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KDX4ID
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Newbie With Questions

Post by KDX4ID »

Hi all. I purchased a low mileage 1997 KDX220 in August. I've spent some time and took the bike down to the frame. Rebuilt the top end, split the cases, greased all the bearings, and gave it the "once over".
I have adorned it with a Motion Pro triple clamp. Scotts Stabilizer, FMF woods pipe and silencer, Clarke Tank, tall seat foam, wider footpegs, and I am running a Trials Tire out back.
I bought and prepped this bike for one thing, technical single track. 1st, 2nd, 3rd gear stuff.
I love the bike! It's sweet! I own other bikes but this one seems to be the best suited for the task at hand (single track).
One problem, I can't seem to get it jetted perfectly. I'm at 6'000 ft. I keep leaning and leaning the mixture and it still seems to run rich. The plug is black-ish.
My carb settings are 145 MJ, 40 Pilot, Jd Jetting "red" needle on the top clip, air screw 4 turns out. I runs ok like this but I know it can be better.
Any thoughts? Thanks.
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Post by canyncarvr »

Rule of thumb on an OEM carb..if you're more than two turns out on the air screw, you're too rich on the pilot. Not saying that's true in your case...but I've been running a 38 pilot over the summer..15-4000' or so...that high side seldom.

I wouldn't bother messing with jetting on a brand new top end. Let the rings/piston seat before you worry about it too much. That's not a long process....

Plug color isn't particular significant, jetting-wise. Consider how many carb circuits there are. all overlapping...hard to say what circuit is doing what without a plug chop for that particular throttle opening.

Needle clip postions are numbered from the blunt end, #1 on the end.



**edit**

Yeah...I don't see where empty boxes with red 'X's in 'em due to complete removal of the gallery are going to be any problem, either. :roll:
______________________________________________

Define 'top clip' with the actual clip position number.

I'd doubt that a needle from JD would very often end up on either end.


Stock cylinder/head?

Air filter oiling procedure is.....what?


Don't base 'runs rich' on that plug color. Performance is a better indicator. Given a carb that's 1/2 fast close to pretty good jetting-wise (notwithstanding other mechanical anomalies) you can feel the difference between 'good' and 'not' within a 1-2 jet size change with your backside.

You're familiar with KIPS dis/assembly/timing? You know that's all good?

What plug do you use?
Last edited by canyncarvr on 01:06 pm Nov 11 2009, edited 1 time in total.

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Post by KDX4ID »

Current situation; 38 pilot three turns out, 142 main, JD Red Needle on # 2. It idles with the idle screw almost all the way in. 50 degrees @6k'
Bottom end feels good (nothing like my KTM300MXC), but it's a 220 and I'm 215 lbs. And I think it's geared real tall.
Top end still feels like it hitting the rev limiter. Shift and it's all good.
It has the stock cylinder and head.
Air filter procedure is approximately 5-6 oz. Maxima completely massaged throughout the foam (as I've done for 20 years).
Plug is a NGK BES.
I'm not familiar with the KIPS timing. I put everything back together as I took it a part.
The top end has 80 miles on it and I agree about the plug reading.
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Post by canyncarvr »

An NGK-WHAT-? That's the question. For all I know, someone put a 9 in it.

If three turns out is where the best throttle response is (as in a throttle response test for the air screw setting), your pilot is likely too big by at least one size.

There is no rev limiter.

Take a read through THIS, check your KIPS to make sure it's in working order. Putting it back together as it was doesn't mean it worked to start with.

What is the final drive gearing btw?

If I had 5-6 oz. of oil on my filter, my bike would be running rich too...no matter what jets I had in the carb. If I'd been doing it that way for 20 years, my bike would've been running rich for all 20 of 'em.


A carb works on pressure differentials. It's not the air going through the carb that sucks fuel out of the carb bowl. It's ambient air pressure that pushes the fuel into the reduced-pressure air stream in the carb. With a restricted intake, the pressure differential increases..more fuel is moved through the jetted circuits...whatever size they are.

80 miles is way past break-in time. If the rings/piston aren't seated by now, they never will be.



My thoughts:

Verify the KIPS operation as noted in the above link.

Put an '8' plug in your bike if that's not what's in there.

Put in a 38 pilot, re-adjust the air screw for best throttle response...which should improve.

I'd certainly use a good 1/3 less oil on that filter too (assuming you don't apply that 5-6 oz. and then squeeze most of it out). Nothing at all wrong with a very well oiled filter...but the bike breathes air..and it does need to be able to GET some.

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Post by KarlP »

I think I'd try a 140 MJ at clip #3.........

Fresh plug?

It sounds like you are almost there, just not quite on the main yet
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Post by KDX4ID »

NGKB8ES and it's new.

Gearing is 13-47. I think I'll go to 50 rear.

I'll cut down on the air filter oil. I do squeeze it out.

Read read the KIPS link (thanks) and I think it's working correctly.

With the 38 pilot it now idles, 2 turns out on the screw.

I rode it yesterday and it runs great on the top end. Powerful and clean.

It still feels weak off-idle. When starting from a dead stop on an up-hill it requires a lot of clutch work. Is this normal? My other bike is a KTM 300 torque monster.
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Post by canyncarvr »

'8' is great.

