Carbs & 91 Octane Pump Gas Variability & Trail Tech

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AZRickD
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Carbs & 91 Octane Pump Gas Variability & Trail Tech

Post by AZRickD »

Lots of stuff to cram in one thread...

I've been mucking around with my 2003 KDX 220 carb trying to get the 1/8th throttle burble/stumble out of it. I live in Phoenix at 1,200 feet MSL, 105 F today and 12% humidity. Airbox lid is off, carb is an R-B Designs carb originally set at 7/8th turn. The head has the squish mod for pump gas.

The guy I bought it from had it set up for him, but he changed it for me, thinking I'd appreciate a little fatter mixture as I re-learned how to ride. 150 main, DEK-3 needle, 38 pilot, A/S at 2 turns (I set it to 2.5 to max the idle).

I swapped out the DEK-3 for a CEK-3 needle thinking that leaner is better. It gave me a boost but didn't cure the burble.

I e-mailed Ron at R-B Designs and he suggested to try 7/8th as 2.5 was likely the SSS (secondary sweet spot). He was right. 7/8th was now allowing me to lift the wheel in first gear but bogging in 2nd on a rolling attempt. It got rid of some, but not all of the burble.

I did some speed runs down the street and found that I had some pinging from 8500 RPM on. I had *just* made another 10-gallon batch of 91-Octane 40-1 pre-mix. I'm wondering if I got a bad batch of pump gas? I might have to get some race gas to do a 50/50 mix.

Anyway (after I get the gas thing fixed)... what do you think about going from a 38 pilot jet to a 35? Or moving from the CEK-3 to a CEK-2, to lean it out a bit?

My neighbor who is a MX racer (KTM/Kawasaki) looked at my old and my new plug today and said that my old plug (medium to dark brown) is how he'd like his plug to look if he were going racing.

Thanks for your help.

Rick
Phx, Az
Last edited by AZRickD on 12:53 am Jul 05 2006, edited 1 time in total.
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Indawoods
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Post by Indawoods »

For the gas issue... try adding 5% Tolulene to the mix.

I had that same hesitation on my RB'd carb but raising the needle one clip fixed it. No hesitation but I am not running in 105 degree weather either. I am running a 150/42 combo.

You might check your float height as if it is sitting to low, it could cause that burble...
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Post by AZRickD »

Thanks for the reply.

The float is still to spec at 16mm.

A half-gallon of toluene for my current ten-gallons of pre-mix sounds better than buying another jug + five gallons of race gas.

I'll do a search on toluene on this forum to see what folks think about it. Thanks for the idea.

You say "raising" the needle fixed the burble for you? You mean put the clip on #4 thus pulling the needle out earlier and making it richer. In my case, I *think* I have to make it leaner. But I could be wrong. :blink: That's what my KTM neighbor said. I'm still considering the pilot jet since that is supposed to be in the 0-1/8th throttle circuit.


Rick
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Post by AZRickD »

Yep. Read the posts on toluene.

Living in Phoenix, I have to get up early to ride before it gets hot. Lowes Hardware is just down the street and opens at 5am. I can only hope that they'll have some toluene. Only hope.

Failing that, I'll just have to keep the revs down.

Rick
I done KX-ed QuailChaser's KDX220R
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Post by RBD »

AZRickD

You have e-mailed with this question and I did answer it !

YOU need to fine tune !

You need to understand that you bought a used bike with my carb mod and I will help you with your riding conditions (105*) !

Are the P/V's working and do you understand the fine tuning sheet that I sent you ?

Thank you,
Ron
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Post by AZRickD »

Ron,

Lo comprendo la direciones'.

I'm workin' widdit but I still have to get this new ping-thing fixed. I'm pretty sure that I've got some 87 Octane instead of the 91 Octane button I pushed. The ping started with that.

I can't be sure the power valve is working, but I get the same RPMs (9200) I did before, just with reduced pull throughout with a ping on the top end of the curve. Once I fix that, then I'll go to fine-tuning.

Wikipedia has a note on PVs, and even mentions KIPS...

http://en.wikipedia.org/wiki/2-stroke_p ... lve_system

Time to ride (to Lowes).

Rick
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Post by AZRickD »

Toluene is tough to come by. Nada at Sherwin Williams, Dunn-Edwards, and and two other shops. I have to go to "ADCO" for the privilege of paying $15/gal. :(

Rick
Last edited by AZRickD on 07:57 pm Jul 04 2006, edited 1 time in total.
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Post by Indawoods »

Yeah... it's not cheap but does help performance. True Value has it here! :grin:
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Post by RBD »

Hi Inda,

So when you say you are adding 5% Tolulene to your mix, so you are using 6.4 oz of Tolulene per gal of gas?

