The XT600 Thread

Discussion in 'Thumpers' started by CR_TurboGuy, Jan 21, 2007.

  1. DutchyKevin

    DutchyKevin Adventurer

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    that sounds very unlikely?
    K&N filter makes for larger jets. Sporty exhaust makes for larger jets.
    Highcomp piston makes for higher temperatures (because of higher compression) so you need to add more fuel to cool the situation down a bit -> thus larger jets.

    So.. larger jets. Or am I wrong here?
  2. jjxlrider

    jjxlrider Part time adult

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    It should need a bit more fuel than stock with that setup. The hi-comp piston itself won't "need" much more than the stock piston, it's the intake and exhaust added flow characteristics that need more fuel added to the extra air running through the motor now.
  3. JensEskildsen

    JensEskildsen Long timer

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    Highcomp piston needs smaller jets, not larger. And the Xt comes with slightly too big mainjets stock.

    Getting the bike on a dyno, or installing a lambdaprobe in the header yourself is the only way to know for sure.
  4. LilYoda

    LilYoda Adventurer

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    Maybe you can make your own, if you can get the sizing of the metal plate, and buy the pegs on the item below

    http://www.ebay.com/itm/ANBAUSATZ-F...52018?pt=DE_Motorradteile&hash=item19e3f33fd2
  5. mopped phil

    mopped phil Adventurer

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    Depending on the current setup of your carb, there is no general answer possible. It depends on its usage, your average riding height and all the changes to the parts.
    You can either change the main jets to bigger size and try your topspeed, then lowering the mainjet seize... there are some generall instructions for it on the net.

    BUT: I have a XT from 1995, an open airbox, sports mainfold, LeoVince X3, camshaft stage 2, cylinderhead overhauled and a modified secondary carb(it opens more earlier). I tried to set it up with a bigger primary main jet and a binary lambda sensor. It was running way to rich.

    I got a broad-band lamba sensor now and with the stock main jets, it shows the engine runs rich. 0,76-0,78 Lambda (AFR 11.172-11,466) on full throttel. only before the secondary carb opens, it gets lean to 0,95 Lambda (AFR 13,965). I will have to change the positions of the jet nedels to correct that.

    So, to be safe, you really need to measure it. Either by lambda sensor or time taking on a track.
  6. DutchyKevin

    DutchyKevin Adventurer

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    Thanks. I was hoping there would be like a standard setting for this stuff. I'll take the bike to a local enduro specialist and have it tuned on the dyno for optimal result:D
  7. mopped phil

    mopped phil Adventurer

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    If he isnt screwing it up, its really worth it. The stock XT is running very rich.
  8. A-Wind

    A-Wind Andreas RD07a

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    Some of these engines are set that way from the factory for better internal cooling. So I would keep fuel-to-air close to stock to be on the safe side.
  9. DutchyKevin

    DutchyKevin Adventurer

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    The guy I'm taking the XT to has over 40 years of experience with thumpers, especially the Yammi's. I trust his judgement haha ;)

    Verstuurd vanaf mijn Nexus 7 met Tapatalk 4
  10. Proveick

    Proveick Long timer

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    Anyone found a tank bag that fits the tall skinny tank? Old one will not work.
    Thanks
  11. Trigxrr

    Trigxrr Adventurer

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    I have an 86 , I have wondered if anyone has made a single carburetor manifold into the dual port head or could you block off one port and run a single carb ?? WHY .. these carburetors are very hard to find here and the set I have have been damaged and I had to JB weld one of the arm holding the float pin and dont trust it .
  12. manco

    manco ****** & Deleted

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    I am all in for an XT meetup or maybe even XT/TT meetup here in the states. My vote is to have it in Colorado. Colorado is centrally located, has 1000's of miles of mountainous terrain to rip around on & cause Colorado kicks arse in general cause its my home state at the moment. :rofl I live in Denver so I can offer my backyard for all the dirt bag bikers that can't afford a hotel room too. :freaky I am sure my neighbors would love it. Nothing like the sound of 100's of thumpers roaring to life in the morning to put the twinkle in the eye of your neighbors I hear. :lol3 After everybody arrives & we terrorize Denver for a day. Then we can get lost in the mountains for a few days & enjoy some real down to earth "Rocky Mountain High." :ricky http://www.youtube.com/watch?v=wP7Chi9MPSg
  13. manco

    manco ****** & Deleted

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    The carbs come up on ebay from time to time.

