Uncorking XR 600

Yah, I know.

Dead horse. Big stick. Healthy beating. yadda, yadda, yadda.

I've just spent over an hour searching several posts from the last couple of years about what to do to properly uncork the XR 600.

Most are pretty similar, but there is enough variation (maybe due to altitude and temperature?) between all the posts that there doesn't seem to be a single no-fail, for sure answer on what the best jetting is.

I know that my bike is absolutely bone stock.

I'm gonna put a Yosh full system on it in the next week or so, and I plan on evaluating the entire intake/exhaust tract.

Never gotten inside the carb before, so I really don't know for sure what kind of jetting it currently has, but I will probably run a 68 pilot and 155 main, needle in either the 3rd or 4th position.

We'll see how this works out. I intend to start messing with it in a few days, so I'll be resurrecting this thread from the dead on a regular basis as I have time to work on it.

Does a 68pj and a 155mj sound about right for SoCal?

There is a plastic restricter piece that goes in the airbox inlet. If your bike it truly stock it will be there. I really doubt it is there as I have never seen one installed.

With an aftermarket system you may need a 158 or even a 160 mj. The only way to know is to try them out. You can change the main jet and needle position without removing the carb.

Check your choke plate. The little flapper is know to fatigue off and get sucked into the engine.

I just came back from Chaparral's parts counter, and the guy there was really helpful with supplying whatever info he could.

Looks like the stock set-up is supposed to be a 62pj and 152mj. I'll crack open the carb and see what it's got first, though I suspect that's what I'll find.

cleonard, my air box has the snorkel in place, held on by two rivets. Like I suspected, totally stock. Thanks for the heads up on the choke plate, I read about that while I was researching my mods, I guess SRC sells a modified plate (or is it XR's Only?). How common is this problem, has anybody here lunched their mill due to this?

This upcoming week's going to be super busy for me, but I'm gonna try to find the time to uncork, pipe, and jet.

.... must learn the way of the pig..........

When I took a look at mine, the flapper was hanging by a thread. I don't think it would have lasted one more ride. Not only was the little flapper shot there was a crack that went about half way through the rest of the choke plate. There have been several reports of damage on this forum.

I totally removed the choke from my carb. I thought that it was going to be hard to cold start, but with the 68 pilot is has not been bad at all. If it is below 55 or so I have to lay the bike over so it floods a little bit. I have started it down to a chilly 30 this way. I have an aftermarket choke plate, but the bike has been easy enough to start so I have not installed it.

I finally found a couple of spare hours where I could start workin' on my bike.

Found something really weird that I just cannot explain. There was a 125 main jet in it. Not a 152, which is what the stock main jet should be, and no, I am not dyslexic. It definitely reads "125". I don't get it. :thumbsup:

Anyway, I've got a question for you folks about the "uncorking" procedure.

I drilled out the two rivets and removed the restrictor from the top of the air box. Is that all that needs to be done to the box? Should I run it without the side cover that gains access to the filter (left side of bike), or would that be too much air getting in?

Should I cut a hole on the opposite side of the air box (right side of bike) and rivet some screen to it?

I know that removing the snorkel from the top of the box really opened it up, but I just want to know if that's sufficient.

I put the Yosh full system on and installed a 68 pilot and a 160 main.

It started up pretty easilly and maintained an even steady idle and revved up briskly without stumbling or back firing. Seems to return right to idle without hanging up.

So far jetting seems okay, but I haven't ridden it yet. Hopefully in the next day or two.

I would have included a photo or two, but my wife is in San Diego for the day with our digital camera.

Socal can be from below sea level at Ocotillo to 7000' at Kennedy Meadows. 2500' to 3500' in the high dez. A 68 and 160 will work great from sea level to 3500' or so but would be way rich at anything higher. About 2 turns out or more on the mixture screw is good, less for higher.

I would stay at 3rd clip on the needle. You don't need to open up the sides of the airbox as long as the snorkel is removed.

All the stock oem snorkels that I have removed were just pull out not riveted on. I have had two XR600r's a 96 and 97. Got a pic of the riveted snorkel??

