Drill the slide?


26 replies to this topic
  • axarob44

Posted August 11, 2007 - 05:15 PM

#1

I installed the dyno-jet kit and I'm kind of luke warm on the results. I have all the usual mod's(exhaust, air etc.). I'm going to put a 55 pilot in when it gets here, but I'm up in the air as far as drilling the slide. I have read numerous threads about guys doing it with the DJ kit and liked the results. Then on the other hand Eddie from the jetting forum says not to drill with the DJ kit and then in a different thread says to go ahead and drill the slide. I am disappointed with the throttle response more than anything, that's why I'm changing the pilot and I think I'm gonna go ahead and drill the slide. What do you think

  • rhodesker

Posted August 11, 2007 - 05:34 PM

#2

i have a 07 650l, dyno jet kit worked just fine for me . 55 jet sounds good. drilled the slide and have no complaints. :ride:

  • Huffa 2

Posted August 11, 2007 - 05:47 PM

#3

I have the kit too, and like you just didn't seem to get that exciting results from it :excuseme:

Maybe I expect too much or others are better at feeling the gains but from the info I read, thought I'd feel a bit more of a kick.

I'm running a 160 main and did not do a plug chop test or fool with the needle so I must be fair and admit there may be more gains and hopefully with what you are doing too.

As far as drilling the slide, what spectrum of the RPM does that effect, what exactly is thast supposed to do ?

I'm in the air about that too.

  • axarob44

Posted August 11, 2007 - 05:54 PM

#4

Huffa, I guess I may have expected more also, I didnt see as much change as I had hoped for. I've been doing a bit of reading past threads and guys seem to like the Daves Mods better. But, I did notice one guy said White Bros. told him to change the pilot with the DJ kit. Seems guys that change the pilot to a 55 and drill the slide makes all the differnce. I let ya know when I swap the pilot and drill the slide

  • Rockjockey

Posted August 11, 2007 - 06:21 PM

#5

What is drilling the slide supposed to do? I have only changed the filter to a UNI, and removed the snorkle, rejetted with the XR's Only jets sent with the pipe and header ordered and could not be happier with the results compared to stock. Bike runs at 225 degrees max with a 60 pilot and a 170 main. All I can see that the drilling of the slide would accomplish is the throttle returning to idle quicker as it is cable/vacuum operated and the cable opens it and it is a spring return. Maybe I'm missing something though. How about an explaination Dave?

  • motomonte

Posted August 11, 2007 - 06:54 PM

#6

Drilling the slide lets more air pass thru the slide bottom, hence the quicker trhottel response.The DJ kit does this by using a softer spring letting the slide move quicker.I went with the Dave's mods and a 55/160 combo.To really get the results you'll need to get more air flowing into the engine .That's what removing the restrictor in top of the airbox (de-snorkeling) and installing an aftermarket filter do.This won't net huge HP gains but will make the bike snnapier.Thanks again to our friend Dave.

  • martinfan30

Posted August 11, 2007 - 10:01 PM

#7

well, i did the djet kit and drilled the slide. you will not get any more HP by doing this. i only noticed a very slight increase in throttle response. it cant hurt!

  • rmhrc630

Posted August 11, 2007 - 11:51 PM

#8

What is drilling the slide supposed to do? I have only changed the filter to a UNI, and removed the snorkle, rejetted with the XR's Only jets sent with the pipe and header ordered and could not be happier with the results compared to stock. Bike runs at 225 degrees max with a 60 pilot and a 170 main. All I can see that the drilling of the slide would accomplish is the throttle returning to idle quicker as it is cable/vacuum operated and the cable opens it and it is a spring return. Maybe I'm missing something though. How about an explaination Dave?


RJ

Drilling the slide as I know it related to the XR600s. The problem was massive sticky throttle odd idle - the bike would have a very very hard throttle pull off idle and so people started drilling the slide to ease the pressure on vacuum.

I think it also was a way to slow down the enormous cough stall that the XRs were famous for.

I've fitted a FCRMX to my XR so the thing goes like stink and never stalls anyway!!!

  • Huffa 2

Posted August 12, 2007 - 01:20 AM

#9

Huffa, I guess I may have expected more also, I didnt see as much change as I had hoped for. I've been doing a bit of reading past threads and guys seem to like the Daves Mods better. But, I did notice one guy said White Bros. told him to change the pilot with the DJ kit. Seems guys that change the pilot to a 55 and drill the slide makes all the differnce. I let ya know when I swap the pilot and drill the slide


Thanks buddy :thumbsup:

I don't think drilling will help much but thanks for doing so, and FOR SURE, let me know.

  • jetfuel

Posted August 12, 2007 - 06:20 AM

#10

Drilling the slide only improves throttle response ... it allows the slide to open more quickly and this combined with the softer slide return spring keeps the slide from going shut on hard lands and G outs causing the engine to stumble. I too was not satisfied with the weak improvement in performance after drilling and rejetting .. I guess it would be OK if you rode the street but for offroading it still wasn't responsive enough so I went with the edelbrock and it was the single best upgrade I did... those CV carbs just won't do on a dirt bike...

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  • Huffa 2

Posted August 12, 2007 - 06:44 AM

#11

Drilling the slide only improves throttle response ... it allows the slide to open more quickly and this combined with the softer slide return spring keeps the slide from going shut on hard lands and G outs causing the engine to stumble. I too was not satisfied with the weak improvement in performance after drilling and rejetting .. I guess it would be OK if you rode the street but for offroading it still wasn't responsive enough so I went with the edelbrock and it was the single best upgrade I did... those CV carbs just won't do on a dirt bike...


