Affect of cutting slide?

[RM_guy]

Thanks Joe. I'll have to play with it once it warms up and I get riding more.

I think it was a mistake riding the other day. Now I'm all pumped up with no place to go:whiner:

 

[whyz]

I,m Lost.

Why would you adjust the choke? Is there symptoms that would make a person adjust it. I just thought you pull it up and push it down. Never knew you could adjust it.Does it give ya more fuel or air? Or coincides with something?:think
Thank You.

 

[Mr. Clean]

MARKLX, I do not have a digital camera so pictures are not an option. This mod does the exact same thing as the cut away mod ,you just remove material from the opposite side; let me explain. Remove the carb. with the slide installed. Look in the venturi from the reed side paying attention to the spot where the needle enters it's holder. Now look from the air filter side. Next, lift the slide to about 1/4 quarter throttle. Look at the area where the cutaway is and you will see an object like a tube rising from the bottom. With the slide removed and looking down at it you will notice it looks similar to the letter C. It rises about a 1/4 inch I guess. The air must pass between the cutaway and this tube. Instead of relieving the cutaway to achieve slow air speeds just remove material from the tube! I started at the top corners and ground the 90 degree corners to 45 degree corners. I removed about 3 millimeters in total. Bear in mind this mod is more sensitive to material removal than the cut away is. Remove a little at first so you will get an idea how much change you get with each attempt. If you mess it up, the carb. must be replaced. Don't get in a hurry and you will do fine.Please remember dropping the needle does not lean this area of the throttle. Repeat this procedure to me in your own words so we can correct any misunderstandings before you start. I hope this helps.

Your ridin' bud Kurt

 

[Chief]

whyz,

My bike has the Keihin pwk carb. The choke knob has 6 clicks to 1 full turn. (360 degrees).

Just quoting the manual. Baseline setting is 12 clicks (2 full turns) out from a full close. recommended settings are from full close to 12 clicks(2 full turns) out, w/24 clicks (4 turns out) max. The choke (bypasss knob) has a big effect on air/fuel mixture at throttle positions fully closed to 1/4 open, then drops sharply to no effect at 3/8 throttle.


As the knob is turned out, the mixture becomes leaner, More air is allowed to enter the mixture as the choke needle is raised. This adjustment only affects the choke needle when the knob is pushed into the down (already warmed up) position. It has little or no effect when the knob is pulled up.

When my bike sputters at low throttle openings, it tends to knock. I have had good results adjusting the bypass knob to reduce the sputter and knock.

It seems ironic that pulling the knob up richens the mixture, yet raising the needle on the same assembly leans it out. There is a collar on the needle assembly that I am guessing works by letting more fuel in when the knob is pulled up.

Joe Chief

 

[whyz]

Hmmmm... So is it like another aid in jetting? :think
And are these choke adjustments on all carbs too?
I think I understand.. Im gonna play with it tomorrow(just to tinker.)
Thank You for the Wisdom there Mr.Chief...:)

 

[NO HAND]

I have a Keihin PWK40 from a 98'KX500, and it doesn't do anything when I turn the choke knob. It doesn't even click or anything. It just spins around forever if I want to. Same thing with my Mikuni TMX36 from the 00'CR125. It's not broken because the choke function is working normaly. I guess only a few carbs have that adjustment on the choke knob.

 

[Chief]

old hat

MarkKLX and VYTAS,

I was wondering how you guys made out w/ the slide cut. Also anyone else that was intending on doing it.

Mark, I had the next fatter needle on hand, (not the half step one), I dropped that in before my first ride. I also used amoco 93 gas and mobil mx2t for the first time. The last 2 weekends have been in the low 60's and it runs really nice. I am surprised at how much difference these changes made. The amoco gas had been recommended several times by Eric, but I never had a can when I passed any stations. Now I really wouldn't want to run without it, and have been keeping stocked up.

It was also the 1st time my air screw adj. made any difference. The real test is when the summer heats up to 80's & 90's. It seems like everyones' bike runs perfect here this time of year.

Hope Everyone is Having Fun!!!

Joe Chief

 

[Marklx]

Chief,

Ended up not doing the slide yet,as I've had a different weird problem that I'm trying to sort thru. It's a thread called something like 2 stroke backfiring. Just today, drained my old gas, got a new batch of 100 octance Unocal (best we've got around here), and mixed it up at 40:1 with Yamalube. Unfortunately, too many neighbors out today and couldn't fire it up. Until I cure the little backfire bah bing thing, I'm not touching anything else.

Curious what clip you're on with the newer needle. Did you effectively lean our or richen the needle setting with the new one. As cutting the slide is leaning things out, wondering if that's what I need now. My goal was to slightly lean it out, but don't think it was the answer. Now thinking I'm 180 deg off and need to richen it down lower. As you stated in an earlier post, it seems when sputtering at low rpm's that it's knocking.

