more xr600?

34 replies to this topic
  • litng1

Posted July 10, 2007 - 08:48 PM


When do you have to change the pilot jet?I keep going up with the main jet and it keeps running better 168 now.But what about pilot?It starts and runs great right now.
What about air box mods to a 93 600 what is this snorkel Ive read about.Can and does running a better Ignition box do anything?Thanks for any things guys.

  • Kawabuggy

Posted July 11, 2007 - 05:01 AM


You are running a 168MJ in the stock carb? And the bike runs well? Tell me more about your set-up. Are you running factory, or aftermarket exhaust? Header or just a slip on? Stock compression ratio? Stock cam? What type of air filter?

I am running a 158MJ right now, and will soon go up to a 160, but never thought about going as rich as you have gone. If the bike runs well there though, I may have to keep moving in that direction to see where power starts to taper off.

  • Kawabuggy

Posted July 11, 2007 - 07:17 AM


Forgot to ask, what pilot jet are you running right now? If you are stock, I believe it will be a 62.

I am currently running a 68S pilot jet and am very pleased with it! The bike is borderline explosive on acceleration.. 1st, 2nd, or 3rd you can loop it just by rolling on the throttle too quickly.

I think you will find that if you go up on the pilot jet, you may have a problem with it running too rich in the mid-range. I say this because there is a place where the MJ starts to come in, but the pilot is still contributing gas as well. During that transition it would make sense that it might be too rich-depending on what jets you have. This is ONLY a hypothesis though, and would need real world testing.

Since you inquired about the pilot-I would highly recommend going to the 68S. BUT----keep a smaller main jet on hand in case the larger pilot makes the bike slow down on the mid-range.

PLEASE PLEASE post your results with whatever changes you make and what your experiences are. Jetting on these bikes seems to change with every person you talk to-and each person has "the best set-up".

  • litng1

Posted July 11, 2007 - 09:21 AM


My mods are are a supertrapp slip on exhaust with a 98MM 11-1 piston and a KN filter.I run a stock PJ and a 168M and it runs very well and its the stock carb and stock cam etc..

  • Kawabuggy

Posted July 11, 2007 - 10:29 AM


Awesome! Are you experimenting with jetting as you are wanting MORE power?

You will note from reading on this web site that a lot of people go up on the pilot jet because it makes the bike easier to start-both when hot & cold! You won't regret increasing the pilot jet. Really makes the bike more enjoyable.

Have you removed the snorkel in the air box, or modified the side panels in any way? I would think that such a large increase in MJ would need additional air.. but what do I know.

The PJ controls low speed operation, up to 1/2 throttle or thereabouts. The MJ is for 1/3(?) on up to full throttle. That is the transition I was referring to earlier.

  • litng1

Posted July 12, 2007 - 08:54 AM


It felt like the bike was holding back so I started jetting up on the MJ I didnt know the pilot jet needed to be done to I will add a PJ what size do you suggest to try?Im guessing mine is stock but Im not sure is it easy to change out?
I havent touched the sidepanels yet and I dont know what the snorkel looks like.It might even be gone already.Is it in the air box?

  • martinfan30

Posted July 12, 2007 - 09:05 AM


the snorkel is a plastic restriction plate at the intake hole, top of air box. two rivets and it comes out.

  • litng1

Posted July 12, 2007 - 09:26 AM


I can take my seat off and see the air cleaner guess someone already did that then.Thanks

  • azmanxman

Posted July 12, 2007 - 10:42 AM


Perfect timing on this discussion guys, I've just got around to opening my carb up and finally getting a grasp of what goes on in there.

I'm in Tucson AZ so year round riding temperatures vary from 105 to the high 30's. Mostly it's warm or hot though. Altitude is around 3200 ft at my home but the rides around here go up to 6000-8000 ft on occassion.

Here's what I've got. Air box snorkel is gone, and I'm using a uni-filter. It's an aftermarket exhuast but I'm not sure what brand, can't find a manufacturers stamp on it anywhere. It's silver, and pretty dented up. Maybe I should think about a new one? Recommendations?? Stock headers.

Right now the carb has a 155 main and a 65 pilot. Airscrew is at 2.5 turns out. Needle is on the 3rd clip (stock). Stock carb.

