Affect of cutting slide?

[Marklx]

I've got a post over on the 2 stroke board that has evolved slightly into a technical thing. My question is, what does cutting the slide do? And how do different slide cutaways affect overall jetting, and which part of the powerband?

As a cut slide is letting in more air, my guess would be the bike will run leaner. Probably a good thing for my RM. I know the '01 RM's are doing it. What about the '02's?

Thanks,

Mark

 

[Jon Sosa]

Mark,

It leans the low-mid jetting. Something that seems to be synomonus with RM's. I had to it to my '98 also.

js

bike for sale
98 RM 250

 

[Marklx]

Affects low/mid. That sounds about right. None of my jetting changes seem to affect the burbling, good or bad. That's what got me thinking that it may not be just the jets.

So what is involved in cutting the slide. Where, how much, etc etc? Just a parallel swipe across the taper on the bottom? I've got friends with machine shops, but I'd need to know exactly how to approach this. Figure a new slide isn't cheap if I blow it, but may be worth the experiment.

Mark

 

[Jon Sosa]

When Eric did mine <Note: I was to chicken to attempt it myself!:eek: $70.00 was and still is alot of money!> It isn't a complete swipe of the bottom of the slide. Kinda like you said, it's parrallel along the bottom of the slide. just the filter <intake?> side of the slide gets cut. I know from talking with Eric, you can do it with a Dremal. It is best to let him or Rich explain the procedure. If it was me, I would call or e-mail him. Better to that then lose $70.00 bucks.

js

bike for sale.
98 RM 250

 

[Marklx]

Thanks Jon,

I've got a dremel and I'm not afraid to use it :scream:

If Eric doesn't spot this thread, I'll give him an email or call and get his take on it. The '02 has been out a few months now, so hopefully some tuners are getting a handle on making it run clean.

Mark

 

[spanky250]

Cutting the slide is easy. Take the needle out, and stand tghe slide up straight on a flat surface. You will see that there is an oval "cuttout" on one side, and the other side will touch flat to the table. What you want to do is to make this cuttout taller, but not wider. Take a permanent marker, and mark a line across the surface above the cuttout where you are going to cut. Now, take a caliper and lightly scratch the surface at the amount you wish to remove, and trace this line from corner to corner of the cuttout, tapering it at the ends to meet at the same corner that exists now. Grind this portion out, then sand the edge clean of burrs.

I can't tell you how much you might need to take off for your bike, but 1mm was perfect for mine.

If you screw it up, or you don't want to attempt it, you can buy leaner slides, but they are pricey. The dealer wanted $90 for one for my bike.

 

[EricGorr]

Spanky's got a good point, a rat-tail file and little TLC are the first thing I'd try before spending $70-90 for a new slide. Heck, 3/4 of that price is just the product liability insurance from people who've sued for stuck throttles.
One note, the amount you need to take off the slide cutaway may need to be 1-3mm depending on your jetting situation. Perrsonally I like a real crisp response from 1/4-1/2 throttle and the slide means so much in that range. If you're confident with your filing and polishing skills, do it a little at a time until it feels right. Some guys like the jetting a little rich down low so its not so crisp and explosive. I think the main reason why Suzuki traditionally uses a rich slide is because they don't want the bike to snap so quickly.
Good luck and let us know how it worked for you, Eric

 

[Marklx]

This sounds great. I'll get some clean dremel bits, and take a look.

Question about how the cutaway should taper go. Spanky250 indicates that the cutout should be tapered off to the corners/bottom of the cutaway. So, don't take an even 1mm off? If it tapers, how quickly should it taper back to the original corners? Should it be a french curve kind of taper, or 1mm all the way to the corner with a quick taper? While I've had the slide off numerous times, I've never looked at the exact shape of the taper, and couldn't find a good picture on the internet. Before and after pictures would be priceless.

And should I hold off on this until I try my new needles, which arrive today? Sounds like the slide will have an impact regardless of what I do here.

Mark

 

[spanky250]

You don't remove a full 1mm from the entire cuttout. You want to make a smooth taper from where you start turning down all the way to the existing corner. you are making a new radius from the same center point, basically.

I would try it before replacing the needle. You may still need a different needle, though, because you are targeting differewnt areas of the throttle. The slide has the most effect from closed throttle to 1/4 throttle, where the needle starts at 1/4 throttle. The slide has some effect up to about half throttle, but it diminishes rapidly past the 1/4 throttle point.