So confusing, but certainly an entertaining challenge. Truth is, the bike runs really well, but I want it perfect.
mg

 

[Vytas]

Chief and MarkKLX,
I did the slide mod and it looked great! Polished the cut area very well and it looked like nothing had ever been done to it. Tried to but some race fuel three weeks ago, but the shop was out. Two weeks ago we had eight inches of snow and this last weekend was frigid with high winds. So, the bike still sits in the heated gararge with no fuel and no where to ride. I will let you guys know how it runs once I finally get it started. Later. Vytas

 

[RM_guy]

The slide cut on mine work real good. It was much crisper off idle. Of course that was riding around my yard so next week I'll give a better report.

 

[Chief]

Good to hear from You Guys,

Mark, I put the clip one up from center on the new needle. This has been a warmer weather setting I've used w/ the original needle as well. I've been able to avoid the colder days and ride at least 40-50 degree days, even up to 60.

Clip position has more effect throughout throttle position range, whereas needle diameter has effect on closed to 3\8 open throttle. I have leaned out lower throttle settings by installing a fatter needle. This has a less dramatic effect than installing a smaller pilot, sort of a fine tuner, but it effects more up to 3/8 opening. The pilot jet affects up to 1/4 throttle, then abruplty drops to nothing.

This is all bench racing, hard to put into words what the bike feels like, I can tell you I like the difference. My own goal has been to achieve a smooth, somewhat more linear power delivery with a very useable low end. I encounter a lot of very tight windy rocky hilly terrain and this is what I like and need. I've ridden bikes like mine that really explode, I'm sure they are faster on a straight line and most tracks, but my bike is still plenty fast for my own abilities and riding conditions.

My experience is it will knock when too rich, but go too lean and it detonates quickly. If everything else is on, the air screw will fine tune it enough to smooth it out perfectly.

Sorry to hear you are having other problems. These guys will surely get you through it.

Vytas,

Hope you get to ride soon. Doh!!! stupid winter!!

RM guy is probably gonna kick my butt next week at Paragon, the best I can hope for is trails so tight he'll get tired just hanging on. I can always hope, right? :cool:

DRN: the next best thing to being there.

Joe Chief

 

[Vytas]

The Time has finally arrived!!
Both fuel and rode the bike this weekend. FREAKIN' AWESOME!!!!
MODS:
1.) New springs front and rear.
2.) Eric Gorr "Mo-Better" porting
3.) V-Force Reeds
4.) Cutting slide.
5.) Needle 2nd groove down, leaner pilot and main.
Running TORCO Mach 110 with TORCO GP-7, 32:1.
Guys I wish that I could have evaluated each of the mods separately but instead I did everything at once and rode. Throttle response is very crisp. The bike pulls from down low and the power delivery is smooth across the band. I did not experience the dramatic mid-range hit of last year from the motor. It starts to pull and the power just keep on coming. I rode for about two hours yesterday in 40 degree temps and had a small dribble of spooge coming out of the silencer. For those out there that have a '01 RM250 I would definately recommend the EG porting. I know that the reed may have helped some but not as much as the porting. After spending many hours on the bike last year, it rides like a totally new bike - a much better bike. For $100 the porting is well worth every penny. Yellow Screamer is back. Talk to ya' later. Vytas:cool:

 

[Marklx]

So I've held off cutting the slide, waiting for time to ride, change of oil/gas and at long last, my Bill's pipe. Running their jetting from the site, the bike runs perfectly. No spooge, no hesitation, just lots of revs, low end bark and predictable acceleration. So at least for '02 RM owners willing to buy a new toy, the pipe did wonders.

mg

 

[reynome]

I was having some jetting problems in the area that the slide cut should have helped. Unfortunately it turned out to be a powervalve adjustment problem instead. I allready cut my slide 1mm. It tunred out real good but I dont think that it was necessary. Does anyone want to trade my stock but modified Kehin 2000 cr250 slide #7 for a uncut one? I can post pics of my work on it if needed.

thanks

 

[Vytas]

Ran the bike is my first race in 21 years last Saturday. The track was very loamy and required lots of low end. Conditions were partly cloudy and around 50 degrees. The bike ran great. Abundant power whenever it was needed. Maybe too much, halfway down the start I pulled wheelies in fourth gear. Best part is that after practice and 2 motos absolutely NO SPOOGE!!!!!

 

[Chief]

I also noticed the spooge dissapeared. I had to switch to a full synthetic. Now I'm back to 32:1 and it burns nice and clean.

 

[whyz]

Just one ??

In my manual it has 3 slides
5.5=Rich
5.75=stock How many mm (from stock)is it different from the rich one and the Lean one?
6.0=Lean

I just want to experiment and cut it or just buy a new one.
$102.00 :think: Ahhhh...nah i'll cut it..
Theres alittle richness down there that i'd like to get rid of.
Thanks...