Thank you,
Ron
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Post by Indawoods »

I put in 32 oz per 5 gallons.
Well... sometimes a little more. Depends on where I get the gas from.
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****'95 KDX 200/****

"People ate cows a thousand years ago for the same reason we eat them now. Cause they are easy to catch.We're not savages,we're just lazy. A cheetah could taste like chocolate heroin. But will never know. Those bastards are fast!!! "
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Post by AZRickD »

It's hotter'n heck out here. 106 + F. :twisted:

I tried 5% and 10% toluene in the tank (5% in the 5-gallon jugs). Power is back but there wasn't much improvement in the "pinging" if that's what it is. The noise is more like a high-pitched, rapid "whoop-whoop-whoop-whoop-whoop." Sounds like an exhaust thing rather than a cylinder thing.

I'm going to post some sparkplug pics.

The first pic shows my old plug on the left which is an NGK BR8EG. The plug on the right is the one I installed yesterday and completed two hours of slow single-track (you guys would go faster, but I'm not there yet). Notice that it is a little black and the electrode coming out of the insulator is wider than the original plug.

The new plug which I purchased from MetroMotorSports in Phoenix is a BR8ES.

Image

The next pic is of the new plug after some high RPM runs. Not quite a "chop" but close enough. Next to it is an unused plug for purposes of color comparison.

I'm going out to the furnace-like garage to take out my 38 pilot and replace it witha 35 just for my edification.

Image
Last edited by AZRickD on 07:33 pm Jul 01 2006, edited 1 time in total.
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Post by Indawoods »

And people wonder why I ride in the woods.... it's a hell of a lot cooler in the woods. :lol:

I would say you are riding the bike in some of the most extreme conditions. Most would park the bike until is got much cooler and I would be one of those. Once it cools off, you better fatten it up or risk a sieze.
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"People ate cows a thousand years ago for the same reason we eat them now. Cause they are easy to catch.We're not savages,we're just lazy. A cheetah could taste like chocolate heroin. But will never know. Those bastards are fast!!! "
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Post by AZRickD »

I just got back from the torture test. I just checked the temp -- it's not 106F. It's 108F (high was 109F).

That's why I ride at 5am to about 7am. The temp starts out at 85F and then climbs to Sweating-like-a-pigF by 7am. Although the air temp at 7am is in the mid 90s, the heat off of the bike has my TrailTech Vapor computer registering nearly 100 around that time. On my last ride tonite, the ambient temp around the Vapor computer was registering about 117F, with the KDX water temp going from 180F to about 220F (if I didn't keep the air moving).

The heat doesn't totally explain what's going on with the bike. I've ridden in this heat before.

Anyway, the torture test with the #35 pilot jet didn't go too badly. The 1/8th throttle stutter has been diminished but not eliminated. I'm getting the wheel in the air a bit easier but still not like the "your wheel will point to the sky once you get the sweet spot on the A/S."

It lifts enough for me to get over a small obstruction on the road. It feels like it's tunable now-- and I'll continue to try... frustrating as it might seem.

You're right about re-jetting when it gets cooler, but Phoenix typically has 90 more days (until about early October or late September, if we're lucky) of 100+F high temps. Unless I can be convinced otherwise (via an expert looking at my bike, or something odd happening to the plugs), I'll keep it as is.

Thanks,

Rick
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Post by AZRickD »

Fixed.

Mostly.

The ping is gone, but it's only 106F at 8pm here, so I almost feel like I'm cheating.

The off-throttle burble is almost entirely gone. I'm still looking for the magic 1/16th of turn, but throttle response has improved.

I'm going riding tomorrow morning to test it.

Rick
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Post by Indawoods »

Better take a jacket.... :grin:

People would be croaking around here at those temps. I think it got to 91 or something like that today.... The AC is running and here I sit.
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Post by quailchaser »

>|<>QBB<
AZRickD wrote:Fixed.

Mostly.

The ping is gone, but it's only 106F at 8pm here, so I almost feel like I'm cheating.

The off-throttle burble is almost entirely gone. I'm still looking for the magic 1/16th of turn, but throttle response has improved.

I'm going riding tomorrow morning to test it.

Rick
4:30 am is for real men.
Glad to hear your getting closer. I went through the same issues (minus the ping) getting it jetted for my riding style. Although, it took me months instead of "days". I'm jealous at how much you get to ride. :mrgreen:

Yep...like we discussed before...1/16th of a turn makes a huge difference. You'll get there.

We'll be truck shopping tomorrow. We may go riding...but not @ 4:30 AM. 4:30 am is for those who can't sleep. :rolleyes: 2 pm @ 118 degrees is for real men! :wink: I'm hoping for that early evening monsoon cloud cover so Garrett and I can hit the trail around that 107 degree time of 5:30 pm.

Later
Robb
Better take a jacket....


