how much more power after uncorking?



13 replies to this topic
  • Bob_o

Posted May 10, 2003 - 09:16 AM

#1

I currently own a yz426 (the red crowd boos!!!) and am looking to switch to a xr650r (the red crowd cheers!!). I rode a 2001 xr650r today that was completly stock. I liked the better ability of this bike to chug along with the kids but was very surprized at the lack of power for a 650. What honest gains are acheived by doing the power up modifications? Will it lose its ability to chug along without stalling. My 426 is also bone stock, its faster than I would ever need (though I enjoy that) but isnt much good for the slow stuff. Thanks for any/all help or advise!

  • Fryboy

Posted May 10, 2003 - 09:58 AM

#2

Hi Bob,

You shoulda bought a WR426. You would be able to lug with anyone and then shred when ready.

I suggest you get a bigger fly wheel weight and perhaps go up 2-3 teeth in back sprocket. You could always go to WR timing and jetting which would mellow out the hit a bit.

Take a look around here using the search button, you may not have to change bikes afterall.

Good Luck,
Fryboy

  • qadsan

Posted May 10, 2003 - 10:49 AM

#3

Maybe an autoclutch like the z-Start might help you out for trail riding...
http://www.rekluse.c...tails.cfm?PID=4

The stock XR650R is a dog and finds it hard to get out of its own way. The bike is a completely different animal when uncorked, which is easy to do. It likes to go very fast and it still wins most of the Baja events, but it can also be ridden slow and it lugs very well in my opinion if properly setup.

I'm the guy who usually takes the little kids on their trail rides when we go camping/riding with a group, so I'm always in 1st gear most of the time on these trail rides and sometimes in 2nd if I get lucky when the kids really want to rip :) It's sometimes very slow going to where I have to get off my bike a half dozen times and leave it idling while I go help some kid pick up his bike and get him/her started again. It's fun, but I like the kids a little bit older to where I can ride mostly in 2nd & sometimes 3rd, but the bike does it all very nicely for me. It also does nicely in the desert with the big boys and has no trouble getting to 90+ MPH. It also makes a very nice dual sport bike from what I've heard if the majority of your riding purpose is to ride off road. It's a heavy bike and not something you'd want for MX type riding, but it hides its weight very well for most types of casual riding and certainly has the grunt and manners to be a fierce competitor in the desert.

  • Dezrider

Posted May 10, 2003 - 04:30 PM

#4

You shoulda bought an XR650RRRRRRRRR!
:)

  • smashinz2002

Posted May 11, 2003 - 06:57 PM

#5

With the XR650R properly uncorked, utilizing the entire kit as required (175 main, competition needle, 40mm intake boot, 40mm exhaust tip, baffles and plate removed from airbox), , you should expect performance as follows: Power output in the low rpms will be extreme, giving way to an even more brutal lower mid-range. Then fading off as upper mid-range is reached, and tapering to flatness in the upper revs. Honestly not as impressive as the extremely broad YZ426 powerband, however, more power is available on the low end and lower mid. There is no top end to speak of with the 650R, unless you consider the "dual sport mod". This mod consists of a 170 main, airbox snorkel and baffle plate removed, 40mm intake boot, and using a modified stock exhaust tip (drilling out the inner core to 34mm, repeat!, 34mm, no more! (removing the inner core along with the fiberglass wrapping). This exhaust mod is difficult, but worth it to make the bike more streetable and moderately quiet. Power output is as follows with this mod: Low end moderately strong allowing slow trails without the extra touchiness of the full power mod. Lower mid-range not impressive, but builds quickly to a very potent upper mid-range/top-end surge, which will require some attention.
The XR will never handle like the 426, but it will last longer and also you can make it street legal fairly easily. I had a '00 426 and loved the power, suspension, handling, but hated that I could'nt do much else with it, it proved to be a pretty sorry trail bike with the hard seat, rough ride and tiny gas tank. Also reliability was a major issue as to why I sold it, hearing horror stories of cracked hubs, broken valves, and other expensive annoyances such as the non O-ring chain, which stretched excessively, causing irritation. I want to ride not work on the thing all the time. The XR has a very good stock O-ring chain which won't stretch much at all after break-in, and after 5500 miles on mine, has only been adjusted twice. Pretty decent stuff. Also not a single thing has ever broken or failed. You will find the 650R to handle quite sluggish compared to the YZ though, but also quite well for such a large and heavy bike.
L.L.

  • Moredesert

Posted May 12, 2003 - 08:42 AM

#6

Bob, The difference is night and day. :)

  • sunnymex

Posted May 13, 2003 - 06:00 AM

#7

Bob,

You ask what kind of diference does it make. I will keep the answer short and simple. A LOT!!!!!!!

