New KDX220R With 2001 35m Carb

[rmacdona]

Hi all,
I am new to this site (but have been listening in for awhile), I have a new 2002 KDX220 and have put a 2001 KDX200 carb on it (with a pro circuit pipe and tossed the air cover), the guy at pro circuit said just move the needle one clip and I should be alright, it seems to run great (air screw is backed way out). Am I risking any internal damage leaving it this way .
Rick

 

[Canadian Dave]

I've got some questions before I can give you any guidance on this one. You're running the stock jetting, are we talking about the stock jetting form the KDX220's stock 33mm carb or from the KDX200s 35mm carb? If you are running the stock jetting from the 220's carb stop!, you'll be WAY too lean on the main jet. Can you tell us exactly what jetting is in the carb right now and give us a feel for what conditions you ride in, your riding style, i.e. lots of low throttle setting stuff or lots of WOT, the altitude there and what weather conditions you are riding in right now.

Talk to ya soon,

David

 

[rmacdona]

I am running the stock 200 jet and am running a combo of woods and wide open. Weather is just north of dallas, not much altitude.

 

[Lew]

rmacdona

was there a noticeable power change with the 200 carb? I have considered getting a used 200 carb for my 220, or have mine bored?? I don't know which way to go, as money is always a factor. Besides I spend enough $ on parts do to crashing.. How much power is enough power?

All coments welcomed..
Lew

 

[rmacdona]

I am not sure that it is the carb that has made a significant difference, but I put the carb on a day after the pipe change and air lid removal and there is an extreme difference with the combo of all three of those changes. It went from a fun bike to a real source of adrenlin. I will say that it seems to pull farther through the curve and maybe even a bit more at the top end after he carb exchange (but keep in mind this is coming from someone who had been a long time four stroke rider until fairly recently). I am expecting even better results once I can jet it properly, having said that I took the bike to marshal creek on the weekend and I can't imagine that it could run any better then it does now.
Rick

 

[canyncarvr]

re:

...I can't imagine that it could run any better then it does now.

Ha! Been there.....about 1/2 dozen times! There's always some tweak/upgrade around the corner that makes me think that all over again!

Don't know what 'AS backed way out' means, exactly..but if it's more than two turns out, something else (pilot jet probably) needs to be changed...or fixed.

THAT circuit being primarily responsible for off-idle throttle response, when you get it right, you'll be back to another 'I couldn't imagine.......'

It'll be deja-vu all over again........:)

To say

I am running the stock 200 jet

doesn't mean anything. THE way to know how it's jetted is to take it apart and look at the numbers. Any advice on what to change without knowing where you're starting from is advice you shouldn't pay attention to.

Note that CDave asked '..exactly what jetting is in the carb right now?' He asked that because it's important..something you need to find out.

Recently was a poster with a 35mm PWK off a 200 that he put on his 220. All other things being normal, he was jetted pretty rich...still showed the kiss of death on his plug (aluminum ash-grey color). In a case like that, telling him to jet richer would be bogus. Something was wrong with that carb or its install. Jetting wasn't going to fix it. KNOWING his jetset from the start indicated a problem other than jetting.

So, post your needle, main, pilot and clip numbers/positions to get any decent, meaningful response.

So, 'am I risking internal damage...?'

Probably not. But maybe so.

re: noticeable power difference

Changing from the stock 33mm 220 carb to the 35mm will certainly be noticeable!!

 

[rmacdona]

Pilot - 48
main - 160
needle - R1174k
Clip - 3rd

Air screw - 4-5 turns
Rick
(thanks for all the help guys)

 

[canyncarvr]

Well now....

..that would be basic kdx200 jetting, huh ;)

Look for CDave to give you the correct scoop for your 220. I don't know how the 35mm works jetting wise on the 220. I'll leave opinion out of it and let someone that KNOWS answer your question.

One thing sure...your AS (and thus pilot, most likely) is out of whack. How did you set it?

Set it to high idle for starters (move the screw slowly to get to that point. The engine won't follow the adjustments you make lightning-quick. Wait for it to settle in).

After that, you'll be looking to adjust the AS to best throttle response. That is likely going to be a bit richer (turned IN) from the high idle position.