The squeezing part is an altogether different situation. Reading, '..Air filter procedure is approximately 5-6 oz....' had me wondering if that's what you rubbed in and left there. THAT would be excessive.


You've mentioned the 300 a couple of times. This ain't that.


If you're interested in a 13-50 you can try a 12T CSS with the 47. That will: Get you in the same ratio area, save you time and $$ over putting on a 50T, enable you to change back in a couple minutes if you don't like it.


Sorry..can't tell you what 'normal' is..largely because I don't know what 'uphill' and a 'lot' of clutch means.

On hills that compression (dead engine) won't hold you, locked brakes barely hold you, a kick start attempt that doesn't start the bike (so it slips backwards a few inches) followed by a brake grab to keep you from falling off the edge of the earth..and THAT results in the front end coming off the ground far enough that you have to kiss your front fender to keep the bike from dumping you on your fanny.........

...if that is what 'uphill' means, then, yes. A good bit of clutch is probably going to be required.

Back to throttle response on the air screw.......or, HOW are you determining that '2 turns' setting?

A too-rich main jet WILL effect idle AND bottom end off-idle response.

Re: ' It idles with the idle screw almost all the way in.'

That's problematic. Unless the idle screw is smushed from turning it in when the slide is down (or any other reason), there is still a jetting situation (everything else mechanically sound) that isn't right.


:hmm: A '97...with what for reeds?


There is no comparison between the 220 and the 300. Looking at the 220 askance because it doesn't run like the 300 is a waste of your time.

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Post by KarlP »

Current situation; 38 pilot three turns out, 142 main, JD Red Needle on # 2. It idles with the idle screw almost all the way in. 50 degrees @6k'
Bottom end feels good (nothing like my KTM300MXC), but it's a 220 and I'm 215 lbs. And I think it's geared real tall.
Top end still feels like it hitting the rev limiter. Shift and it's all good.

What happened between the above and this:

With the 38 pilot it now idles, 2 turns out on the screw.

I rode it yesterday and it runs great on the top end. Powerful and clean


13/47 is pretty good gearing for that motor. I've been tempted to go the other way, in fact, to 13/45 maybe. 'course, I am a flatlander.

I rode a buddies clapped out '99 300 yesterday. My RBD modified, carefully tuned, running like a champ KDX 220 motor is no match for that 300. Thank god for clutch levers, eh?
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Post by canyncarvr »

Re: 'is no match for that 300.'

Which way is that meant?

Re: 'What happened between the above and this...'

I wondered 'bout that...and the 'top clip' '..#2 clip' too.

Generally..it's helpful to have a 'line' of actions and their sequence of occurence to be able to somewhat judge what's going on.


Oh..classic KIPS failure symptoms is poor bottom end. I did read the 'I think' part of that...but..I don't know what it means. Spoken with confidence and clarity, 'Yea and verily it doth work magnificently!'...is that what 'I think' means? :wink:

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Post by KarlP »

Re: 'is no match for that 300.'

Which way is that meant?

Meaning that wore out and smoky 300 had MORE everywhere. Mine performed much better and is way more 'rideable'. I might be getting that bike off him, too.

A little more tuning and the OPs bike will be right, I think. Down a size on main, maybe, move the clip one spot down if the smaller main is too small. Anyway, I think he got what he wanted and left.
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Post by canyncarvr »

I think he got what he wanted and left.
Well now. I am affronted!

Why buy an old clapped out 300 when you can get a NEW one with a button!!??

...it's only money. Write'em a check....... Do your part for Economic Recovery. Sign the check 'Barry Muhommed Obamarama'.

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Post by KDX4ID »

Sorry about the lack of continuity. I'm trying to recall everything and work at the same time. Not so great at multi-tasking. Thanks for bearing with me.

In a nutshell, I'm getting close on the jetting. The reeds appear to be in good shape, no fray's or tears. I think they're stock.

I determined the air screw adjustment with the slot on top of the screw.

Two questions regarding the KIPS valve; what are the odds it's worn out given the age of the bike? Also is it adjustable similar to the KTM?

The 300 is a heckofa bike. But the KDX feels better on super tight-technical single track. I feels lighter too. The 300 can be a handful at times.




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Post by canyncarvr »

This thread got lost somewhere along the way.........

Question: 'HOW are you determining that '2 turns' setting?'

Response: 'I determined the air screw adjustment with the slot on top of the screw.'


I wasn't asking how you figured the screw was in fact '2 turns' out.


The question is, how are you coming to the conclusion that '2 turns' is the optimum setting?

Maybe you're adjusting to hi-idle. That won't work.

Maybe you're using the 'lean roll' method of adjustment. That's better.


So...what method do you use to determine that '2 turns' is correct?



Re: '...regarding the KIPS valve; what are the odds it's worn out given the age of the bike?

There isn't much to wear out. Break/fail? Yes, but not 'wear out'. There is 'packing' on the RH subport drum activating rod that will tend to leak over time but that's not a terrible thing.


Re: 'Also is it adjustable similar to the KTM?'

It can be 'adjusted' in a similar fashion..by changing the spring in the centrifigal assembly. It cannot be 'adjusted' in a similar fashion...using different springs provided by Kaw (no OEM red, green, yellow choices like punkins) and it is NOT a a quick change like punkins, either.

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