Kdx 220 Carb Bore

spivv39 · Mar 16, 2004

Hi from England and a newbie,

I just bought a 2000 220 and have seen that a carb bore by 2mm would be a good idea. I see that some people advertise in the USA to do this but for me to send would be cost prohibitive and it would probably be cheaper to buy the 200 carb body from the dealer. i have a freind in the aerospace industry who could perform a straight foreward bore to increase by 2mm but is that all that needs doing? Airbox lid has only the front half in place and I have just bought a full FMF system (rev pipe and turbine core silencer). Sorry if this has been asked and i missed it.

many thanks for any input

canyncarvr · Mar 16, 2004

Doubt any response you get unless it's from a machinist that's done it. Sure...it looks like a 'straightforward bore', but a machinist doing the work may well chamfer some of the edges and such. Having a friend down the street punch a hole in the carb would likely NOT be the same.

What's going to happen with the jetblock, fer instance? It's going to be left sitting up in the air?

My money would be on getting a 200 carb if it's 35mm that you're after.

Or...instead of sending your carb off to the colonies and then waiting around to pay to have it sent back, howabout just BUYING a carb in the first place? Get one'a rb-designs modified airstryker carbs and be done with it.

You won't regret it!

Have him put in one of his cute finger-adjustable air screws, too!

skipro3 · Mar 16, 2004

How come Ron doesn't have anything on his site about the airstryker? I can't seem to find anything about it.

canyncarvr · Mar 16, 2004

Because he has absolutely nothing to do but hide the facts from you. He's gone to great trouble to determine that you are looking for such information and hides it from you.

...or not. :)

I dunno why. Cuz he's busier than a one-armed paper hanger I 'spose.

There isn't a huge difference between the two (oem pwk and airstryker), but I reckoned it to be a considerable improvment in off-idle and mid-throttle response. If you're in the market for a carb, why bother with a plain 'ol 35mm pwk when you can get a 36mm AS from mr. ron. Why...you even get a bunch of extra hoses to mess with!!

Fred T · Mar 16, 2004

Or you can send the carb to Fredette and have him bore it.
www.frpoffroad.com

wibby · Mar 16, 2004

Or you can send the carb to Fredette and have him bore it.

Hope you don't plan on riding for a month or so :eek:

Ron bored mine and sent it back within a week or so

:thumb:

skipro3 · Mar 16, 2004

See, I told you I had reason to be paranoid!!!

Robcolo · Mar 16, 2004

Actually, for a machinist it's a really simple job. Remove the jet block with a torx driver [tamperproof design or just drill out the little safety nubs] clamp the carb down to the table, then set up tlhe boring head for the new bore diameter [approx 35.5mm]. Bore it OFF CENTER -upwards so that the bottom of the new bore coincides exactly with the bottom of the original bore. ie - all material is removed above the bottom of original bore. I blended the new bore into the intake bell with a bit of 220 paper. Reinstalling the jet block finds it in exactly the same location in the new bore as in the original. Top end improvement is substantial.

spivv39 · Mar 17, 2004

Thanks robcolo, What you have done is what we figured and were going to do anyway but i just wondered if anyone else had tried it, any clues on jetting? just a larger mainjet? I am running standard at present (main 145 ) as have only just bought FMF system and not checked jetting since i was going to do it after carb bore.

Mrobbins · Mar 17, 2004

Since it is not on his web site, anyone know what the price for a AS carb from RB is vs the $165 for the PWK mod? Maybe I could trade in the PWK to RB or just sell it?

m0rie · Mar 17, 2004

Mrobbins said:
Since it is not on his web site, anyone know what the price for a AS carb from RB is vs the $165 for the PWK mod? Maybe I could trade in the PWK to RB or just sell it?

Wibby posted this earlier today in another thread...