Don't bother adjusting it until you get a good pilot starting point.

It's not a 48! That's a fer sure.

 

[Canadian Dave]

I'm going to guess you need to back your airscrew out so much because you are quite rich on the pilot and main circuit. Given your riding profile and area are quite general with no extremes right now I'd suggest you go with the following starting point: Main 155, pilot 42 stock needle in the second from the top clip position (#2), start with the air screw at 1 turn out. You'll need to lean your jetting as the summer rolls around and temps rise. While your are ordering jets I'd also pick up a 45 pilot jet, a 150 and 152 main jet.

You might also consider ordering a CEL and a BEL jet needle from your local Sudco distributor. Check out the achieves section of the DRN forums and click on the “Emergency RB Jettingâ€￾ thread. There's more needle selection info there that you can shake a stick at. Basically the BEL will offer a similar power delivery to your stock needle but not so prone to loading up at lower throttle setting. The CEL will produce more abrupt/aggressive power delivery than the stock needle. Both will offer better throttle response than the stock needle if you feel like doing some playing around. You should be able to use the base line jetting those with RB modified carb have been using.

Don't be concerned if you have to adjust your jet needle between 0.5 and 0.75 turns out with the stock needle to get sharp throttle repsonse with out some lean hesitation when you wick the throttle open. This is normal.

Hope that helps and let us know how it turned out.

David

 

[rmacdona]

O.K.
I have installed the 45 pilot, 152 main and 1173 needle (3rd clip), still having to turn out the air screw 3 and a 1/2 turns. Where should I go from here? Runs good but seems to run out at the top.
Rick

 

[rmacdona]

sorry, I mean a 155 above

 

[fishhead]

you might try one step leaner jetting on the pilot but It would be helpful to know how you are adjusting the A/S, for high idle or best throttle response. Best throttle response is the correct criteria. When the pilot is too lean the bike will idle high as it gets hot after a hard pull or it will surge at idle or rev up on choke at startup.

The pilot and straight section of the needle overlap significantly so there is an optimum combo that provides good throttle response and clean running. The choice of reeds also affects pilot preference. 45 isn't to far off for most 220's but temps will affect you choice. I found 45 worked good with carbon reeds but I would go a step leaner with composite reeds like the boyesen power reeds. With the stock slide a cel-3or 4 needle or a dcl-3 or 2 or ddl-3 or 2 needle will be worth a try. The d tapers will be richer at 3/8- 3/4 throttle which can be a big help for those who are running in cooler temps, sub 60F.

 

[rmacdona]

Good question, at about 3 turns out it is at high idle and it take 3 more to get it down to "normal". running in 80 to 90 degrees outside. thinking about boyesen rad reeds, any experience with them (they are supposedly bolt on).
Where do I purchase cel needles.
Rick

 

[canyncarvr]

Like CDave said:

You might also consider ordering a CEL and a BEL jet needle from your local Sudco distributor

Sudco can be reached directly @: 1-800-998-3529

Needles are $5 each. S&H is something like $7 if I remember rightly.

CDave also listed a number of jets. Might as well 'stock up' for the S&H charges.

You mention the AS being 3 1/2 out, but the last post indicates 6 out!?

..at about 3 turns out it is at high idle and it take 3 more to get it down to "normal"

I'm sure I misunderstand something.... NOT sure what it is you mean.

Are you talking about the IDLE screw (the black nylon screw at an angle to the carb body)??

The AirScrew is the brass screw..common slot...just above the fuel bowl toward the airbox. It's never going to be 3 + 3 turns in ANY direction.

Boyesen rad reeds? You mean 'carbon' over their 'power' reeds? Don't order boyesen carbon replacements for a rad valve for use with your stock cage. Won't fit.

Maybe I just need another cuppa coffee........

One more thing...CDave said

..stock needle in the second from the top clip position (#2)

.....you said 1173 needle (3rd clip).

I hope you are counting from the TOP for one thing...but at #3, you are for certain NOT '2 from the top'.

 

[rmacdona]

You are dealing with a carb rookie/idiot, so I am likeley not explaining myself correctly.
I am speaking about the idle screw (I did not know the difference), where should that be set. And how should I set the air screw.
I am counting down from the top for the clip and used what Pro Circuit suggested (3rd), should I go up one?