I have a beast of a time starting this thing when cold. Once it's warm it's not a problem.

What do you think of this set-up?? Is it worth trying a 68 pilot? Sounds like this might help with starting?

As far as I know the motor is stock.

I would love to get a little more 'kick' out of it. It runs well but it certainly does not want to lift the front end in 3rd.

Your suggestions are very welcome.

  • martinfan30

Posted July 12, 2007 - 10:50 AM


68 pilot may help, but that seems pretty rich to me. on my 650L i use a 160main, 55 pilot (fcr 41 pumper). im sure you have the whole find tdc and kick thing down. exhaust, in my opinion get the complete kit from xr's only, stainless header and pipe. happy motorin!:thumbsup:

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  • Kawabuggy

Posted July 12, 2007 - 11:59 AM


If you go to a 68-you SHOULD get the 68 S... Please note the S at the end is different than a standard 68. I don't know how it will work in your machine, but in mine the 68S is absolutely perfect. Most of my time is spent on low speed operation-where the pilot is active-and my spark plug is a nice caramel color. Textbook example of what it is supposed to look like.

If you switch to an after-market air filter, I feel like they should be sold together-the jets and the air filter. Definitely go up to the 68S just to experiment. I am going up on my main jet just to see if the mid-range, and top end improve much/any.

  • HeadTrauma

Posted July 12, 2007 - 04:51 PM


I have full Yoshimura exhaust, stock PD carb, and a Unifilter with barely any airbox around it. IIRC, I have a 65/168 set in it right now and I forget where the clip is. I can only assume the rest of the engine is stock since the cases were split sometime before I got it. It starts easily with no choke, but pings when I get out of the primary jet. Maybe I need a smaller primary and larger main....:thumbsup:

  • litng1

Posted July 13, 2007 - 07:16 AM


So does the 68s say on it 68s or just 68?

  • litng1

Posted July 13, 2007 - 11:03 AM


My local shop didnt have a 68PJ so I had to order one.I did try going from a 168 main up to 175 main and the bike didnt pick up anything felt like it might have been little slower so Im back with the 168 now.My bike has a 62PJ in it now I guess thats stock.
Also in the carb does that little white plastic part in the fuel bowl around the main jet snap in place to hold it up while you put the bowl back on?Or is there a trick to getting it to stay as you put bowl back on?Thanks:confused:

  • HeadTrauma

Posted July 13, 2007 - 11:25 AM


Man, seven jet sizes is a lot to bite off in one try, almost 10%. I would have gone up to a 170 and maybe tried a 172 just for kicks, but a 175 is really big. Even 168 isn't that small.

I think that little plastic bell is there to prevent sloshing. I don't have one in my carb and it seems to work fine.

  • litng1

Posted July 13, 2007 - 11:48 AM


Yea I know it was a big jump but its the only one bigger I had so I tried hehe.Im going to try 170 when i get one.Thanks for the replys:ride:

  • DelTronXR

Posted July 13, 2007 - 12:07 PM


well it's a beautiful day in orange county, about 80 deg, and no surf, so i find myself on the computer, in hopes to find a answer to my problem. Mods on motor 0.020 bored over, xr's only exaust, k&n filter, opened up carb to see why the bike run's like crap, and this is what i found. main jet 165 and pilot is at 65, do's this sound right, or do i just need to fix air screw, or do i need to go with a different setup, just bought the bike 2 weeks ago and i can't ride it because it craps out on me..

  • litng1

Posted July 15, 2007 - 11:31 AM


Try going back to close to stock on jetting and see what that does first.Try 62PJ and a 155 or so Main jet.What do you mean by craps out on me?

  • DelTronXR

Posted July 15, 2007 - 12:12 PM


when i'm riding no more than a block, the bike sputters when i try to give it throttle. I have the entire carb sitting in carb cleaner right now, and i put a 158 main in, so hope this works.

  • Kawabuggy

Posted July 16, 2007 - 08:10 AM


I know it sounds simple.. but it has happened to me. Are you sure the choke is in the "off" position? The jetting you have sounds like it should have worked fine-unless something was plugged up inside the carb. I would clean it, then go back to the jetting that it had when you got it. Make sure choke lever is DOWN or in OFF position. Please post back with your results.

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