KDX 200 RB carb bog issues

[DougB]

Getting ready to drop kick the KDX. I'm wearing out the carb I've had it off and on so many times. Can't get rid of the bog when I snap the throttle on in 3rd or 4th. 3rd gear roll on is OK, good power, pulls hard. I had a bog before the carb work but I'm focusing on it now. I've had the bike for a year. Was "supposed" to have low hours on a complete rebuild when I bought it. That's all I know about it's history.

Specs: (now) 152/42, CEK-5, 40:1 mix, float level -1mm from mating carb point
I installed Boyeson reeds
RB carb mod w/ long mixture screw about 2 5/16 out.
Stock gearing 13/47. Maybe I should go to 13/49?

I've checked compression. It's consistently 145lbs.
I'm not using any tranny oil, so it doesn't seem like crank seals are bad.
Bought the float tool so I could set float precisely. I have read confusing remarks on float height. I haven't changed this since I set it.
Carb boots are tight. I

I'm in the NW, temps are low 40's to low 50's.
Tried every combo of jets from 40/150 to 45/155 and CEK,DEK -3,4,5.
Leaner jets and needle settings made the bog worse.

I've adjusted the mixture screw till I'm blue in the face. Spent hours riding on dirt roads fine tuning it by 1/16 increments +- from 2 1/2 turns out to try to get rid of the bog. Seems the best performance I can get is: the bike will just rip thru the gears, front tire coming up, with me holding on tight, very good lugging too, just walking up hills and then it will accelerate. Sounds great right?
In normal woods riding this would get me by in very good fashion. The only time the bogging shows up is on road riding. I have been trying to dial in the SSS and that's how I noticed the bog. I seem to be in the SSS judging by the roll on and low end performance, but on the road when I stab it in 3rd going up a slight hill it bogs. Someone else said "not like a small engine bog but a BoooWAH bog" if that makes sense. It bogs and eventually when it hits the Kips it takes off.

I appreciate your well thought out responses. This is dead serious to me and the fate of the KDX rests on it. She's shaking in her boots after that comment, but seriously this is getting ridiculous. I've never had this much trouble jetting a bike. I'm desperate or I wouldn't be writing this! Maybe this is the best she can be, or there is something mechanically wrong, but judging by what I've read there's room for improvement. Most of you say you have NO hesitation/bogging. This could be due to more mods or not. There are so many posts that are not finished or the info is confused but I thought I would give this a try. I'm sure there's something I haven't tried or left out.


Thanks guys,

Doug

[Indawoods]

The SSS will make it a lot less snappy and more 4 stroke tractor like. If you are indeed in the SSS then it could be what you are describing.

I don't think she is behaving wrong.... do you still have lots of power to make it up the hills? If so... I think you are there.

The carb can be tuned to be two different animals. The bike will behave completely different. So, if you think that when it is tuned to the SSS it will behave the same as tuned normally, then that is where the problem is.

[canyncarvr]

Oregon...where?

Do you oil your air filter with the 'soak/wring out excess' method? If so, try something else...a slight dampening with oil followed by a good kneading until evenly spread.

IF 'stab it in 3rd going up a slight hill it bogs' means a flick to WOT (or close to that) from a low-rev point..that doesn't sound wrong to me. With no accelerator pump, no TPI to change timing and air/fuel delivery..that's what you're gonna get. When you say, '..eventually when it hits the Kips..' makes me wonder just how far away that is.

Any chance your reed cage is upside down? The tab goes to the OUTside.



...a couple of things to think of.......

Re: 'Most of you say you have NO hesitation/bogging.'

I would say that. ..and you could ride my bike and make it happen, too. There's more to going faster quicker than yanking a full twist of throttle. THAT action is going to get me a LOT less response than a controlled throttle opening.


I DO use tranny oil. All the time. I wouldn't think of NOT using it!

[DougB]

Inda, "do you still have lots of power to make it up the hills?" yes, tons of low end torque. I tried a few short steep hills and I lugged it in 2nd and cracked the throttle a little at the steepest part and it just instantly responded and walked up the rest.

CC-I need to change my location (in my profile, I'm already HERE ) to WA. Moved to Battle Ground (by Washougal MX and Jones Creek OHV) a few months ago.
I spray on oil and knead it in.
Tab on reed cage is as pictured.
Sounds like I may be expecting too much or maybe I misinterpreted what has been posted here in the RB area. I kinda suspected that. Disclaimer: BTW, Ron is a stand up guy and I was not criticizing him or his work in any way, just not sure what to expect. It didn't seem right to wick open a lugged down 2T going up a hill, to WOT or close to it and expect a clean "crisp" (as many are fond of saying) response.
I'm glad you two answered. You have both helped me out in the past with your posts, thanks for that. Your reply's and knowledge much appreciated.

(now using tranny oil) Doug

[skipro3]

From experience with a 220, I would say it's a lean bog. Why? Probably the reeds. I'm sure you inspected them and all but they can still get "tired" and not work as well as new ones.