This is the only thing that cleaned up the low-end on my bike. I could not make it run clean down low even with the smallest pilot jet made for my carb, and with leaner needles in the top clip position. With the leaner slide, I was able to go up two sizes on the pilot from the smallest and still have clean, crisp response.

 

[Marklx]

Originally posted by spanky250
you are making a new radius from the same center point, basically.
.

Spanky250,

That is a perfect description. It's what I thought you meant, but wasn't quite sure. Someone had said you do an even cut all the way, so I was confused. But looking at a picture of a slide I finally found, what you are saying seems very doable. I caught Eric on his car phone, and he said about the same thing. If I cut an even 1 mm all the way across, it will idle high, which I don't want.

Since the needles are paid for, I'll try them before hacking, but looks like I'm going to need to leave work early today for some tinkering. I can't wait to get the bike running right. Funny thing is, on the track, I don't notice the burble at all. I'm either on the gas hard, or off (more often off). But it drives me nuts when I'm putting around. My hunch is the bike will accelerate better on the track once this is taken care of, even if my ear doesn't hear it.

Mark

 

[Vytas]

Thanks for posting this question Mark. Now I also know where to slice and dice the slide, sort of. Fortunately I have an old carb that I can practice on. Eric if you read this I am going to bring my slide to the seminar so that I can get some specifics. Thanks to all.

 

[Marklx]

Glad to hit on a subject that brings some interest. This apparently has more people curious than I thought. I'll be doing the deal today/tonight, and will take some digi pics before and after. If the bike runs right, I'll post them. If it doesn't run, well, the spending is never ending.....:(

Mark

 

[Vytas]

I know how the spending issue feels. The wife is complaining that she doesn't bust her butt at work to support the bikes. But in actuality she does. I have four bikes to maintain. Already spent $500 in the last month on springs, porting and additional part. Not finished yet. Have to tell the wie to work more. I need an enclosed trailer.

2001 RM250
2000 KX65
1999 JR50
1997 CR80

 

[Marklx]

rotflmao!!!

If my wife worked, the $ would go nowhere near my garage. Does she wash 'em too? I'm already around $600 out this year....just bought asterisk braces and blew the budget, but I love them anyways. And I've been eyeing some toyhaulers too. Yikes.

mg

 

[RM_guy]

So what about the back side of the cutout? I understand the intake side of the cutout but do you remove any material from the other side of the cutout (at the bottom of the slide)?

I attached a picture with a crude line drawn on where I have the question about. Keep in mind I failed coloring on kindergarten :silly:

 

[Marklx]

After taking my slide out last night, I've got a similar question to RM_Guy. Only I didn't think to attach a photo.

Referring to RMguys photo, where he drew the line on the airboot side is where I think the cut should be, but do you take an even parallel amount off all the way to the intake manifold side? I understand that you radius the cut from the same starting point side to side, but what about front to back. Is the 1mm cut parallel, or should it also taper down to the bottom front of the slide.

Different(clearer?) way to ask would be, if looking at the slide from the side with superman xray vision, does the 1mm cut parallel the existing cut, or taper down toward the front of the slide?

Thanks,

Mark

 

[RM_guy]

Chief emailed me some pictures of his modified slide and it looks like the cut is not parallel to the existing cut. It tapers as it goes toward the manifold. Also, there doesn’t appear to be any additional cuts past the flat part of the slide. Does this sound right?

Thanks Chief.

 

[Marklx]

Rm_guy/Chief,

I need those pictures. I'm ready to do this, and would love to see some actual shots. Please please. Please email them, if possible to Ridgebro@pacbell.net Oh, from everything I've read and heard, you don't want to touch the flat front part ofthe slide. That'll screw up idle etc.

Thanks a bunch,

Mark

 

[Vytas]

Post the pics of the modified slide if possible. Thanks.

 

[RM_guy]

The pictures are too blurry to post. I tried to clean them up but they didn't come out very good. I asked Chief to retake a couple and send them to me. I won't beable to post anything until Monday though.

 

[desert_racer]

Well hurry up I wanna see too.... j/k :) :)

 

[acutemp]

Left-#5 slide cut to #7. Right-unmodified #6--Dan

 

[Marklx]

Maybe I'm blind, but I honestly don't see the cut on the left side slide. Or they used something from a machine, or they have an incredibly steady hand. Help me see the way.:confused:

Mark

 

[Jon Sosa]

Mark if you look real close at the hump part, you will it tapers back further. You are right, they had a really steady hand.

js

 

[Keith M]

Great thread! I think I got it :confused: after seeing the picture of the slide and the cut out I like it! man I hate reading stuff and not being able to to get it!