RB modified Airstryker $325 / including shipping

RB Carb Mod. $165 / including shipping

-Maurice

Mrobbins · Mar 18, 2004

Thanks, decision time.

m0rie · Mar 18, 2004

Mrobbins said:
Thanks, decision time.

Either choice is going to be good. I'd go for the AirStryker if you can afford it. You'll get to keep your existing carb so you'll have no downtime and can sell it to make up some of the difference in price between the two. Either way though you still come out a winner :thumb:

-Maurice

canyncarvr · Mar 18, 2004

Just because you're paranoid doesn't mean they aren't out to get you!

OK...so robcolo's a machinist type that's done it. Sorry, but I'd still be skeptical about handing MY carb to some 'guy' with the intent of having him remove some metal from my carb.

Like..why suppose that reboring with the metal removal from the top is a good thing? Does the slide now even clear the bore? Maybe the jet block should be moved down in the first place? I know that's true of a number of carbs ron works with..he resets the jet block AND makes changes to the jet block screen.

I'm not urinating on rob's parade or doubting his ability or result...just that my choice would be a machinist that spent a LOT of time with a kdx strapped to a dyno to refine his carb mod procedure. That would be ron (of rb-designs).

And then there's the jaguar types that retime their bike's transfer ports with epoxy, do their own machine work and generally fix anything wrong with their bike with ingenuity, chewing gum and bit of spit.

Congrats to him and those of his type. Me? I'll send my stuff off....for eight weeks. :(

wibby · Mar 18, 2004

I'll send my stuff off....for eight weeks.

And now he's turning into a PUNKIN! :eek:

And he rides even faster than before! :worship:

I'll never catch up! :whiner:

skipro3 · Mar 18, 2004

I know what you mean Wib. My riding bud swapped his KDX for a KX 500. So of course I mess with it when he isn't looking, how else can I keep him in sight? Fuel petcock when he isn't looking as well as a little "tuning" with the pocket screwdriver on the A/S and the shock settings, remove the nut on the wheel lock, (guaranteed to rip a valve stem with all that torque). A guys gotta do, what a guys gotta do.
Make him throw in that air stryker carb when you buy that bike from him too. Didn't Ron give it to him anyway to test?

Canadian Dave · Mar 18, 2004

Spivv39, Robcolo's description of boring the 33 to a 36 is excellent. What you will end up with is the bore of the carb being centered in the carb body rather than offset to the bottom of the carb as it is with the stock 33.

After being bored the jetting starting point will be that same as that used on a KDX200. You can find a starting point on the JustKDX web site or there are a number of excellent starting points directed at different types of power delivery on any number of RB Designs Carb discussions as well as jetting discussions.

Good luck.

David

spivv39 · Mar 21, 2004

Thanks for all the help and advise on this, the carb is with the machinist now and will be done exactly as robcolo and Dave describe. I was only looking to gain back the top end that Kawasaki dialled out by fitting the smaller bore carb at present. This will cost me a drink to my friend at Airbus (where Concorde was built) so is a cheap quick option for me. I am sure that the RB designs man has spent a lot of time and money on his carbs and that they will give benifits over a simple bore job and I will consider further mods in this department at a later date, but for now i will spend my money on fork and shock upgrades as mentioned in other threads on this excellent site.

spivv39 · Mar 21, 2004

Forgot to mention that being a newbie i had not explored all the links etc and after posting my original question i did find the carb tuning section which is excellent and gives me a great starting point and tells me what jets i need to order in advance to cover all eventualities.
Thanks Dave

Spivv

spivv39 · Mar 29, 2004

Best £10 I ever spent on tuning a motorcycle. Got it all back together and first trail ride yesterday and the top end gain is substantial!!! I managed to bore out to 35.80mm without removing material from the bottom of the bore and first impressions are that the bottom end performance is unnaffected.

kmccune · Mar 29, 2004

Very cool, I'm glad it worked...now if I just had a machinist friend :)

Kdx 220 Carb Bore

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spivv39

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Kdx 220 Carb Bore

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