus far. I thought I read some where that a smaller carb up jetted gives a better response a faster acceleration than a bigger carb? Or did I dream that up some where? Lol... maybe it was the other way around.. I dunno I'm tired and been in a garage painting so fumes may have got me buzzed...

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Posted

A slightly smaller carb venturi will have a stronger and faster intake velocity making the response and lower rpm power better,,,lots of people think bigger is better and that's not the case ,,I had problems in my (ahem) engine building career,,I over carbed more than one engine,,the results were engines that didn't have good throttle response and power delivery was mushy and vague,,smaller carbs cleaned it up and I had engines that were very tractable and drivable,,hence forth I build "torque " engines and sacrifice a few horses at the top where I never ride anyways

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Posted (edited)

Cool.  That's what I am looking for.  I hope the 28mm will be ok for now. Thanks for the tip. Actually I should check real fast if the measurements are gone be the same for 4 valve head. 

Edited by bubsoxs

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Posted

I don't see any info about the intake size on the 4 valve head. I guess it's the same size so my manifold should fit right on?

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Posted

 

 Hey Dan you got any recommendations on those O2 sensors and meters, at least something worth getting that won't kill my wallet like my wife does lol. Been having serious troubles getting mine to run at idle, stripped everything off the bike where only the frame and cargo on it come to find out I've been sparking/arcing some wires causing trouble. So replacing it all so might as well get some other things.

Yes, there are cheap ways of hooking up an o2 sensor.... At the minimum, you need the following:

  • o2 sensor (and a way to provide power where needed)
  • bung (what you screw the o2 sensor into)
  • a low voltage digital meter

In short, you don't get an A/F gauge or any controller, you just hook the volt meter to o2 sensor and then convert the voltage to the lambda scale.... There are a lot of different ways and parts to select from... Here, watch this guys youtube video and skip it and start watching from the 11 minute mark.... YOUTUBE link  That should give you the basic idea.... It's the cheapest method I know of. 

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If you have wires "sparking/arcing", that may be the reason you can't get it to idle.... What wires are sparking? 

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Posted

 

If you have wires "sparking/arcing", that may be the reason you can't get it to idle.... What wires are sparking? 

It was at a junction point, not even covered, just so happened to be another junction point that wasn't even an inch away. I do believe it was the stator wires crossing the ground. 

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Posted

It was at a junction point, not even covered, just so happened to be another junction point that wasn't even an inch away. I do believe it was the stator wires crossing the ground. 

Did it help with the engine idling issue?

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