You say you use Boysen reeds. I don't like them on a KDX220 so maybe you can get some feed back on them from the 200 owners who have them. I do like the V-Force reeds. The latest and greatest. They are really good in the conditions you describe and I don't have any lean bog on the bike anywhere.

What makes it worse? If leaning it out, i.e., raise the needle clip one position, then that tells you which direction to go in.

In the end, I'd say to try a different brand of reeds and recommend V-Force. Then if it's still there, dink with your fuel. Change brands and octane ratings. Just thinking out loud here....

[DougB]

Skipro-Lowering the clip (enriching) the needle seemed to make the bog less.
I'll consider the V-force reeds. Can you buy just the reeds or do you have to buy cage and reeds?
I'm gonna give myself and the carb a rest for awhile. Maybe wait for some warmer weather to dial it in a little more. Maybe some "summer" gas will help!
Thanks,
Doug

[canyncarvr]

The V-Force reeds fit on the V-Force cage.

Or...you cannot put V-Force reeds on an OEM cage.

Might not hurt to advance your timing a tad.

TOLUENE!!!! 5-10%



Re: ' It didn't seem right to wick open a lugged down 2T going up a hill, to WOT or close to it and expect a clean "crisp" (as many are fond of saying) response.'

Don't seem right to me, either. Good thing, too! If it did, you would get one of two things: Wheelspin, or a Loop-it.

No thanks to neither!


My bike does have a clean 'crisp' response in the situation you note..with the exception of 'lugged down' and 'up' (depending on how UP that is) a hill. It's fun on open roads, skids and the like. The thing SCOOTS!..and spits hunks of road for a LONG ways (and wears out tires!!)!

On a single-track 'up'hill that I have to squeeze tight with my knees to keep from falling off the back? I want none of that.

C'mon down for a ride...we'll see what's what.

[DougB]

CC-Might take you up on coming down for a ride! I pm'd you before I saw this post. That would be a fun way to see "what's what".

Doug

EDIT: CC I can't seem to send you a PM. I wrote to the site administrator to see if it can be fixed. I'll be sending you an email re the reeds as soon as I can.

[canyncarvr]

'Might take you up on coming down for a ride!'


Threats.....pffft!

[Indawoods]

CC-Might take you up on coming down for a ride! I pm'd you before I saw this post. That would be a fun way to see "what's what".

Doug

EDIT: CC I can't seem to send you a PM. I wrote to the site administrator to see if it can be fixed. I'll be sending you an email re the reeds as soon as I can.

That'd be me! Not sure why you can't send PM's... got a popup blocker on perhaps?

[DougB]

Turns out I CAN send them...didn't realize you have to wait till the message is read before it goes to your sent box. DOH!

[canyncarvr]

Learn sumthin' every day!!! Keep the Dr. away!

...sumthin' like that.

[Mr. Wibbens]

Inda, "do you still have lots of power to make it up the hills?" yes, tons of low end torque.

You realize where Inda lives don't ya?

Ya think he's ever seen a hill?

Sorry Vince, we'll show ya some hills, when ya come out!

[Indawoods]

We have hills.... those are the things with the ants coming out of em right?

[Mr. Wibbens]

Oh yeah, I forgot about those

[Mr. Wibbens]

I dunno, I have not spent to much time reading this thread

But IMHO, there's good bog and bad bog...

With an RB'd carb, and anywhere close to the SSS, the bike will bog when you have it under a great load. Applying more throttle, It will continue to bog and if the terrain lets it, it will climb (in RPM's) out of that bog

Without an RB'd carb. Applying more throttle after a bike starts to bog usually kills it

[fuzzy]

We have em, especially if you get near a river, they are just short.

[DougB]

Here's the update after the VForce2 reeds. I like the reeds, seem to give more bottom end. The bike runs pretty much the same otherwise. No night and day difference. My needle is now a DEK at #4 position.
So, at this point my conclusion is that the bike is running normally.
There could be something mechanically wrong but jetting more isn't going to solve it. I need to ride another KDX or have somebody ride mine to really tell I think. I may all have been a PERCEIVED problem on my part. I've always ridden 4 strokes. This is my first 2T and I haven't had it for very long. 2T's have their advantages in weight and simplicity and 4T's are more forgiving to ride. 2 different beasts. I'm used to a linear power band and that might be the problem. ME!
One thing for sure. The RB carb mod has really added A LOT of power thru the whole band. If you do this mod be careful when you first ride it after you install it. The power caught me by surprise and I looped out. The front end wants to walk up pretty FAST now!
Thanks to Canyncarvr for helping me out with the reeds and support. Great guy!

[Mr. Wibbens]

IMHO 4 strokes are boring

[Indawoods]

I love the DEK.... It is smooth power vs the CEK which is abrupt.

You have made some fine choices my freind! Hopefully you can hook up with CC and he can confirm or deny your perceived issues....