 

[Chief]

Educated guess, stock would be cut .25mm deeper than rich and .25mm shallower than the lean slide. (Not a whole lot of cut). I'm pretty sure some folks have cut between 1 and 3 mm from the stock slide, but maybe .25 is a good starting point. you just might have to be a little patient if you go .25 at a time before you get results. If this is what the manual says, then maybe it's all you need for your bike. Better to cut too little than too much. Also, remember you'll probably want to use the same slide if your temps get colder so a little burble when it's in the 90's might be worth putting up with. Mine burbles at low rpms, but it's still a lot smoother than it was before. (cut 1mm and sqishband widened on the head) I'm happy with it. If you follow what's on this post as far as cutting, you should get a good idea of what you have to do.

Happy Riding,

Chief

 

[whyz]

What i'm looking for is

Right off off slowing down i'd like it to respond better(faster) without clutchin all the time. It hits alot while the revs are up(one twist and your gone but i want it down low)
Its hard to explain..When i'm riding slow and twist it WFO really fast theres that spot that id like to get rid of.
I tried a leaner PJ,richer needle/leaner needle,, AS adjustment everywhere.
Maybe i'm just finicky,Maybe i need a bigger bike :scream:
Thanks Chief

 

[Chief]

Your'e 6 years older than me, I bet I'm topping out at about 200 lbs right now, and the 250 has MORE than enough power for me. I jet it rich down low just to mellow it out for low end. (I don't ride mxtracks, but I do ride some very fast pole lines, railroad beds etc. but also a lot of tight rocky stuff. I need the slow boggy grunt for those spots.) I say go for the slide, enjoy the light bike, and if you still don't get what you want, trade up to a 250. A lot of people including myself never got the results they were looking for until they went with a leaner slide. No such thing as too finicky when it comes to your ride. You gotta be happy. From what you are saying, the leaner slide could be the ticket.

It seems to me that the 125's are the screamers. I often envy those guys being able to rev it to kingdom come. The guys with the 250's have less clutchwork, and an easier ride, I ride with all the 250's we all seem to do 50 percent grunting around, can't always open it up the way I'd like to. I guess it's a tradeoff depending on what's important to you. Maybe try to catch a ride on a few 250's and see if that's really what you want. They are more cumbersome weightwise. Try the slide, you have a lot to gain (possibly) and 102 dollars to lose. Just my opinion.

One more thing, a 125 by nature has a much narrower powerband than a 250.

Chief

 

[whyz]

Originally posted by Chief

One more thing, a 125 by nature has a much narrower powerband than a 250.

What does that mean :think: Do you mean (shorter)? or?
I'm by no means a good rider ,,im a rookie still learning how not to crash on 1/8 throttle :confused: I worked some OT last week and i think im going to buy the slide and see what it does.If it still not to my satisfaction i'll have a spare to practice on I guess (ouch > 102)
Now im confused.. I'm going to my room.
See ya Chief and Thanks again..
I should call EG. :eek: (lightbulb) duhh on me....

 

[Chief]

Whyz,

Sorry for not being more clear. What I meant was to cut the slide, not buy a new one. If you read all of this post, it will hopefully give you a good idea of how to cut it. If you get it right, it cost you nothing. If you screw it up, you end up spending money. Why spend the money first? You might not have to if you get the cut right.

I've owned 125's, so I know from experience, and Eric does also mention in the performance handbook that 125's have the useable power at the upper end of the rpm range whereas a 250 will have useable pull that begins lower in the rpm range. (gee, I'm going out on a limb here) That's why everyone talks about more clutch fanning, etc. on a 125. It's to keep the revs up in the power range as opposed to a 250 being able to grunt up tighter spots in the lower rpms.


I'm an out of shape veteran rider who just got back into riding last year after a 20 year layoff. At this point I consider myself an improved mediocre rider. No Pro by any means, just great to be out there and have fun.

BTW the performance handbook is worth the few bucks. Lot of experience and info.

Later,

Joe Chief

 

[00kawa125]

Where is the one person on this board who can definately answer the questions concerning the correct way to cut the slide? Eric Gorr, I am sure could clear up all questions. :eek:

Come on Eric, especially for a 99 Yz 125, which I am sure you know needs it.

 

[Chief]

With the pics that were posted here, you should get a good idea of what to do.

Eric is usually busy, and I think he's really busy lately, but if you call him you should get a hold of him. It may take a few tries to reach him, but he will give you a few minutes of his time, and give you a good idea of where to head in your particular situation.

I have a pic somewhere of my slide and where it was cut, if you want it I will post it. It's an easy cut, RM_GUY used a 3/8 rattail file and did a nice job. I think some guys use a dremmel, but that would make it easier to cut too deep too fast IMO. First you can measure and mark how deep you are gonna cut, then just cut down to the mark.

BTW eric cut mine when I sent the cylinder out for re-plating. I didn't do mine.

Chief

 

[maninuniform66100]

send the slids area picture highlight the area to cut ...if ya have time thanks mike in ca