    Single carb manifolds haven't been known to work as there is not enough room.

    I am sorry to say but blocking off one port & running one carb is a horrible idea. Its one of those, "If you have to ask then you probably wouldn't understand." kind of things. Just don't do it.

    Either find carb parts to repair your carbs or swap the old carbs for a different set of carbs. Some company makes an overpriced set of aftermarket carbs for the XTs. If you dig through this thread you will find info on them. I believe they are made by Keihin. You can also swap the carbs for a set of carbs off of a Raptor 660 four wheeler.

    Another would be to take the carb body to a professional welder. It should be possible to have the broken arm repaired proper by brazing.

    Here is a nice set of rebuilt XT600 carbs on ebay right now for $250 http://www.ebay.com/itm/PROFESSIONA...Parts_Accessories&hash=item2331e1e113&vxp=mtr

    Here are the Raptor carbs that will work on ebay. Scroll down to see more affordable options. If you are patient you can get a set of Raptor carbs for around $150 http://www.ebay.com/sch/i.html?_odk...retor+660&_nkw=raptor+660+carburetor&_sacat=0
  14. joefj1200

    joefj1200 Adventurer

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    I probably have a spare set of stock XT600 carbs out in the garage. PM me and I'll take a look.
  15. jjxlrider

    jjxlrider Part time adult

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    I have 4 sets of them also,if Joefj1200 doesn't hook you up I can.
    The Raptor carbs work good also, it does require the intake boots to be opened up for the bigger carb snouts.The airbox boots also don't fit and you need to make up a whole new filter/boot setup. Kind of a PITA. The Keihins are $450 ish and end up with no airbox also.

    I'd be in for an XT ride, don't know if I could make it to Colorado,but do agrre it would be a great place along with Utah or Arizona. Neither a better option for me unfortunately.
  16. RLK

    RLK 4,949

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    I see a bunch of people who live at or below sea level talking about their bikes running rich and I see an invitation for everyone to come to Colorado where the fun starts at 6500 feet above sea level.

    I want my bike to be a little lean at 5000 feet so it will be just a little rich at 14000, the way the stock jetting is rich at sea level. Around here you can start the day at 6000 and be at 14000 feet in 20 miles. Any ideas?
  17. manco

    manco ****** & Deleted

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    Thanks for filling in the details on the carb swaps. I was wondering if the Raptor carbs would need some horsing with to install. At least the airbox will still work. That is a plus.

    Utah would be sweet for a meetup. Especially if it was some place near Moab. That part of the world is beautiful.
  18. manco

    manco ****** & Deleted

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    I can give a little input on this. I live at 5000 feet in Denver. Like you I can ride up to 14,000 in a couple hours. Most of my rides will start around 5000 & get up to 8000-10,000 feet on average. When it comes to finding a tune that will work in such an elevation range there is a few things that you can do. Bear in mind unless the bike has fuel injection with oxygen / altitude compensation there really is no perfect solution. You can either run the bike too rich or too lean for certain areas of elevation & that is about it.

    Here are a few things & methods to consider:

    1. Don't just imagine you & your bike eternally existing on some epic 14000 foot precipice. Get real about your average riding elevation. If 80% of your riding is between say 5000-8000 feet & sometimes you get higher then that then tune your bike for 5000-8000 feet & leave it be. If you plan on doing some rides in higher elevations sometimes then either let it run rich & hope for the best or take a jet kit & go camp out for a few days at say 10,000 feet. Completely retune the carbs to run proper at the high elevation. Take notes on what jets, needle & carb settings were best for the lower elevations before retuning for the higher elevations. Then when the bike is tuned proper for higher elevations take notes on what jets, needle & carb settings were best for the higher elevations. When it comes time to return from the tuning camp out return the carbs back to the tune for the lower elevations & head home. This way you have two setups. One for high elevations & one for lower elevations.