:excuseme: Why is it they put them on then ? Are they a lot cheaper to mass produce, can run leaner jetting for emissions or what ?

I guess each idividual may have slightly worse/better results with the DJ kit and daves mod, depending on how the bike ran in the 1st place and what their altitude is but for me it was just a ho-hum improvement, nothing to go ......... WOW!!! (so far anyway )

  • jetfuel

Posted August 12, 2007 - 07:45 AM

#12

CV carbs have been on street bikes forever ..My old '72 CB350 twin had them along with alot of others and worked just fine for that application.. But for better performance people got rid of them in favor of cable actuated round or flat slide carbs which were more tunable and more responsive. Are CV's cheaper to mass produce??:excuseme: probably . Only Honda knows why they chose it for our bikes. we just have to live with it or upgrade it. I got a whole new bike with my carb upgrade :thumbsup:

  • Huffa 2

Posted August 12, 2007 - 08:34 AM

#13

CV carbs have been on street bikes forever ..My old '72 CB350 twin had them along with alot of others and worked just fine for that application.. But for better performance people got rid of them in favor of cable actuated round or flat slide carbs which were more tunable and more responsive. Are CV's cheaper to mass produce??:excuseme: probably . Only Honda knows why they chose it for our bikes. we just have to live with it or upgrade it. I got a whole new bike with my carb upgrade :thumbsup:


Can you or did you at one time explain in detail how the performace is better?

Does it rev out farther, lift the front wheel easier, more torque down lower, get worse or better gas milage, etc,etc ......

I'm just curious, that's all.

  • axarob44

Posted August 12, 2007 - 08:44 AM

#14

If drilling the slide and changing the pilot don't improve the throttle response I think I'm going to look into getting either the 41mm flat slide of a pumper. I hate not being able to loft the front wheel over obstacles on the trail. I'm going to drill the slide when the 55 pilot gets here. If it doesn't work I'm just going to change over to "Dave's Mod's".

  • AaronBrown

Posted August 12, 2007 - 03:44 PM

#15

Does anyone have a pic of a drilled slide or a link to DIY? I have searched but I came up with nothing. I am pretty new here and haven't had a bike in over ten years so I am behind the curve a bit.

  • Huffa 2

Posted August 12, 2007 - 04:05 PM

#16

Does anyone have a pic of a drilled slide or a link to DIY? I have searched but I came up with nothing. I am pretty new here and haven't had a bike in over ten years so I am behind the curve a bit.


Whole carb mod including drilled slide .............

http://www.4strokes....xr650lcarbmods/

  • AaronBrown

Posted August 12, 2007 - 04:48 PM

#17

Thanks for the link :)

  • jetfuel

Posted August 12, 2007 - 09:31 PM

#18

Can you or did you at one time explain in detail how the performace is better?

Does it rev out farther, lift the front wheel easier, more torque down lower, get worse or better gas milage, etc,etc ......

I'm just curious, that's all.


The edelbrock is night and day better than stock.. but, some what of a compromise for tuning , If you adjust it for more low end you'll lose some top end and vice versa. Mine is setup for more low end snap.. I prefer being able to lift the front end easily over things as I do most riding on single track. The response is instantaneous, and very smooth. you lose a little gas mileage but thats often the price of better performance and it also depends on riding conditions and of course how much you whack the throttle and squirt the acc. pump.. its a very user friendly carb. the FCR is even more tunable but it won't compensate for elevation changes and floods the motor when layed over. after a tip over and picking up a 300 lbs. bike I really hate dealing with a flooded engine and/or a fouled plug and the edelbrock has eliminated this problem all together. The main reason for me upgrading was I would still occasionally have the stock carb cut out over rough landings or large bumps sending me up against the bars which just wasn't acceptable.. My FCR works perfectly on my WR .. but a few people have changed them out for an edelbrock simply for the above reasons. Do some searches and you'll find more info ... For my application the edelbrock was perfect... after all its not a race bike. its well ...a "Pig" not overly fast but will eat anything you throw at it. :thumbsup:

  • XR650L_Dave

Posted August 13, 2007 - 08:33 AM

#19

To weigh-in a bit-

Drilling the slide improves the throttle response. For me, the DJ kit was a big disappointment in the whack-it-open department.
Drilling the slide made it possible to loft the front at will in 1st and 2nd.

I don't do a lot of jumping, but I've never had the throttle 'shut off' or close or anything during a landing or a G-out.

I think the DJ spring lets the slide open more for a given steady-state throttle setting, but I don't think it makes it open much faster.

The CV carb is so it can be jetted leaner, and so people don't pull wheelies-loop out-sue Honda, and also a CV carb can be bigger without causing a bog. The XRL carb is bigger than the XR650R carb (in specs, anyway).

Drilling the slide will get you closer to non-CV carb throttle response, but not all the way.



Dave

  • jetfuel

Posted August 13, 2007 - 09:31 AM

#20

Thanks for the input Dave. I don't do monster jumps with mine either but sometimes with more harsh landings than normal (for me anyway) it would send me against the bars and I'm sure you know what thats like. Since changing out the carb its been totally eliminated. The mental confidence I've regained in the bike was well worth the price of the carb. I really like not having a choke anymore also. It does kind of spoil you though I couldn't figure out why the WR wouldn't light off the other day until I remembered ..the choke dummy..:bonk:





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