I've got a question for those who have removed the breather hose and container that mounts to the frame on the 600R.

Once the octopus is off, do you guys attach a vent filter directly to the vent on the engine, or do you run some 1/2" hose up under the seat and mount a filter there?

Ever had problems with oil puking out of the hose/filter (after a fall, for instance) since the catch bottle is no longer attached, or do you guys add a catch bottle? I'm just going to cap off the vent return hose to the airbox, but the crankcase vent obviously has to be functional. The hose coming off the carb that tied into the catch bottle should just be a vent line that can be opened to the atmosphere, right?

here are a couple of photos showing what I'm talking about.

Open vent on crankcase and front of airbox.


Octopus (catch bottle with associated hoses).


Hey Redlines, here's a pic of the snorkel/restrictor that I removed from the top of the airbox. Notice the holes on either side where I drilled out the rivets that were holding it in place.


Was just checking out xrmanu's thread on his ultramotard project and I'm gonna borrow his idea.

Here's how he did his on his 650R, so I'll rig up something similar on my 600.


on my 650L i ran a tube up to the top, just under the front of the seat. using a small (crankcase vent filter) K&N filter. no problems at all. also it is unnoticeable.


its not in this pic., but if you can imagine, its mounted just to the right of the upper shock mount. viewed from the top, looking forward.

Hey sploogemonkey what year is your XR 600R a 2000 since the frame is silver? I have never seen one riveted on before so maybe its a CA model extra smog deal to be able to meet green sticker requirements that year because I don't have the octopus/charcoal canister that you have and the XRL 650's have or the rivited snorkel. I have a 98 XR600R which I am pretty sure was bought new in CA and a 97 XR600R that I bought new in CO and neither one have the canister or the rivited snorkel, both had the pull out snorkel and no canister.

Below is a link to the snorkels that just pull out of the top of the airbox that I have always yanked and thronw away, you rarely see them. I couldn't figure out how to post a pic in the thread, so click the link below to view it. If you have a 2000 XR600R with the red tank and oem silver frame paint I think those looks sweet.


I took my 600R out for some extended riding and tuning today, and I think I may try a 165 main. Seems to be running a bit lean at WFO. Otherwise, it seems to be running pretty well.

Now for the results..... Daaammmmmnnn! I thought uncorking, jetting, and putting a full exhaust system would give me a liitle more power here and there and be most noticeable on top end, but I've got loads more power throughout the RPM range, everywhere.

This set of mods definitely woke my bike up.

Here's a shot I took today.


I just got done rejetting my 97 XR600R this weekend. I have a Pro Circuit T-4 slip on, airbox uncorked, UNI filter. Per Scott Summers rec I just added #68 slow jet and #155 main, pilot 2.5 turns out. I didnt think it was running too lean before jet change, but what a difference the change made. Bike starts easier, sounds, and smells, better. And is a wheelie machine to boot. Almost scary-fast now.

I read somewhere that '98 and later 600R's came with a restricted intake manifold much like 650R's do. If that's the case and it's (the restriction) still there you've got more power still waiting to be had....Sweet yoshi!

Already did the intake manifold. I think that probably a bit too.

I have a 2000 cali model 600R I bought a couple of months ago.  Low hours 100% stock.  My airbox snorkel was riveted. Removed it. Removed the crank case canister and routed directly to the air box.  Installed Summers jetting, 68 pilot and 155 main. 49 state needle 3rd position.  Part numbers for the needle are different between the Cali to 49 state model.  Installed 49 state insulator boot.  On the cali model the orifice on the insulator boot is about 1/2 the size of the 49 state model.  Changing it really opens up carb flow.  Still have stock pipe.   When I first rode the 600 I thought it had a little more torque and was a little faster than my 400. Was nice but not all that impressive.  After the changes the bike now has a lot more torque and speed everywhere.  It's almost intimidating.  Amazing difference with these changes. Was thinking about aftermarket pipe - now I'm not sure but don't feel any urgency. 

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