    2. If you are always riding 8000 feet of elevation change & you want to try to get a tune that will work in all the elevation range you are gonna need to make some sacrifices. You will need to tune for the middle of the elevation range. Bear in mind that if you do this then you will be running too lean in lower elevations & too rich in upper elevations. While its probably fine to run too rich, running too lean can cause premature engine wear or damage as too lean cause overheating, burned pistons, valves ect. This is why up above I mentioned you need to get real about your average riding. If you ride 10,000 miles a year around 5000 feet & only a few hundred over 10,000 then obviously your bike needs to be tuned for 5000 feet not 10,000 as if it was tuned for 10,000 feet then 90% of the year it will be running too lean in this scenario.

    3. Something I have noticed about dramatic elevation change with bikes is that the lower rpm/throttle range is what is effected the most. So the most important jets to worry about is gonna be the idle/pilot jets. The main jet can be rich in upper elevations as it mostly kicks in at high rpms. At these high rpms the motor can more easily handle being too rich as by the time the main jet kicks in the motor is really screaming & will just deal with the extra gas by belching it out. What the motor can't deal with at higher elevations is building rpms from an idle or even idle for that matter if the idle/pilot jet are too rich. On several bikes & rides I have been in situations where the bike is just ripping along fine tearing up the side of a mountain. It will be running great that is until I pull over & stop for a picture. Then when the bike drops its rpms down to an idle... blaaaaaa the bike barely runs & refuses to build rpms. At this point what is happening is the idle/pilot jet is way too rich & at lower rpms the motor can't do anything but flood with. I have found two on trail solutions for this: 1 pull the spare leaner idle/pilot jet out of the tool kit, swap it in & keep ripping OR 2 if no leaner jets are in the tool kit just point the bike downhill & take off letting the elevation assist the bike in building rpms until the rpms are high enough to get the extra fuel to just blow through. Note if option 2 is chosen as a solution do yourself a favor & just head back down the mountain.

    4. So overall a good compromise I have found is a combination of all the above. First of all I just get real & face the fact that 80% of the time I ride between 5000-8000 feet. I keep my bike tuned for this range of elevation. If I am gonna get higher usually I am probably gonna hit as much as 10,000 feet, I am not gonna be there very long cause its a mountain pass not a plateau usually & I just let the bike run rich & its fine. If I know I am going up into higher elevations over 10,000 feet & staying up there for extended periods of time/miles then I either retune at home & then take off too lean or I just swap the jets on the trail.

    5. Overall if at possible I try to keep the bike tuned for optimum performance for the chosen riding of the moment even if it means some carb fiddling on the trail. That way I know the bike is performing at its best. If your riding all day or for a couple of days 5-10 minutes of carb fiddling every now & then is no big deal when you think about it.

    6. If you have to pick a sloppy tune to be able to clear a huge range of elevation just run rich, keep the throttle pinned, & don't stop at high elevations is a good bet as the highest points of a ride are usually brief moments on mountain passes that climb to an apex & then immediately descend.

    7. Another tip I should mention that really makes elevation change easier to tune for is KEEP THE OEM AIR BOX & DO NOT DRILL SO MUCH AS A PIN HOLE IN IT. Air boxes help create a stable & constant inlet pressure. Taking them off is for close to sea level folks surrounded by dense air, racers that need bleeding edge performance & are willing to tune the carb every 20 miles to get it & wankers that like to install & brag about shiny new parts more then they ride. Whether the bike is a 2T or a 4T air boxes are crucial to having a consistent tune. The higher the elevation the lower the air density. The lower the air density the more air that needs to move over a jet to suck gas up. Keeping the air box on will help create a situation that the suction force on the jet stays consistent as the motor is always working at pulling air through the box. Pulling an air box off & running can filters will cause a bike to perform like crap as soon as the bike moves out of the elevation that it is tuned for because with can filters nothing holds the atmospheric pressure inside the throttle body in check, ie the atmospheric pressure in the throttle body becomes more susceptible to changes in the environments atmospheric air pressure. I am not going to go into the science of this scenario as it is beyond the scope of this post & no doubt wankers will cry foul no matter what anyway. Suffice to say if you do the research & some testing at high elevation you will find I am correct in this matter.

    8. Similar concepts from tip #7 relating to carbs also apply to mufflers as well. A stock muffler will generally allow a more consistent tune then a derestricted exhaust because the extra back pressure of a stock exhaust will hold the tune in check.