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  • Wilson-1

Posted May 14, 2003 - 07:54 PM

#8

The stock 650 is a little tame if you want to cut loose. After the proper modifications the bike will make ridiculous low-end torque and true open class power up to a strong usable upper mid range. In my opinion one the best open desert bikes ever made. Its weight will be a disadvantage in tight stuff, but the bike still moves well in the hands of an experienced rider. I've been blown away by the mighty 650's many times on open desert rides only to catch back up in the more technical areas that require alot of precise rail work in the corners. The 650 is very stable at speed, has a planted heavy front end that turns much better than the 600 ever did. It needs alot of attention to rear sag to turn properly. Great overall bike less the Jenny Craig issue.

  • JR650

Posted May 15, 2003 - 03:06 PM

#9

I rode my pig stock 4 about a day, it was a 400 with no top speed. then i uncorked it, scared the crap right out of me first time i dropped the clutch and almost went off the back. it went from being pretty docile when I nail it to struggling to hang on and hoping it doesnt go over. a header and cam is in the works, way too much power is damn near enough. Remember the golden rule of horsepower, "There is no replacement for displacement". One more thing I should mention, it still has good low speed manners but touchy throttle, amazing torque though, not at all stall prone. I havent found it to be a tank in the woods yet either, ya its heavy when you drop it but when you are on top, I love it. even in tight crap that my buddy has trouble riding his 250 in. you cant really go wrong with the 650 (assume uncorked) unless you cant pick it up. it is docile enough to putt around on but a real beast when you get on the gas. I have raced an '02 rm 250 on mine an it kicked the crap out of him till he ran out of gears, then it left him looking like he stalled :D. I have determined that the 650 started life as a beast and got detuned by the damn environmentalists. sorry for ranting, Yamaha sucks :).

  • wy4tt

Posted May 19, 2003 - 11:26 AM

#10

could you guys direct me to the best link describing the uncorking process? my buddy just got a new 650, and wants to let it breathe a little better. also, any breakin tips or inexpensive mods for a new '03 xr650 would be greatly appreciated too! thanks guys.

  • smashinz2002

Posted May 19, 2003 - 06:38 PM

#11

I could send you a link describing the uncorking process, but since there are some differences (such as using the stock needle, or the competition needle, and, using the 40mm exhaust tip or modifying the stock one to 34 or 36mm), I will instead just tell you how to do it for max power.
Buy the following, either as a kit from baja designs or some other company. Anyway, uncorking goes as follows:
1. 175 main jet (elevations below 1,000')
2. Competition jet needle set to 3rd clip position, OR,
Stock jet needle set to 4th position
3. 40mm intake boot (available from Honda shop)
4. 40mm exhaust tip (available from Honda shop)
5. Remove airbox rubber snorkel
6. Remove airbox baffle plate (flat plastic part on
upper back side of airbox)
7. ALL OF THESE MUST BE DONE TOGETHER AND CORRECTLY!
Skipping one or more of the instructions will not
give you the results you want. Changing the needle
clip is a hassle for beginners, so be careful but
be sure to do it!
8. Start bike and warm it up for about 2 minutes. (It will
now start a lot easier than when it was stock)
9. The tame bike has now become a brutal Beast! Enjoy!
10. Don't forget to hang on! It's very powerful and touchy
on the gas especially at low rpms. And when I say
touchy, I mean VERY VERY touchy! It WILL get out from
under you if you're not paying attention! Have fun!

  • qadsan

Posted May 19, 2003 - 08:00 PM

#12

could you guys direct me to the best link describing the uncorking process?



smashinz2002 already described it nicely, but here some more reading on this topic with pictures, etc.

Uncorking info...
http://www.xr650r.net/nonepa.html

Uncorking info...
http://www.qsl.net/n...ing the brp.htm

Here's a XR650R FAQ with some good info...
http://www.wtvl.net/n1rzc/xr650r_faq/

Some issues to be aware of...
http://www.wtvl.net/n1rzc/issues/

  • wy4tt

Posted May 30, 2003 - 04:27 PM

#13

wow. my thanks for all the info posted here. i'm sure my buddy will love the beast...when it's set free! thanks again.

  • Moredesert

Posted May 31, 2003 - 04:13 PM

#14

The stock 650 is a little tame if you want to cut loose. After the proper modifications the bike will make ridiculous low-end torque and true open class power up to a strong usable upper mid range. In my opinion one the best open desert bikes ever made. Its weight will be a disadvantage in tight stuff, but the bike still moves well in the hands of an experienced rider. I've been blown away by the mighty 650's many times on open desert rides only to catch back up in the more technical areas that require alot of precise rail work in the corners. The 650 is very stable at speed, has a planted heavy front end that turns much better than the 600 ever did. It needs alot of attention to rear sag to turn properly. Great overall bike less the Jenny Craig issue.


Ya, you hit it.





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