Vince, we don't start wearing jackets here until it gets really cold ussually some time in October. When it hits 75 degrees.
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Post by AZRickD »

"Mostly."

I just got back from a ride with my buddy and his WR450F. He's been raggin' on me for weeks for buying a two-stroke. :butthead:

He took me all over the place. He was giving me instruction on whoops and ledges.

We left his house at 6am and rode 2-track and jeep trail from Happy Valley and 99th Ave, up around some mountainettes, then down to 51st Ave and the CAP canal. I had no idea we had traveled so far. Then we headed back and got into some foothills which gave us some fairly technical single-track. After that he dubbed me "ready for Pima & Dynamite," adding, "you're much better than this sucky guy we ride with."

The KDX was soaking up the bumps admirably and I did my hand at some minor jumps where the whoops were spaced out far enough so that it didn't matter if I ended up short or long. I'm sure I got 6-inches of air once or twice.

One thing I noticed, which I will have to check after I get done with a well-deserved nap, is my high-RPM performance. Recall that I was getting this whoop-whoop-whoop hesitation at 9200 RPM that I thought was a ping but now have my doubts? It started happening at 8200RPM this morning.

I wonder if the power valve is sticking so that it doesn't open up all the way nor close all the way. That could explain some things. I'll have to do a search on "power valve" + "trouble shooting." I may have a date with a mechanic.

Rick
Last edited by AZRickD on 12:56 am Jul 05 2006, edited 1 time in total.
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Post by Indawoods »

Sounds like your KIPS isn't opening all the way or isn't timed right.

Pretty easy to check though by pulling the pipe and KIPS cover on the right. Stick your fingers in the exhaust port and feel to the left and right while turning the kip acuating arm open and closed. You can feel the subports open and close fully. If not... you ports is out-a-time.

If it turns hard or not at all, you will have to disassemble the topend and de-goo your KIPS parts.
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"People ate cows a thousand years ago for the same reason we eat them now. Cause they are easy to catch.We're not savages,we're just lazy. A cheetah could taste like chocolate heroin. But will never know. Those bastards are fast!!! "
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Post by AZRickD »

Sounds like a worthy exercise.

I'll look for a URL that has KIPS blow-by-blow (with pics) so I can get this job done.

Edit -- I removed the pipe and actuator thingy. The valves looked fine and lubed. I rotated the actuator lever with a 10mm box-end wrench. Everything moved freely and returned to position.

Thinking that the KIPS powah valve wasn't the problem, I bolted everything together and gave it a kick to see if it would blow up (I have a habit of forgetting to put stuff back together correctly).

I let it warm up in the 99F night-time air (which is actually warmer than our morning ride). It started right up. I coasted it around the neighborhood getting it warm and making sure something didn't fly apart. I eventually got it out on the main road and up to high-revs.

Hmmm. No "voop-voop-voop" as it climbed past 8200 RPM and topped out at 9200 RPM as per the old normal. It climbed to rev epeatedly. Might be my imagination but the throttle response felt better (I'm thinking placebo-effect). Still had some of the off-idle burble, but I'm learning to live with it.

Now, I'm the first guy to take credit for happenstance, but if I had just seen what I saw in the internal action of the KIPS, I would have said, "That ain't the problem." There was no dragginess, nothing that shouted "problem." And yet, maybe my wrenching did something. I don't know. But one can't argue with short-term success, even if it's imagined.

Time will tell. I might take it out for a morning run tomorrow before work.

Rick
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Post by AZRickD »

Looks like I've still got the voop-voop-voop.

It's somewhat RPM independent, which means that it could be throttle related -- which means carb.

If I had to guess, I'd say about half-throttle is where the voops begin, but they don't stop at higher throttle. The needle circuit is still functioning when the main kicks in so perhaps it is the needle.

I'm thinking about digging into the carb again and either moving the clip on the CEK needle from 3 to 4 to richen it up, or I might go with the DEK, but move from 3 to 2 to lean it a bit.

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

Since I couldn't find any KIPS pics on the net, I decided to post some here.

First up is a macro+ pic of the power valve just inside the exhaust header area. The valve is that dark, little square shaped thing center-right of the photo. The piston is the shiny thing on the left. The pic doesn't show it well, but the entire area is well lubed with spooge.

Image

Next up is the actuator assembly on the kick-start side of the motor. That's my 10mm wrench on the nut which I used to moved the action back and forth. I had a few minutes of confusion trying to figure out how that rubber seal on the bottom of the cover was supposed to slide back into the cover while at the same time I negotiated all of the other mechanicals.

Image

Last and surely least, in case any of you wondered what's under the cover on the shifter-lever side of the motor which has "KIPS" cast into it... the answer is not much... anyone know what this is for?

Image
Last edited by AZRickD on 12:59 am Jul 05 2006, edited 1 time in total.
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