    9. As a matter of fact in general the less modified a bike is the larger range of elevation it will cover without going out of tune. Remember bikes when they come from the factory are designed to be sold all over the world so they are designed for consistency rather then performance. This consistency is what is needed to handle changing elevations. Tuning for 1000s feet of elevation change is completely different then tuning for maximum performance. When it comes to elevation even if it means a loss of a few HP consistency is what needs to be sought after. Concepts like this are why a bike like a stock Honda Trail 90 will run fine from the ocean to the top of a 10,000' mountain & back without any tuning what so ever while a modified motocross bike would need several jet changes along the way to do the same ride.

    10. As far as what is the best tune setup for a wide range of elevation what I have found to work & be safe for the motor is this: Tune the lower end of the throttle spectrum to the upper elevations & the upper end of the throttle spectrum to the lower elevations. This will create a carb tune that will be running lean at lower elevations & proper at upper elevations during idle & the initial twist of the throttle while running proper at lower elevations & rich in the upper elevations during the mid to upper spectrum of the throttle. So how such a carb tune works for example between 5000' & 10,000' feet is that the bike will be lean during idle & the initial twist of the throttle & proper in the mid to upper spectrum of the throttle when the bike is at 5000' feet. Then when the bike is at 10,000' feet the carb tune will be proper during idle & the intial twist of the throttle & too rich in the mid to upper spectrum of the throttle. This setup will avoid the bike dying out at low rpms at high elevations & compartmentalize the effect of being too lean to only during idle & the initial twist of the throttle at lower elevations. The gist of such a tune is this; use idle/pilot jets that are tuned for say 10,000' feet and a main jet tuned for 5000' feet. So if you are considering a tune for say between 5000 & 14,000 feet I would suggest tuning the low end of the carb to 12,000' the high end of the carb to 7000' and hope for the best when you are at 5000' or 14,000' feet. If you live at 5000' & really want to be able to hit 14,000' a smoother setup may be tuning the low end of the carb to 10,000' & the high end of the carb to 6000'. Then while the bike may be a little lean at low rpms & idle rough at 5000' it will be fine because as soon as the throttle is opened the carb will get a proper fuel mixture. Then when you are over 10,000' as you head up to 14,000 feet the bike will idle & take off fine & just run rich when the rpms are high & the motor can handle it. Then at high elevations all you will need to do is keep the throttle wide & the rpms high as you rip up the side of the mountain to your favorite 14,000 precipice.
  19. jjxlrider

    jjxlrider Part time adult

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    How about starting out lean, but using partial choke, then reducing choke(handlebar mount is the only one this controllable) as you go up. I kind of use this method for early morning on the way to work when it's 15F and going home it's 40-45F. Obviously not the "best way" but may work for short times when starting out and then going up. I'm rather leary of messing with the carbs when it's 20-50 miles from civilization unless absolutely necessary. Which part will fall and get lost?
  20. manco

    manco ****** & Deleted

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    <rant>After reading the posts that responded to this post... -->

    <-- ...I wrote several scathing rants & ended up deleting them as I didn't want to stir up too much muck. However I would like to at very least point out that with the exception of the following two posts -->

    <-- pretty much all of the rest of the posts giving advice are either inexperienced myopically focused posts relating specifically to other bikes, builds, elevations, environments, ect OR WORSE ARE COMPLETE RUBBISH!

    Seriously some of you need to spend some more time studying books & manuals and then do some tuning on a good many more bikes before you dispense advice on forums. Just because you bought a bike & read some other wanker's incorrect posts on a forum somewhere else doesn't qualify you as a tuner capable of dispensing knowledge. For crying out loud people the original poster's bike is getting an overhaul because some wanker was too dingbat nutty to properly up jet the carb after the bike was modified! OF COURSE THE CARB NEEDS TO BE UP JETTED ---> THE AIR FLOW THROUGH THE MOTOR HAS BEEN INCREASED & AS SUCH THE FUEL FLOW MUST BE INCREASED ALSO TO MAINTAIN PROPER AIR TO FUEL RATIO!!! Had the original poster followed the advice in some of the other posts the bike would have ended up right back in the shop with blown motor all over again.

    </rant>
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