 

[fishhead]

First things First
You will do well to read the carb tuning section in Canadian Daves JustKDX page. And PLEASE approach lean limits carefully, always make changes one step at a time and sneak up on the lean limit from the rich side. Signs of leanness are pinging, surging, high idle after a hard section, high idle on choke at startup, overheating, loss of power and major engine damage. Being too lean on the main or the bottom of the needle is the worst. What works in one bike might toast another.

Regarding reeds I used the stock ones, Boyesen power reeds, Boyesen pro reeds and a Rad valve. In a bang for the buck mode the power reeds were the best and in total perfomance the rad valve was great. The stock reed cage is pretty lame by todays standards and I surmise that interfered with the gains that I expected from the pro reeds.

Regarding your A/S adjustment somthing doesn't add up. highest idle at 3 turns out sounds about right, but usually that will cause a bog or hesitation at 1/8-1/4 throttle. You will want to turn it in until the bog goes away. The caveat is to tune for throttle response under load, thats where it does the most good. Canadian Dave has a section in carb tuning that really covers the subject well.

 

[canyncarvr]

CDave's justkdx site is here:

http://justkdx.dirtrider.net

The idle (black nylon) is set for desired idle speed after the bike is at operating temperature.

The AS (the small brass one)is set as folows: Read what fishhead said ;)

CDave suggested #2 clip. That's one up from what you have now.

First things first is a great idea..Check out CDave's Justkdx site

 

[rmacdona]

O.K have found air screw and set, seems to run better at about 2.5 turns, also bought 152 and 150 main and a 42 pilot. My Boyesen rad valve and Pro circuit silencer have arrived (to go with the pipe I installed a month ago). It is my intention to install the 150 main and 42 pilot and move the needle up one clip(all suggested by Boyesen), any advice on installing the rad valve?
Rick

 

[canyncarvr]

advice on installing rad valve:

Yep. Don't.

Return it and buy a DeltaForceII from Moto Tassinari.

 

[rmacdona]

Any particular reason? or just personal preference

 

[canyncarvr]

Well...since you asked...

Here's the short version (kinda)

My riding buddy and I both got '00 200s at the same time. We did pretty much the same mods at the same time (pipes, RB carb, jetting changes, suspension mods and such). There came a time he could consistently beat me in a drag race. No..that's not relevant to 99.9% of the riding we do, but it's a fun way to compare 'stuff'.

About that time, he'd put in the DeltaForceII and I'd put in a rad valve (he was a tester for their II product. At the time he'd purchased it, he THOUGHT it was a II, it was a labeling mistake. They told him they didn't even MAKE a II for the kdx. They sent him something to try, it sucked..they tweaked it...it sucked etc. Finally he got something that worked.)

During his try this'n'that I kinda lost track of how his bike was responding to what mod.

OK...so a year later, I took my rad valve out to check the reeds. They were junk!! Cracked, chipped, split...in every way messed up. His reeds look brand new! Yeah...boyesen says replacement once a year is a good idea, still! The difference in the two was stark!

He's since replaced his kdx with an exc ktm. I have his DeltaForceII in my bike now.

Another stark difference...the performance between the two assemblies.

The DeltaForceII gives me a stronger bottom end, increased overrev. It's better in every way.

imo :)

I don't know if it's still there...but on CDave's site at one time he said that a radvalve wasn't that big of a 'bang for your buck'.

The DeltaForceII is.

So...it amounts to particular reasons...AND personal preference.

 

[rmacdona]

anybody! should I hold off installing my rad valve?

 

[rmacdona]

Guess that does it rad valve going back, where do I get delta force?

 

[KelvinKDX]

MX South sells the Delta Force but they do not list a model for the KDX. $148. What kind of advantage is there with the Delta Force over the Boyssen #607 Power Reeds??

 

[fishhead]

I had good results with the rad valve. Better mid and top than the power reeds and better bottom end than the pro reeds. my friends have used them on 200's with good results.

Freddette recommends the rad valve over the Delta force. I have not heard of anything like CC posted on the reeds fragging.

You pay your money and you take your chances.

Might want to ask Sage